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AS/NZS 2885.2:2016

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AS/NZS 2885.2:2016

Australian/New Zealand Standard™

Pipelines—Gas and liquid petroleum

Part 2: Welding

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AS/NZS 2885.2:2016 This Joint Australian/New Zealand Standard was prepared by Joint Technical Committee ME-038, Petroleum Pipelines. It was approved on behalf of the Council of Standards Australia on 12 May 2016 and by the New Zealand Standards Approval Board on 20 April 2016. This Standard was published on 31 May 2016.

The following are represented on Committee ME-038: APGA Research and Standards Committee Australasian Corrosion Association Australian Industry Group Australian Institute of Petroleum Australian Petroleum Production and Exploration Association Australian Pipeline and Gas Association Department of Industry, Skills and Regional Development, NSW Department of Mines and Energy, NT Department of Mines and Petroleum, WA Department of Natural Resources and Mines, Qld Department of State Development, SA Energy Networks Association Energy Safe Victoria Gas Association of New Zealand New Zealand Institute of Gas Engineers Welding Technology Institute of Australia Worksafe New Zealand

Keeping Standards up-to-date Standards are living documents which reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments which may have been published since the Standard was purchased. Detailed information about joint Australian/New Zealand Standards can be found by visiting the Standards Web Shop at www.saiglobal.com or Standards New Zealand web site at www.standards.govt.nz and looking up the relevant Standard in the online catalogue. For more frequent listings or notification of revisions, amendments and withdrawals, Standards Australia and Standards New Zealand offer a number of update options. For information about these services, users should contact their respective national Standards organization. We also welcome suggestions for improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Please address your comments to the Chief Executive of Standards Australia or the New Zealand Standards Executive at the address shown on the back cover.

This Standard was issued in draft form for comment as DR AS/NZS 2885.2:2015.

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AS/NZS 2885.2:2016

Australian/New Zealand Standard™ Pipelines—Gas and liquid petroleum Part 2: Welding

Originated as AS CB28—1992. Previous edition AS 2885.2—2007. Fourth edition revised and redesignated as AS/NZS 2885.2:2016.

COPYRIGHT © Standards Australia Limited/Standards New Zealand All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher, unless otherwise permitted under the Copyright Act 1968 (Australia) or the Copyright Act 1994 (New Zealand). Jointly published by SAI Global Limited under licence from Standards Australia Limited, GPO Box 476, Sydney, NSW 2001 and by Standards New Zealand, PO Box 10729, Wellington 6011.

ISBN 978 1 76035 501 2

AS/NZS 2885.2:2016

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PREFACE

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This Standard was prepared by the Joint Standards Australia/Standards New Zealand Committee ME-038, Petroleum Pipelines, to supersede AS 2885.2—2007. The inclusion of roles and responsibilities in AS/NZS 2885.2:2016, was approved by the Standards Development Committee on 1 May 2015, as a one-off exemption to the directives of Standardisation Guide 009: Preparation of Standards for Legislative Adoption. The objective of this Standard is to provide requirements for the welding of pipelines designed and constructed in accordance with AS 2885.1. The objective of this revision is to include technical changes which became necessary as a result of experience in the use of the Standard in the intervening years since the previous edition, in particular in relation to the construction of large diameter pipelines in recent years: (a)

Definitions have been updated to match AS 2885 definitions, where applicable.

(b)

The sections in the document have been re-arranged to match the sequence of steps in qualifying a welding procedure and the subsequent welding and testing.

(c)

The qualifications for welding engineers, welding supervisors, welding inspectors, welders and welder operators have been defined and put in a new Section 3, Qualifications.

(d)

The materials section has been updated to put limits on boron in welding consumables; and the welding consumable table has been modified to reflect currently available consumables.

(e)

The welding design requirements have been updated and added to Section 5 (Design of a welded joint).

(f)

Section 6 (Qualification of a welding procedure specification) has been updated to include other welding processes and their specific requirements.

(g)

Requirements for qualifying aluminothermic and pin brazing welding have been added to Section 6.

(h)

Section 7 (Assessment of the test weld to qualify a welding procedure) has been updated to include requirements for sub-size Charpy tests and additional mechanical testing for some types of procedure qualification including repairs.

(i)

Section 13 (Post-weld heat treatment and post-weld cooling) has been updated to make it a requirement for weld procedure qualification requirements (WPS) to test the weld and base metal in the heat treated condition.

(j)

The items to consider prior to in-service welding has been added to Section 16 (Welding onto an in-service pipeline).

(k)

Section 17 (Criteria of acceptance for girth weld discontinuities) has been updated to include more comprehensive requirements for using Tier 3; and in addition, the Tier 1 acceptance criterion for ultrasonic testing has been added. The use of Tier 2 has been extended to include material grade with yield strength 485 MPa subject to undertaking all-weld metal tensile tests.

(l)

Figure 18.1 (Maximum height of external weld reinforcement in butt welds that are to be radiographed in order to achieve effective radiography) has been updated to relax the maximum height of external reinforcement in butt welds for radiographic testing (RT).

(m)

Section 19 (Non-destructive testing) has been modified to require 100% NDT.

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AS/NZS 2885.2:2016

(n)

Section 22 (Ultrasonic testing) has been updated to refer to a new Appendix H on the requirements for qualifying and using AUT on pipelines.

(o)

The Appendices have been re-arranged and include three new Appendices that provide additional requirements and supporting information on weld procedure requirements associated with changes to the consumable classification system, additional requirements for automated/mechanized welding and AUT system requirements.

The above list of changes is not intended to be complete. Users of this Standard should not rely upon the list in order to ascertain whether there have been changes made to the previous version of the Standard. Statements expressed in mandatory terms in notes to tables and figures are deemed to be requirements of this Standard. The terms ‘normative’ and ‘informative’ have been used in this Standard to define the application of the appendices to which they apply. A ‘normative’ appendix is an integral part of a Standard, whereas an ‘informative’ appendix is only for information and guidance.

AS/NZS 2885.2:2016

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CONTENTS

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Page SECTION 1 SCOPE AND GENERAL 1.1 SCOPE .................................................................................................................... ... 10 1.2 APPROVAL .............................................................................................................. 11 1.3 QUALIFICATION..................................................................................................... 12 1.4 RETROSPECTIVITY ................................................................................................ 12 1.5 REFERENCED DOCUMENTS ................................................................................. 12 1.6 DEFINITIONS........................................................................................................... 12 1.7 ROUNDING OF NUMBERS .................................................................................... 20 1.8 PIPELINE ASSEMBLIES ......................................................................................... 20 SECTION 2 SAFETY 2.1 PRODUCTION WELDING ....................................................................................... 21 2.2 WELDING OR CUTTING ON A PIPELINE AFTER COMMISSIONING .............. 21 2.3 SAFETY AND PROTECTION FROM IONIZING RADIATION ............................. 22 SECTION 3 QUALIFICATIONS 3.1 GENERAL ................................................................................................................. 23 3.2 WELDING ENGINEERING ..................................................................................... 23 3.3 WELDING SUPERVISION ...................................................................................... 24 3.4 WELDING INSPECTION ......................................................................................... 25 3.5 WELDERS AND WELDING OPERATORS ............................................................ 25 SECTION 4 MATERIALS 4.1 GENERAL ................................................................................................................. 26 4.2 CONSUMABLES ...................................................................................................... 26 SECTION 5 DESIGN OF A WELDED JOINT 5.1 GENERAL ................................................................................................................. 28 5.2 BUTT WELDS BETWEEN COMPONENTS OF EQUAL NOMINAL THICKNESS ............................................................................................................. 28 5.3 BUTT WELDS BETWEEN COMPONENTS OF UNEQUAL NOMINAL THICKNESS ............................................................................................................. 28 5.4 REINFORCEMENT OF A BUTT WELD ................................................................. 28 5.5 LONGITUDINAL BUTT WELDS ............................................................................ 28 5.6 FILLET WELD.......................................................................................................... 29 5.7 WELDING OF THREADED JOINTS ....................................................................... 30 5.8 REINFORCEMENT OF A WELDED BRANCH CONNECTION ............................ 30 5.9 REINFORCEMENT OF MULTIPLE OPENINGS .................................................... 30 5.10 FORGED BRANCH FITTING .................................................................................. 30 5.11 EFFECT OF COMPONENTS UPON PIG PASSAGE............................................... 31 5.12 OFFSET OF LONGITUDINAL WELDS .................................................................. 31 5.13 DISTANCE BETWEEN WELDS .............................................................................. 31 5.14 LOCATION OF ALUMINOTHERMIC WELDS AND PIN BRAZING CONNECTIONS ....................................................................................................... 31 5.15 ATTACHMENT OF ELECTRICAL CONDUCTORS .............................................. 31 5.16 GOLDEN WELDS .................................................................................................... 31

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AS/NZS 2885.2:2016

SECTION 6 QUALIFICATION OF A WELDING PROCEDURE SPECIFICATION 6.1 WELDING PROCEDURE SPECIFICATION (WPS) ............................................... 35 6.2 PURPOSE OF QUALIFYING A WELDING PROCEDURE .................................... 35 6.3 TYPES OF WELDS REQUIRING QUALIFICATION ............................................. 35 6.4 METHODS OF QUALIFICATION ........................................................................... 35 6.5 CHANGES IN A WELDING PROCEDURE ............................................................ 38 6.6 CONDUCT OF THE QUALIFICATION WELDS .................................................... 38 6.7 PROVISONS FOR SPECIFIC WELDING METHODS ............................................ 40 SECTION 7 ASSESSMENT OF THE TEST WELD TO QUALIFY A WELDING PROCEDURE 7.1 METHOD OF ASSESSMENT .................................................................................. 49 7.2 VISUAL EXAMINATION ........................................................................................ 49 7.3 NON-DESTRUCTIVE TESTING ............................................................................. 49 7.4 DESTRUCTIVE TESTS ............................................................................................ 49 7.5 RE-TESTS AND FURTHER TESTING .................................................................... 53 7.6 RECORD OF RESULTS ........................................................................................... 53 7.7 PERIOD OF VALIDITY ........................................................................................... 54 7.8 DISQUALIFICATION OF A QUALIFIED WELDING PROCEDURE .................... 54 7.9 ALUMINOTHERMIC WELDS AND PIN BRAZING CONNECTIONS.................. 54 SECTION 8 WELDING POSITIONS 8.1 DESIGNATION ........................................................................................................ 56 8.2 LIMITS OF QUALIFIED POSITIONS ..................................................................... 56 SECTION 9 QUALIFICATION OF A WELDER OR WELDING OPERATOR 9.1 PURPOSE OF QUALIFYING A WELDER OR WELDING OPERATOR ............... 62 9.2 SCOPE OF WELDER OR WELDING OPERATOR QUALIFICATION.................. 62 9.3 METHODS OF QUALIFICATION ........................................................................... 62 9.4 QUALIFICATION BY TESTING ............................................................................. 62 9.5 ESSENTIAL VARIABLES FOR WELDERS AND WELDING OPERATORS ....... 62 9.6 TEST PIECE .............................................................................................................. 63 9.7 ASSEMBLY OF TEST PIECES ................................................................................ 63 9.8 AUTOMATIC WELDING EQUIPMENT ................................................................. 64 9.9 MAKING A TEST WELD......................................................................................... 64 9.10 SUPERVISION OF A TEST WELD ......................................................................... 64 9.11 IDENTIFICATION OF A TEST WELD.................................................................... 64 9.12 QUALIFICATION OF ALUMINOTHERMIC WELDING AND PIN BRAZING OPERATORS ............................................................................................................ 64 SECTION 10 ASSESSMENT OF TEST WELDS FOR WELDER OR WELDING OPERATOR QUALIFICATION 10.1 METHOD OF ASSESSMENT .................................................................................. 65 10.2 VISUAL EXAMINATION ........................................................................................ 65 10.3 NON-DESTRUCTIVE TESTING ............................................................................. 65 10.4 REPEATED TEST ..................................................................................................... 65 10.5 RECORD OF RESULTS ........................................................................................... 66 10.6 PORTABILITY OF A WELDER’S OR WELDING OPERATOR’S QUALIFICATION..................................................................................................... 66

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SECTION 11 WELDER OR WELDING OPERATOR QUALIFICATION AND DISQUALIFICATION 11.1 RECIPROCITY OF A WELDER’S OR WELDING OPERATOR’S QUALIFICATION..................................................................................................... 67 11.2 PERIOD OF VALIDITY ........................................................................................... 67 11.3 QUALIFICATION RECORD .................................................................................... 67 11.4 DISQUALIFICATION OF A WELDER’S OR WELDING OPERATOR’S QUALIFICATION..................................................................................................... 67 SECTION 12 PRODUCTION WELDS 12.1 WELDING PROCESS ............................................................................................... 68 12.2 WELDING EQUIPMENT ......................................................................................... 68 12.3 WELDER AND WELDING PROCEDURE .............................................................. 68 12.4 SUPERVISION OF WELDING ................................................................................ 68 12.5 SAFETY IN WELDING ............................................................................................ 68 12.6 STORAGE AND HANDLING OF ELECTRODES, FILLER RODS AND FLUXES ........................................................................................................... 68 12.7 WELDING IN ADVERSE CLIMATIC CONDITIONS ............................................ 68 12.8 PREPARATION FOR WELDING ............................................................................ 68 12.9 METHOD OF MAKING THE WELD PREPARATION ........................................... 69 12.10 ACCURACY OF ALIGNMENT ............................................................................... 69 12.11 LINE-UP CLAMP ..................................................................................................... 69 12.12 TACK WELDS .......................................................................................................... 69 12.13 WORKING CLEARANCE ........................................................................................ 69 12.14 PLACEMENT OF WELD PASSES........................................................................... 69 12.15 ARC STRIKE AND ARC BURN .............................................................................. 70 12.16 CLEANING ............................................................................................................... 70 12.17 PEENING ................................................................................................................ .. 70 12.18 INSERT PATCHING................................................................................................. 70 12.19 PREHEAT AND INTERPASS TEMPERATURE ..................................................... 70 12.20 POST-WELD HEAT TREATMENT (PWHT) .......................................................... 70 12.21 IDENTIFICATION OF A PRODUCTION WELD .................................................... 71 SECTION 13 POST-WELD HEAT TREATMENT (PWHT) AND POST-WELD COOLING 13.1 POST-WELD HEAT TREATMENT ......................................................................... 72 13.2 POST-WELD COOLING .......................................................................................... 72 SECTION 14 ASSESSMENT OF PRODUCTION WELDS AND REPAIR WELDS 14.1 GENERAL ................................................................................................................. 73 14.2 METHODS OF EXAMINATION.............................................................................. 73 14.3 PRODUCTION CUT-OUT WELDS ......................................................................... 73 SECTION 15 WELDING AND CUTTING ON A PIPELINE AFTER COMMISSIONING OR AFTER HYDROSTATIC TESTING 15.1 GENERAL ................................................................................................................. 74 15.2 SAFETY .................................................................................................................. .. 74 15.3 HOT REPAIR OF LEAKING GAS-FILLED PIPELINES ........................................ 74 15.4 WHERE GAS IS NOT ESCAPING ........................................................................... 74 15.5 PIPELINES CONTAINING PETROLEUM FLUIDS OTHER THAN LEAN NATURAL GAS ....................................................................................................... 75 15.6 QUALIFICATION OF WELDER(S) ......................................................................... 75 15.7 QUALIFICATION OF WELDING SUPERVISORS AND WELDING INSPECTORS ........................................................................................ 75 15.8 FIT-UP BEFORE WELDING AND CUTTING ........................................................ 75 15.9 EXAMINATION AND TESTING ............................................................................. 75

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15.10 CRITERIA OF ACCEPTANCE ................................................................................ 75 SECTION 16 WELDING ONTO AN IN-SERVICE PIPELINE 16.1 PIPELINE CONTAINING FLAMMABLE OR PRESSURIZED FLUID .................. 76 16.2 PRECAUTIONS TO BE UNDERTAKEN BEFORE IN-SERVICE WELDING ....... 76 16.3 LINING .................................................................................................................. ... 77 16.4 SAFETY .................................................................................................................. .. 77 16.5 INSPECTION BEFORE WELDING ......................................................................... 77 16.6 ULTRASONIC TESTING BEFORE WELDING ...................................................... 77 16.7 WELDING CONSUMABLES ................................................................................... 77 16.8 PREHEAT ................................................................................................................. 78 16.9 QUALIFICATION OF WELDING PROCEDURES ................................................. 78 16.10 WELDING SEQUENCE ........................................................................................... 78 16.11 QUALIFICATION OF WELDER(S) ......................................................................... 81 16.12 QUALIFICATION OF WELDING SUPERVISORS AND WELDING INSPECTORS ........................................................................................ 81 16.13 FIT-UP BEFORE WELDING .................................................................................... 81 16.14 EXAMINATION OF TESTING ................................................................................ 81 16.15 CRITERIA OF ACCEPTANCE ................................................................................ 81 16.16 WELDING OF TEST ASSEMBLY ........................................................................... 81 SECTION 17 CRITERIA OF ACCEPTANCE FOR GIRTH WELD DISCONTINUITIES 17.1 GENERAL ................................................................................................................. 82 17.2 TIER 1 CRITERIA—WORKMANSHIP STANDARD (RT)..................................... 84 17.3 ULTRASONIC TESTING ACCEPTANCE CRITERIA (AUT, MUT, PAUT AND TOFD WHERE APPLICABLE) ....................................................................... 90 17.4 TIER 2 ACCEPTANCE CRITERIA—GENERALIZED FITNESS FOR PURPOSE STANDARD ............................................................................................ 95 17.5 TIER 3 CRITERIA—ENGINEERING CRITICAL ASSESSMENT ....................... 100 SECTION 18 VISUAL EXAMINATION 18.1 PURPOSE ................................................................................................................ 102 18.2 METHOD OF EXAMINATION .............................................................................. 102 18.3 EXTENT OF VISUAL EXAMINATION ................................................................ 102 18.4 CRITERIA OF ACCEPTANCE .............................................................................. 102 18.5 UNDERCUT DEPTH MEASUREMENT ................................................................ 102 SECTION 19 NON-DESTRUCTIVE TESTING 19.1 GENERAL ............................................................................................................... 1 04 19.2 ORGANIZATIONS UNDERTAKING NON-DESTRUCTIVE TESTING.............. 104 19.3 QUALIFICATIONS OF PERSONNEL ................................................................... 104 19.4 METHODS .............................................................................................................. 10 4 19.5 AMOUNT OF NON-DESTRUCTIVE TESTING ................................................... 104 19.6 NON-DESTRUCTIVE TESTING OF GOLDEN WELDS ...................................... 104 19.7 EXEMPTION FROM RADIOGRAPHIC OR ULTRASONIC TESTING ............... 104 19.8 TIMING OF NON-DESTRUCTIVE TESTING ...................................................... 105 SECTION 20 QUALIFYING A RADIOGRAPHIC PROCEDURE 20.1 RADIOGRAPHIC PROCEDURE ........................................................................... 106 20.2 METHOD OF QUALIFYING THE RADIOGRAPHIC PROCEDURE................... 107 20.3 TEST CONDITIONS ............................................................................................... 107 20.4 RADIOGRAPHIC PROCEDURE SPECIFICATION DOCUMENTATION ........... 107 20.5 PERIOD OF VALIDITY ......................................................................................... 107

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SECTION 21 RADIOGRAPHIC TESTING 21.1 GENERAL ............................................................................................................... 1 08 21.2 SAFETY AND PROTECTION FROM IONIZING RADIATION ........................... 108 21.3 DENSITY ................................................................................................................ 108 21.4 IMAGE QUALITY .................................................................................................. 108 21.5 UNDERCUT DEPTH MEASUREMENT ................................................................ 109 21.6 GAS PORE DEPTH MEASUREMENT .................................................................. 110 21.7 INTEPRETATION AND ASSESSMENT OF RADIOGRAPHS ............................. 111 21.8 CRITERIA OF ACCEPTANCE .............................................................................. 111 21.9 REPORT OF RADIOGRAPHIC TESTING ............................................................ 112 21.10 RETENTION OF RADIOGRAPHS ........................................................................ 112 SECTION 22 ULTRASONIC TESTING 22.1 ULTRASONIC TESTING ....................................................................................... 113 22.2 AUTOMATED ULTRASONIC TESTING (AUT) .................................................. 114 SECTION 23 MAGNETIC PARTICLE TESTING 23.1 PURPOSE ................................................................................................................ 115 23.2 METHOD ................................................................................................................ 1 15 23.3 QUALIFICATION OF PERSONNEL ..................................................................... 115 23.4 CRITERIA OF ACCEPTANCE .............................................................................. 115 SECTION 24 DYE-PENETRANT TESTING 24.1 PURPOSE ................................................................................................................ 116 24.2 METHOD ................................................................................................................ 1 16 24.3 QUALIFICATION OF PERSONNEL ..................................................................... 116 24.4 CRITERIA OF ACCEPTANCE .............................................................................. 116 SECTION 25 REPAIR OF AN UNACCEPTABLE WELD 25.1 GENERAL ............................................................................................................... 1 17 25.2 REPAIR METHODS ............................................................................................... 117 25.3 QUALIFICATION OF REPAIRS USING A DIFFERENT WELD PROCEDURE THAN THE ORIGINAL WELD...................................................... 117 25.4 QUALIFICATION OF THE REPAIR WELDING PROCEDURE .......................... 117 25.5 INSPECTION .......................................................................................................... 117 25.6 CRITERIA OF ACCEPTANCE .............................................................................. 117 SECTION 26 REMOVAL OF AN ARC BURN 26.1 GENERAL ............................................................................................................... 1 18 26.2 REPAIR BY GRINDING ........................................................................................ 118 26.3 METHOD OF INSPECTION................................................................................... 118 26.4 CRITERIA OF ACCEPTANCE .............................................................................. 118 26.5 CLEANING AFTER TESTING .............................................................................. 118 SECTION 27 CUTTING OUT AN UNACCEPTABLE WELD OR AN ARC BURN ........... 119 SECTION 28 RECORDS ....................................................................................................... 120 APPENDICES A B C D

ITEMS REQUIRING APPROVAL ......................................................................... 121 LIST OF REFERENCED DOCUMENTS................................................................ 123 AVOIDANCE OF HYDROGEN ASSISTED COLD CRACKING (HACC) ........... 127 SELECTION AND SPECIFICATION OF CELLULOSIC WELDING ELECTRODES ..................................................................................... 131

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E F G

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H

AS/NZS 2885.2:2016

WELD PROCEDURES ASSOCIATED WITH CHANGES TO THE WELDING CONSUMABLE CLASSIFICATION SYSTEM ..................................................... 135 ADDITIONAL RECOMMENDATIONS FOR AUTOMATIC/MECHANIZED WELDING OF PIPELINE GIRTH WELDS ............................................................ 139 GUIDANCE ON ‘GMAW’ WELDING CONSUMABLES FOR MECHANIZED AND AUTOMATIC PIPELINE WELDING PROCESSES ..................................... 142 AUTOMATED ULTRASONIC TESTING (AUT) SYSTEM AND OPERATOR REQUIREMENTS ................................................................................................... 143

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STANDARDS AUSTRALIA/STANDARDS NEW ZEALAND Australian/New Zealand Standard

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Pipelines—Gas and liquid petroleum Part 2: Welding

S E C T I O N

1

S C O P E

A N D

G E N E R A L

1.1 SCOPE This Standard specifies the minimum requirements for safety, welding consumables, weld preparations, welding processes, qualifications of welding procedures and personnel, and fabrication and inspection requirements for the construction and maintenance welding of carbon and carbon-manganese steel pipelines down to 3.2 mm wall thickness designed and constructed in accordance with AS 2885.1. The welding of corrosion resistant alloy steel pipelines, or pipelines with nominal thicknesses less than 3.2 mm, is not precluded, but is not expressly covered by this Standard. The welding of such pipelines has to be given special consideration. The following types of welds are covered by this Standard: (a)

Mainline.

(b)

Tie-in.

(c)

Special class e.g. golden weld.

(d)

Repair welds (see Section 25).

(e)

Welds on or between components.

(f)

Temporary welds used in construction e.g. test headers.

(g)

Structural attachments.

(h)

Aluminothermic or pin brazing welds for electrical attachments.

(i)

In-service welds.

(j)

Welds made in accordance with other standards.

(k)

Pipeline assemblies.

The welding may be done by a manual metal arc, submerged arc, gas tungsten arc, gas metal arc, flux cored arc or by a combination of these using a manual, semi-automatic, or automatic welding technique or a combination of these techniques. The welds may be produced by position or roll welding, or by a combination of position and roll welding. This Standard is applicable to the welding of joints in or on pipelines, and the welding of pipeline assemblies manufactured from pipes and fittings (see Figure 1.1 for examples). NOTE: The welding of fittings may present special difficulties when using typical pipeline welding procedures (see Appendix C).

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AS/NZS 2885.2:2016

It is not intended that this Standard should be applied to the following: (i)

Station pipework as defined in AS 2885.1.

(ii)

Longitudinal welds or spiral welds made during the manufacture of a pipe or a component.

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(iv)

Hyperbaric welding.

C o m p o n e nt C o m p o n e nt s

M ainline (a) M a i n l i n e val ve a s s e m b l y

(b) In sul at in g j o int a s se m b ly

In d u c t i o n b e n d M ainline C o m p o n e nt s

Pi p e s u p p o r t M ainline (c) S c r a p er tr a p a s s e m b l y

C o m p o n e nt

C o m p o n e nt (d) Pi g g in g bar te e a s se m b ly

M ainline or pipe su p p or t (e) A n c h or fl an g e

FIGURE 1.1 EXAMPLES OF ASSEMBLIES THAT MAY BE WELDED IN ACCORDANCE WITH THIS STANDARD

1.2 APPROVAL Each document prepared for a pipeline in accordance with this Standard shall be approved as required by AS 2885.0. NOTE: Appendix A summarizes the documents that require approval in this Standard.

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1.3 QUALIFICATION Welding shall be performed by qualified personnel as described in Section 3 of this Standard and in accordance with documented qualified and approved welding procedures. 1.4 RETROSPECTIVITY

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It is not intended that this Standard be applied retrospectively to existing installations. Welding procedures and welder qualifications complying with appropriate previous editions of this Standard may continue to be used for the maintenance of existing installations. New welding procedures and qualifications shall be in accordance with this Standard. 1.5 REFERENCED DOCUMENTS The documents referred to in this Standard are listed in Appendix B. 1.6 DEFINITIONS For the purpose of this Standard, the definitions given in AS 1929, AS 2812, AS 2832.1 and those below, apply. 1.6.1 Approved and approval NOTE: Refer to AS 2885.0.

1.6.2 Automated ultrasonic testing (AUT) Mechanized or semi-mechanized ultrasonic inspection for girth welds using ultrasonic inspection techniques. 1.6.3 Automatic welding Welding in which all operations are preset and performed automatically during the process. NOTE: The welding operator is not able to change or adjust any weld parameters or variables once the welding operation has commenced.

1.6.4 Burn-off rate The ratio of electrode length consumed to the length of weld pass deposited, which is proportional to the heat input, divided by the square of the electrode core wire diameter. NOTE: WTIA Technical Note 1 provides information relating burn-off rate to heat input.

1.6.5 Buttering A surface variation in which one or more layers of weld metal are deposited on the weld face of one member (e.g. a high alloy weld deposit on steel base metal that is to be welded to a dissimilar base metal). NOTE: The buttering provides a suitable transition weld deposit for subsequent completion of the butt joint.

1.6.6 Carbon equivalent (CE) For the purpose of this Standard, the carbon equivalent (CE) is calculated in accordance with the International Institute of Welding (IIW) formula, i.e.— CE = C +

Mn Cr + Mo + V Cu + Ni + + 6 5 15

NOTE: Where CE is reported on a test certificate using another formula, it should be re-calculated using the formula above for application within this Standard

1.6.7 Cellulosic welding Arc welding with a high hydrogen welding consumable. COPYRIGHT

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1.6.8 Competent person NOTE: Refer to AS 2885.0.

1.6.9 Component

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Any part of a pipeline, other than a pipe, for which the dominant function is pressure containment. NOTES: 1 Components include, but are not limited to, valves, fittings, flanges, mechanical connectors or joints, closures etc. 2 Components do not include items for which pressure-containment is incidental to some other dominant function, such as instrumentation.

1.6.10 Construction Activities required to fabricate, construct and test a pipeline, and to restore the right of way of a pipeline. 1.6.11 Crack tip opening displacement (CTOD) test A destructive test which provides a quantitative fracture mechanics based measure of the fracture toughness of the weld metal in girth welds. NOTE: See Clause 7.4.7.2, Crack tip opening displacement (CTOD) test.

1.6.12 Defect A discontinuity or imperfection of sufficient magnitude to warrant rejection on the basis of the requirements of this Standard. 1.6.13 Design temperatures The range of the metal temperatures to be expected in construction, testing and operation including consideration of depressurization and repressurization. NOTE: See AS 2885.1 for details.

1.6.14 Diameter The outside diameter nominated in the material order, ignoring the manufacturing tolerance provided in the specification under which the pipe was manufactured. 1.6.15 Discontinuity A generic term for imperfections (see Clause 1.6.34), (see Clause 1.6.12) and non-rejectable irregularities.

which

includes

defects

1.6.16 Dye-penetrant inspection (DPI) A widely applied low-cost inspection method used to locate surface-breaking defects in all non-porous materials, e.g. metals, plastics, or ceramics. NOTE: Also known as liquid penetrant inspection (LPI) or penetrant testing (PT).

1.6.17 Electrical discharge machining (EDM) A manufacturing process whereby a desired shape is obtained using electrical discharges (sparks), which remove material from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. NOTE: Also known as spark machining, spark eroding, burning, die sinking, wire burning or wire erosion.

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1.6.18 Engineering critical assessment (ECA) A formal process for the assessment of structures containing discontinuities, in order to determine whether the structure is fit for purpose.

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NOTE: The process involves the use of fracture mechanics and requires consideration of the discontinuity, the stress, and the material properties for the likelihood of failure arising from fracture, plastic collapse, fatigue, buckling, creep, corrosion/erosion, and leakage.

1.6.19 Engineering design The detailed design of a pipeline system, developed from process and mechanical requirements, complying with the requirements of this Standard and including all necessary specifications, drawings, and supporting documents. 1.6.20 Environment The combination of climatic, demographic, geotechnical, oceanographic, and biotic factors that acts on a pipeline influencing the design, construction, testing, inspection, operation, and maintenance. 1.6.21 Essential variable Variable in which a change outside specified limits requires requalification of welding. 1.6.22 Finite element analysis (FEA) A numerical technique that encompasses methods for connecting many simple element equations over many small subdomains, named finite elements, to approximate a more complex equation over a larger domain. 1.6.23 Fitting A component used to join pipes, to change the direction or diameter of a pipeline, to provide a branch, or to terminate a pipeline. NOTE: Fittings made from API 5L PSL2 pipe and that meet the mechanical properties of the pipe material in the welded condition can be treated as pipe in relation to welding procedure qualification.

1.6.24 Fluid Any liquid, vapour, gas or mixture of any of these. 1.6.25 Flux core arc welding (FCAW) Arc welding using a consumable continuous flux cored electrode that provides the filler metal and shielding is provided by the flux contained within the electrode. NOTE: Additional shielding may be obtained from an externally supplied gas or gas mixture.

1.6.26 Full screen height (FSH) The height of the display on a conventional flaw detector screen. 1.6.27 Gamma radiography High-energy, short wavelength electromagnetic radiation, emitted by a nucleus or source (IR-192, Se-75 or Co-60). NOTES: 1 Energies of gamma rays are usually between 0.010 and 10 mev. X-rays also occur in this energy range, but are non-nuclear origin. Gamma radiation usually accompanies alpha and beta emissions and always accompanies fission. Gamma rays are very penetrating and are best attenuated by dense materials like lead and depleted uranium. 2 Gamma rays can only be used where ultrasonics or X-ray is not practical or accessible and requires client approval.

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1.6.28 Gas Any hydrocarbon gas or mixture of gases, possibly in combination with liquid petroleum condensates or water. 1.6.29 Gas metal arc welding

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Arc welding using a consumable continuous solid electrode that provides the filler metal and shielding is provided entirely from an externally supplied gas or gas mixture. 1.6.30 Golden weld A weld that will not be subject to a hydrostatic strength test. 1.6.31 Heat input (arc energy) A weld pass for heat input is calculated as follows: Q=

60 EI × V 1000

where Q = welding energy input, in kilojoules per millimetre of a pass of a weld E = arc voltage, in volts (RMS value for a.c.) I = welding current, in amperes (RMS value for a.c.) V = welding speed, in millimetres per minute NOTES: 1 Both the arc voltage and welding current have to be measured accurately with voltage measured between the electrode holder or contact tube and the work piece. 2 For waveform power sources, refer to Clause 6.7.2 for an alternative method to determine heat input.

1.6.32 Hot repair Repair welding on a pipeline containing hydrocarbon gas under controlled conditions with a burning gaseous atmosphere present due to escape of the pipeline contents. 1.6.33 Hydrogen assisted cold cracking (HACC) A form of brittle cracking that occurs at near-ambient temperature in the weld or heat affected zone of ferritic steel weldments, due to the combined effects of hydrogen arising from welding, together with tensile stress and a susceptible microstructure. NOTE: The time delay after welding at which HACC occurs depends upon the particular circumstances, especially the hydrogen concentration. With low levels of hydrogen it may be 24 h or more.

1.6.34 Imperfection A material discontinuity or irregularity that is detectable by inspection in accordance with this Standard. 1.6.35 Inert gas shielding The use of a gas or gas mixture in GTAW, GMAW or FCAW to shield the weldment from oxidation effects of the atmosphere wherein the gas or gas mixture is selected primarily on the basis of being non-reactive (‘inert’) with the weldment and therefore depends on the process and consumable, and is usually specified by the consumable manufacturer. NOTE: Depending on the desired mechanical properties of the finished weldment, a manufacturer may specify different options for gas mixtures for use with a particular consumable.

1.6.36 In-service welding Welding onto a product-filled pipeline. COPYRIGHT

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1.6.37 Interpass temperature The temperature in a multi-run weld and adjacent parent metal immediately prior to the application of the next run, which is normally expressed as a maximum temperature.

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1.6.38 Lamellar tearing Cracking in the parent metal adjacent to the weld and arising from weld stresses in the through thickness direction of the plate, which occurs in a stepped configuration, associated with lamellar non-metallic inclusions in the plate, parallel to the fusion boundary. 1.6.39 Licensee NOTE: Refer to AS 2885.0.

1.6.40 Location class The classification of an area according to its general geographic and demographic characteristics, reflecting both the threats to the pipeline from the land usage and the consequences for the population should the pipeline suffer a loss of containment. 1.6.41 Magnetic particle testing (MPT) A non-destructive method of inspection for determining the existence and extent of possible defects in ferromagnetic materials, wherein finely divided magnetic particles, applied to the magnetized part, are attracted to and outline the pattern of any magnetic-leakage fields created by discontinuities. 1.6.42 Mainline pipework Those parts of a pipeline between stations and comprising only linepipe including cold field bends and induction bends formed from linepipe. 1.6.43 Manual metal arc welding (MMAW) Arc welding with a covered electrode manually applied by the welder, without automatic or semi-automatic replacement of the electrode and shielding is provided only by decomposition of the electrode covering. 1.6.44 Matching (overmatching, undermatching) The ability of a girth weld, containing discontinuities at the limit of the acceptance criteria, to match the strength of the pipe and to ensure, that under displacement controlled loading, plastic strain is transferred to at least one adjoining pipe before the weld breaks. NOTE: Weld strength matching includes weld reinforcement, pipe wall thickness and work hardening characteristics as defined by yield to tensile ratio.

1.6.45 May Indicates the existence of an option (see also ‘shall’ and ‘should’). 1.6.46 Mechanized welding Welding in which the welding parameters are maintained within a suitable tolerance by mechanical or electronic means. NOTE: The welding operator is able to change or adjust some parameters or variables but only within a limited and controlled range.

1.6.47 Multiple wire system Where two or more consumable welding wires are fed into the same weld pool. 1.6.48 Nominal thickness (tN ) The wall thickness nominated for pipe manufacture or certified on supplied pipe.

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1.6.49 Non-destructive testing (NDT) A wide group of analysis techniques used in industry to evaluate the properties of a material, component or system without causing damage. 1.6.50 NDT technician

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Personnel involved in non-destructive testing (NDT) and qualified to a minimum Level 2 of an approved NDT qualification program. 1.6.51 Non-essential variable Variable in which a change outside specified limits does not require requalification of the welding procedure. NOTE: Non-essential variables are those Items in Table 6.1 that do not appear in the list of essential variables in Table 6.2.

1.6.52 Non-planar discontinuity Weld discontinuities not included in the planar category, including volumetric discontinuities such as porosity, root concavity, burn-through, hollow head, and slag inclusions. 1.6.53 O-let An integrally reinforced forged branch outlet fitting that is designed and manufactured according to MSS SP-97. NOTE: ‘O-let’ also refers to similar integrally reinforced branch fittings e.g. threadolets, sockolets, latrolets, elbowlets, nipolets, sweepolets.

1.6.54 Peening The mechanical working of weld metal by means of hammer blows or the like, or bombardment with shot or similar pellets. 1.6.55 Phase array ultrasonics (PAUT) A mosaic of transducer elements in which the timing of the elements’ excitation can be individually controlled to produce certain desired effects, such as steering the beam axis or focusing the beam into the weld metal or inspection item. NOTE: Phased array ultrasonics can be provided manually or semi-automated.

1.6.56 Pig A device inserted in a pipeline for operation or inspection, and transported through it by the flow of the fluid in the pipeline. 1.6.57 Pig trap (launcher/receiver) A pipeline assembly to enable a pig to be inserted into or removed from an operating pipeline. 1.6.58 Pipeline assemblies An element of a pipeline system assembled from pipe complying with a nominated Standard and pressure-rated components complying with a nominated Standard or of an established design and used within the manufacturer’s pressure and temperature rating, and wholly designed and fabricated in accordance with this Standard or a nominated station piping or pressure vessel Standard. NOTES: 1 See also station definition (Clause 1.6.72). 2 Pipeline assemblies include but are not limited to scraper assemblies, valves assemblies and branch connection assemblies.

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1.6.59 Planar defect

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A category of unacceptable weld discontinuities that are assumed to have only two dimensions and which, in fracture mechanics terms, are considered to be equivalent in behaviour to a crack. NOTE: The fitness for purpose based acceptance criteria in Tier 2 of this Standard classifies the various discontinuity types into planar and non-planar categories. The workmanship based acceptance criteria in Tier 1 does not require classification of discontinuities according to whether they are planar or non-planar.

1.6.60 Probability of detection (PoD) A statistical method used to determine the probability of detecting minimum flaw sizes by the non-destructive testing method being evaluated. 1.6.61 Post-weld heat treatment (PWHT) A method for reducing and redistributing the residual stresses in the material that have been introduced by welding, which involves a controlled heating of the material, holding for a period of time, and then controlled cooling. 1.6.62 Preheat maintenance temperature The minimum temperature in the weld zone which has to be maintained if welding is interrupted. 1.6.63 Preheat temperature The temperature of the work piece in the weld zone immediately prior to any welding operation NOTES: 1 It is normally expressed as a minimum and is usually equal to the minimum interpass temperature. 2 A minimum preheat temperature may be required, e.g. to avoid hydrogen cracking in the weld metal or heat-affected zone. A maximum value may also be specified in order to achieve particular levels of toughness and/or strength. It is recommended that preheat be measured at least 75 mm from the weld line.

1.6.64 Pretest A pressure test of pipe, pipeline assemblies or a component that is undertaken separately from the pipeline and may not be retested after installation e.g. pipe used at crossings, spare pipe, isolation valve assemblies. NOTE: Also known as pretested.

1.6.65 Procedure qualification record (PQR) A record of welding variables used to produce a test weldment and the results of tests conducted on the weldment to qualify a welding procedure specification. 1.6.66 Proposed welding procedure specification (pWPS) A document which specifies a nominal proposed range of welding essential variables which is used as the basis for producing a test weldment for the purpose of qualifying a weld procedure in accordance with this Standard. 1.6.67 Radiographic testing (RT) The process of making a radiograph via electromagnetic radiation (X-rays) or ionising radiation (gamma rays) penetrating photographic film or a digital detector. NOTE: The preferred method of radiography is X-ray.

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1.6.68 Shall Indicates that a statement is mandatory (see also ‘may’ and ‘should’). 1.6.69 Should Indicates a recommendation (see also ‘may’ and ‘shall’).

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1.6.70 Sour service Piping normally conveying crude oil or a natural gas containing hydrogen sulfide together with an aqueous liquid phase in a concentration that may affect materials. NOTE: The limits defined in NACE MR0175/ISO 15156 are deemed, for the purposes of this Standard, to constitute sour service.

1.6.71 Specified minimum yield strength (SMYS) The minimum yield strength for a pipe or component material that is specified in the manufacturing Standard with which the pipe or component complies. 1.6.72 Station Facilities that allow for control, measurement, storage or pressure maintenance of pipeline fluids, including compressor and pump stations, storage facilities, pressure regulation and metering facilities. NOTES: 1 Other facilities that involve frequent operational activity may also be designated stations for the purpose of this Standard. 2 Pipeline assemblies (see Clause 1.6.59) are not considered stations in this Standard. They may, however, be located within the physical boundaries of a station. Piping within stations (other than including pipeline assemblies) is designed to piping codes other than AS 2885.

1.6.73 Time of flight diffraction (ToFD) An ultrasonic inspection method which differs from the traditional pulse echo technique in that it processes diffracted signals from the edges of features which then directly relate to the true position and size of the feature, as opposed to the magnitude of the reflection from the feature as compared to a reference reflector. 1.6.74 Undercutting adjacent to the cover pass [SUC (ext)] A groove melted into the base metal adjacent to the cover pass and left unfilled by weld metal. 1.6.75 Undercutting adjacent to the root pass [SUC (int)] A groove melted into the base metal adjacent to the root pass and left unfilled by weld metal. 1.6.76 Ultrasonic testing (UT) A NDT process that uses high frequency sound energy to conduct examinations and make measurements. NOTE: Ultrasonic inspection is used for flaw detection/evaluation, dimensional measurements, material characterization, and more. To illustrate the general inspection principle, a typical pulse/echo inspection configuration will be used.

1.6.77 Weld metal deposition repair Repair method for loss of nominal thickness. NOTE: For example, repairing corrosion defects by surfacing with deposited weld metal while the pipeline is in service.

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1.6.78 Welding procedure specification (WPS) A document given to a welder/operator, which specifies the required range of welding variables within which the welder/operator may weld so as to ensure the weld will be sound when undertaken within the range of variables specified.

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NOTE: The variables specified on the welding procedure specification are those recorded on the procedure qualification record (PQR) to which the essential variables has been applied.

1.6.79 Weldability The ability of a metal to be welded under given fabrication conditions in a specific weldment, resulting in satisfactory service performance. 1.6.80 X-radiography An imaging technique that uses electromagnetic radiation other than visible light, especially X-rays, to view the internal structure of a non-uniformly composed and opaque object (i.e. a non-transparent object of varying density and composition) such as weld metal. NOTES: 1 To create the image, a heterogeneous beam of X-rays is produced by an X-ray generator and is projected toward the object. A certain amount of X-ray is absorbed by the weld metal, which is dependent on the particular density and composition of that weld. The X-rays that pass through the weld are captured behind the weld by a detector (either photographic film or a digital detector). The detector can then provide a superimposed 2D representation of all the weld’s internal composition. 2 X-ray is the preferred method of test where radiography is to be used.

1.6.81 Yield strength (σ Y) The SMYS specified in the Standard with which the pipe or component complies. NOTE: The preferred method for determining the tensile properties of the line pipe complying with API Spec 5L is given in AS 2885.1, Appendix J, Preferred method for tensile testing of welded line pipe during manufacture.

1.7 ROUNDING OF NUMBERS An observed or calculated value shall be rounded to the nearest unit in accordance with AS 2706. 1.8 PIPELINE ASSEMBLIES Pipeline assemblies shall be designed, fabricated and tested either— (a)

in accordance with AS 2885.1—2012 Section 5 using pipe and components in accordance with AS 2885.1 Section 3 and testing in accordance with AS/NZS 2885.5—2012; or

(b)

in accordance with the materials, design fabrication, and testing requirements of a nominated piping standard.

NOTE: Pipelines assemblies in accordance with AS 2885 are intended to take advantage of high strength materials. This enables the assemblies to be made from materials of compatible thickness and grade to the pipeline, thus avoiding mismatched internal diameter, transition pieces and special welding procedures. Pipeline assemblies in accordance with a piping standard may not offer these advantages.

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S A F E T Y

2.1 PRODUCTION WELDING

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2.1.1 General Production welding shall be considered in the construction safety plan that is required in accordance with AS 2885.1. NOTE: The guidance in WITA Technical Note 7 should also be considered.

2.1.2 Electrical safety during welding Production welding shall comply with AS 1674.2. NOTE: The guidance in WITA Technical Note 7 should also be considered.

2.1.3 Welding environment A thorough check shall be made in and around the welding site in accordance with AS 1674.2 to ensure welder safety and confirm that there are no substances that could constitute a risk of fire or explosion. 2.1.4 Equipment and compressed gases Arc welding equipment shall be of a size and type suitable for the work and shall be maintained in a condition that ensures acceptable welds, continuity of operation, and safety of personnel. Arc-welding equipment shall be operated within parameter ranges given in the qualified welding procedure. Equipment that does not meet these requirements shall be repaired or replaced. Equipment used with compressed gases, including regulators, shall be properly maintained to prevent hazards such as gas leaks. NOTE: They should be frequently checked whether cylinders and regulators are visibly damaged or corroded, and whether they are within test date. Gas pipes, fittings, hoses and tubing can easily become damaged over time so these should also be inspected regularly.

2.1.5 Electric and magnetic fields (EMF) Electric current flowing through any conductor causes localized electric and magnetic fields (EMF). Welding current creates EMF around welding cables and welding machines. WARNING: EMF MAY INTERFERE WITH SOME PACEMAKERS, AND WELDERS HAVING A PACEMAKER SHOULD CONSULT THEIR PHYSICIAN BEFORE WELDING.

2.2 WELDING OR CUTTING ON A PIPELINE AFTER COMMISSIONING 2.2.1 General All of the activities associated with welding or cutting on pipelines containing flammable and/or pressurized substances involve a high risk. The procedures that are qualified in accordance with Sections 15 and 16 shall include a thorough risk assessment. The risk assessment shall include the safety of the public, operations personnel and the suitability of equipment. The risk assessment shall be approved (see Clause 1.6.1). NOTE: In-service welding risk assessment guidance in WTIA Technical Note 20 should be considered. WARNING: SPECIFIC ATTENTION SHOULD BE PAID TO THE RISK OF IGNITION OR ELECTROCUTION DUE TO THE PIPELINE BEING AT AN ELEVATED POTENTIAL WITH RESPECT TO EARTH, AND THE LIKELIHOOD THAT IT MAY CARRY SUBSTANTIAL CURRENTS.

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Bonding cables should be installed prior to cutting, to effectively bypass any current that may be flowing in the pipeline, especially if the methods of cutting employed are not expected to cause ignition.

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Consideration should be given for earthing the pipeline prior to the commencement of welding or cutting. Due to the potentially hazardous nature of the earthing procedure, the earthing procedure shall be approved (see Clause 1.6.1). The formation of mixtures of flammable vapour, including gas and air, shall be prevented, unless work is to be carried out in line with Clause 15.3. 2.2.2 Risk assessment Welding or cutting on a pipeline that is operational or during construction activity involves increased risk to public safety and operating personnel. A project specific risk assessment for the activities involved shall be undertaken which considers as a minimum the following: (a)

Qualification of the welding to simulate the field installation.

(b)

Failure of equipment including the power supply.

(c)

Failure of valves to isolate.

(d)

Confirmation of the mechanical properties of the operational pipeline and the components to be used in the completed assembly.

(e)

Leak and strength testing of the completed assembly.

(f)

Competency of supervision, technicians, welders and NDT technicians used in the process.

(g)

Emergency shutdown and depressurization.

(h)

Loss of supply as a result of an incident.

2.3 SAFETY AND PROTECTION FROM IONIZING RADIATION All radiographic testing shall be carried out in accordance with statutory State and Federal health and safety regulations.

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Q U A L I F I C A T I O N S

3.1 GENERAL

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Personnel involved in pipeline welding activities in accordance with this Standard shall be competent persons. Clauses 3.2–3.5 describe key welding tasks and the qualification required to demonstrate competence to undertake those tasks. 3.2 WELDING ENGINEERING The following tasks shall be undertaken by a competent welding engineer: (a)

Review of design data including— (i)

a material summary listing pipe grade, nominal thickness, diameter, carbon equivalent (CE) and specification and CE for all fittings;

(ii)

the boundary limits between stations and mainline pipework;

(iii) the safety management study information related to NDT and welding including golden welds; (iv)

the design minimum temperature; and

(v)

for in-service welding, the pipeline operating pressure range and velocity range.

(b)

Design of all welding procedure qualification test welds and specification of the requirements for examination and testing.

(c)

Development of a weld map that shows where each welding procedure is to be used.

(d)

Selection and approval of welding procedure specifications.

(e)

Approval of an alternate welding Standard in accordance with Clause 6.4.3.

(f)

Direct supervision of any weld being qualified by the method of engineering in accordance with Clause 6.4.5.

(g)

Specification of the non-destructive and mechanical test requirements for production welds.

(h)

Specification of acceptance criteria and defect assessment in accordance with Sections 17 and 19.

(i)

Approval of any repair to a repair weld in accordance with Section 25.

(j)

The specification of requirements for welder or operator qualification test welds and examination and testing.

(k)

Approval of the qualifications of the welding supervisor and inspector in accordance with Clauses 3.3(v) and 3.4(vi).

(l)

Approval of the qualification program for NDT personnel and approval of NDT procedures.

(m)

Approval of any proposed PWHT activities.

NOTES: 1 One or more welding engineers may be engaged to undertake welding engineering tasks on a pipeline and welding engineers may be engaged from different organizations to undertake different tasks. 2 For further guidance on the responsibilities of personnel involved in welding-related tasks refer to ISO 14731. COPYRIGHT

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A welding engineer shall only undertake tasks that require an approval when they have been authorized by the licensee (refer to AS 2885.0, Section 3).

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A competent welding engineer shall have one or more of the following qualifications: (i)

Hold an International Institute of Welding (IIW) qualification at the level of International Welding Engineer (IWE) diploma.

(ii)

Hold postgraduate diploma or degree in welding engineering from a recognized university or a registered training organization.

(iii) Have other approved qualifications or experience acceptable to the licensee, including specific technical knowledge and experience in the welding of pipelines. In addition to the requirements above, a welding engineer shall be qualified by previous experience and specific training if they are involved in the following tasks: (A)

Welding onto a pipeline that has been hydrostatically tested or commissioned, where the pipeline will not be subjected to another pressure test before it is returned to service.

(B)

Welding onto a pipeline that has contained hydrocarbons.

(C)

In-service welding on pipelines.

A welding engineer shall approve both the weld procedure and risk assessment for these activities. 3.3 WELDING SUPERVISION The welding supervisor shall be responsible for planning, execution and supervision of weld procedure qualification test welds and production welds. The following tasks shall be undertaken by a competent welding supervisor: (a)

The planning, execution, supervision and recording of all welding procedure qualification test welds and their examination and testing.

(b)

The planning, execution, supervision and recording of all welder or operator qualification test welds and their examination and testing.

(c)

The coordination of all production welding.

(d)

The coordination of all production NDT.

(e)

Producing and maintaining reports and records as required.

NOTES: 1 One or more welding supervisors may be engaged to undertake welding supervision tasks on a pipeline and supervisors may be engaged from different organizations or work teams to perform different tasks. 2 For further guidance on the responsibilities of personnel involved in welding-related activities refer to ISO 14731.

Where approved by the licensee, a welding supervisor may also perform the role of the welding inspector. The welding supervisor shall have a minimum of three years’ experience in welding pipelines and have one or more of the following qualifications: (i)

A welding supervisor certificate in accordance with AS 1796 Certificate No. 10, or a New Zealand Institute of Welding supervisor certificate.

(ii)

An International Institute of Welding (IIW) diploma at the level of International Welding Specialist (IWS), International Welding Technologist (IWT) or International Welding Engineer (IWE). COPYRIGHT

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(iii) A New Zealand Institute of Welding certificate in welding engineering. (iv)

A postgraduate certificate, diploma or degree in welding engineering from a recognized university or a registered training organization.

(v)

Have other approved qualifications or experience acceptable to the licensee, including specific technical knowledge and experience in the welding of pipelines.

For welding supervision of welding onto a pipeline that has been hydrostatically tested or commissioned the welding supervisor shall also be qualified by experience and training in the welding or cutting of pipelines containing, or having contained, hydrocarbons. For in-service welding the welding supervisor shall also be qualified by experience and training specifically related to in-service welding on pipelines. 3.4 WELDING INSPECTION The following tasks shall be undertaken by a competent welding inspector: (a)

The witnessing of all welding procedure qualification test welds and the subsequent removal of test samples.

(b)

The witnessing of all welder or operator qualification test welds and the subsequent removal of test samples.

(c)

The examination of all production welds including visual inspection.

(d)

Ensuring that all reports and records are made as required.

NOTES: 1 One or more welding inspectors may be engaged to undertake welding inspection tasks on a pipeline and welding inspectors may be engaged from different organizations or work teams to perform different tasks. 2 Further guidance on welding inspection activities is provided in ISO 14731.

Welding inspectors shall have appropriate qualifications, training and experience in the inspection of pipeline welding. A welding inspector shall have one or more of the following qualifications: (i)

An International Institute of Welding (IIW) diploma as a welding inspector, at the appropriate level.

(ii)

A Welding Technology Institute of Australia (WTIA) certificate as a welding inspector, at the appropriate level.

(iii) A New Zealand Institute of Welding certificate as a welding supervisor or a welding supervisor’s certificate in accordance with AS 1796 Certificate No. 10. (iv)

A Certification Board of Inspection Personnel (CBIP) New Zealand Welding Inspector.

(v)

A CSWIP Certificate as a welding inspector, at the appropriate level.

(vi)

Other approved qualifications and experience.

3.5 WELDERS AND WELDING OPERATORS Welders and welding operators shall be qualified in accordance with Section 9 of this Standard.

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M A T E R I A L S

4.1 GENERAL

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The requirements of this Section are applicable to the welding of materials that comply with AS 2885.1. NOTE: Changes to the weld consumable classification system are described in Appendix E, Tables E1 and E2.

4.2 CONSUMABLES 4.2.1 General Consumables shall comply with the Standards listed in Table 4.1 as appropriate. All-weld metal chemical analysis for boron shall be analysed and reported. All-weld metal boron content greater than 0.0010% shall be subject to an engineering assessment. Consumables that do not comply with the listed Standards may be used, provided they have chemical and mechanical properties that are as specified in the listed Standards and meet the boron requirements listed in this Section. NOTE: The following should be taken into account for manual arc welding electrodes: (a) Lower strength electrodes (see welding process column in Table 4.1) should be used for welding of all passes for pipe and components in material up to and including grade X52. (b) Unless it can be shown that it is difficult to meet the required mechanical properties [see Clause 17.4.1(c)], lower strength electrodes should be used for the first pass, when welding pipe and components of material that are greater than grade X52. (c) Electrodes for cellulosic manual metal-arc welding should be selected and specified in accordance with Appendix D. (d) The selection of wires for automatic welding should take into account the information given in Appendix G.

4.2.2 Storage and handling of consumables Consumables shall be stored and handled as follows: (a)

Electrodes—in accordance with one or more of the following: (i)

Recommendations of the manufacturer.

(ii)

Requirements of the relevant Standard.

(iii) Recommendations in WTIA Technical Note 3. (b)

Filler rods and fluxes—in accordance with one or more of the following: (i)

Recommendations of the manufacturer.

(ii)

Requirements of the relevant Standard.

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TABLE 4.1 WELDING CONSUMABLES

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Welding process

Standard

Consumable type

Manual metal-arc welding using lower strength cellulose electrodes

AS/NZS 4855-B ISO 2560-B AWS A5.1

Cellulose MMA

Manual metal-arc welding using medium strength cellulose electrodes

AS/NZS 4857-B ISO 18275-B AWS A5.5

Cellulose MMA

Manual metal-arc welding using lower strength hydrogen-controlled electrodes

AS/NZS 4855-B ISO 2560-B AWS A5.1

Basic coated MMA

Manual metal-arc welding using medium strength hydrogen-controlled electrodes

AS/NZS 4857-B ISO 18275-B AWS A5.5

Basic coated MMA

Submerged arc welding 1

AS/NZS ISO 14171 AWS A5.17 AS/NZS ISO 26304-B AWS A5.23

Fused or bonded flux

Gas tungsten-arc welding 2

AS/NZS 1167.2 ISO 150636 AWS A5.18 AS/NZS 16834-B ISO 16834-B AWS A5.28

Solid wire

Gas metal-arc welding 2

AS/NZS 14341-B ISO 14341-B AWS A5.18 AS/NZS 16834-B ISO 16834-B AWS A5.28

Solid wire

Gas metal-arc welding 2

AS 4882

Shielding gas

AS/NZS ISO 17632 ISO 17632-B AWS A5.20 AS/NZS ISO 18276-B ISO 18276-B AWS A5.29 AWS A5.36

Gas- or self-shielded flux-cored wire

Flux cored arc welding

3, 4

Solid wire

NOTES: 1

Any combination of electrodes and fluxes may be used to qualify a procedure. Each combination shall be identified by its complete classification number e.g. F6A2-EM12K or F7A1-EL12 as specified in AWS A5.17, B-S49A2 AB SU32 as specified in AS/NZS ISO 14171-B.

2

Any combination of electrodes and gases may be used to qualify a procedure. Each combination shall be identified by its complete classification number e.g. ER 70S-6 as specified in AWS A5.18 with each shielding gas to be specified by brand name or mix analysis, B-G 49A 6 M S3, SG-ACO-16/2.75 as specified in AS/NZS 14341-B and AS 4882.

3

Any combination of electrodes (with or without gas) may be used to qualify a procedure. Consumables shall be identified by the complete classification number, e.g. B-T492T8-1NAUH15 as specified in AS/NZS ISO 17332-B. Where a shielding gas is used, this shall be specified by brand name or mix analysis.

4

Any combination of electrodes may be used to qualify a procedure. Consumables shall be identified by the complete classification number e.g. root pass E71T-GS, other passes E71T8-K2.

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5

D E S I G N

O F

A

W E L D E D

J O I N T

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5.1 GENERAL A welded joint shall be designed to be capable of withstanding the design forces, and strains presented by AS 2885.1; for pressure-containing components it shall be leak tight in accordance with AS/NZS 2885.5. Details of the weld preparations shall be in accordance with those shown in the qualified welding procedure specification. The welding procedure specification shall include tolerances for all of the specified dimensions. 5.2 BUTT WELDS THICKNESS

BETWEEN

COMPONENTS

OF

EQUAL

NOMINAL

The weld preparation for a butt weld between components of equal nominal thickness shall be single V type, double V type, or an approved preparation. For a manual metal-arc welding process, joints using the combination of weld preparations shown in Figure 5.2 may be used. For other welding processes, the weld preparation shall have been shown to be satisfactory by being qualified in the welding procedure test. The weld preparation selected shall take into consideration the proposed production NDT method. 5.3 BUTT WELDS THICKNESS

BETWEEN

COMPONENTS

OF

UNEQUAL

NOMINAL

The weld preparations on a butt weld between components of unequal nominal thickness shall be as shown in Figure 5.3. When the SMYS of the components to be jointed are unequal, the deposited weld metal shall have tensile strength at least equal to that of the thinner component as demonstrated by carrying out a transverse butt tensile strength test in accordance with Clause 7.4.2. This may be demonstrated by a joint using the thinner material only. In the case of the thicker component, the thickness for design internal pressure shall be not greater than 1.5 times the nominal thickness of the thinner component unless additional analysis is undertaken. Grade ratios greater than 1.5 may be used provided that stress analysis shows the axial stresses are between 10% and 60% of SMYS. NOTE: Care should be taken analysing stresses on transitions near bends, in pipelines with large tie-in stresses or thermal variation, or where ground movement may occur as these situations are likely to increase axial loadings.

5.4 REINFORCEMENT OF A BUTT WELD The height of the weld reinforcement of a butt weld shall comply with Clause 18.4.2, and with any requirements specified in the engineering design. NOTE: Unless otherwise specified in the design, this Standard does not specify minimum levels of weld reinforcement beyond filling the joint flush with the parent metal.

5.5 LONGITUDINAL BUTT WELDS Longitudinal butt welds on sleeves shall be attached using a procedure which does not allow penetration of the weld into the carrier pipe. NOTE: One method is to use a backing bar. COPYRIGHT

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5.6 FILLET WELD

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5.6.1 Dimensions of a fillet weld A fillet weld may be slightly convex or slightly concave and shall have the specified leg length or throat thickness. The size of fillet weld shall be the leg length of the largest isosceles triangle that can be inscribed in the weld section. The size, convexity or concavity and leg lengths shall be measured to the nearest 0.5 mm on a section scribed with lines as shown in Figure 5.4. The depth of the concavity or the height of the convexity shall be equal to or less than 2 mm. For production welds, any gap between the two parts being joined shall be subtracted from the fillet leg length and throat thickness. 5.6.2 Fillet welding a lug, boss, pig bar or pad A fillet-welded lug, boss, pig bar or pad shall comply with the following: (a)

Dimensions The length of a lug shall be not less than 50 mm. A boss should be circular with a diameter not less than 50 mm. Rectangular or square pads may be used, provided the corners of the pad are rounded.

(b)

Lugs The long sides of a rectangular lug shall be in the circumferential direction of the pipe.

(c)

Surface preparation The area of the pipe to which the connection is to be made shall be clean and be free from oil, scale, and surface-connected defects.

(d)

Fit up The attachment shall fit up to the circumference of the pipe or pressurecontaining component.

(e)

Pig bars The bars shall not be welded directly to the high stress areas around the extrusion neck. The bars transverse to the flow direction should be welded to a pup piece and the bars parallel to the flow direction should be welded to the transverse bars only. In situations where this is impracticable, alternative designs should be considered in order to avoid peak stresses at the ends.

The lugs, bosses, pig bars or pads shall be welded to the pipe or pressure containing component using an approved WPS. 5.6.3 Sleeve fillet welds The fillet welds for sleeve fittings shall be sized according to Figure 5.1. The fillet size shall be determined from Figure 5.1. The strength of the weld metal meets or exceeds the specified minimum yield strength of the pipe and fitting material. NOTE: For pipes with a SMYS greater than 480 MPa, it is recommended that the E70XX electrodes are utilized with the weld size adjusted to take into account undermatching.

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Chamfer/ t a p er = 4 5° m in. (a p prox.)

Ef fe c t i ve we l d t hroat = 1.0 t N

S to p p l e fit t in g

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Gap (m inimize or eliminate if p o s s i b l e)

Pi p e wal l t h i c k n e s s = t N Fill et we l d l e g = 1.4 t N + g a p

Ef fe c t i ve we l d t hroat = 0.7t N to 1.0 t N Gap (m inimize or eliminate if p o s s i b l e)

S l e eve o r n o n - sto p p l e f i t t i n g

Pi p e wal l t h i c k n e s s = t N Fill et we l d l e g = (1.0 to 1.4) t N + g a p

FIGURE 5.1 CROSS-SECTION OF SLEEVE AND STOPPLE FITTING FILLET WELD

5.6.4 Flanges and forged socket fittings The size of fillet welds for flanges and forged socket fittings shall be as specified in AS 4041. 5.7 WELDING OF THREADED JOINTS Welding shall not be carried out on threaded joints for any purpose, including sealing against leakage unless approved by an engineering assessment. 5.8 REINFORCEMENT OF A WELDED BRANCH CONNECTION The design of welds involving pipe to pipe branch connections (whether sit-on or set-in) shall be in accordance with AS 2885.1, Appendix Z. 5.9 REINFORCEMENT OF MULTIPLE OPENINGS The reinforcement of multiple openings shall be determined from AS 2885.1, Appendix Z. 5.10 FORGED BRANCH FITTING A forged branch fitting with integral reinforcement shall be designated sit-on or set-in. The weld between a set-in branch fitting and a pipe shall be designated a tee-butt weld. The weld between a sit-on branch fitting and a pipe shall be designated a single bevel butt weld. NOTE: The welding of forged branch type fittings with integral reinforcement, such as weldolets, is shown in AS 4041. The weld joint design shall be in accordance with AS 2885.1. The weld toe detail at branches shall meet the requirements of AS 4041.

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5.11 EFFECT OF COMPONENTS UPON PIG PASSAGE

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The method of welding components into pipelines, which may require pigging during their design life, shall— (a)

allow free passage of pigs in the main pipeline; and

(b)

prevent entry of main pipeline pigs into any branch line.

5.12 OFFSET OF LONGITUDINAL WELDS Longitudinal welds on the opposite sides of a girth weld shall be staggered circumferentially. The minimum circumferential offset distance between longitudinal welds shall be not less than six times the pipe wall nominal thickness. 5.13 DISTANCE BETWEEN WELDS A weld for any branch connection (whether integrally reinforced or not) or any welded attachment to the pipe should be located a minimum distance of approximately six times the pipe nominal thickness from any circumferential weld in the pipe. The minimum distance between girth welds should be 1.5 times the pipe diameter. 5.14 LOCATION CONNECTIONS

OF

ALUMINOTHERMIC

WELDS

AND

PIN

BRAZING

Aluminothermic welds and pin brazing connections shall be located at a distance greater than 150 mm from an existing pipeline longitudinal or circumferential weld. Where multiple cable connections are required, the spacing between them shall be greater than 75 mm. 5.15 ATTACHMENT OF ELECTRICAL CONDUCTORS Conductors shall be attached to pipelines using aluminothermic welding, pin brazing or by fillet welding a lug, boss or pad. 5.16 GOLDEN WELDS The number and location of golden welds shall be considered in accordance with AS 2885.1, Appendix B, and shall be approved (see Clause 1.6.1).

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10 ° ±1.0 °

3 0 ° +- 05°°

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37. 5° ± 2. 5°

1.6 ± 0.8

1.6 ± 0.8

S t a n d ar d e n d p r e p a r at i o n of p i p e

S u g g e s te d e n d pre p ar at i o n of t h i c k wal l e d p i p e

(a) En d pre par at i o n s

10 ° ±1° 3 0 ° +- 05°° 6 0 ° to 70 °

37. 5° ± 2. 5°

1.4 ± 0.6

1.4 ± 0.6

(b) Ac c e pt a b l e c o m b inat i o n s of e n d p r e p a r at i o n s

NOTE: The standard root face dimension is 1.6 ±0.8 mm. DIMENSIONS IN MILLIMETRES

FIGURE 5.2 END PREPARATIONS AND ACCEPTABLE COMBINATIONS OF END PREPARATIONS

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tN

tN

2.8 max.

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AS/NZS 2885.2:2016

tp

3 0 ° m a x. 14° m in.*

0. 5 t N m a x . N ot lim ite d (ii)

(i) (a) O ut s i d e d i am eter s e q u al

3 0 ° m a x. 14° m in.*

3 0 ° m a x.

3 0 ° m a x.

tp

tN

tN

0. 5 t N m a x.

0. 5 t N m a x . (ii)

(i) (b) In s i d e d i am eter s e q u al

3 0 ° m a x. 14° m in.* 3 0 ° m a x.

tp

tN

3 0 ° m a x. 14° m in.*

0. 5 t N m a x . N ot lim ite d

(c) O ut s i d e an d in s i d e d i am eter s un e q u al

*N o m inimum w h ere t h e pare nt m et al s have t h e s am e S M YS LEGEN D: t N = n o m i n a l wal l t h i c k n e s s of t h e t h i n n er p i p e t p = t h i c k n e s s for d e s i g n i nter n a l p r e s s ur e

NOTES: 1

The standard root face dimension is 1.6 ±0.8 mm. Other joint preparations are acceptable subject to qualification.

2

In joints of unequal thickness and/or grade, where local allowable hoop stress may be exceeded, an option is to demonstrate fitness for purpose using FEA.

3

Match boring may be required with wall thickness changes if AUT is used.

FIGURE 5.3 WELD PREPARATIONS FOR BUTT WELDS—UNEQUAL NOMINAL THICKNESS OR GRADE

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Ac tual throat and ef fe c t ive throat

Ac tual throat C o nvex i t y Le g an d s ize

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Ef fe c t i ve throat

C o n c av i t y Le g S ize

Le g an d s ize

Le g

Theoreti c al throat

Theoreti c al throat (a) C o nvex we l d

(b) C o n c ave we l d

FIGURE 5.4 CROSS-SECTION OF A FILLET WELD

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6 Q U A L I F I C A T I O N O F A W E L D I N G PR OC EDUR E S P E CI F I CA TI O N

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6.1 WELDING PROCEDURE SPECIFICATION (WPS) The purpose of a welding procedure specification is to document the nominal and, where appropriate, average values of the essential and non-essential variables of the welding procedure, and the limits of these variables. The WPS constitutes the work instruction for the weld. Table 6.1 lists the items that shall be defined for each welding procedure. The essential variables for qualified welding procedure specifications shall be in accordance with Table 6.2. NOTE: The terms ‘essential variable’ and ‘non-essential variable’ are defined in Clause 1.6.

6.2 PURPOSE OF QUALIFYING A WELDING PROCEDURE A welding procedure shall be qualified to demonstrate that the production welds made in accordance with the welding procedure— (a)

have the required mechanical properties such as strength, toughness, ductility and hardness;

(b)

produce sound result, i.e. free from cracks, unacceptable porosity or other defects; and

(c)

are free from the risk of hydrogen assisted cold cracking (HACC).

6.3 TYPES OF WELDS REQUIRING QUALIFICATION The types of welds requiring a qualified procedure are as follows: (a)

The production welds listed in Clause 1.1, which shall be qualified by one of the methods listed in Clause 6.4.

(b)

In-service welds, which shall be qualified in accordance with Section 15 or Section 16 of this Standard.

(c)

Repair welds, which shall be qualified in accordance with Section 25 of this Standard.

(d)

Welds made wholly in accordance with other Standards, which shall be qualified in accordance with the relevant Standard (see Clause 6.4.3).

6.4 METHODS OF QUALIFICATION 6.4.1 General There are four methods of qualifying a welding procedure, as follows: (a)

Qualification by testing.

(b)

Qualification to an alternate approved welding Standard.

(c)

Qualification by prequalification without testing.

(d)

Qualification by engineering.

A flow chart illustrating these methods is shown in Figure 6.1. NOTE: Developing a repair procedure at the same time as the production procedure is good practice.

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Q u a l i f i c at i o n by te st in g

36

Q u a l i f i c at i o n to a n alter nate a p prove d we l d i n g s t a n d ar d

Q u a l i f i c at i o n by pre - q ualifi c ation w i t h o u t te s t i n g

Q u a l i f i c at i o n by e n g i n e er i n g

PQ R to a n o m i n ate d s t a n d ar d

C o m p l i a n c e w i t h s et conditions (Cl au se 6.4.4)

En g in e er in g a s s e s s m e nt / j u s t i f i c at i o n

A p pr oval of pro p o s e d we l d i n g pro c e d ur e specification if required (pWPS)

Re c or d of su c c es sful pro c e dure q u a l i f i c at i o n te st we l d (PQ R)

We l d i n g pro c e d ur e s p e c ifi c at i o n ( WPS)

A p proval

FIGURE 6.1 FLOW CHART SHOWING QUALIFICATION OF PROCEDURE

6.4.2 Qualification by testing The process for qualification of a weld procedure by testing shall be as follows: (a)

The pWPS shall be prepared by a welding engineer to document the proposed method of welding for a joint type. The pWPS shall specify all essential and non-essential variables in accordance with Tables 6.1 and 6.2. NOTE: Specified variables include the process, consumable, consumable brand name, preheat, typical heat inputs, etc.

(b)

The pWPS shall be approved prior to proceeding with the welding and testing associated with the qualification process.

(c)

Procedure qualification test welds shall be produced in accordance with the requirements of Clause 6.6 and shall be subjected to examination and testing in accordance with the requirements of Section 7.

(d)

The test results shall be recorded in a PQR.

(e)

The information supporting, or justifying, qualification by testing shall be recorded and appended to the PQR.

(f)

Where the weld meets all the criteria of acceptance, the welding procedure shall be considered qualified.

(g)

The pWPS shall be amended to reflect the permissible parameter ranges based on the PQR and issued as a WPS.

(h)

Each qualified WPS shall be uniquely identified.

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(i)

AS/NZS 2885.2:2016

The WPS shall be approved (see Clause 1.6.1). NOTE: A WPS may be presented in any suitable form (written or tabular), that suits the needs of the responsible organization.

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6.4.3 Qualification to an alternate approved welding Standard This method of qualification shall apply only to welds between pipeline assembly components, and the welding of mainline pipe to pipeline assembly components. It is permissible only when reviewed and approved by a welding engineer qualified in accordance with Section 3. The WPS shall be considered qualified when all requirements are demonstrated by a complying PQR in accordance with one of the following Standards when used in its entirety (including NDT requirements): (a)

AS 4041 or AS 1210 through AS 3992.

(b)

ASME B31.3, ASME B31.4 or ASME B31.8 through ASME IX.

NOTE: The essential variables of this Standard do not apply under this Clause.

6.4.4 Qualification by prequalification without testing This method of qualification shall not be used for the welding of fittings or welding on live pipelines or where the design minimum temperature is below 0°C. A welding procedure may be qualified by being deemed to be prequalified when all the following criteria are met: (a)

The welding process is cellulosic MMAW using E6010 electrodes in the vertical down direction.

(b)

The joints are butt joints between pipes of equal nominal thickness.

(c)

The weld preparation is in accordance with Figure 5.2.

(d)

The pipe diameter is within the range DN 50 to DN 500.

(e)

The pipe nominal thickness is equal to or greater than 4.8 mm and less than 10 mm.

(f)

The pipe grade does not exceed X52 and the carbon equivalent does not exceed 0.40.

(g)

The number of passes is not less than 3.

(h)

The time lapse between starting the root pass and starting the hot pass does not exceed 8 min.

(i)

The arc energy is not less than 0.5 kJ/mm, or burn-off rate is not less than 1.00 for 3.2 mm electrodes or 0.50 for 4.0 mm electrodes.

(j)

Preheat is not less than that determined by reference to WTIA Technical Note 1.

(k)

The lifting and lowering practice either— (i)

conforms with the requirements for ‘normal lifts’ as defined in Appendix C, Paragraph C9.2.1; or

(ii)

where an extreme lift is required, the procedure meets the requirements listed in Appendix C, Paragraph C9.2.2.

(l)

The welds are made by welders qualified in accordance with this Standard.

(m)

All consumables are used within the manufacturer’s recommendations.

NOTE: Prequalified welding procedures, which are qualified under this Clause, are deemed suitable for use by dint of their long satisfactory use and do not require testing in accordance with Clause 6.4.2.

A prequalified welding procedure shall be documented in a WPS which shall include a statement of compliance which addresses each of the above listed requirements. COPYRIGHT

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6.4.5 Qualification by the use of engineering

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In special circumstances and where qualification by testing or documentation is not practicable, a limited number of special welds may, with approval, be made by qualified welders working under the direct and continuous supervision of a qualified welding engineer. NOTE: An example of these special circumstances might be the welding into a pipeline of a large and expensive fitting where it would not be practicable to meet the test weld requirements of this Standard.

The welding engineer shall have formal qualifications in welding engineering, and shall be experienced in the welding of a pipeline, including specifically, qualification in the type of welds that are proposed. The welding procedure used for supervised welds shall be documented in a WPS which shall include a statement of compliance referencing this Section, and shall be approved (see Clause 1.6.1). The documentation shall include a statement of the qualifications and experience of the welding engineer who will supervise the welds. 6.5 CHANGES IN A WELDING PROCEDURE 6.5.1 Change in an essential variable Where a change is made to an essential variable beyond the qualified range of the welding procedure specification, or the permissible limit in Table 6.2, the welding procedure specification shall be requalified or re-approved. 6.5.2 Change in other than an essential variable Where a change is made to other than an essential variable, the welding procedure specification shall be modified but need not be requalified. 6.6 CONDUCT OF THE QUALIFICATION WELDS 6.6.1 Planning a procedure qualification weld Where a welding procedure is to be qualified by testing, a sufficient number of test welds having regard to the range of essential and non-essential variables in the pWPS and the intended use of the procedure, shall be made. Where the procedure is intended to qualify a range or ranges of essential variables that are broader than the permissible limits given in Table 6.2, it shall be necessary to qualify the procedure using more than one test weld. Values of the essential variables shall be chosen to span the qualified range, taking into account the tolerances in Table 6.2. The specified ranges of the essential variables may be extended at any time by the welding and testing of additional test welds. Such changes shall be documented in a revised WPS. The ranges of non-essential variables shall be extended by documentation. NOTE: The welding procedure qualification test may also be used to qualify a welder [see Clause 9.3(b)].

6.6.2 Test piece size The size of the test piece(s) used for welding procedure specification qualification test welds shall involve at least one complete welded joint of the type for which the procedure is to be qualified, and shall be sufficient to provide the required number of test specimens. NOTE: Where AUT is to be used for qualification testing, pup pieces of sufficient length are required. Ordinarily, 450 mm (total welded length 900 mm) is sufficient.

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6.6.3 Test piece material

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The test piece material shall comply with the following: (a)

The test piece material, pipe and or components used for welding procedure qualification test welds shall be of the same specification, grade or class, and shall be the same nominal diameter as will be used in the major part of the production. The wall thickness shall take into account the limits in the essential variables and, where there is a choice, it is preferable that the upper end of the range be qualified.

(b)

For material grades of SMYS greater than 480 MPa and welded with cellulosic consumables, the test piece material shall be from the same steel manufacturer, and shall have essentially the same composition as the material to be used in construction. NOTE: Combinations of materials from different manufacturers that have been individually qualified do not require separate qualification for the combination (see Table 6.2).

(c)

Where a weld is to be made between a material grade of SMYS less than 480 MPa, and another with material grade of SMYS greater than 480 MPa, a welding procedure qualification test weld made on the higher grade shall qualify the combination.

NOTE: Test certificates for the test material should be available at the time of qualification testing.

6.6.4 Preparation and assembly of test pieces The joint preparation of test pieces shall be in accordance with the proposed welding procedure specification and shall be within the specified dimensional tolerances. NOTE: The preparation should be made by the same method as will be used in production welding.

Test pieces shall be assembled in the required position so that the weld can be made in accordance with the proposed welding procedure specification. Tack welding shall only be carried out in accordance with the welding procedure. 6.6.5 Test conditions Subject to the requirements of Appendix C, the test weld (or welds) shall be made under conditions that simulate the worst case likely to be encountered during construction or operations. 6.6.6 Identification of the test weld Each test weld shall be uniquely identified. This identification shall be clearly marked on the test piece adjacent to the weld. 6.6.7 Recording a test weld Welding parameters shall be recorded using manual or automated means. Inspection equipment shall be appropriately calibrated. Records shall identify the name of the welder or welding operator and where appropriate the segment of weld undertaken by each welder. 6.6.8 Supervision of the test weld Procedure qualification test welds shall be made under continuous supervision of a welding supervisor qualified in accordance with Section 3 to ensure that all the requirements of the welding procedure specification are complied with and that the weld is free from unauthorized repairs. NOTE: The test may be terminated at any stage if it becomes apparent to the welding supervisor that a satisfactory weld cannot be made.

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6.7 PROVISONS FOR SPECIFIC WELDING METHODS 6.7.1 Cellulosic welding The purpose of welding procedure specification qualification for cellulosic welds is to demonstrate freedom from the risk of hydrogen assisted cold cracking (HACC).

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The basis of the design of the welding procedure for the avoidance of HACC shall be documented in the welding procedure specification. NOTE: Recommended methods for ‘designing out’ HACC from welding procedures are given in Appendix C.

Where required by Appendix C, a welding procedure specification shall be qualified by the use of full-length suspended pipes, line-up clamps, lowering off, support and expected environmental conditions. To establish the absence of HACC, the welding preheat, heat input or burn-off rate shall be at or near the lower end of the range to be qualified. NOTE: If the low heat input test weld is not considered the worst case for attributes other than freedom from HACC, additional welds may be undertaken to demonstrate compliance across the range of essential variables.

Where delay in completing some joints is anticipated, the test weld shall simulate that delay. 6.7.2 Provisions for waveform power sources During welding procedure qualification, where a controlled waveform power source is used, a data-logger shall record peak/background current, voltage, time and frequency. Alternatively, the welding machine model and settings may be recorded. In this instance the welding machine model shall be an essential variable. NOTE: Power sources that are generally marketed as synergic, programmable, or microprocessor controlled are normally capable of waveform controlled welding. Where any doubt exists, the welding equipment manufacturer should be consulted.

On waveform controlled power sources some welding characteristics are controlled by software or firmware internal to the power source. The heat input from these power sources cannot be measured using the method shown in Clause 1.6.31, due to the rapidly changing outputs, phase shifts and synergic changes. For waveform controlled power sources the heat input shall be determined by instantaneous energy (joules) or power (joules/second or watts). When the waveform control features of the power source are not being used, the heat input method shown in Clause 1.6.31 shall be used. If the power source does not display instantaneous power or energy, an external meter with high frequency sampling capable of displaying instantaneous power or energy shall be used, or the equipment shall be upgraded or modified to display instantaneous power or energy. 6.7.3 Aluminothermic welding 6.7.3.1 General An aluminothermic weld on a pipeline may be made without qualification where it is in accordance with Clause 6.7.3.2. An aluminothermic weld not made in accordance with Clause 6.7.3.2 shall be qualified in accordance with Clause 6.7.3.3 and tested in accordance with Clause 7.9. 6.7.3.2 Aluminothermic welding without qualification Aluminothermic welding without qualification shall comply with the following: (a)

The nominal thickness of the pipe shall be not less than 4.8 mm.

(b)

The size of the aluminium powder and copper oxide cartridge for aluminothermic welding shall be not more than 15 g.

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AS/NZS 2885.2:2016

(c)

The cross-sectional area of the cable conductor for each weld nugget shall be not more than 10.5 mm2 or the equivalent of four wires each of 1.78 mm diameter.

(d)

The depth of insertion of the conductor shall be sufficient for the weld material to contact the conductor and at the same time obtain a good weld to the pipeline.

(e)

The surface of the pipe for an area of not less than 50 mm square shall be cleaned by filing or grinding to remove all surface coatings.

6.7.3.3 Aluminothermic welding with qualification Aluminothermic welding with qualification shall comply with the following: (a)

An aluminothermic weld not carried out in accordance with Clause 6.7.3.2 shall be qualified separately for each material composition, size of conductor, cartridge size and type of surface preparation.

(b)

A procedure test shall be conducted on three nuggets, each of which shall pass a test of one firm side blow from a hammer having a mass of approximately 1 kg, after which each nugget shall be visually examined for adequate bonding and the absence of lifting. One of the test nuggets shall then be sectioned and metallographically examined for copper penetration (including penetration of the grain boundaries) using optical microscopy at a magnification of at least 100×. Copper penetration shall be as follows: (i)

For nominal thicknesses of 4.8 mm or greater—not more than 0.50 mm.

(ii)

For nominal thicknesses of less than 4.8 mm—not more than 10% of the nominal wall thickness.

6.7.4 Pin brazing Pin brazing connections on a pipeline shall be qualified and tested in accordance with the following: (a)

A qualification shall be performed separately for each material composition, size/type of brazing pin, size/type of brazing ferrule, type of surface preparation, position, and pin brazing equipment manufacturer.

(b)

Resistivity between the brazed conductor and the pipe shall be less than 0.1 Ω.

(c)

A procedure test shall be conducted on three brazed joints, each of which shall pass a test of one firm side blow from a hammer having a mass of approximately 1 kg, after which each brazed joint shall be visually examined for adequate bonding and the absence of lifting.

(d)

One of the brazed joints shall then be sectioned and metallographically examined for copper penetration (including penetration of the grain boundaries) using optical microscopy at a magnification of at least 100×.

(e)

(i)

The fusion line shall not extend beyond 1.0 mm of the surface.

(ii)

Copper penetration shall not extend beyond 0.5 mm of the fusion line

Two parallel hardness traverses shall be performed at a spacing of 1.0 mm ± 0.5 mm from the surface with indentations spaced at 0.5 mm, in accordance with AS 1817.1. Hardness traverses shall sample the parent metal, heat affected zone, brazing metal and fusion line, finding regions of minimum and maximum hardness. Hardness measurements shall not exceed 350 HV for non-sour environment and 250 HV for sour environments.

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TABLE 6.1 ITEMS FOR QUALIFIED PROCEDURES Item (see Note 1 of Table 6.2)

Remarks

PIPE

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1

(a) Material specification

Pipe and components complying with the AS 2885 set of Standards, another relevant Australian Standard, or another Approved Standard

(b) Material manufacturer

Where material grade yield strength ≥480 MPa

(c) Material carbon equivalent (CE)

CE = C +

Mn Cr + Mo + V Cu + Ni + + 6 5 15

2

Nominal thickness

Nominal thickness of each component of the joint

3

Diameter group

Applicable to the diameter of each pipe, branch pipe or component

PROCESS 4

Welding process

The arc welding process e.g. MMAW, automatic GMAW, GTAW, SAW, FCAW or a nominated combination

DESIGN 5

Preparation

Joint preparation, e.g. type and details of bevel, root face, and gap, and the dimensional tolerances upon the preparation. For high-low limits refer to Clause 18.4.3

6

Weld shape and size

Shape and size of welds

7

Backing

Type of backing or consumable insert (if used)

8

Passes

Number and sequence of passes (including stripper passes)

9

Position

Positions shown in Table 8.1

10

Direction of welding

Vertical up or vertical down

FILLER 11

Filler metal

Diameter and classification of electrode for each pass. For mechanized GMAW, electrode brand name

SHIELDING 12

13

Shielding gas

Shielding flux

(a)

Type, composition and flow rate of gas or gas mixtures used for shielding or backing

(b)

Nozzle or cup size

Type, size, classification, make and brand number

ELECTRICAL 14

Electrical characteristics

Arc type (globular, spray, pulsed, short circuit), current, polarity, voltage and wave form for each size and type of electrode

15

Waveform power sources

A change in the welding machine model

16

Contact to work distance

A change in the distance (continued)

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TABLE 6.1 (continued) Item (see Note 1 of Table 6.2)

Remarks

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PROCEDURE 17

Number of welders

Minimum number of root and hot pass welders

18

Type of line-up clamp

Internal clamp, external clamp, no clamp

19

Removal of line-up clamp, and/or type of lift (see Note 7 of Table 6.2)

Minimum percentage of root pass to be completed before release of clamp. Where less than 100%, the location of the completed proportion shall be specified (see Notes 6, 7 and 8 of Table 6.2). The type of lift shall also be specified

20

Tack welding (if used)

Number and size of tacks employed

21

Time lapse between individual passes (see Table 6.2)

Maximum time lapse— (a)

between the start of the root pass and the start of the hot pass; and

(b)

between subsequent passes

22

Preheat temperature and interpass temperature

Heating method, width heated, preheat temperature and interpass temperature

23

PWHT and post-weld cooling

(a)

For PWHT, the heating method, width heated, minimum and maximum temperature, time at temperature, method of temperature measurement, and control of maximum and minimum cooling rates

(b)

For deliberate accelerated post-weld cooling above 100°C, the method or the rate of cooling

24

Heat input or burn-off rate (see Note 5 of Table 6.2)

Heat input or burn-off rate for each pass

CLEANING 25

Cleaning

Equipment and method used

METHOD OF QUALIFICATION 26

The method of qualification as listed in Nominate the method of qualification Clause 6.4

NOTE: Item indicates the specification topic.

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TABLE 6.2 ESSENTIAL VARIABLES FOR QUALIFIED WELDING PROCEDURES Item and essential variable (see Note 1)

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Pipe

Welding process Cellulosic MMAW

Low GMAW and hydrogen FCAW MMAW

SAW

GTAW

1. Material: (a)

Change of SMYS > 45 MPa, material with a SMYS > 480 MPa

X

X

X

X

X

(b)

Where material SMYS ≥480 MPa—Steel manufacturer (combinations between different steel manufacturers do not require separate qualification [see Clause 6.6.3(b)]

X

—

—

—

—

For actual CE values of 0.05 above that used for the procedure test weld

X

—

—

—

—

For actual CE values of ≥0.35, an increase of carbon equivalent of > 0.03 above that used for the procedure test weld

X

—

—

—

—

For actual CE, an increase of carbon equivalent of > 0.10 above that used for procedure test weld

—

X

X

X

X

For material that is to be PWHT, a change to or from quenched and tempered or thermo-mechanically processed condition

X

X

X

X

X

Tier 1: Change of material nominal thickness in a component of a joint

0.5t–1.2t

0.5t–1.5t

0.5t–1.5t

0.5t–1.5t

0.5t–1.5t

Tier 2: Change of material nominal thickness in a joint

t–1.2t

t–1.2t

t–1.2t

t–1.2t

t–1.2t

Tier 3: Change of material nominal thickness in a joint

t

t

t

t

t

X

X

X

X

X

X

X

X

X

X

(c)

(d)

(e)

(f)

2. Wall thickness

3. Diameter group Change in diameter outside the diameter groups qualified as follows: (a)

D ≤60.3 mm

(b)

60.3 mm < D ≤508 mm

(c)

D > 508 mm where D is the diameter of the test weld

Or, as an alternative to the diameter groups given above, where there is a change in diameter from a qualified procedure of more than 50% of the diameter

(continued)

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TABLE 6.2 (continued) Item and essential variable (see Note 1) Pipe

Welding process Cellulosic MMAW

Low GMAW and hydrogen FCAW MMAW

SAW

GTAW

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4. Welding process (a)

A change from one welding process or combination to another

X

X

X

X

X

(b)

Change from a manual operation to semiautomatic or automatic operation, or vice versa

—

—

X

X

X

(c)

Change of automatic welding system used

—

—

X

X

X

(d)

Change of bug manufacturer or model

—

—

X

X

X

DESIGN 5. Preparation (a)

Any change to the nominal dimensions of the weld preparation and their tolerances

X

X

X

X

X

(b)

An increase in the permitted level of high-low beyond the limits of Clause 18.4.3

X

X

X

X

X

X

X

X

X

X

—

X

X

X

X

X

—

—

—

—

Change in position other than as permitted by Table 8.1

X

X

X

X

X

Change in lead angle beyond range qualified

—

—

X

X

X

X

X

X

—

X

6. Weld shape and size Change beyond that permitted by joint design tolerances (see Section 5) 7. Backing Deletion or addition or change of a backing material or consumable insert 8. Passes Reduction in number of passes to less than 4 9. Position

10. Direction of welding Change between vertical up and vertical down

(continued)

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TABLE 6.2 (continued) Item and essential variable (see Note 1) Pipe

Welding process Cellulosic MMAW

Low GMAW and hydrogen FCAW MMAW

SAW

GTAW

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11. Filler metal (electrodes, filler wire) (a)

(b)

(c)

Any change in welding consumable classification (as defined within a nominated standard (Table 4.1.)

X

X

X

X

X

Change in electrode brand name or diameter used for the root pass of electrode, filler wire or rod

X

X

X

X

X

For Cellulose or Cellulosic electrodes a change in any of the following:

X

—

—

—

—

(i)

X

—

—

—

—

X

—

—

—

—

Manufacturer and factory of origin

(ii) A change in electrode classification used beyond 5% of the nominal thickness SHIELDING 12. Shielding gas (a)

Change between one gas or mixture and another gas or mixture

—

—

X

—

X

(b)

Decrease in shielding gas flow rate by more than 10% or decrease in the nozzle or cup size

—

—

X

—

X

Change of gas backing type, composition or flowrate

—

—

X

—

X

(c)

13. Shielding flux (a)

Change in flux, type, classification or make number

—

—

—

X

—

(b)

Change in flux/electrode combination resulting in different classification number

—

—

—

X

—

ELECTRICAL 14. Electrical characteristics (a)

Change of polarity of the electrode

X

X

X

X

X

(b)

Change of electrical current between a.c. and d.c.

X

X

X

X

X

(c)

Change of arc type between spray arc, globular arc, pulsed arc, and shortcircuiting (dip transfer) arc or between the use of a conventional power source and a controlled waveform power source

—

—

X

X

X

(d)

Change in the welding machine model

—

—

X

X

—

(e)

Change of more than 25% in contact tipto-work distance

—

—

X

X

— (continued)

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TABLE 6.2 (continued) Item and essential variable (see Note 1) Pipe

Welding process Cellulosic MMAW

Low GMAW and hydrogen FCAW MMAW

SAW

GTAW

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15. Number of welders Decrease in number of welders used on any root pass, or hot pass, in the procedure test weld

X

—

X

—

—

A reduction in the proportion of root pass welded before the line-up clamp is released

X

X

X

X

X

A change from normal to extreme lift (see Appendix C)

X

—

—

—

—

X

X

X

X

X

16. Removal of line-up clamp (see Note 8) (a)

(b)

17. Tack welding A reduction in the number or size of tack welds or both. 18. Time between individual passes (see Note 4) (a)

Increase in time lapse beyond the qualified range for the root to hot pass

X

—

—

—

—

(b)

Increase in time lapse between other passes

X

—

—

—

—

For material grades of SMYS480 MPa a decrease in material temperature of more than 10°C below or an increase of more than 75°C above that used in the procedure test weld

X

X

X

X

X

19. Preheat and interpass temperatures (a)

(b)

NOTE: Refer to Clause 6.6.5 which requires the test weld to be made under conditions that simulate the worst case to be encountered in production. 20. PWHT and/or cooling (a)

Change in PWHT

X

X

X

X

X

(b)

Change in post-weld cooling method and intensity, or rate of cooling (see Clause 13.2)

X

X

X

X

X (continued)

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TABLE 6.2 (continued) Item and essential variable (see Note 1) Pipe

Welding process Cellulosic MMAW

Low GMAW and hydrogen FCAW MMAW

SAW

GTAW

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(a)

(b)

For each individual pass of mechanized or automatic welding a change of heat input of more than 15% from the average determined using data associated with corresponding weld pass from the procedure test weld

—

—

X

X

—

For manual welding a change of heat input or burn off rate of more than 15% above and below the range used in the procedure test weld. At the licensee’s discretion, extreme high or low heat input outliers may be deleted from the range

X

X

X

—

X

X

X

X

X

X

22. Cleaning Equipment and method used NOTES: 1

‘X’ indicates applicability.

2

The essential variable specifies the limits outside which requalification is required. Changes in nonessential variables require documentation but do not require requalification.

3

In tapered joints or branch welds the nominal thickness to be considered shall be the effective thickness on the thicker side of the joint. The effective thickness shall be as defined in WTIA Technical Note 1.

4

The method of defining time lapse shall be the same for production welds as is used for procedure qualification welds. It is recommended that the time lapse from start of root pass to start of hot pass be the defined method to avoid uncertainties associated with root repairs.

5

Burn-off rate is defined as the ratio of length of electrode consumed to the length of weld pass deposited. WTIA Technical Note 1 provides information relating burn-off rate to heat input.

6

The essential variables in Table 6.2 primarily address the risk of HACC. This is clearly evident by the latitude extended to the range of nominal thickness (Item 2). Tier 2, however, permits increased defect limits based on demonstrated mechanical properties, i.e. weld metal strength matching and fracture toughness. Although Tier 2 defect limits are proportional to nominal thickness, variations in nominal thickness can strongly influence defect tolerance. This is principally a consequence of the fact that planar defects are assumed to be one weld pass deep (i.e. 3 mm). Such an assumed defect depth in thin-walled pipe can significantly change the requirement of weld strength matching (despite the proportional decrease in defect limit). For this reason the Tier 2 and Tier 3 lower limit multiplier for nominal thickness range is more restrictive than that for Tier 1.

7

Research work carried out by the CRC for welded structures (CRC-WS) has shown that for normal lifts (see Appendix C, Paragraph C9.2.1) the additional strains over and above the weld contraction strains, caused by lifting and lowering, are small for pipe diameters less than DN 500. It has also shown that providing due attention is paid to the other factors governing the risk of HACC, the removal of the lineup clamp after at least 50% of the root pass is completed, does not by itself cause cracking.

8

The proportion of the root pass completed before clamp release shall be ≥50%.

9

Where the proportion of the root pass completed before the line-up clamp is released is 323.9 All

2

>114.3 ≤323.9

1

2

>114.3 ≤323.9

≤114.3

1

1

>33.4 ≤60.3 >60.3 ≤114.3

1

Tensile (Note 2) (Clause 7.4.2) ≤33.4

mm

All

>13

≤13

mm

Diameter (D)

Fillet

Circumferential butt

Type of weld

Nominal thickness (t N )

TABLE 7.2 WELDING PROCEDURE TEST WELDS—TYPE OF DESTRUCTIVE TEST AND NUMBER OF SPECIMENS

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55 AS/NZS 2885.2:2016

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56

S E C T I O N

8

W E L D I N G

P O S I T I O N S

8.1 DESIGNATION

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Positions for test welds shall be designated as shown in Figure 8.1, and shall be within ±15° of the nominal position. Where the position of a production weld cannot be related to one or more of the designated weld positions, a special test position shall be used. 8.2 LIMITS OF QUALIFIED POSITIONS The position used in the welding procedure qualification test and welder qualification tests shall also qualify other positions as shown in Table 8.1. The type of weld qualified by the welder shall also qualify the welder for other types of weld as shown in Table 8.2.

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TABLE 8.1 POSITIONS FOR WELDING PROCEDURE AND WELDER QUALIFICATION TESTS FOR BUTT, FILLET, SLEEVE AND BRANCH WELDS ON PIPE AND RECIPROCITY OF TYPES OF WELD AND POSITION (see Note 1) Type of weld and position qualified (see Note 2)

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Qualification test on pipe Type of weld Description

Butt (girth)

Position of axis Butt

Fillet

Branch

Sleeve

Horizontal (flat)

1G

—

—

—

Vertical— fixed

Horizontal

1G and 2G

2F and 2FR

—

—

5G

Horizontal— fixed

Multiple

1G and 5G

Any

—

—

6G

Inclined 45°— fixed

Multiple

Any

Any

—

—

2G and 5G1 (see Note 3)

Vertical— fixed, and horizontal— fixed

Horizontal and multiple

Any

Any

—

—

2F

Vertical— fixed

Horizontal

—

2F and 2FR

—

—

2FR

Horizontal— rotated

Horizontal

—

2FR

—

—

4F

Vertical— fixed

Horizontal (overhead)

—

2F, 2FR, and 4F

—

—

5F

Horizontal— fixed

Multiple

—

Any

—

5F (sleeve)

2B

315° to 45°

Horizontal (flat)

1G and 2G

2F and 2FR

2B

—

4B

135° to 225°

Horizontal (overhead)

1G and 2G

2F, 2FR, and 4F

2B and 4B

—

5B

45° to 135°

Multiple

1G and 2G

Any

Any

—

5F

Horizontal— fixed

Multiple

—

Any

—

Any

1G Plate

Downhand butt plate

Downhand (flat)

—

Any

—

1G Plate

2G Plate

Horizontal butt plate

Horizontal

—

Any

—

1G and 2G Plate

4G Plate

Overhead butt plate

Overhead

—

Any

—

Any

2G and 4G

Vertical fixed

Horizontal and horizontal (overhead)

—

—

—

—

2G and 4G (spherical)

5G

Horizontal fixed

Multiple

—

—

—

—

All (spherical)

Symbol

Pipe

Weld

1G

Horizontal— rotated

2G

Spherical

Fillet

Branch (see Note 4)

Sleeve

Spherical circumferential

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NOTES TO TABLE 8.1: 1 Table 8.2 gives reciprocity of weld types for welder qualification (see also Clause 10.6). 2 Refer to Figure 8.1 for the types of welds and positions. 3 Qualified by separate tests for each position or a combination of 2G and 5G test welds.

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4 Tee butt welds qualify fillet welds as listed. Fillet welds do not qualify tee butt welds. Butt welds qualified by branch connection weld procedure qualification tests shall be restricted to the types of butt welds involved in the branch connection (see also Clause 5.9).

TABLE 8.2 RECIPROCITY OF WELD TYPES FOR WELDER QUALIFICATION Weld types qualified in welder qualification test Type number of weld

Weld type number qualified without further testing (Note 1)

Description of weld

1

1G butt weld with pipe horizontal and rotated

1

—

—

—

—

—

—

—

—

—

2

2G butt weld with pipe vertical and fixed

1

2

—

—

—

—

—

—

—

—

3

5G butt weld with pipe horizontal and fixed

1

—

3

—

—

6

—

—

—

—

4

2G and 5G butt weld or a 6G butt weld with pipe inclined 45° and fixed

1

2

3

4

—

6

—

—

—

—

5

Mark out, cut, fit and weld in position 5B either a sit-on bevelled end forged fitting or a sit-on tee-butt pipe branch

—

—

—

—

5

6

7

—

—

—

6

Make a fillet weld in position 5F on the socket weld end of a forged fitting, a socketed pipe, a slip-on flange, a bracket, a pad or a plain end sit-on branch

—

—

—

—

—

6

—

—

—

—

7

Mark out, cut, fit, and weld in position 5B either a forged set-in branch or a nonreinforced set-in pipe branch

—

—

—

—

5

6

7

—

—

—

8

Fit and weld either a circumferential split sleeve or a tee fitting with a longitudinal single V butt weld with backing strip and ends fillet-welded

—

—

—

—

—

6

—

8

—

—

(continued)

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TABLE 8.2 (continued)

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Weld types qualified in welder qualification test

Weld type number qualified without further testing (Note 1)

Type number of weld

Description of weld

9 (see Note 2)

Mark out, cut, fit and weld in position 5B either a sit-on bevelled end forged fitting or a sit-on tee-butt pipe branch under simulated accelerated cooling conditions (live welding qualification)

—

—

—

—

5

—

—

—

9

—

10 (see Note 3)

Fit and weld either a circumferential split sleeve or a tee fitting with a longitudinal single V butt weld with backing strip and ends fillet-welded under simulated accelerated cooling conditions (live welding qualification)

—

—

—

—

—

—

—

8

—

10

NOTES: 1

For reciprocity of welding positions, see Table 8.1.

2

A suitable test medium should be used which creates a quench effect equal to, or more severe than, the conditions to be encountered during production welding (refer to Clause 16.17 and Figure 16.1).

3

Qualified by separate tests in each position or a combination of 2G and 5G test welds.

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Type of weld

Welding positions

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Butt weld Axis of pipe horizontal Pipe rotated Flat position, 1G

Axis of pipe vertical Pipe fixed Horizontal position, 2G

Axis of pipe horizontal Pipe fixed Multiple position, 5G

Axis of pipe inclined 45° Pipe fixed Multiple position, 6G

Axis of pipe horizontal Pipe rotated Horizontal position, 2FR

Axis of pipe vertical Pipe fixed Horizontal position, 2F

Axis of pipe horizontal Pipe fixed Multiple position, 5F

Axis of pipe vertical Pipe fixed Overhead position, 4F

Axis of pipe horizontal Pipe rotated Multiple position, 5F Circumferential fillet

1G Plate with backing strip Longitudinal weld

2G Plate with backing strip Longitudinal weld

4G Plate with backing strip Longitudinal weld

Fillet weld

Sleeve/ Stopple fitting weld

To p of p i p e at 0 °

To p of p i p e at 0 °

4 5° m a x.

4 5° m a x.

4 5° m a x. Branch weld (including set-in, seton and ‘O-let’ type fittings)

To p of p i p e at 0° 4 5° m a x. 4 5° m a x. Axis of pipe horizontal Axis of branch normal Pipe and branch fixed Branch weld positioned within 45° to 135° Multiple position, 5B

4 5° m a x.

Axis of pipe horizontal Axis of branch normal Pipe and branch fixed Branch weld positioned within 135° to 225° Overhead position, 4B

Axis of pipe horizontal Axis of branch normal Pipe and branch fixed Branch weld positioned within 315° to 45° Horizontal position, 2B

FIGURE 8.1 (in part) WELD TEST POSITIONS

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90°

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Spherical butt weld— Fitting to fitting

4 5° max.

90° 4 5° max. 0°

18 0 °

270 °

Spherical butt weld— Fitting to pipe

4 5° max.

4 5° max. 4 5° max. 0°

18 0 °

4 5° 90° max.

18 0 °

270 °

Axis of pipe horizontal Split of spherical horizontal Pipe and spherical fixed Butt weld position within 315° to 45° Horizontal position, 2G

4 5° max.

AS/NZS 2885.2:2016

0°

270 °

Axis of pipe horizontal Split of spherical vertical Pipe and spherical fixed Butt weld position within 45° to 135° Multiple positions, 5G

Axis of pipe horizontal Split of spherical 45° incline Pipe and spherical fixed Butt weld position within 0° to 90° Multiple positions, 6G

Axis of pipe vertical Pipe and spherical fixed Horizontal position (overhead), 4G

Axis of pipe horizontal Pipe and spherical fixed Multiple position, 5G

4 5° 90° max.

18 0 °

0°

270 ° Axis of pipe vertical Pipe and spherical fixed Horizontal position, 2G

FIGURE 8.1 (in part) WELD TEST POSITIONS

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9 Q U A L I F I C A T I O N O F A O R W E L D I N G O P E R A T O R

W E L D E R

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9.1 PURPOSE OF QUALIFYING A WELDER OR WELDING OPERATOR A welder or welding operator shall be qualified in order to demonstrate an ability to follow the appropriate qualified welding procedure and the dexterity to make welds using that procedure to the requirements of this Standard. 9.2 SCOPE OF WELDER OR WELDING OPERATOR QUALIFICATION A qualified welder or welding operator may weld the type or types of weld, the weld pass(es), and the section of the weld and in the positions qualified (see Table 8.1) provided the qualification is limited by the essential variables for the welder and welding operator (see Clause 9.5). 9.3 METHODS OF QUALIFICATION A welder or welding operator shall be qualified by one of the following methods: (a)

Assessment of the welder or welding operator’s first production weld in accordance with Clause 10.1.

(b)

The production of documentary evidence showing that the test piece required for the qualification of the welding procedure has been welded by the welder or welding operator, and that the procedure has been qualified.

(c)

The welding of a test piece that simulates the production weld, and its subsequent examination, testing, and assessment in accordance with Section 10.

9.4 QUALIFICATION BY TESTING Where a welder or welding operator is to be qualified by testing, a test weld shall be made on a suitable test piece in accordance with a qualified welding procedure. The test weld shall be examined and tested. Where the weld complies with this Standard and the results have been recorded (see Clause 9.5), the welder or welding operator shall be qualified. Where two or more welders or welding operators qualify on a single test piece, each welder or welding operator shall be qualified for that position used and section or portion of the weld made. Part or all of the welder or welding operator qualification tests may be waived on production of evidence that similar welds, within the limits of the essential variables (see Table 9.1) have been made within the previous 12 months. 9.5 ESSENTIAL VARIABLES FOR WELDERS AND WELDING OPERATORS Essential variables for welders or welding operators shall be as listed in Table 9.1. NOTES: 1 Essential variables for a welder or welding operator are those variables in which a change outside the limits shown in Table 9.1 is considered likely to result in a change in the mechanical properties and soundness of a weld, e.g. a change in technique or welding process; or a change in welding position. 2 The essential variables associated with the welder or welding operator qualification and welding procedure qualification are not the same.

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TABLE 9.1 ESSENTIAL VARIABLES FOR QUALIFIED WELDERS AND WELDING OPERATORS Welding process (see Note) Item

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1

Manual

Automatic/mechanized

X

X

X

X

X

—

Change of basic joint design used for the welding procedure qualification test e.g. angle of bevel, root gap, root face

X

X

Deletion of backing strip or a consumable insert in a singlesided butt weld

X

X

X

X

X

X

X

X

X

X

Welding process Change of welding process or combination of welding processes

2

Material—Nominal thickness Change of material nominal thickness (δN) beyond the range δN/2 to 1.5δN, where δN equals the nominal thickness used in the welding procedure qualification test weld

3

Material—Diameter Change of outside diameter beyond the range qualified in the welding procedure qualification test weld

4

5

Joint design

Welding position Addition of welding positions not qualified by the welder qualification test weld

6

Direction of welding Change of direction of welding between vertical-down and vertical-up

7

Filler metal Change of flux type from one flux type to another, e.g. cellulose to basic or solid wire to flux cored

8

Electrical characteristics Change between spray arc, globular arc, pulsed arc, and short-circuiting arc (dip transfer)

NOTE: ‘X’ indicates applicability.

9.6 TEST PIECE The size of the test piece(s) used for a welder or welding operator’s qualification shall be sufficient to provide the required number of test specimens. The material for the test piece(s) shall be within the limits of the welding procedure essential variables and the welder and welding operator essential variables. The joint preparation shall be within specified tolerances for production, and should preferably be made by the same method as that used in production. 9.7 ASSEMBLY OF TEST PIECES A test piece shall be assembled so that the weld can be made in accordance with the qualified welding procedure and in the required position. If tack welds are used, they shall be made in accordance with the qualified welding procedure.

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9.8 AUTOMATIC WELDING EQUIPMENT Where a welding operator is to be tested on automatic welding equipment, the equipment shall be identical to that used in production, and it shall have been demonstrated that the equipment can make an acceptable welding procedure test weld. The welding operator shall be adequately trained on the automatic welding equipment before making the test weld.

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9.9 MAKING A TEST WELD The test weld shall be made in accordance with the qualified welding procedure. A welder shall make one or more of the types of welds classified in Table 8.2. A welding operator shall make a butt weld using automatic or mechanized welding equipment. 9.10 SUPERVISION OF A TEST WELD A test weld for a welder or welding operator qualification test shall be made under the continuous supervision of a welding supervisor, to ensure that the requirements of the welding procedure specification are followed and that the weld is free from unauthorized repairs. The test should be terminated at any stage when it becomes apparent to the welding supervisor that the welder or welding operator does not have the ability required to produce a satisfactory weld. 9.11 IDENTIFICATION OF A TEST WELD The identification of the qualified welding procedure specification and each welder or welding operator’s identification shall be clearly marked on the test weld. The top (or other appropriate orientation) shall also be marked on the test weld. For test pieces containing more than one welder or welding operator’s work the limits of each person’s work shall be identified. 9.12 QUALIFICATION OF ALUMINOTHERMIC WELDING AND PIN BRAZING OPERATORS Operators for aluminothermic welding and pin brazing shall be— (a)

trained in use of the equipment and have a certificate of competency; and

(b)

perform three conductor connections that shall pass a test of one firm side blow from a hammer having a mass of approximately 1 kg and have a joint resistance of less than 0.1 Ω.

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S E C T I O N 1 0 A S S E S S M E N T O F T E S T W E L D S F O R W E L D E R O R W E L DI N G O P E R AT O R QUALI FICAT I ON

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10.1 METHOD OF ASSESSMENT A test weld made for welder or welding operator qualification shall be assessed by each of the following methods: (a)

Visual examination.

(b)

Assessment of the test weld by non-destructive testing using the appropriate methods for the assessment of production welds. NOTE: Destructive tests may be used to supplement non-destructive testing.

(c)

Where the joint configuration is a set-on branch, set-in branch or fillet weld, assessment by macro-examination in accordance with Clause 7.4.5. Four specimens are required.

(d)

Where more than one welder or welding operator is involved in making a test weld, assessment shall be made of each person’s work in accordance with the requirements above.

(e)

Where the production welding involves welding onto an in-service pipeline— (i)

for heat input control procedures, the welder shall be able to demonstrate the ability to maintain a heat input level within the range specified; and

(ii)

for temper bead procedures, the welder shall be able to demonstrate proper bead placement.

10.2 VISUAL EXAMINATION The external surface and, where practicable, the internal surface of the test weld shall be visually examined in accordance with Section 18. The visual examination shall include measurement of the height of weld reinforcement in order to ensure compliance with the requirements of Figure 18.1, where applicable. NOTE: Experience has shown that excessive weld reinforcement height particularly at the top and bottom of welds, has been a problem in the field, and there have been serious difficulties in meeting the density requirements in radiographic inspection. For this reason it is important that an assessment be made of the capability of the welder to produce welds within the required reinforcement limits.

10.3 NON-DESTRUCTIVE TESTING The test weld shall be subjected to non-destructive testing in accordance with Section 19. 10.4 REPEATED TEST 10.4.1 General Where the test weld fails to comply with the acceptance criteria and subject to approval one further test weld may be specified to the same examination. 10.4.2 Repeated failure If the second test weld fails to comply with the criteria of acceptance under similar circumstances, the cause shall be investigated. NOTE: Where appropriate, the welding procedure should be an aspect of the investigation.

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10.5 RECORD OF RESULTS A record of the results of the assessment of each test, including any repeated test, shall be made for each welder or welding operator qualification test.

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Where tests have demonstrated that the weld is satisfactory, a record stating that a weld made to the particular qualified welding procedure and complying with this Standard shall be approved by the welding supervisor, thus qualifying the welder or welding operator. 10.6 PORTABILITY QUALIFICATION

OF

A

WELDER’S

OR

WELDING

OPERATOR’S

Subject to approval, welder or welding operator qualification tests undertaken by others may be accepted provided these tests have been— (a)

carried out in accordance with this Standard; and

(b)

fully documented.

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S E C T I O N 1 1 W E L D E R O R W E L D I N G OPER ATOR Q U A L I FI CA T I O N A N D D I S Q U A L I F I C A T I O N

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11.1 RECIPROCITY QUALIFICATION

OF

A

WELDER’S

OR

WELDING

OPERATOR’S

A welder who has qualified to make a weld having one type number shall be qualified to make welds having other type numbers in accordance with Table 8.2. 11.2 PERIOD OF VALIDITY A welder’s or welding operator’s qualification shall remain valid until withdrawn (see Clause 11.4) provided, during the preceding 12 months, the welder or welding operator has been engaged in welding to the same qualified welding procedure, or a procedure that is within the essential variables for qualified welders and welding operators in Table 9.1. 11.3 QUALIFICATION RECORD A record shall be made of the tests undertaken by each welder or welding operator and of the detailed results of each test. A list of qualified welders or welding operators, including the identification symbol or mark, and the qualified welding procedures for which each is qualified shall be maintained. 11.4 DISQUALIFICATION OF A WELDER’S OR WELDING OPERATOR’S QUALIFICATION Where production welds made by a specific welder or welding operator frequently fail to comply with the criteria of acceptance, thus demonstrating that the welder or welding operator no longer has either the ability to follow the qualified welding procedure or the dexterity to make a satisfactory weld, the qualification shall be withdrawn. The welder or welding operator shall be requalified again before making further production welds or repairs to welds.

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1 2

P R O D U C T I O N

W E L D S

12.1 WELDING PROCESS

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Production welds shall be made in accordance with previously defined and qualified procedures in accordance with Section 6, and within the limits of essential variables. NOTE: It is recommended that gas tungsten arc welding be used for butt welds on pipes with a diameter of 42.2 mm or less.

12.2 WELDING EQUIPMENT Welding equipment shall be of a size and type suitable for the work. It shall be maintained in a condition that will ensure the production of satisfactory welds, the continuity of operation and the safety of personnel. 12.3 WELDER AND WELDING PROCEDURE All welds shall be made using a qualified welding procedure by qualified welders or welding operators in accordance with Sections 6 and 9 of this Standard. 12.4 SUPERVISION OF WELDING Production welding shall be coordinated by a welding supervisor. The welding inspector shall examine and undertake visual inspection of all production welds. NOTE: See Section 3.

12.5 SAFETY IN WELDING Refer to Section 2. 12.6 STORAGE AND HANDLING OF ELECTRODES, FILLER RODS AND FLUXES Electrodes, filler rods and fluxes shall be stored and handled in accordance with Clause 4.2.2, in such a manner that will prevent damage or deterioration. Consumables in opened containers shall be protected from deterioration. Damaged material shall not be used. 12.7 WELDING IN ADVERSE CLIMATIC CONDITIONS Welding shall not be carried out under climatic conditions that contribute to persistent defects. Where a gas-shielded arc-welding process is used and winds or draughts could impair the quality of the weld, welding habitats or windshields should be used. 12.8 PREPARATION FOR WELDING 12.8.1 Edge preparation Surfaces and edges to be welded shall be smooth, uniform and free from cracks, fins, tears, and other defects that could affect the soundness of the weld. Surfaces to be welded and surfaces adjacent to the weld shall be free from paint, scale, slag, moisture, rust, grease, or other foreign matter.

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12.8.2 Internal cleaning The internal surface of the pipe shall be free of loose debris. It should be swabbed if necessary. 12.9 METHOD OF MAKING THE WELD PREPARATION

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The weld preparation shall be made in the manner specified in the qualified welding procedure specification. 12.10 ACCURACY OF ALIGNMENT Components shall be assembled to provide alignment within the limits of Clause 18.4.3. 12.11 LINE-UP CLAMP Line-up clamps shall— (a)

provide rounding of pipe ends (removal of ovaling does not expand pipe diameters);

(b)

accommodate dimensional tolerances in abutting pipes;

(c)

provide even distribution of ‘high/low’;

(d)

have appropriate gap setting;

(e)

provide access for welding operation;

(f)

not damage pipe coating (either the internal or external); and

(g)

not contaminate the weld (pick up impurities).

The line-up clamp shall be released only after the length of root pass is equal to or greater than the minimum specified in the qualified welding procedure specification. NOTE: Line-up clamps require specific settings and maintenance.

The use of copper backing shoes for GMAW procedures shall be evaluated during the procedure qualification testing to ensure copper contamination is not causing liquid metal embrittlement. The root pass of the test welds shall be ground flush on the inside of the pipe and MPI undertaken on the root face to confirm no indications of copper induced cracking. 12.12 TACK WELDS Tack welds shall only be used as a means of alignment during welding when tack welding is specified in the qualified welding procedure. Tack welds shall be deposited only in the weld groove and, where the tack weld is to be incorporated into the finished weld, full fusion at the root shall be obtained. The length of individual tack welds shall not be less than 25 mm or 20% of the outside diameter of the pipe, whichever is the lesser. Tack welds that are unsound shall be ground out. 12.13 WORKING CLEARANCE There shall be safe access and clearance for welding. These items shall be covered in the construction safety plan AS 2885.1 to ensure that identified threats are adequately mitigated. 12.14 PLACEMENT OF WELD PASSES Consecutive or adjacent weld passes shall not be started at the same circumferential position.

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12.15 ARC STRIKE AND ARC BURN An arc shall be struck only on the fusion faces or the surfaces of the parent material that will be fused into the weld. An arc burn that results from an inadvertent arc strike shall be removed in accordance with Section 26 or Section 27. The work return clamp shall make good electrical contact with no evidence of arcing.

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12.16 CLEANING Each pass of weld metal shall be cleaned in the manner specified in the qualified welding procedure. 12.17 PEENING Peening shall not be carried out on the root pass or the capping pass or passes. On filler passes, peening shall be carried out when specified in the qualified welding procedure. 12.18 INSERT PATCHING Insert patching shall not be carried out. 12.19 PREHEAT AND INTERPASS TEMPERATURE 12.19.1 General The preheat and interpass temperature shall be that specified in the qualified welding procedure. Both parts of the parent metal shall be at the required temperature at the time that welding is commenced. 12.19.2 Application of preheat and interpass temperature The specified preheat and interpass temperatures shall be maintained during all stages of welding including tack welding. 12.19.3 Extent of heating The full thickness of both parts of the parent metal shall be heated to the required temperature. The width of the heated band on either side of the centre-line of the weld shall be not less than 75 mm, or three times the width of the weld, whichever is the greater. 12.19.4 Monitoring of preheat and interpass temperature The temperature shall be monitored at positions that are not less than 25 mm from the weld position by the use of temperature-indicating crayons, thermocouples, pyrometers, or other appropriate methods. 12.19.5 Condensation Where preheating is specified in the qualified welding procedure, and where a gas flame is used for preheating, no condensation or moisture shall remain. NOTE: Where the metal temperature is less than 100°C, the flame should not be directed into the weld preparation.

12.20 POST-WELD HEAT TREATMENT (PWHT) Where specified in the qualified welding procedure, PWHT shall be carried out in accordance with Section 13. Any proposed PWHT shall be reviewed by a welding engineer.

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12.21 IDENTIFICATION OF A PRODUCTION WELD

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A production weld and supporting records shall be fully traceable in the documentation generated as part of the pipeline as-building process. This includes the weld unique identification that can then be used to define the location, the welder and the NDT records for the weld. The methodology to achieve this traceability shall be approved (see Clause 1.6.1).

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P O S T - W E L D H E A T T R E AT M E NT A N D P O S T - W E L D C O O L I N G

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13.1 POST-WELD HEAT TREATMENT The thickness at which PWHT is required shall be determined from the engineering design. If the thickness exceeds 32 mm further testing and examination is required. The method of PWHT will be in accordance with AS 4458. The thermal cycle from PWHT shall not damage pipeline components such as ball valves and monolithic insulating joints. The welding procedure qualification test weld shall undergo the same heat treatment cycle(s) that the final completed welds and parent material will be exposed to during installation. Each lot of material that is required to be heat treated shall undergo mechanical testing in accordance with the material manufacturing standard to which it complies to confirm its mechanical properties in the heat treated condition. This requirement includes qualifying the weld and parent material for multiple cycles of heat treatment if repairs are going to be undertaken. NOTE: Consideration should be given to undertaking preliminary NDT prior to PWHT to minimize the number of thermal cycles the weld and parent material is exposed to.

The effect of PWHT on high strength materials shall be investigated. 13.2 POST-WELD COOLING The use of deliberate accelerated cooling of a weld shall be permissible provided— (a)

it shall not be used before the weld has cooled to 300°C; and

(b)

if it is used before the weld has cooled to 100°C, it shall be regarded as an essential variable and shall be qualified as an item of the welding procedure.

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1 4 A S S E S S M E N T O F P R O D U C T I O N W E L D S A N D R E P A I R W E L D S

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Production welds shall be examined and assessed in accordance with Section 14. 14.2 METHODS OF EXAMINATION Production welds shall be subjected to the following: (a)

Visual examination in accordance with Section 18.

(b)

Non-destructive testing in accordance with Section 19.

14.3 PRODUCTION CUT-OUT WELDS On pipelines longer than 10 km a minimum of three production weld cut outs shall be taken at random from production welds and shall be subject to the same mechanical testing requirements as the PQR and are required to meet the testing requirements of Section 6. If the pipeline is less than 10 km at least one production cut-out weld shall be taken.

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S E C T I O N 1 5 W E L D I N G A N D C U T T I N G O N P I P E L I N E A F T E R C O M M I S S I O N I N G O R A F T E R H Y D R O S T A T I C T E S T I N G

A

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15.1 GENERAL This Section specifies the requirements for welding or cutting in special situations on a pipeline after commissioning or hydrostatic testing (e.g. a pipeline repair where gas is escaping) where the pipeline will not be subjected to another pressure test before it is returned to service. All welding procedures shall be qualified, documented and approved under conditions that simulate those that are expected during field welding. Pipeline repair welding shall be continuously supervised. NOTE: Guidance on methods for the repair of pipelines is given in WTIA Technical Note 20.

15.2 SAFETY Refer to Section 2. 15.3 HOT REPAIR OF LEAKING GAS-FILLED PIPELINES Hot repair of leaking gas-filled pipelines shall only be permitted when all of the following conditions prevail: (a)

The pipeline contents are known to be natural gas as defined in AS 4564.

(b)

A slight flow of gas is kept moving toward the point where thermal cutting or welding is being done.

(c)

The gas pressure is controlled to a slight positive pressure of approximately 150 Pa gauge.

(d)

All slots or open ends are sealed with tape, tightly fitted canvas or both, or other suitable means, as soon as they are made so as to maintain positive pressure and prevent the formation of an explosive air/gas mixture.

(e)

Two openings are not uncovered at the same time. NOTE: This is particularly important where the two openings are at different elevations.

(f)

Any escape of gas is ignited and kept burning.

In addition to the requirements of Clauses 15.1 and Section 2, the hot repair procedures shall include approved procedures for the following: (i)

The detection of explosive mixtures.

(ii)

The means of maintaining work site to mainline valve communication.

(iii) The method of regulating gas pressure. 15.4 WHERE GAS IS NOT ESCAPING Where work is to be carried out on a pipeline containing gas, but where gas is not escaping, the requirements of Section 16 shall apply.

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15.5 PIPELINES CONTAINING PETROLEUM FLUIDS OTHER THAN LEAN NATURAL GAS Welding shall only be carried out on a pipeline containing petroleum fluids other than lean natural gas (see AS 2885.1) when no fluid is escaping from the pipeline.

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A pipeline that contains, or has contained, petroleum fluids other than lean natural gas but has not been purged shall only be cut by mechanical means. Care shall be taken to prevent ignition due to electrical sparking (see Clause 2.2.2). Where a pipeline is filled with air and connected to a source of petroleum fluids other than lean natural gas that cannot be completely isolated, the following procedure should be adopted during welding, thermal cutting, or repair operations: (a)

Purge the pipeline.

(b)

Ensure that— (i)

combustible hydrocarbon fluid cannot flow towards the work site; and

(ii)

valves that isolate the work from the source of hydrocarbon fluids do not leak. NOTE: It may be necessary to install stopples or spheres on each side of the work site.

(c)

Continuously monitor the atmosphere at the work site to ensure that an unsafe accumulation of hydrocarbon fluid does not occur as work progresses.

15.6 QUALIFICATION OF WELDER(S) The welder(s) shall be qualified in accordance with Section 9 for the welding position, the welding process and the configuration of the joint. 15.7 QUALIFICATION INSPECTORS

OF

WELDING

SUPERVISORS

AND

WELDING

The welding supervisor and welding inspector shall be qualified in accordance with Section 3. 15.8 FIT-UP BEFORE WELDING AND CUTTING Weld preparations shall be accurate, and shall be in accordance with the qualified welding procedure. 15.9 EXAMINATION AND TESTING The finalized weld and adjacent material shall be subjected to appropriate 100% non-destructive testing. 15.10 CRITERIA OF ACCEPTANCE Welds shall comply with the visual inspection and non-destructive testing acceptance criteria of this Standard (see Sections 18 and 19).

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S E C T I O N 1 6 W E L D I N G O N T O IN-SERV I CE P I P ELI N E

A N

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16.1 PIPELINE CONTAINING FLAMMABLE OR PRESSURIZED FLUID Where a pipeline contains stationary or flowing flammable fluid, or the internal pressure is greater than 50 kPa gauge, welding shall comply with the requirements of Clauses 16.2– 16.17. NOTES: 1 Examples of in-service welding include fully welded repair sleeves, hot tap fittings, branch connections, inspection fittings, O-lets and weld metal deposition repairs. 2 Guidance on methods for repair of pipelines is given in WTIA Technical Note 20. 3 At times there may be a need for control of the operating pressure, gas temperature and flow rates in order to provide suitable conditions for in-service welding. 4 Welding onto pipelines that contain multiphase fluids requires special consideration. 5 Welding onto pipelines with a nominal thickness less than 4.8 mm requires special consideration. Research by CRC-WS has shown that the variability in heat input with MMAW for nominal thicknesses less than 6.4 mm revealed a significantly high risk of burn-through.

16.2 PRECAUTIONS TO BE UNDERTAKEN BEFORE IN-SERVICE WELDING 16.2.1 Avoidance of hydrogen assisted cold cracking (HACC) and burn-through The selection of heat input and preheat for welding onto a pipe with flowing hydrocarbons is a compromise between two opposing possibilities. At high heat input, the drop in the yield stress of the steel pipe at elevated temperature may lead to localized blow-out or generalized bulging. Pressure reduction may be necessary. At low heat input, the heat sink effect from the flowing fluid and the usually thick enclosing sleeve may promote hydrogen assisted cold cracking, and preheat is usually necessary. The heat sink effect makes the achievement of effective preheat difficult. 16.2.2 Items to be considered before in-service welding The following items shall be considered for each in-service welding operation: (a)

Material specification for hot tap, stopple, sleeves and fittings.

(b)

Pipeline conditions for live line welding.

(c)

Control of the weld cooling rate.

(d)

Thermal analysis of the in-service welding conditions.

(e)

Weld procedure and welders qualifications.

(f)

Risk assessment.

(g)

Pre-installation plan and on site activities.

(h)

Approvals and permits.

(i)

Support equipment and spares.

(j)

Emergency management plan.

16.2.3 Risk assessment and risk management plan Refer to Section 2.

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16.3 LINING The effect of welding on internal linings shall be considered. 16.4 SAFETY

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A job-specific risk assessment shall be undertaken and approved before work begins (see Section 2). NOTE: In-service welding risk assessment guidance in WTIA Technical Note 20 should be considered.

16.5 INSPECTION BEFORE WELDING The location of pipe to be welded shall be defined and the specification of the pipe shall be established. The pipe in the region of the welding shall be free of all coating material that is deleterious to the weld, or which could interfere with the inspection of the pipe. The pipe to be welded shall be inspected visually and by non-destructive means and as a minimum, the following shall be reported: (a)

Actual wall thickness.

(b)

Diameter, ovality and correct tolerance for fit-up of fittings or sleeves.

(c)

Any external or internal corrosion.

(d)

Any defects, gouges and corrosion pits.

(e)

Any laminations or inclusions in the vicinity of the area to be welded.

(f)

Any unsoundness of a longitudinal weld or spiral weld in the vicinity of the area to be welded.

(g)

Remaining wall thickness in the corrosion pit areas for weld metal deposition repairs.

16.6 ULTRASONIC TESTING BEFORE WELDING 16.6.1 Purpose of testing The purpose of testing is to determine and record the integrity of the pipe wall in the area that is to be affected by the welding operation. 16.6.2 Method The method of testing and the reference sensitivity shall be as specified in AS 1710 for nominal thicknesses greater than 5.0 mm. Where the nominal thickness is between 3.2 mm and 5.0 mm, a 5–10 MHz twin crystal probe shall be used. 16.6.3 Criteria of acceptance The following applies: (a)

Welding shall only be carried out where the pipe is demonstrated to be free of significant laminations, inclusions, or unsoundness of any longitudinal seam or spiral seam.

(b)

The results of the ultrasonic testing shall be the subject of an engineering assessment prior to any welding being undertaken.

16.7 WELDING CONSUMABLES Welds shall be made with a hydrogen-controlled process.

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16.8 PREHEAT The preheating temperature shall be checked by the use of a suitable method to determine that the required preheating temperature is obtained prior to, and maintained during, the welding operation. A preheat temperature of >100°C shall apply when an oxygen/propane heating tool is used.

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16.9 QUALIFICATION OF WELDING PROCEDURES Welds shall be made in accordance with a documented, qualified and approved welding procedure developed in accordance with Section 6, which takes into account pressure and cooling effects from the flow of fluid in the pipeline upon which welding is to be conducted, and which simulates site conditions. The essential variables in their entirety in Table 6.2 only apply to welds that are not directly affected by product pressure and cooling effects, such as the longitudinal seams on hot tap fittings or sleeves. These joints shall be fitted with a low carbon steel back-up strip or suitable tape to prevent penetration of the weld into the carrier pipe. All welding that is affected by product pressure and cooling effects such as circumferential fillet welds, weld metal deposition and branch welds shall be qualified by simulated testing. No essential variables apply to these welds; however, grouping of certain conditions may be permitted when approved. The grouping of conditions shall involve sound engineering judgement and be fully investigated and documented with respect to burn-through and hydrogen cracking potential and should include worst case welding procedure qualification testing. The procedure qualification requirements for welds that are affected by product cooling effects shall apply as per Table 6.2, except for the alternative/additional requirements specified in Section 16 including: (a)

Pipe diameter applicable to circumferential fillet welds in accordance with Table 6.2.

(b)

On site heat sink test results showing heat sink rate greater than during procedure qualification.

(c)

Pipeline operating conditions (flow, pressure, temperature) that could affect heat sink rate.

(d)

Increase of CE value of 0.03 is allowable to sleeve/fitting material.

(e)

Pipe CE can only be increased by 0.03 if thermal analysis confirms this is acceptable.

(f)

Material grade or tensile strength and the nominal thickness of the sleeve/fitting shall be designed to allow in-service welding without the need for PWHT.

(g)

Change in nominal thickness of the parent material shall be taken into account when considering the thermal severity during welding due to pipeline operating conditions.

NOTES: 1 Figure 16.1 describes the suggested procedure qualification test assembly. 2 Thermal analysis tools are available from Battelle and Pipeline Research Council International (PRCI).

16.10 WELDING SEQUENCE The recommended welding sequences shown in Figure 16.2 shall be followed. Backstep welding technique for the longitudinal joints should be considered to minimize weld shrinkage effects in the case of thin wall carrier pipe.

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79

Fluid in

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En d p l ate

Flui d o ut

FIGURE 16.1 SUGGESTED IN-SERVICE WELDING TEST ASSEMBLY

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3

1

2

2

4

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1

(a) We l d se q u e n c e 1, 2. Ty p i c al u nre infor c e d br an c h

(b) We l d se q u e n c e 1, 2, 3, 4. Ty p i c al re infor c e d pad 5

2

3 1

4

6 4

1

2 (d) Ty p i c al e n c ir c l e m e nt

(c) We l d se q u e n c e 1, 2, 3, 4. Ty p i c al r e i n fo r c i n g s ad d l e

7 4

2

1

3

4

3 5

7 3

6

1

2 (f ) Ty p i c a l e n c ir c l e m e nt s l e eve a n d s ad d l e

(e) Ty p i c al e n c ir c l e m e nt te e

5 6 4

2

1 3

(g) Ty p i c a l e n c ir c l e m e nt s ad d l e

NOTE: Longitudinal butt welds Item 2 in (d), (e), (f), and (g) require suitable tape or backing strip (see Clause 16.9).

FIGURE 16.2 RECOMMENDED WELDING SEQUENCES

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16.11 QUALIFICATION OF WELDER(S) The welder(s) or welder operators shall be qualified in accordance with Section 9. 16.12 QUALIFICATION INSPECTORS

OF

WELDING

SUPERVISORS

AND

WELDING

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The welding supervisor and welding inspector shall be qualified by experience and training specifically related to in-service welding on pipelines and in accordance with Section 3. 16.13 FIT-UP BEFORE WELDING Weld preparations shall be made accurately, and shall be in accordance with the qualified welding procedure. All components shall fit the pipe, and care shall be exercised to ensure that any longitudinal weld preparations are suitably aligned. NOTES: 1 Buttering passes may be required on the carrier pipe or fitting to accommodate gaps above those specified in the welding procedure. 2 Consideration should be given to suitable means of preventing compression of the pipe due to the contraction of the longitudinal welds on the fitting.

16.14 EXAMINATION OF TESTING The finalized weld and adjacent material shall be subjected to the appropriate 100% non-destructive testing, including tests for the presence of lamellar tearing. NOTE: Before cutting the line pipe with a hot tapping tool, the weld and adjacent material should be leak tested at a pressure not greater than the current internal pressure of the pipeline.

Delayed cracking due to residual hydrogen in the weld metal may occur. Final non-destructive testing shall be carried out not sooner than 24 h after completion of welding, followed by leak testing. 16.15 CRITERIA OF ACCEPTANCE The criteria of acceptance for all in-service welding shall be as specified in Tier 1 acceptance criteria as specified in Clause 17.2. 16.16 WELDING OF TEST ASSEMBLY For in-service welding, pipeline operating conditions that affect the ability of the flowing contents to remove heat from the pipe wall shall be simulated while test joints are being made. NOTE: Filling the test section with water and allowing water to flow through the test section while the test joint is being made has been shown to produce thermal conditions equivalent to or more severe than any typical in-service welding application (see Figure 16.1). Other content (e.g. water mist or motor oil) may be used to simulate less severe thermal conditions.

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S E C T I O N 1 7 C R I T E R I A O F A C C E P T A N C E F O R G I R T H W E L D D I S C O N T I N U I T I E S

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17.1 GENERAL The criteria of acceptance for girth weld discontinuities in this Standard are based on a three-tier system. The choice of which tier is applicable shall be approved (see Clause 1.6.1) and is shown in Figure 17.1. Welds that comply with the selected criteria of acceptance shall be deemed to comply with this Standard. Production welds that do not comply with the selected criteria shall be repaired (see Section 25) or cut out (see Section 27). Acceptance criteria are as follows: (a)

Tier 1 (see Clause 17.2) Tier 1 acceptance criteria are based on commonly achievable standards of good workmanship. NOTE: Such acceptance criteria are very similar to API 1104, which is the de facto international Standard of workmanship for pipeline girth welds. They are also similar to the requirements of the superseded editions of this Australian Standard except for nominal thicknesses less than 7 mm where limits on embedded defects have been reduced from 50 mm to 25 mm in length, as a result of Australian research.

(b)

Tier 2 (see Clause 17.4) Tier 2 acceptance criteria are based on generalized fitnessfor-purpose criteria. Weld discontinuities that would not be acceptable under the workmanship standards of Tier 1 may be acceptable under Tier 2. NOTE: The principal basis for the Tier 2 criteria is the European Pipelines Research Group (EPRG) paper EPRG guideline on defects in transmission pipeline girth welds, April 1994 edition. Australian experience, which formed the basis for the 1987 edition of this Standard, and the results of Australian research work undertaken by the CRC for Welded Structures have also been taken into account (see also Preface). Compliance with Tier 2 acceptance criteria requires certain special requirements to be met. The most important of these, is that because the limits are based on experimentally validated plastic collapse considerations, the welds have to be shown to have adequate toughness in order to ensure that failure does not occur by brittle fracture. Australian research has shown that when strength matching can be demonstrated the Tier 2 limits can be extended down to 5 mm nominal thickness and up to material grade with a yield strength of 555 MPa. However, in practice, the demonstration of strength matching is difficult, and this Standard [see Clause 17.4.1(d)] only allows the application of Tier 2 for material grades with a yield strength above 448 MPa and up to and including 485 MPa when all-weld metal tensile tests, wide plate or full section pipe tensile tests are used to demonstrate overmatching. The application of Tier 2 criteria to nominal thicknesses less than 7 mm is not allowed.

(c)

Tier 3 (see Clause 17.5) Tier 3 acceptance criteria are fitness for purpose criteria developed from an engineering critical assessment (ECA) carried out expressly for the project concerned.

Pre-existing laminar imperfections in the parent metal, which comply with the requirements of API Spec 5L, shall be acceptable, unless they do not meet the requirements for ultrasonic inspection of Section 22.

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Pr o j e c t d ef i n e d

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Cr iter i a of ac c e pt an c e d eter m in e d by li c e n c e, or pro p o se d by c o ntr ac tor an d a p prove d by li c e n c e

Choose c r i ter i a

T i er 1

T i er 2

T i er 3

Wor k m an s hi p c r i ter i a

G e n er a l ize d f i t n e s s for pur p o se c r iter i a ba se d o n limit- load as sum ptions and re q uir in g a nu m b er of fr ac ture to u g h n e s s, s t r e n g t h a n d ot her prerequisites as d e s c r i b e d in S e c t i o n 17.4

We l d s p e c ifi c or proj e c t s p e c ifi c fit n e s s for p ur p o s e c r i te r i a established using ap prove d pro c e dures e.g. BS 7910 or API 110 4

C o m p li a n c e w i t h r e q u ir e m e nt s similar to API 110 4 No

En g in e er in g critical a s s e s s m e nt (ECA)

C o m p li a n c e w i t h T i er 2 (S e c t i o n 17.4.1)

Ye s

No

Ye s

Ye s

No

C o m p li a n c e w i t h ECA c r i ter i a

No Ye s RE ANALYSE, REPAIR OR CUT OUT

ACCEP T

NOTE: Figure 17.1 does not show access to Tier 2 acceptance criteria from the workmanship standards of Tier 1. This is because in normal circumstances the prerequisite conditions in Clause 17.4 would not have been met, which is not intended to prevent the application of quality control practices aimed at the normal achievement of workmanship standards while allowing a fall-back position to Tier 2. In such circumstances, the abovementioned prerequisite conditions shall be met.

FIGURE 17.1 PROCEDURE FOR SELECTION OF CRITERIA FOR ACCEPTANCE FOR GIRTH WELD DISCONTINUITIES

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17.2 TIER 1 CRITERIA—WORKMANSHIP STANDARD (RT) 17.2.1 Inadequate penetration

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Inadequate penetration without high/low lack of penetration (LP) is defined as the incomplete filling of the weld root. This condition is shown schematically in Figure 17.2(a). Lack of penetration shall be unacceptable when any of the following conditions exist: (a)

The length of an individual indication of LP exceeds 25 mm.

(b)

The aggregate length of indications in any continuous 300 mm length of weld exceeds 25 mm.

(c)

The aggregate length of indications of LP exceeds 8% of the weld length in any weld less than 300 mm in length.

A summary of Tier 1 acceptance criteria for girth weld discontinuities is shown in Table 17.1. 17.2.2 Inadequate penetration due to high/low Inadequate penetration (LP) due to high/low LP(H/L) is defined as the condition that exists when one edge of the root is exposed (or unbonded) because adjacent pipe or fitting joints are misaligned, and where ‘high/low’ (H/L) is a condition where the pipe or fitting surfaces are misaligned. NOTE: This condition is shown schematically in Figure 17.2(b).

Inadequate penetration (H/L) is deemed not to be a defect and shall be acceptable unless incomplete fusion is also present. 17.2.3 Incomplete fusion due to cold lap Incomplete fusion due to cold lap [lack of inter-run fusion (LI) or lack of side wall fusion (LS)] is defined as a discontinuity between two adjacent weld beads, or between the weld metal and the base metal that is not open to the surface. NOTE: This condition is shown schematically in Figure 17.2(d) and 17.2(c).

It shall be unacceptable when any of the following conditions exist: (a)

The length of an individual indication exceeds 25 mm for tN 2 mm

Width >3 mm

>50 mm or width >2 mm

—

More than one of any size present and the density of more than one of the images exceeds that of the thinnest adjacent base metal

>13 mm where density of BT’s image exceeds that of thinnest adjacent base metal

>8%

Root concavity (SRC)

>25 mm

>25 mm

17.2.4

t N ≥7 mm t N 8% weld length

Aggregate length/width/diameter in weld 25 mm

Aggregate length/width/diameter in any continuous 300 mm length of weld

17.2.2

>25 mm

Individual length/width/diameter

Inadequate penetration (without H/L) (LP)

Type of discontinuity

17.2.1

Clause

Acceptability limits

SUMMARY OF TIER 1 ACCEPTANCE CRITERIA FOR GIRTH WELD DISCONTINUITIES (RT)

TABLE 17.1

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93 AS/NZS 2885.2:2016

— —

>50 mm >20% weld length

Cluster (PG): —other than finish pass —finish pass

Hollow bead (HB) If HB reduces weld thickness to less than that of thinner parent, or by the width of the discontinuity then it is unacceptable.

Cracks (KL, KT, KE, KC)

Undercutting (SUC) all nominal thicknesses if depth >0.8 mm

t N ≥7 mm; if depth >0.8 mm

t N 0.4 mm

Root slag intrusion—shall be classified as undercutting, see 17.2.11.

Accumulation (exclude incomplete penetration due to high/low and undercutting) t N 50 mm

>13 mm, or through thickness dimension of individual pore >30% of the nominal thickness

—

Aggregate length/width/diameter in any continuous 300 mm length of weld

Acceptability limits

>20%

—

—

Aggregate length/width/diameter in weld 20% (individual or aggregate)

>8% (individual or aggregate)

—

Coincident discontinuities with length limit

>50 mm (individual or aggregate)

>25 mm (individual or aggregate)

>20% weld length

—

—

16.2.13(a)

>20% weld length

>20% weld length

>50 mm

All cracks shall be unacceptable except shallow crater or star cracks with a maximum dimension of 4 mm

>13 mm or individual lengths each >6 mm are separated by 13 mm dia., or through thickness dimension of individual pore >30% of the nominal thickness

Through thickness dimension of individual pore >30% of the thickness or any dimension of surface breaking porosity >1.5 mm

Porosity: Individual gas pore (GP)

17.2.6(a)

Individual length/width/diameter

Type of discontinuity

Clause

TABLE 17.1 (continued)

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17.4 TIER 2 ACCEPTANCE PURPOSE STANDARD

CRITERIA—GENERALIZED

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FITNESS

FOR

17.4.1 General

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Discontinuities, other than cracks that do not reduce the weld thickness to less than 90% of the thinner of the parent metal thicknesses, are acceptable. The generalized fitness for purpose criteria of Tier 2 are based on limit load/net section plastic collapse considerations. All of the following requirements apply: (a)

Either— (i)

the welds shall be made in their entirety with E4110 electrodes; or

(ii)

Charpy V-notch impact tests, performed as part of the welding procedure qualification test, shall meet a minimum requirement of 40 J minimum average and 30 J minimum individual at the lowest design temperature at which the combined stress exceeds 30% SMYS.

The requirement in Item (ii) is applicable to full-size test pieces. The test piece size shall be the largest standard size that can be obtained. The requirement shall be reduced by using the multiplication factors in Table 7.1. (b)

For welds in material greater than 13 mm thick, crack tip opening displacement (CTOD) tests shall be performed in accordance with AS 2205.7.3 and shall meet a requirement of 0.15 mm minimum average and 0.10 mm minimum individual at the lowest design temperature at which the combined stress exceeds 30% SMYS (see Clause 7.4.7.2).

(c)

For pipes with an SMYS less than or equal to 448 MPa transverse butt tensile tests shall be performed as part of the welding procedure qualification test with the weld reinforcement removed by dressing. The tests are acceptable if the specimens fail in the pipe material or if the specimens break in the weld metal with a tensile strength greater than, or equal to, the specified minimum tensile strength of the pipe material.

(d)

For pipes with an SMYS greater than 448 MPa and up to and including 485 MPa, all-weld metal tensile tests shall be performed as part of the procedure qualification test. The tests are acceptable if the weld metal yield strength is greater than, or equal to, the specified minimum tensile strength of the pipe material.

(e)

Each defect is assumed to be confined to a single weld pass not greater than 3 mm in depth. If there is a suspicion of a single defect being greater than 3 mm then Tier 2 acceptance criteria shall not be applied. These criteria shall only be applied to pipeline girth welds between pipes of equal grade and nominal thickness.

(f)

The pipe SMYS shall not exceed 485 MPa.

(g)

Service conditions shall not include onerous fatigue conditions (see Note 2).

NOTES: 1 The weld discontinuity acceptance limits in this Standard are based on those in the EPRG Guidelines referred to elsewhere and also on Australian research by the CRC for Welded Structures, which has assessed thin walled high strength pipeline girth welds. The values of defect length are founded upon plastic collapse calculations that include assumptions regarding the flow stress and the yield/tensile ratio of the girth weld metal and the pipe parent metal, and the requirement that the yield strength of the weld metal be equal or exceed that of the parent pipe. The Australian research has demonstrated that a certain level of weld metal yield strength undermatching can be tolerated within the requirements of Tier 2 while maintaining defect tolerance.

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It should be noted that, as mentioned in Appendix D, Paragraph D3, the notched tensile test, which was used to determine yield strength matching, has been removed from this Standard along with a return of Tier 2 criteria to those in the 1995 edition of this Standard; however, the wide plate and full section pipe tension tests can still be used to define defect limits for particular weld consumable pipe grade combinations and can be applied to those pipe grades now excluded from Tier 2.

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2

Normal daily pressure fluctuations due to line packing are not deemed to constitute onerous fatigue conditions.

17.4.2 Tier 2 acceptance criteria The Tier 2 acceptance criteria shall be as described in Table 17.2 and as given in Figure 17.3. Equations to the lines in Figures 17.3 are set out in Table 17.3. Tier 2 acceptance limits for some common pipe sizes shall be as given in Table 17.4. TABLE 17.2 WELD DISCONTINUITY ACCEPTANCE LIMITS FOR TIER 2 Type of discontinuity

Tier 2 acceptance criteria

External profile (non-planar)

The maximum height of external weld reinforcement shall comply with Figure 18.1. The weld shall be completely filled

Planar root concavity (see Note 3)

Root concavity that does not reduce the thickness of the weld below 90% of the nominal thickness of the parent metal shall be acceptable regardless of length

Non-planar root cavity (see Note 4)

Root concavity that reduces the thickness of the weld below 90% of the nominal thickness of the parent metal shall be assessed against the all defects lines in Figure 17.3

Non-planar undercut

Depth less than 0.8 mm—no limit

Planar undercut

Depth greater than 0.8 mm—planar defect in Figure 17.3

Inadequate penetration and all lack of fusion defects (planar)

Planar defect in Figure 17.3

Cracks (planar)

Not allowed

Crater cracks (see Note 5) (non-planar)

Maximum dimension of 4 mm

Burn-through (non-planar)

Burn-throughs less than 6 mm long and less than one weld pass (3 mm) depth have no structural significance and are not limited under Tier 2. Burn-throughs longer than 6 mm shall be assessed using the root concavity limitations if the depth is less than one weld pass. Burn-throughs more than one weld pass (3 mm) deep are not allowed

Porosity (non-planar)

The depth of individual gas pores in the through-thickness dimension exceeds 30% of the nominal thickness. Other porosity is of no structural significance and is not limited by Tier 2

Hollow bead (see Notes 3, 4 and 7) (non-planar)

All defects in Figure 17.3. Hollow bead that does not reduce the thickness of the weld below 90% of the nominal thickness of the parent metal shall be acceptable regardless of length.

Slag inclusions (see Note 6) (non-planar)

All defects in Figure 17.3

(continued)

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TABLE 17.2 (continued)

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Type of discontinuity

Tier 2 acceptance criteria

Interaction (planar and non-planar)

If the defect is separated from a planar defect by a distance smaller than the length of the shorter of the two defects, then re-categorize as a single planar defect (defined for the purposes of Figure 17.3 as an interacting planar defect) of length equal to the two individual lengths plus separation. Figure 17.3 gives limits for interacting planar defects

Coincident defects (see Note 2)

Discontinuities that have length limits in this Table are unacceptable regardless of length when they are superimposed in the same position in the weld so that the total assumed defect depth at that position exceeds one weld pass (3 mm) Discontinuities that do not have length limits in this Table are acceptable regardless of length when they are superimposed in the same position in the weld provided that they do not collectively reduce the thickness of the weld below 90% of the thickness of the parent metal

Systematic and repeated defects

At the option of the pipeline licensee, systematic and repeated occurrences of defects of workmanship may be sentenced according to the requirements of Tier 1

NOTES: 1

Clause 17.4.1 requires that discontinuities that do not reduce the remaining weld thickness below 90% of the thinner parent metal nominal thicknesses be ignored. This applies to all types of discontinuity in Table 17.2.

2

The discontinuities that do not have length limits are as follows: (a)

Defects that do not reduce weld thickness below 90% of the thinner parent metal nominal thickness.

(b)

Undercut less than 0.8 mm, where the depth does reduce the weld thickness below 90%. This can occur in thicknesses less than 8 mm.

(c)

Porosity having a maximum pore size of less than 3 mm.

3

The remaining weld thickness relative to the 90% minimum limit when the volumetric defects root concavity, burn-through, and hollow bead are present is a matter for the radiographer’s judgement, assisted by reference to the density of the parent metal and the images of the grooves on the undercut comparator shim.

4

Root concavity, burn-through, and hollow bead that reduce the remaining weld thickness below 90% of the nominal thickness of the parent metal are assumed to be one weld pass deep.

5

As per Tier 1.

6

Includes WTs.

7

The permitted reduction in weld metal thickness to 90% of parent metal thickness for hollow bead is allowed in the Tier 2 fitness for purpose acceptance criteria in recognition of the demonstrated achievement of matching strength in the procedure qualification requirements for Tier 2.

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10

20

30

40

50

60

5

7

9

13

15

17

MINIM U M OR ME ASURED WALL THICK NESS, mm

11

Inter ac t in g p l anar d efe c t

19

FIGURE 17.3 WELD DISCONTINUITY ACCEPTANCE LIMITS FOR TIER 2

21

In d i v i d u al p llanar anar d efe c t

Tot al — all p l anar d efe c t s

Tot al — all d efe c t s

NOTES: 1 This Figure is adapted from Figure 4.1 of The European Pipeline Research Group’s proposed ‘Guidelines on pipeline girth weld defects’. 2 The equations to the lines are given in Table 17.3. 3 Table 17.4 gives an example by tabular presentation of the acceptance limits for some common wall thicknesses. 4 The information for thicknesses less than 7 mm is shown for illustration purposes only. Tier 2 is not applicable to thicknesses less than 7 mm.

DEFECT LEN GTH, % PIPE CIRCU M FEREN CE

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23

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TABLE 17.3 EQUATIONS TO THE LINES IN FIGURE 17.3 Coordinates at maximum defect length

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Line

Equation (% circumference) Wall thickness mm

Defect length %

Total—all defects

3.91 × (nominal thickness) + 0.11

12.8

50

Total—all planar defects

2.37 × (nominal thickness) − 5.50

13.0

25

Interacting planar defect

1.54 × (nominal thickness) − 1.92

17.5

25

Individual planar defect

1.04 × (nominal thickness) − 2.48

26.5

25

NOTE: These equations apply only to the sloping portion of the lines.

TABLE 17.4 TIER 2 ACCEPTANCE LIMITS FOR SOME COMMON PIPE SIZES (All measurements in millimetres) Maximum acceptable discontinuity length Pipe diameter

Total all defects in any weld

Total all planar defects in any weld

Volumetric defects that reduce nominal thickness below 0.90δ N , i.e. certain root concavity, burnthrough, and hollow bead conditions

7.1 7.9 8.7

192 213 235

78 91 104

192 213 235

34 39 45

62 70 79

9.5 11.0 12.7

256 297 342

117 142 169

256 297 342

51 62 74

87 103 121

7.1 7.9 8.7

239 266 293

97 113 130

239 266 293

42 49 56

77 88 98

9.5 11.0 12.7

320 370 427

146 176 211

320 370 427

63 77 92

109 129 151

7.1 7.9 8.7

284 316 347

115 135 154

284 316 347

50 58 67

92 104 117

9.5 11.0 12.7

379 439 507

173 209 250

379 439 507

75 91 109

129 153 180

7.1 7.9 8.7

312 347 382

127 148 169

312 347 382

55 64 73

101 115 128

9.5 11.0 12.7

417 482 557

190 230 275

417 482 557

83 100 120

142 168 197

Nominal thickness

Individual planar defects, i.e. undercut Interacting deeper than 0.8 mm and planar all inadequate defects penetration and lack of fusion defects

219

273

324

356

(continued)

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TABLE 17.4 (continued) (All measurements in millimetres) Maximum acceptable discontinuity length

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Pipe diameter

Individual planar defects, i.e. undercut Interacting deeper than 0.8 mm and planar all inadequate defects penetration and lack of fusion defects

Total all defects in any weld

Total all planar defects in any weld

Volumetric defects that reduce nominal thickness below 0.90δ N , i.e. certain root concavity, burnthrough, and hollow bead conditions

7.1 7.9 8.7

355 395 435

144 169 193

355 395 435

63 73 84

115 131 146

9.5 11.0 12.7

475 550 635

217 262 314

475 550 635

94 114 137

162 192 225

7.1 7.9 8.7

400 445 490

163 190 217

400 445 490

70 82 94

129 147 165

9.5 11.0 12.7

535 619 715

244 295 353

535 619 715

106 129 154

182 216 253

Nominal thickness

406

457

NOTE: Table 17.4 lists Tier 2 weld discontinuity acceptance limits for discontinuities listed in Table 17.3 and shown graphically in Figure 17.3. The values have been calculated from the equations listed in Table 17.3.

17.5 TIER 3 CRITERIA—ENGINEERING CRITICAL ASSESSMENT 17.5.1 General The discontinuity acceptance criteria may be determined using an engineering critical assessment (ECA) procedure. The ECA procedure used shall be approved in accordance with Appendix A. ECA procedures are included in API 1104 Appendix A and BS 7910. The output from an ECA will be a set of girth weld defect acceptance criteria that considers defect location, weld geometry, pipe properties, and weld metal properties (where required), longitudinal pipe stresses during installation and operation and AUT uncertainties. Automated ultrasonic testing shall be used where an ECA is applied. Note that any inaccuracy from the AUT system needs to be added to ECA defined criteria. 17.5.2 ECA input assumptions The ECA input assumptions shall be fully defined and included in the basis for the design of the pipeline, as defined by AS 2885.1. Input assumptions include but are not limited to the following: (a)

Pipe materials: (i)

Pipe OD.

(ii)

Pipe nominal thickness.

(iii) Nominal thickness tolerance. (iv)

Yield strength.

(v)

Tensile strength.

(vi)

Yield to tensile ratio.

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(vii) Pipe mill certificate test data. (viii) Coating thickness.

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(b)

(ix)

Toughness.

(x)

Stress strain curves if FEA is used.

Pipe fabrication details: (i)

Internal high/low.

(ii)

External high/low.

(iii) Cap width. (iv) (c)

Geometrical features, e.g. bevel, long seam peaking and ovality.

Pipe installation details: (i)

Minimum and maximum installation temperature.

(ii)

Maximum installation stress or strain.

(iii) Hydrotest longitudinal stress. (d)

Pipeline operational details: (i)

Minimum design temperature.

(ii)

Maximum design temperature.

(iii) Pipeline service, i.e. sour service. (iv)

Design life.

(v)

Level of cathodic protection.

(vi)

Operational fatigue stress range and number of cycles.

(vii) Safety factor to be applied. 17.5.3 Coincident load conditions Coincident load conditions shall be clearly stated in the ECA. This is where the worst case combinations do not occur at the same time. This includes assumptions such as minimum design temperature coincident with minimum pressure. 17.5.4 Locations to be tested The fracture toughness testing shall be as per Clause 7.4.7.2 of this code as a minimum. 17.5.5 Defect positions to be analysed The following defect positions are to be analysed: (a)

Root/ID, surface breaking.

(b)

Cap/OD, surface breaking.

(c)

Lack of side wall fusion—embedded flaws at various depths through the thickness.

(d)

Lack of inter-run fusion.

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SEC TI ON

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1 8

V I S U A L

E X A MI N A T I O N

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18.1 PURPOSE The weld shall be examined visually to determine that the surfaces of the weld are free from unacceptable discontinuities and the weld is dimensionally correct including that the height of weld reinforcement is within the limits necessary to achieve effective radiography as shown in Figure 18.1. 18.2 METHOD OF EXAMINATION Visual examination shall be undertaken using appropriate measuring tools and gauges. 18.3 EXTENT OF VISUAL EXAMINATION The full length of each weld shall be examined. 18.4 CRITERIA OF ACCEPTANCE 18.4.1 All-welds The result of visual examination shall be documented by the person responsible. Welds shall not contain any visible discontinuities that exceed those specified in Section 17. The dimensions of the weld shall comply with those shown in the welding procedure specification. 18.4.2 Butt welds The weld preparation shall be completely filled. In order to permit effective radiography of those welds that are to be radiographed, the height of external weld reinforcement shall be not greater than that specified in Figure 18.1. Welds that are to be radiographed, which do not comply with the weld reinforcement limits, shall be ground in order to achieve compliance. 18.4.3 Alignment (high/low) The alignment of pipe ends shall minimize the offset between abutting surfaces. For pipe ends of the same nominal thickness, the offset should not exceed 3 mm for pipe with nominal thicknesses greater than 6.4 mm, and 2 mm for pipe with nominal thicknesses equal to or less than 6.4 mm. High/low in excess of the recommended limits can be accepted if the procedure is qualified with the high/low at the required limit and an engineering assessment is made to ensure the joint configuration does not introduce stresses beyond the allowable limits. 18.5 UNDERCUT DEPTH MEASUREMENT Undercut depth measurement shall consist of the following: (a)

External undercut The only permitted method for measuring and sentencing external undercut shall be visual examination or mechanical measurements.

(b)

Internal undercut The primary means of measuring internal undercut depth shall be visual or mechanical measurements. Where direct measurement is not possible, undercut comparator shims or reference radiographs in accordance with Clause 21.5 shall be used.

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3.5

O ver verall all m ma a xximum imu m at any p o s it i o n (h = (t N + 5)/6)

M A XIM U M HEIG HT (h) OF E X TER NAL WELD REINFORCEM ENT, m m

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3 .0

2.5

2.0 Maximum permissible over at l ea st 8 0% of c ir c umfere n c e (h = (t N + 2)/6) 1. 5

1.0 W h e n u s i n g s i n g l e wal l, s i n g l e i m ag e r ad i o g r a p hy i n t h i c k n e s s e s b e l ow a b out 7 m m t h e c o m b in e d ef fe c t of inter nal an d ex ter nal re infor c e m e nt m ay m ake it d iiff ffii c u ult l t to c o m p lly y w iitt h t h e d e n s iitt y ire r e q u ir e m e nt s (refer to C l au s e 21. 3)

0. 5

0.0 0

5

10

15

N O MINAL PIPE WALL THICK NESS (t N ), m m

FIGURE 18.1 MAXIMUM HEIGHT OF EXTERNAL WELD REINFORCEMENT IN BUTT WELDS THAT ARE TO BE RADIOGRAPHED IN ORDER TO ACHIEVE EFFECTIVE RADIOGRAPHY

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N O N - D E S T R U C T I V E

T E S T I N G

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19.1 GENERAL The methods of non-destructive testing, the equipment, and the examining personnel shall be collectively capable of producing indications of discontinuities in welds, which can be interpreted and evaluated in order to determine whether the criteria of acceptance have or have not been attained. Discontinuities shall be evaluated in accordance with Section 17. 19.2 ORGANIZATIONS UNDERTAKING NON-DESTRUCTIVE TESTING Organizations undertaking non-destructive testing shall be certified to AS ISO/IEC 17025. 19.3 QUALIFICATIONS OF PERSONNEL Non-destructive testing personnel engaged in the supervision or interpretation of results shall be qualified to Level 2 in the relevant test method and product sector in accordance with AS ISO 9712. Manual ultrasonic testing personnel certification is not suitable for ToFD and PAUT examination. Time of flight diffraction (ToFD) and PAUT non-destructive testing personnel shall be Level 2 in TOFD or PAUT. 19.4 METHODS Non-destructive testing shall be made in accordance with a qualified procedure using one of the following methods, unless an exemption applies (see Clause 19.7): (a)

Radiographic testing (RT).

(b)

Ultrasonic testing (UT). NOTE: The preferred method of inspection shall be ultrasonic testing with a mechanized AUT system in accordance with Clause 22.1.1 for pipe wall thickness greater than 6.4 mm, and with manual phased array for pipe wall thickness 3.9 mm to 6.4 mm. Welds made by GMAW welding should be examined with mechanized ultrasonic testing.

These tests shall be supplemented with one or both of the following non-destructive tests: (i)

Magnetic particle testing (MPI).

(ii)

Dye-penetrant testing (DPI).

19.5 AMOUNT OF NON-DESTRUCTIVE TESTING One hundred per cent of welds shall be subject to NDT. 19.6 NON-DESTRUCTIVE TESTING OF GOLDEN WELDS Golden welds shall be subject to two forms of NDT. NOTE: Typically this would be RT or UT and either MPI or DPI.

19.7 EXEMPTION FROM RADIOGRAPHIC OR ULTRASONIC TESTING Subject to the approval of the pipeline licensee, where it is not practicable to carry out radiographic testing or ultrasonic testing due to the weld geometry, approved non-destructive testing by magnetic particle testing or dye-penetrant testing shall be done. Radiographic testing may be used to verify gap setting on socket welds. Fillet welds, branch welds and socket welds shall be inspected by magnetic particle testing or dye-penetrant testing. COPYRIGHT

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19.8 TIMING OF NON-DESTRUCTIVE TESTING

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The time between weld completion and NDT shall be a minimum of 24 h except for welds made in accordance with procedures in which the risk of HACC has been ‘designed-out’ in accordance with Appendix C.

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S E C T I O N 2 0 Q U A L I F Y I N G A RADI OGR A P H I C P RO C ED U R E

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20.1 RADIOGRAPHIC PROCEDURE A radiographic procedure shall be developed and documented in accordance with AS 2177 and the requirements of this Standard. It shall include all the necessary information to enable radiographs to be taken, processed, and interpreted to the requirements of this Standard. The documented radiographic procedure shall include the following information: (a)

Pipe size classified according to the dimensions, nominal bore, diameter and nominal thickness and joint design.

(b)

Material specification.

(c)

Construction specification.

(d)

Acceptance specification or Standard, or both.

(e)

Welding process.

(f)

Method of weld identification.

(g)

Radiographic method designation (see AS 2177).

(h)

Equipment consisting of the following:

X-radiography (i)

Gamma radiography

Orthogonal panoramic

(i)

Panoramic

Focal spot size

Source type

Tube voltage

Source size

(ii) Directional

(ii) Directional

Focal spot size

Source type

Tube voltage

Source size

(i)

Film type.

(j)

Intensifying screens (type and thickness).

(k)

Diagnostic film length.

(l)

Source to film distance.

(m)

Source offset angle.

(n)

Image quality indicator (type and designation).

(o)

Undercut comparator.

(p)

Film processing/chemicals/type used.

(q)

Density range to be achieved.

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20.2 METHOD OF QUALIFYING THE RADIOGRAPHIC PROCEDURE Radiographs of a complete weld shall be taken, processed and interpreted in accordance with the radiographic procedure. The weld may be selected from a number of welding procedure qualification and/or welder qualification welds or any production weld. The resultant radiograph(s) shall comply with the approved procedure.

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The maximum height of reinforcement shall be in accordance with Figure 18.1 unless otherwise qualified in the radiographic procedure. Images of discontinuities observed on the radiograph shall be reported and recorded in accordance with Clause 21.9. The radiographic results of this weld shall be documented in a report having the same format as reports issued for inspection of production welds. 20.3 TEST CONDITIONS A test radiograph shall be made under conditions that simulate those to be encountered during construction. 20.4 RADIOGRAPHIC PROCEDURE SPECIFICATION DOCUMENTATION Where the assessment has demonstrated that the radiograph is satisfactory and discontinuities in the weld can be identified, a record should be entered into the radiographic procedure specification documentation. This record should indicate that the radiograph taken, complies with the radiographic procedure defined in this Standard. 20.5 PERIOD OF VALIDITY A qualified radiographic procedure shall remain valid until it is withdrawn.

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T E S T I N G

21.1 GENERAL

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The radiographic testing shall comply with all of the requirements of this Standard. The procedure shall be documented and qualified, or be previously qualified and approved. Gamma radiography (GR1 only) shall only be used where either ultrasonic or X-radiography is not accessible to the weld under test. Where there is an unacceptable risk of HACC, gamma radiography shall not be used. Real time and digital radiography is permitted provided it meets the sensitivity requirements of AS 2177. NOTES: 1 Non-destructive radiographic testing (RT) procedures shall be a combination of AS/NZS 2885.2 and AS 2177. 2 The preferred technique of RT of welds in pipelines is that of using an internal orthogonal radiographic X-ray crawler as the detectability of imperfections including cracks is superior to that obtained using high-energy gamma rays or double-wall exposure techniques.

21.2 SAFETY AND PROTECTION FROM IONIZING RADIATION See Section 2. 21.3 DENSITY The radiographic density through the parent metal shall be as follows: (a)

X-radiography ............................................ not less than 2.5 and not greater than 4.0.

(b)

Gamma radiography.................................... not less than 3.0 and not greater than 4.0.

The radiographic density through the weld metal shall not be less than 1.8. Weld reinforcement shall be within the limits of Figure 18.1, with— (i)

tn < 4 mm = maximum reinforcement of 1.5 mm either side; and

(ii)

tn >14 mm = maximum reinforcement of 3 mm.

If the radiographic density in the parent metal falls within the range specified above but the required minimum for the weld metal is not met, then the weld reinforcement shall be ground in the regions of insufficient density and the radiograph(s) shall be retaken so that the above requirements are met. 21.4 IMAGE QUALITY The image quality indicator (IQI) shall be a wire type complying with AS 2314. NOTE: The specification of wire type IQI in AS 2314 complies with ISO 19232-1, ISO 19232-2.

Radiographic image quality is indicated by the smallest wire visible in the radiograph assessed through the parent metal. Image quality indicator wire numbers for corresponding nominal thicknesses shall comply with Table 21.1.

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TABLE 21.1 IMAGE QUALITY INDICATOR (IQI) SENSITIVITY vs MATERIAL NOMINAL THICKNESS IQI to ISO 19232-1 and ISO 19232-2 IQI on film side

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Nominal thickness mm

Single wall/single image Number

Diameter mm

Double wall/single image Number

Diameter mm

> 3.0 > 4.5 > 6.2

≤ 4.5 ≤ 6.2 ≤ 8.4

15 14 14

0.125 0.16 0.16

14 13 13

0.16 0.20 0.20

> 8.4 > 12.0 > 15.9

≤ 12.0 ≤ 15.9 ≤ 20.0

13 12 11

0.20 0.25 0.32

12 12 11

0.25 0.25 0.32

> 20.0 > 32.0 > 40.0

≤ 32.0 ≤ 40.0 ≤ 50.0

10 10 9

0.40 0.40 0.50

10 10 9

0.40 0.40 0.50

21.5 UNDERCUT DEPTH MEASUREMENT Where radiography is used as the only method of determining internal undercut (see Clause 18.5), the images of discontinuities that have been identified as undercut shall be assessed for approximate depth by comparing the density of its film image with the density of the film images of grooves of given sizes machined into an undercut comparator shim. Alternatively, undercut may be assessed for depth by comparing production radiographs with reference radiographs prepared from weldments of the same nominal thickness and welding procedure, and where the depth of real examples of undercut has been measured by macro examination. Undercut comparator shims shall comply with the following: (a)

Material A comparator shim shall have the same radiographic opacity as the material under testing.

(b)

Dimensions The dimensions of comparator shims shall be as shown in Figure 21.1.

(c)

Location A comparator shim shall match the curvature of the pipe and shall be placed alongside and parallel with the edge of the external weld with the grooves on the inside radius. The shallowest groove on the comparator shim shall be placed closest to the weld.

(d)

Number of comparator shims Comparator shims shall be visible as follows: For panoramic exposures, a minimum of two comparator shims spaced approximately equidistant shall appear on the radiograph. The separation of comparator shims shall not exceed 400 mm. NOTES: 1 Where a multi-exposure method is used, comparator shims should be located adjacent to the image quality indicators or at locations where undercut is expected. 2 Where a multi-exposure or multi-film method is used, at least one shim should be visible on each cut length of film of 400 mm or less.

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Method of assessment of undercut using comparator shims To assess the relative depth of undercut, the density of the actual undercut shall be compared with the density observed in the machined grooves of known depth in the undercut comparator.

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NOTE: This may be achieved by totally masking all areas of the radiograph, with the exception of a window that is of comparable size with the actual undercut, and comparing the density observed in the same size window of the machined grooves.

S e e d et a i l 5 0 (t y p i c a l) A

1. 5

A

3

3 d 1 = 0.4

Cur ve d to suit o ut s i d e sur fac e of pipe Gro ove s m ay b e m ad e b efore c ur v in g to s ha p e

d 2 = 0.6 d 3 = 0.8 S EC T I O N A - A

R o ot r ad i u s 0. 25 a p prox.

d

2 2 . 5° 2 2 . 5° 90°

D E TA I L O F G RO OV E

NOTES: 1

Tolerance on depth of groove ±0.05 mm.

2

A Charpy V-notch tool should be used to produce the grooves. DIMENSIONS IN MILLIMETRES

FIGURE 21.1 DIMENSIONS OF UNDERCUT COMPARATOR SHIM

21.6 GAS PORE DEPTH MEASUREMENT The images of discontinuities that have been identified as gas pores (GP) shall be assessed for depth (through thickness dimension) by comparing the density of its film image with the density of the film images of a 6 mm diameter flat bottom hole. The gas pore comparator shim shall comply with the following: (a)

Material The comparator shim shall have the same radiographic opacity as the material under testing.

(b)

Dimensions The dimensions of the comparator shim shall be as shown in Figure 21.2.

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Method of use Reference radiographs shall be made of the comparator shim and test weld. These reference radiographs shall be used in order to assess the depth of gas pores in production radiographs.

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50

Ø6 15

PLAN VIEW

3

0. 5

1.0

2.0

END VIEW

3 .0

H o l e d e pt h s SIDE VIEW

Ø6 mm

T hir d an g l e prote c t i o n

Gas p ore shim DIMENSIONS IN MILLIMETRES

FIGURE 21.2 GAS PORE COMPARATOR SHIM

21.7 INTEPRETATION AND ASSESSMENT OF RADIOGRAPHS Discontinuities observed on radiographs shall be identified, sized, and assessed in accordance with Section 17. Defects shall be correlated with the radiograph, located with respect to the weld and recorded on a test report. Defects shall be identified, and symbolized in accordance with AS 4749. NOTE: Where the terminology and abbreviations used in AS 4749 do not adequately describe some of the discontinuities found in pipeline welds, additional descriptive abbreviations may be required e.g. internal (i), external (e); hollow bead in the root (EC), arc strike (AS), absence of defects (A), debris in pipe (DIP).

21.8 CRITERIA OF ACCEPTANCE The weld shall comply with Section 17.

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21.9 REPORT OF RADIOGRAPHIC TESTING A test report shall be made in accordance with AS 2177 and the requirements of this Standard. 21.10 RETENTION OF RADIOGRAPHS

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Radiographic images or digital copies of the images shall be retained for life of the pipeline by the licensee.

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T E S T I N G

22.1 ULTRASONIC TESTING

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22.1.1 General Ultrasonic inspection of welded joints (AUT or manual phased array line scanning) shall be the preferred inspection method, capable of producing a permanent record. The technique shall be performed using an approved documented and qualified procedure. For weld inspections, ‘manual phased array inspection’ shall be capable of a permanent record of A-Scan, B-Scan, C-Scan, S-Scan and ToFD, for the semi- or fully automated ultrasonic testing of fusion welded joints in metallic materials with a minimum nominal thickness of 3.9 mm. Where material-dependent ultrasonic parameters are specified, they shall be based on steels having an ultrasonic sound velocity of (5920 ±50) m/s for longitudinal waves, and (3255 ±30) m/s for transverse waves. NOTE: It is necessary to take this fact into account when examining materials with a different velocity. Refer to ISO 13588 for PAUT application.

The effectiveness of the ultrasonic procedure shall be demonstrated on a ‘mock up’ weld that is typical of the discontinuities found in production and containing artificial discontinuities in the form of appropriately placed side-drilled holes or machined grooves. The type and number of discontinuities shall be approved (see Clause 1.6.1). 22.1.2 Purpose The purpose of an ultrasonic testing is to detect discontinuities in the weld, the heat-affected zone, and in the parent metal immediately adjacent to the weld. Manual ultrasonic testing may be suitable— (a)

as an alternative to radiographic testing in pipe where the weld root geometry is consistent, such as is achieved with automatic welding methods;

(b)

as a supplement or an alternative to radiographic testing in the determination of particular discontinuities; and

(c)

where due to geometry or lack of access (radiographic testing is not appropriate).

22.1.3 Method The methods of test shall be appropriate to the type of weld to be examined. When using manual phased array ultrasonic inspection— (a)

a scan plan shall be provided for each nominal thickness (WT) and diameter of each weld requiring inspection; and

(b)

a permanent record of the weld scan shall be recorded for the area of interest, in an unprocessed form with no threshold.

Where there is a possibility of transverse cracking in the weld, appropriate transverse scanning patterns shall be employed (such as pitch and catch or ToFD scanning at 45° to the weld). NOTE: The testing of the weld root area for discontinuities in single preparation welds poses problems associated with the root profile/penetration bead, which usually gives a strong ultrasonic reflection. This reflection needs to be separately identified from indications given by other discontinuities.

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22.1.4 Surface preparation It shall be ensured that the minimum surface preparation is adequate for and appropriate to the level of testing. NOTE: The shape of weld reinforcement may limit interpretation. In such cases additional surface preparation may need to be carried out. To fully evaluate a weld, surface preparations categorized by AS 2207 as SP1, SP2, SP3 and SP4, may be necessary. Licensed to Mr Paolo Corronca on 10 June 2016. 3 concurrent user network licenses. Copying and copy/pasting prohibited. (10607402). Get permission to copy from this publication www.saiglobal.com/licensing

22.1.5 Sensitivity Welds shall be scanned using an adequate level of sensitivity to ensure that all relevant discontinuities are detected. Discontinuities so detected shall be subsequently evaluated using the appropriate sensitivity and recording requirements as follows: (a)

Tiers 1 and 2 Evaluation sensitivity shall be Level 2 in accordance with AS 2207.

(b)

Tier 3 Engineering Critical Assessment (ECA). Evaluation sensitivity shall be Level 1 in accordance with AS 2207. NOTE: See Section 17 for further information about Tiers 1, 2 and 3.

Irrespective of the evaluation sensitivity used, all cracks shall be sized for length and height. 22.1.6 Assessment An assessment of the discontinuities detected in a weld shall be made. Discontinuities shall be identified and symbolized. The terminology and abbreviations described in Clause 21.7 and AS 4749 may be used for this purpose. 22.1.7 Criteria of acceptance The weld shall comply with Section 17. 22.1.8 Report The results of tests shall be reported in accordance with AS 2207. 22.1.9 Qualification of personnel Personnel shall be qualified in accordance with Clause 19.3. 22.2 AUTOMATED ULTRASONIC TESTING (AUT) 22.2.1 General This Standard provides rules and the issues to be addressed when automated ultrasonic testing is being considered for inspecting the girth welds of new onshore pipelines in construction. Construction and testing shall be carried out by competent contractors using a well-trained, qualified, and experienced workforce, using reliable, modern, and well-maintained technology and the work shall comply with safe and environmentally sound working practices at all times. In particular non-destructive testing and inspection personnel shall be properly trained and qualified to recognized industry standards by examination and/or by individual test and be widely experienced in operations with the equipment. The AUT system and operator requirements shall be in accordance with Appendix H.

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P A R TI CLE

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23.1 PURPOSE The purpose of a magnetic particle test is to locate discontinuities that are on or near the surface of the weld and adjacent parent metal. 23.2 METHOD Magnetic particle testing shall be carried out in accordance with AS 1171 and the following: (a)

Method of magnetization The method of magnetization shall be magnetic flow (sustained).

(b)

Cleaning after testing Magnetic particle medium shall be removed after testing. The preferred method of cleaning is by sand blasting. A corrosion inhibitor may be applied in certain weather conditions or where coating is delayed.

(c)

Test report To be issued as per AS 1771.

23.3 QUALIFICATION OF PERSONNEL Personnel shall be qualified in accordance with Clause 19.3. 23.4 CRITERIA OF ACCEPTANCE The weld shall not contain any discontinuities that are on or near the surface of a weld and adjacent parent metal that do not comply with Section 17.

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D Y E - P E N E T R A N T

T E S T I N G

24.1 PURPOSE

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The purpose of dye-penetrant testing is to locate discontinuities that are open to the surface of a weld and adjacent parent metal. 24.2 METHOD Dye-penetrant testing shall be carried out in accordance with AS 2062 and the following: (a)

Type of testing medium The type of testing medium shall contrast in colour and be water washable.

(b)

Cleaning after testing The penetrant and the developer shall be removed after testing, preferably by abrasive blasting. A corrosion inhibitor may be applied.

(c)

Reports Reports shall be issued as per AS 2062.

24.3 QUALIFICATION OF PERSONNEL Personnel shall be qualified in accordance with Clause 19.3. 24.4 CRITERIA OF ACCEPTANCE The weld shall not contain any discontinuities that are open to the surface of a weld and adjacent parent metal that do not comply with Section 17.

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S E C T I O N 2 5 R E P A I R O F A N U N A C C E P T A B L E W E L D

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25.1 GENERAL A weld not meeting the defect assessment criteria in accordance with Section 17 shall be repaired or cut out. 25.2 REPAIR METHODS A repair to a weld containing a defect shall be made using an approved repair procedure documented and qualified in accordance with Section 6. Repairs to repair welds are not prohibited by this Standard; however, they shall be subject to the specific approval of a welding engineer on a case by case basis. The repair procedure should be developed in consideration of the material in Appendix C, and in particular Paragraph C9.4. The procedure specification shall include details of the following: (a)

The means of removing the defect, including the length of sound metal to be removed at each end.

(b)

Welding procedure items according to Section 6.

(c)

The means of providing assurance that HACC will not be encountered.

(d)

The non-destructive testing methods used to confirm the repair meets the defect acceptance criteria.

(e)

The method and the timing of non-destructive testing of the completed repaired production weld.

(f)

Mechanical testing in accordance with Table 7.2.

25.3 QUALIFICATION OF REPAIRS USING A DIFFERENT WELD PROCEDURE THAN THE ORIGINAL WELD Testing shall be in accordance with Table 7.2. 25.4 QUALIFICATION OF THE REPAIR WELDING PROCEDURE The following procedures for qualification of repair welding apply: (a)

Qualification of a repair weld shall comply with the methods of qualification identified in Clause 6.4.

(b)

Where qualification by testing is required, a test weld shall be prepared to represent the location and depth of repair.

(c)

Repairs involving a single pass only shall require separate qualification.

(d)

Repairs made using cellulose consumables shall have a minimum of two passes.

NOTE: Repair weld procedures that involve a full thickness repair may be used for partial thickness repairs.

25.5 INSPECTION The repaired weld shall be inspected in accordance with Sections 18 and 19. 25.6 CRITERIA OF ACCEPTANCE The criteria of acceptance of a repaired weld shall be as specified in Section 17. COPYRIGHT

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O F

A N

A R C

B U R N

26.1 GENERAL

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An arc burn on pipe that is to be operated at a pressure that produces a hoop stress equal to or greater than 40% SMYS shall be— (a)

repaired by grinding; or

(b)

cut out.

26.2 REPAIR BY GRINDING Where a repair is made by grinding, the area of the metallurgical notch created by the arc burn shall be removed completely, and the remaining nominal thickness shall be not less than 90% of the nominal thickness of the pipe. 26.3 METHOD OF INSPECTION The ground area shall be etched with either a 10% solution of ammonium persulfate or a 5% solution of nital, and shall be visually inspected. NOTE: If a blackened spot appears, the metallurgical notch produced by the arc burn has not been removed.

26.4 CRITERIA OF ACCEPTANCE The swabbed area shall be free of any black spot. 26.5 CLEANING AFTER TESTING Regions that have been etched shall be cleaned after testing is complete. A corrosion inhibitor may be applied.

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S E C T I O N 2 7 C U T T I N G O U T A N U N A C C E P T A B L E W E L D O R A N A R C B U R N

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A permanent repair shall be made by cutting out a cylindrical piece of pipe containing the unacceptable weld or arc burn and— (a)

making new weld preparations and welding the joint; or

(b)

replacing it with another cylinder of pipe that complies with the engineering design.

Where a repair is made on a tested pipeline, a cylinder cut from pre-tested pipe shall be used.

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S E C T I O N

2 8

R E C O R D S

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In addition to the requirements of Section 13 of AS 2885.1, a record shall be made showing the following, by relation to a kilometre post, survey control station, or coordinates: (a)

The unique identity and location and type(s) of non-destructive testing shall be noted for each weld.

(b)

The unique identity and location of welds that failed to comply and were subsequently successfully repaired.

(c)

Consumable certificates.

(d)

Project welding procedures specification, welder qualifications and procedure qualification records.

(e)

Project NDT procedures and records.

(f)

Location and type of pipe repairs including arc strike repairs.

(g)

Location of golden welds.

(h)

Production cut out weld non-destructive testing and mechanical test records.

This record shall be retained and maintained by the pipeline licensee until the pipeline is abandoned or removed.

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APPENDIX A

ITEMS REQUIRING APPROVAL

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(Normative) This Appendix sets out the welding and non-destructive testing specifics for approval. NOTE: AS 2885.0 defines the approval for pipelines. Clause

Subject

Item requiring approval

1.6.50

NDT technicians

NDT technician qualification program

2.2.1

Welding or cutting on a pipeline after commissioning

Risk assessment

2.2.1

Welding or cutting on a pipeline after commissioning

Earthing procedures

3.2

Welding engineering

Welding procedure specifications*

3.2

Welding engineering

Alternative welding standard*

3.2

Welding engineering

Repair to a repair

3.2

Welding engineering

Qualifications of the welding supervisor and inspector*

3.2

Welding engineering

Qualification program for NDT personnel and NDT procedures*

3.2

Welding engineering

PWHT procedures*

5.2

Butt welding between components of equal nominal thickness

Alternative joint preparations than those specified

5.5.2

Fillet welding a lug, boss pig bar or pad Welding procedure specifications for fillet welding a lug, boss pig bar or pad

5.6

Welding on threaded joints

Welding on threaded joints

5.15

Golden welds

The number and location of golden welds

6.4, 6.4.3

Methods of qualification

Qualification to an alternative welding standard

6.4.2

Qualification by testing

A pWPS

6.5

Qualification by the use of engineering A WPS

6.5.1

Change in an essential variables

A change in essential variables beyond the qualified range requires re-approval of the WPS

Table 6.1

Material specification

Alternative standards from those nominated

7.4

Test weld destructive tests

The testing requirements

10.4.1

Repeated test

Authorization to repeat a welder test

10.5

Records of the results

Welder/welder operator qualification

10.6

Portability of a welders or welder operators qualification

Portability of welder/welder operator qualifications

12.20

PWHT

PWHT activities

12.21

Identification of a production weld

The method to achieve traceability ( continued )

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Clause

122

Subject

Item requiring approval

15.1

Welding and cutting on a pipeline after Welding procedures commissioning or after hydrostatic testing

1.5.3

Hot repair of leaking gas filled pipelines

Procedures for the following: (i)

The detection of explosive mixtures.

(ii)

The means of maintaining work site to mainline valve communication.

(iii)

The method of regulating gas pressure.

16.4

Safety (in-service welding)

Risk assessment

16.10

Qualification of welding procedures (in-service welding)

WPS

16.10

Qualification of welding procedures (in-service welding)

Grouping of certain conditions

17

Criteria of acceptance for girth weld discontinuities

Choice of tier

17.5

Tier 3 criteria—Engineering critical assessment

The ECA procedure

19.7

Exemption from radiographic or ultrasonic testing

Approval to use alternative testing methods and approval of the test method

20.2

Radiographic testing

The testing procedure

22.1

Ultrasonic testing

The testing procedure

22.1

Ultrasonic testing

The type and number of discontinuities in the mock up weld

25.2

Repair methods

The repair WPS and each repair on a repair*

C9.1

Restrictions

Other methods for designing out HACC from those described

C9.2.1

Normal lifts

Alternative methods for demonstrating the risk of HACC is remote

H1

System requirements

Calibration blocks designed to ASTM E1961-11

* Requires approval by a welding engineer with qualifications in accordance with Clause 3.2.

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APPENDIX B

LIST OF REFERENCED DOCUMENTS

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(Normative) AS 1171

Non-destructive testing—Magnetic products, components and structures

particle

testing

of

ferromagnetic

1210

Pressure vessels

1674 1674.2

Safety in welding and allied processes Part 2: Electrical

1710

Non-destructive testing—Ultrasonic testing of carbon and low alloy steel plate and universal sections—Test methods and quality classification

1796

Certification of welders and welding supervisors

1817 1817.1

Metallic materials—Vickers hardness test Method 1: Test method (ISO 6507-1:1997, MOD)

1929

Non-destructive testing—Glossary of terms

2062

Non-destructive testing—Penetrant testing of products and components

2177

Non-destructive testing—Radiography of welded butt joints in metal

2205 2205.1 2205.2.1 2205.3.1 2205.5.1 2205.6.1 2205.7.1 2205.7.3

Methods for destructive testing of welds in metal Method 1: General requirements for tests Method 2.1 Transverse butt tensile test Method 3.1: Transverse guided bend test Method 5.1: Macro metallographic test for cross-section examination Method 6.1: Weld joint hardness test Method 7.1: Charpy V-notch impact fracture toughness test Method 7.3: Fracture mechanics toughness tests (K lc, critical CTOD and critical J values)

2207

Non-destructive testing—Ultrasonic testing of fusion welded joints in carbon and low alloy steel

2314

Radiography of metals—Image recommendations for their use

2706

Numerical values—Rounding and interpretation of limiting values

2812

Welding, brazing and cutting of metals—Glossary of terms

2832 2832.1

Cathodic protection of metals Part 1: Pipes and cables

2885 2885.0 2885.1

Pipelines—Gas and liquid petroleum Part 0: General requirements Part 1: Design and construction

3992

Pressure equipment—Welding and brazing qualification

4041

Pressure piping

4458

Pressure equipment—Manufacture

4564

Specification for general purpose natural gas COPYRIGHT

quality

indicators

(IQI)

and

AS/NZS 2885.2:2016

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AS 4749

124

Non-destructive testing—Terminology of and abbreviations for fusion weld imperfections as revealed by radiography

4882

Shielding gases for welding

AS/NZS 1167 1167.2

Welding and brazing—Filler metals Part 2: Filler metal for welding

1553 1553.1

Covered electrodes for welding Part 1: Low carbon steel electrodes for manual metal-arc welding of carbon steels and carbon-manganese steels

2717 2717.1

Welding—Electrodes—Gas metal arc Part 1: Ferritic steel electrodes

2885 2885.5

Pipelines—Gas and liquid petroleum Part 5: Field pressure testing

4855

Welding consumables—Covered electrodes for manual metal arc welding of non-alloy and fine grain steels—Classification

4857

Welding consumables—Covered electrodes for manual metal arc welding of high-strength steels—Classification

14341

Welding consumables—Wire electrodes and weld deposits for gas shielded metal arc welding of non alloy and fine grain steels—Classification (ISO 14341:2010, MOD)

16834

Welding consumables—Wire electrodes, wires, rods and deposits for gas arc welding of high strength steels—Classification shielded (ISO 16834:2012, MOD)

AS ISO 9712 AS ISO/IEC 17025

Non-destructive testing—Qualification and certification of NDT personnel General requirements for the competence of testing and calibration laboratories

AS/NZS ISO 14171 Welding consumables—Solid wire electrodes, tubular cored electrodes and electrode/flux combinations for submerged arc welding of non alloy and fine grain steels—Classification 17332

Cinematography—Manufacturer-printed latent image identification information for 35 mm motion-picture colour-printed film—Specifications

17632

Welding consumables—Tubular cored electrodes for gas shielded and nongas shielded metal arc welding of non-alloy and fine grain steels— Classification (ISO 17632:2004, MOD)

17634

Welding consumables—Tubular cored electrodes for gas shielded metal arc welding of creep-resisting steels—Classification

18276

Welding consumables—Tubular cored electrodes for gas shielded and nongas shielded metal arc welding of high-strength steels—Classification (ISO 18276:2005, MOD)

26304

Welding consumables—Solid wire electrodes, tubular cored electrodes and electrode-flux combinations for submerged arc welding of high strength steels—Classification COPYRIGHT

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ISO 636

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2560

Welding consumables—Rods, wires and deposits for tungsten inert gas welding of non-alloy and fine-grain steels—Classification Welding consumables—Covered electrodes for manual metal arc welding of non-alloy and fine grain steels—Classification

10863

Non-destructive testing of welds—Ultrasonic time-of-flight diffraction technique (TOFD)

13588

Non-destructive testing of welds—Ultrasonic testing—Use of automated phased array technology

14171

Welding consumables—Solid wire electrodes, tubular cored electrodes and electrode/flux combinations for submerged arc welding of non alloy and fine grain steels—Classification

14341

Welding consumables—Wire electrodes and weld deposits for gas shielded metal arc welding of non alloy and fine grain steels—Classification

14731

Welding coordination—Tasks and responsibilities

15653

Metallic materials—Method of test for the determination of quasistatic fracture toughness of welds

16828

Non-destructive testing—Ultrasonic testing—Time-of-flight diffraction technique as a method for detection and sizing of discontinuities

16834

Welding consumables—Wire electrodes, wires, rods and deposits for gas shielded arc welding of high strength steels—Classification

17632

Welding consumables—Tubular cored electrodes for gas shielded and nongas shielded metal arc welding of non-alloy and fine grain steels— Classification

18275

Welding consumables—Covered electrodes for manual metal arc welding of high-strength steels—Classification

18276

Welding consumables—Tubular cored electrodes for gas-shielded and nongas-shielded metal arc welding of high-strength steels—Classification

19232 19232-1

Non-destructive testing—Image quality of radiographs Part 1: Determination of the image quality value using wire-type image quality indicators Part 2: Determination of the image quality value using step/hole-type image quality indicators

19232-2 26304

testing—Use

Welding consumables—Solid wire electrodes, tubular cored electrodes and electrode-flux combinations for submerged arc welding of high strength steels—Classification

API 1104 Spec 5L

Welding of pipelines and related facilities Specification for line pipe

ASME B31.3 B31.4 B31.8

Process Piping Pipeline Transportation Systems For Liquids And Slurries Gas Transmission and Distribution Piping Systems

AWS A5.1 A5.5

of

Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding Specification for Low-Alloy Steel Electrodes for Shielded Metal Arc Welding COPYRIGHT

AS/NZS 2885.2:2016

AWS A5.17 A5.18 A5.20

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A5.23 A5.28

A5.29 A5.36 BS 7910 NACE * MR0175-ISO 15156

126

Specification for Carbon Steel Electrodes for Flux Cored Arc Welding Specification for Low-Alloy Steel Electrodes and Fluxes for Submerged Arc Welding Specification for Low-Alloy Steel Filler Metals for Gas Shielded Arc Welding Specification for Low-Alloy Steel Electrodes and Rods for Flux Cored Arc Welding Specification for Carbon and Low-Alloy Steel Flux Cored Electrodes for Flux Cored Arc Welding and Metal Cored Electrodes for Gas Metal Arc Welding Specification for Carbon Steel Electrodes for Flux Cored Arc Welding Specification for Low-Alloy Steel Electrodes and Fluxes for Submerged Arc Welding Guide to methods for assessing the acceptability of flaws in metallic structures Petroleum and natural gas industries—Materials H2S-containing environments in oil and gas production Note Note Note Note Note

for

use

in

WTIA

Technical Technical Technical Technical Technical

1 The Weldability of Steels 3 Care and Conditioning of Arc Welding Consumables 7 Health and Safety in Welding 20 Repair of Steel Pipelines 22 Welding Electrical Safety

DNV-OS-F101

Offshore Standard Submarine Pipeline Systems

DNV-RP-F118

Pipe Girth Weld AUT System Qualification and Project Specific Procedure Validation

EPRG †

EPRG Tier 2 guidelines for the assessment of defects in transmission pipeline girth welds

ASTM E1961-11 Standard Practice for Mechanized Ultrasonic Testing of Girth Welds Using Zonal Discrimination with Focused Search Units MSS-SP-97

* †

Integrally Reinforced Forged Branch Outlet Fittings—Socket Welding, Threaded And Buttwelding Ends

NACE is the designator for the American National Association of Corrosion Engineers. EPRG is the designator for the European Pipeline Research Group. COPYRIGHT

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APPENDIX C

AVOIDANCE OF HYDROGEN ASSISTED COLD CRACKING (HACC) (Normative) Licensed to Mr Paolo Corronca on 10 June 2016. 3 concurrent user network licenses. Copying and copy/pasting prohibited. (10607402). Get permission to copy from this publication www.saiglobal.com/licensing

C1 SCOPE This Appendix sets out requirements for the selection and specification of welding procedures designed to avoid hydrogen assisted cold cracking (HACC) in the heat-affected zone (HAZHACC) or weld metal (WMHACC) in pipeline girth welds that are made with cellulosic electrodes. C2 BACKGROUND HACC, especially HAZHACC, is a widely known problem in welding technology, and a large body of research and practical technological literature exists on the subject. C3 HACC IN PIPELINE WELDING The problem of HACC in pipeline welding is unique, due to the following: (a)

Cellulosic electrodes are commonly employed, leading to very high levels of hydrogen in the weld metal of 30 ppm or more. These levels of hydrogen are never encountered in other safety critical large scale welded constructions.

(b)

Pipeline steels are among the strongest steels used for welded constructions, and the deliberate use of consumables having such high hydrogen levels is never encountered in other applications using high strength steels.

(c)

Pipeline girth welds are subjected to externally applied loads during welding as a result of lifting and lowering-off.

(d)

In high-strength pipe, the composition of the weld metal will, in order to achieve a strength level that matches the strength of the pipe, be substantially less weldable than the pipe. The pipe will be more leanly alloyed and hence more weldable than the weld metal because it has benefited from thermomechanical controlled processing (TMCP) during strip or plate rolling. (The same does not apply to fittings, and for this reason special care needs to be taken with the development of welding procedures for fittings.)

(e)

HACC can occur up to 24 h after the weld is completed and therefore may not be detected by the proposed NDT method, therefore a minimum 24 h delay should be considered in WPS development before NDT is undertaken.

C4 WELD METAL HYDROGEN ASSISTED COLD CRACKING (WMHACC) Unlike HAZHACC, there are no available methods for predicting the onset, and hence providing methods for avoidance of WMHACC are not available. In the welding of modern high-strength pipelines WMHACC is the much more likely form of HACC.

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C5 DETECTION OF HACC WITH NDT

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In pipeline construction practice, the most common form of non-destructive testing (NDT) is radiography, which is not the most ideal tool for detection of HACC. High-quality X-radiography performed with fine-grained film and a single-wall single-image technique, with the primary beam normal to the longitudinal axis of the pipe, has a high probability of detecting cracks, but it is not as effective as ultrasonic testing. Other forms of radiography have a much lower probability of detecting cracks. In other safety critical welding applications, the NDT is conducted at least 24 h after the completion of welding so as to ensure that delayed HACC will have taken place by the time the NDT is performed. In pipeline construction practice, considerable effort is expended to keep the NDT crew as close behind the welding crew as possible. NDT is often completed in under 24 h. C6 THE EFFECT OF DELAY TIME In pipeline welding with cellulosic electrodes, when cracking does occur, it usually takes place within minutes of welding because the hydrogen concentration is already saturated, and the accumulation of hydrogen by diffusion (which is the rate-dependent process responsible for delayed cracking) is not required. The single most important factor that controls whether or not cracking will occur is the time delay between the root pass and the hot pass. Delays of more than 6 min between the completion of the root pass and the deposition of the hot pass greatly increase the risk of HACC occurring. The hot pass increases the weld throat thickness, reduces the notch effect strain concentration in the WT region, refines and tempers the microstructure, and most importantly raises the temperature of the weldment above the critical level for the onset of HACC and reduces the weld cooling rate to enhance hydrogen effusion. C7 THE EFFECT OF STRENGTH Another important practice that is adopted in pipeline welding is the deliberate use of low strength, often undermatching, electrodes for the root pass. This is a very effective method of reducing the risk of HACC by the use of lower strength, more ductile, weld metal that is less susceptible to the detrimental effects of hydrogen. C8 WELDING PROCEDURE QUALIFICATION Section 6 of this Standard requires the development and qualification of a welding procedure in order to demonstrate that the production welds made in accordance with that procedure (i.e. within the limits of the essential variables and the permitted changes to the essential variables) will, among other things, be free from HACC. A cellulosic welding procedure may be qualified by— (a)

testing;

(b)

use of a qualified procedure called up by a pipework design standard;

(c)

prequalification; or

(d)

engineering.

In any of these cases, HACC is a serious threat to the integrity of the pipeline. Due to the difficulty in its detection during construction by NDT, and its potential systemic nature if it does occur, it is of critical importance that it be designed out of the procedure. This is a key part of procedure development and qualification. The risk of occurrence should be ‘remote’ under any welding condition that is within the envelope encompassed by the qualified procedure. This means that under the nominal (or mid-range) conditions there should be a substantial margin of safety. The likelihood of HACC under the nominal conditions of the procedure should be ‘improbable’. COPYRIGHT

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The means of achieving and, importantly, demonstrating this outcome is not simple. All of the tools that are required do not exist in a convenient form.

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There is no simple test that fully simulates the field welding situation. While there are wellestablished guidelines for the avoidance of HAZHACC, there are no guidelines for the avoidance of WMHACC. The development of such guidelines is a key part of ongoing research programs. C9 METHODS FOR ‘DESIGNING-OUT’ HACC FROM WELDING PROCEDURES C9.1 Restrictions These methods apply only to the following circumstances: (a)

Welding with conventional cellulosic electrode procedures.

(b)

Where the delay time between the start of the root pass and the start of the hot pass does not exceed 8 min.

(c)

Normal methods of onshore pipeline construction used in Australia.

(d)

The typical range of climatic conditions normally encountered in pipeline construction in Australia.

(e)

Welding of new pipe and fittings.

Other methods may be used for circumstances outside the restrictions; however, such methods shall be fully documented, and shall be approved (see Clause 1.6.1). C9.2 Welding of pipe C9.2.1 Normal lifts Where no more than two standard (up to 18 m) pipe lengths are lifted clear of the skids and where in all other respects the lifting and lowering off stresses are normal as for a largely level right of way without bends of any kind, the following applies: (a)

In pipe up to 14.5 mm nominal thickness and DN 500, and up to and including X52 welded entirely with E6010 electrodes, the risk of HACC may be considered to be ‘remote’. The use of controlled heat input, preheat and other measures designed to reduce the risk of HACC is not required and the welding procedure qualification test weld (if required) need not simulate lifting and line up stresses or other conditions expected to affect HACC.

(b)

In pipe up to 10 mm nominal thickness and DN 500, up to and including X70, and with carbon equivalent (CE) values up to a limit of 0.40, weld with E6010 electrodes in the root and with electrodes up to E8010 specified in accordance with the requirements of this Appendix, in the remaining passes, the risk of HACC may be considered to be ‘remote’ provided the electrode burn-off rate does not fall below the equivalent of 0.5 kJ/mm. The use of preheat is not required, and the welding procedure qualification test weld (if required) need not simulate lifting and line up stresses or other conditions expected to affect HACC.

(c)

In circumstances outside those covered by Items (a) and (b) above, the risk of HACC may be considered ‘remote’ provided the welding procedure incorporates a minimum preheat and interpass temperature of 100°C.

(d)

Alternative methods of demonstrating that the risk of HACC is ‘remote’ may be used. These may be based on full scale testing, involving simulation of the worst case condition that will be encountered in the field, or other methods such as correlations with laboratory tests such as Welding Institute of Canada tests. Such methods shall be fully documented, and shall be approved (see Clause 1.6.1).

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C9.2.2 Extreme lifts For lifting conditions other than in Paragraph C9.2.1, a minimum preheat temperature of 100°C shall be used and the hot pass shall be completed prior to lifting or lowering off. The delay time between the start of the root pass and the start of the hot pass should not exceed 6 min.

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C9.3 Welding of fittings The development of welding procedures for fittings presents special problems such as— (a)

fittings of equivalent grade are likely to be less weldable than pipe;

(b)

the development of a welding procedure by testing, of necessity, results in the destruction of a fitting; and

(c)

the methods of holding fittings for welding are quite different from that used for pipes.

For fittings in material grades up to and including X52 or equivalent, the risk of HACC in the welding of fittings may be considered to be ‘remote’ providing low hydrogen welding procedures are used and the minimum preheat and interpass temperature is not less than that determined using WTIA Technical Note 1, or 100°C, whichever is higher. For fittings in higher grades, the carbon equivalent shall be known and unique procedures shall be developed and qualified. NOTE: Non-destructive testing of welds in fittings should be undertaken at least 24 h after the completion of welding.

C9.4 Repair welding The risk of HACC during repair welding is significant. Specific consideration shall be given to the following: (a)

Repairs to the root bead from inside the pipe should be avoided due to the high risk of HACC in un-tempered low heat input welds and their HAZs.

(b)

Single pass cosmetic repairs to the capping pass should be avoided for the same reasons as in Item (a). If repairs to the capping pass are necessary, they shall be subjected to a qualified, documented, and approved procedure.

(c)

Low heat input stripper passes used to even out the extent of groove filling can constitute a risk of WMHACC, and should be avoided.

(d)

In general, the level of residual stress associated with repair welding will be higher than in the original welds, and the need for preheat is likely to be higher.

NOTE: While the use of low hydrogen electrodes is good practice for repair welding in order to reduce the risk of HACC, consideration needs to be given to the fact that when low hydrogen welding is undertaken the delay time before NDT should be at least 24 h. This is of course not a reason to avoid the use of low hydrogen welding methods. It means however, that where a delay time of 24 h cannot be accommodated there needs to be a very high level of confidence that HACC has been designed out of the welding procedure and, in addition, that the procedure is adhered to.

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APPENDIX D

SELECTION AND SPECIFICATION OF CELLULOSIC WELDING ELECTRODES

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(Informative) D1 SCOPE This Appendix provides advisory information and advice on the selection and specification of cellulosic manual metal arc welding (MMAW) electrodes for pipeline welding. It also provides guidance on the desirable supplementary measures, which may be used to deliver increased confidence in the integrity of the welds. The need for these supplementary measures is an important part of the pipeline project engineering process. In the past, the quality assurance processes in the procurement of welding consumables received too little attention; both in absolute terms and in comparison with pipe procurement. Over the last 20 years or so there have been major advances in the strength and the weldability of pipe steels. This has caused a situation where if welding problems are to occur they will most likely be in the weld metal, and this, combined with the limitations of current welding electrode Standards, has necessitated the development of this Appendix. D2 BACKGROUND Cellulosic (EXX10) electrodes have been the primary choice for the welding of pipelines because of their unique combination of high welding speeds and their ability to make single-sided full penetration welds. The principal disadvantage of EXX10 electrodes is the high level of hydrogen they contribute to the weld metal, and the resulting risk of hydrogen assisted cold cracking (HACC) in the heat-affected zone (HAZ) or in the weld metal (WMHACC). Pipeline grades above X60, and up to and including X70, have been satisfactorily welded with cellulosic electrodes in various combinations; however, there have been widely documented problems, including serious instances of WMHACC. Australian experience, in particular, has stressed the advantages of using low strength (i.e. E6010) electrodes in the root pass in order to achieve the benefits of high toughness and reduce risk of WMHACC, and AS 2885.1 was specifically amended to delete the use of root bend tests so as to allow low strength electrodes to pass the procedure qualification test. Experience has shown that for pipeline grades up to around grade X52 (depending on the nominal thickness), E6010 (E4110) electrodes can be used successfully while obtaining adequate strength matching between the weldment and the pipe. The welds made with E6010 electrodes also give good toughness, and have a low risk of WMHACC. Recent research has shown that EXX10 electrodes can suffer loss of coating moisture when they are exposed to the atmosphere, and this loss of moisture can result in an increased likelihood of WMHACC due to increased transfer of alloying elements across the arc. Care needs to be taken to see that electrodes are supplied in packaging that prevents the loss of moisture, and that once the packaging is opened, the contents are discarded if not used on the same day.

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D3 STRENGTH MATCHING

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An important factor in the selection of girth welding consumables is the matching of pipe strength. In general, it is desirable that welds be stronger than the pipe they join so that, in the presence of a weld imperfection, if displacement controlled loads are experienced by the pipeline, the pipe will be plastically strained rather than the displacement being concentrated within the weld joint (see Clause 1.6.44). The subject of strength matching is extremely complex, and it is not possible to show in all circumstances that matching is achieved by means of simple tests. Recent research on the relatively thin-walled pipelines used in Australia has shown (by interpolation) that strength matching is achieved by the use of E6010 electrodes up to grade X60, and by combinations of E6010 and E8010 electrodes up to X65. The research has also shown that E6010 and E8010 combinations can undermatch X70 grade pipe and that adequate strength matching in 5 mm nominal thickness X80 cannot be achieved with any existing cellulosic consumables. These observations are very much simplified and depend on a number of critical factors such as the actual strength of the pipe in the longitudinal direction, the test method used to assess the level of matching, and the pipe nominal thickness. This experience is expected to be valid for circumstances in which the distribution of yield strength of the pipe is within the range of common Australian experience; however, the use of unexpectedly strong pipe will make it very difficult to achieve strength matching, especially in thin pipe in the higher grades. It is good practice, for a number of reasons, to limit the range of the transverse yield strength of the pipe, and attention is drawn to the option of specifying an upper limit to the yield strength of the pipe by utilizing the supplementary requirements of API Spec 5L PSL 2. The method of measurement of the pipe yield strength is also important. Depending on the method of manufacture, the longitudinal strength of the pipe may be greater than or less than the transverse value, and the transverse value will be affected by the type of test piece, that is, whether a flattened strap test piece or a ring expansion test is employed. While hardness testing and conventional joint tensile testing can provide useful information, which would help someone familiar with the research form a judgement on the degree of matching achieved, these tests cannot objectively determine whether matching is actually achieved. The notched tensile test, which was previously included in this Standard, has been found to be difficult to interpret and has been withdrawn pending further research. This change is accompanied by a return of the Tier 3 criteria to those in the 1995 edition of this Standard. Required levels of weld metal strength matching may be assessed using the wide plate test; however, it has been shown that they are still width sensitive up to around 300 mm or so and, at the time of preparing this Appendix, the only method that could be relied upon to represent the displacement controlled axial load case is the full section pipe tension test, which evaluates the entire joint circumference. D4 ELECTRODE QUALITY The performance of pipeline girth welds made with EXX10 electrodes depends heavily upon the design formulation and upon the manufacturing quality assurance of the electrodes. Unfortunately, however, the national specifications that are used for these electrodes do not meet the current needs of the pipeline industry. The specifications for the higher strength E7010, E8010 and E9010 low alloy steel electrodes as per AS/NZS 4857 and AWS A5.5 are particularly inadequate.

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D5 SUPPLEMENTARY RECOMMENDATIONS

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The following should be considered: (a)

A risk management approach should be taken to this aspect of the design of the welding procedures. On this basis, large projects using high strength pipe with, e.g. significant areas of unstable ground, will justify greater effort in treating the risks of undermatching (see Paragraph D3).

(b)

On the basis of longstanding satisfactory experience, E6010 electrodes are suitable for use in circumstances where their application is warranted without supplementary requirements.

(c)

E7010-G, E8010-G, and E9010-G electrodes, without supplementary specification requirements, should not be used unless the risks identified are acceptable. Successful experience in the use of electrodes from a particular supplier in similar circumstances may be a suitable input to the risk assessment process.

(d)

In general, electrodes conforming to E7010-P1 and E8010-P1 (or equivalent) classifications are preferred, and if a higher strength electrode is required, then a specification for E9010-P1 should be negotiated with the supplier, even though such a classification does not currently exist in the Standards. NOTE: P1 classifications incorporate Charpy V-notch fracture toughness requirements.

(e)

In addition to the use of P1 classification electrodes, it is recommended that all-weld metal limits of 0.17% carbon and a maximum IIW carbon equivalent (CE) be stipulated. The maximum CE values should not exceed the following: (i)

E7010 ......................................................................................................... 0.40.

(ii)

E8010 ......................................................................................................... 0.44.

(iii) E9010 ......................................................................................................... 0.46. These limits will help avoid the production of deposits of excessive strength and susceptibility to HACC. (f)

The electrodes should be manufactured under an approved quality assurance system and individual batches should be certified on test certificates.

(g)

For X70 pipelines less than 7 mm nominal thickness, and for all X80 pipelines, special consideration should be given to girth weld strength matching. This may include the need for special tests such as the full section pipe tension test.

(h)

Electrodes should be supplied in hermetically sealed metal containers and should be discarded if not used on the day the container is opened.

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D6 REFERENCES 1

Barbaro F., Bilston K., Fletcher L., Kimber M. and Venton P., Research shows that X80 pipe can be economically and safely welded by conventional methods, The Pipeliner, No 98, July 1999.

2

Bilston K., ‘Capabilities and limitations of cellulosic electrodes. A user’s perspective’, WTIA/APIA Panel 7 Research Seminar, Wollongong, October 1995.

3

Bilston K., Dietsch A., and Fletcher L., ‘Performance requirements for onshore pipeline girth welds in Australia: A discussion paper’, WTIA/APIA Panel 7 Research Seminar, Wollongong, October 1995.

4

Bowie G F. and Barbaro F J., ‘Assessment of workmanship defect acceptance levels in high strength thin walled pipeline girthwelds’, International Conference on Pipeline Construction Technology, Wollongong, 4–5 March 2002.

5

Weaver R J. and Ogborn J S., ‘Cellulosic covered electrode storage conditions— Influence on weld properties’, IBP_05, Rio Pipeline Conference and Expositions 2005, Instituto Brasileiro de Petrόleo Gás – IBP.

6

Yurioka N. (editor) ‘Proceedings WTIA/APIA First International Conference on Weld Metal Hydrogen Cracking in Pipeline Girth Welds’, CRC for Welded Structures, March 1999. Published February 2000.

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APPENDIX E

WELD PROCEDURES ASSOCIATED WITH CHANGES TO THE WELDING CONSUMABLE CLASSIFICATION SYSTEM

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(Informative) E1 GENERAL Australia and New Zealand have adopted the harmonized ISO welding consumable classification system (see Table 4.1) for the manual metal arc welding (MMAW) and fluxcored arc welding (FCAW) of carbon and other steels. For these steels, the new ISO-based consumable classification system (see Table 4.1) brings together two seemingly incompatible systems in common usage. System A is used in Europe where consumables are classified predominantly by yield strength and the temperature at which 47 J minimum impact energy is guaranteed. System B is used extensively around the Pacific Rim and North America where consumables are classified by tensile strength and the temperature at which 27 J minimum impact energy is guaranteed. Australia and New Zealand have generally followed the AWS-based System B practice using a tensile strength based classification system with local variations including a 47 J minimum impact energy requirement at the temperature of test as the basis for its consumable classification requirements. For the MMAW process, the system used remained similar to that used by AWS. For the FCAW and other processes, Australia developed its own unique classification systems. With the adoption of the harmonized ISO system, it is expected that usage of the AWS-based System B classification system will continue to dominate. However, there will be situations where the European-based System A classification system will be preferred. To extend the validity of weld procedures qualified under previous classification systems to utilize consumables classified under the harmonized ISO-based classification system, the procedure described in this Appendix should be adopted, and where contractually required, approved prior to the commencement of welding to minimize the need to requalify weld procedures. It is also recognized that consumables classified under the former Standards systems will remain available in the market for some time, and these may continue to be used. When welding to this Standard (AS/NZS 2885.2), the new classification should be obtained from the manufacturer and the change of classification noted on both the weld procedure qualification record (PQR) and weld procedure specification (WPS) documents. For other situations where equivalency cannot be established, the weld procedure should be requalified in accordance with the requirements of this Standard. E2 SYSTEM CHANGES E2.1 Strength Consumable strength designations have been realigned for all consumable types and a summary of these changes is given in Table 4.1. These designations are now consistent for all welding processes for which the harmonized ISO system has been applied. NOTE: ISO uses the term ‘symbol’ rather than ‘designation’.

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E2.2 Impact resistance Impact temperature designations have also changed. However, for processes other than MMAW, it is simpler, with the designator being more indicative of the temperature of test in a manner similar to that used in the superseded Standards AS/NZS 2717.1 and AS/NZS 1553.1. Under System B though, only 27 J minimum impact energy is required at the temperature of test unless the consumable classification incorporates the optional ‘U’ designation (47 J minimum impact energy). Consumables bearing the ‘U’ designation have equivalent impact energy requirements to those specified within the former Australasian designation systems. For MMAW consumables, the situation is more complex as impact energy requirements for System B classified consumables follows the current AWS practice of defining minimum requirements for each electrode class and composition. The System A classification though remains consistent with the method used for other consumables types. E2.3 Flux designations (MMAW) Changes to the flux designations for MMAW consumables are summarized in Table E.2. The ISO System B is consistent with AWS designations, which largely means that for most MMAW consumables, the flux type designation will remain unchanged from those used in the superseded AS/NZS 1553.1. NOTE: ISO uses the term ‘electrode covering’ rather than ‘flux designation’.

E2.4 Usability designations (FCAW) Flux core and usability were not designated in the former Australasian FCAW classification system thus direct comparison in either system is difficult. Where impact resistance test temperature is known, it can be assumed that, e.g. a gas shielded FCAW consumable with a test temperature of −40°C or colder would be a B (basic) designation under System A, or usability designation T5 under the System B (consistent with AWS). For other than metal cored consumables (classed in System A as Type M or in System B as T15), other gasshielded FCAW consumables commonly sold in Australia and New Zealand were the AWS usability designation T1, consistent with the ISO System B T1 usability designation and similar to the P designation of ISO System A. E2.5 Positional designations For System A classified consumables, consumables of the former positional Class D are equivalent to position Designation 3 (including 4) and P are equivalent to Designation 1 (including 2–5). For System B classified FCAW consumables, the former positional indicator D now uses the symbol 0 and P uses 1, consistent with AWS practice. System A MMAW consumables also utilize this positional designation system, however, for System B MMAW consumables positional characteristics are defined for each coating type, consistent with current Australasian and AWS practice. E2.6 Weld metal hydrogen The three-tiered linear weld metal hydrogen designation system used within the harmonized ISO Standards (see Table 4.1) is identical to that currently used in Australasia, these being H5 (very low hydrogen), H10 (low hydrogen) and H15 (medium hydrogen) designations of hydrogen control. No change is required. E3 EXTENSION OF WELD PROCEDURE QUALIFICATION Extending the considering the straightforward consumable are

qualification of a weld procedure can be accomplished by carefully changes noted. In most cases extending the procedure qualification will be particularly if both the trade name and classification of the welding known.

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Where the consumable used to qualify a weld procedure has been identified on the weld procedure using its trade name and classification, a note should be appended on the original procedure qualification record (PQR) noting the change of classification for the welding consumable. For existing welding procedure specification (WPS), a similar notation should also be made on these. For new WPS documents issued, the WPS should include the classification current at the time of issue. Changes affecting impact resistance designation should also be carefully considered with the former and new rating indicated in the records where there is a variance. Where there is a significant variation in consumable impact rating under System B, a number of options are available. The consumable used to qualify the procedure may continue to be used for new WPS documents based on the original procedure qualification provided— (a)

they continue to have an impact rating under System A equivalent to that shown on the original weld procedure; or

(b)

weld metal impact tests establish compliance with the requirements of this Standard.

Alternatively, when the consumable used to qualify a weld procedure has only been identified on the weld procedure using its former classification, identify a welding consumable with an identical classification under the superseded classification system using manufacturer’s literature. Record the trade name of the consumable and its AS/NZS ISO classification on the original PQR and WPS documents as noted above. All new WPS documents should then refer to this modified classification as shown in the following examples: (i)

A cellulose MMAW consumable is classified to superseded AS/NZS 1553.1 as E4110-2 and has an AWS classification of E6010. Its AS/NZS 4855 classification will be either A-E35 2 C 2 under System A or B-E4310AU under System B.

(ii)

A gas shielded flux cored wire is classified to superseded AS 2203.1 as ETP-GMpW503A CM1 H10. Its AWS classification is E71T-1 MJ H8. Under AS/NZS ISO 17632 it will be classified as either A-T42 3 R M 1 H10 or B-T49 3 T1-1 MA H10.

In all other cases or where equivalence cannot be established, it will be necessary to requalify the weld procedure in accordance with the requirements of this Standard. E4 OTHER PROCESSES To establish equivalence with ISO-based consumable Standards for the GMAW and SAW process, the procedure is similar to that for the FCAW process. This is largely due to the ISO-based classifications for most processes adopting similar strength, impact resistance and hydrogen control designations. Existing welding procedures do not need to be requalified or redocumented to reference the ISO-based classification system. As with previous examples, a note should be appended on the original procedure qualification report (PQR) noting the change of classification for the welding consumable, with a similar notation being made on WPS documents. For new WPS documents, the WPS should include the classification current at the time of issue.

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TABLE E1 EQUIVALENT STRENGTH DESIGNATIONS MMAW

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AS/NZS ISO

FCAW

AS/NZS 1553

AWS

AS/NZS ISO

AS 2203.1

AWS

A-E35, B-E43XX

E41XX

E60XX

A-T35, B-T43

W40XX

E6X

A-E42, B-E49XX

E48XX

E70XX

A-T42, B-T49

W50XX

E7X

A-E50, B-E55XX

E55XX

E80XX

A-T50, B-T55

W55XX

E8X

A-E55, B-E62XX

E62XX

E90XX

A-T55, B-T62

W62XX

E9X

TABLE E2 EQUIVALENT MMAW FLUX DESIGNATIONS ISO System B

ISO System A

AS/NZS 1553

AWS

03 10 11

RB C, RC C, RC

13 10 11

10 11

12 13 14

R R RR

12, 13 14

12 13 14

15 16 18

B B B

15 16 18

15 16 18

19 20 24

RA A RR

19 20 24

19 20 24

27 2 40

A B

27 28 99

27 28

48

B

46, 48

48

NOTE: This Table identifies nearest equivalent designations. Some consumables may have classifications that vary from those shown.

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APPENDIX F

ADDITIONAL RECOMMENDATIONS FOR AUTOMATIC/MECHANIZED WELDING OF PIPELINE GIRTH WELDS

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(Informative) F1 SCOPE This Appendix provides recommendation for automatic/mechanized welding. NOTE: This Appendix does not cover semi-automatic welding.

F2 AUTOMATIC/MECHANIZED WELDING SYSTEMS Automatic/mechanized welding systems may be used for the production of onshore pipeline girth welds to this Standard. It is recommended that during the tender stage of the project that a track record of similar onshore pipelines completed by the proposed automatic/mechanized welding system be provided to the company for review and approval. In the event that the track record is found to be inadequate then a program of trial welds can be proposed to demonstrate suitability for the proposed system for the specific application. Agreement of the extent of any such trials will be agreed at the tender stage. The weld procedure specification should state which parameters the operator has control over. Where these parameters have a direct effect on heat input, e.g. voltage, amperes and travel speed, then the limits or range of the operator’s control should also be stated, e.g. amperes, voltage, travel speed, oscillation, etc. F3 ITEMS FOR CONSIDERATION WHEN AUTOMATIC GMAW WELDING IS CONSIDERED F3.1 Equipment F3.1.1 Welding equipment The same make and model of welding equipment used during the test weld should also be used for production welding. This requirement should also include the system software and revision. The welding system’s weld parameter display and weld parameter recording systems should be calibrated before the start of qualification and production welding. A change in the automatic welding system being used is an essential variable (see Section 6, Qualification of a welding procedure specification). The welding bug manufacturer and model is an essential variable (see Section 6, Qualification of a welding procedure specification). F3.1.2 Auxiliary equipment Appropriate power sources and shielding gas should be selected for the application. Changes in power sources and shield gases are covered in Section 6, Qualification of a welding procedure specification. The primary power supply used for qualification testing should be of the same frequency and voltage as that to be used on site.

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F3.2 Pipeline welding spread

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F3.2.1 General The equipment associated with an automatic/fully mechanized pipeline spread will be different from that used on a shielded metal arc welded SMAW spread. Welding enclosures need to fully enclose areas to prevent breezes disrupting shielding coverage. The extra weight of these units (typically >1000 kg) effects the lifting methods and stability of the mobile platform base (type of vehicles), and other support equipment. This is also true for the access required to the pipe; including the height of the pipe off the group for welding clearance. Due consideration should be given to the selection of the equipment and the design of the spread and right of way. F3.2.2 Line up clamp The type and model of clamp used during weld qualification should also be used during installation welding. For line up clamps fitted with backing shoes, these should be regularly inspected and maintained to ensure the required weld quality is maintained. A sufficient quantity of backing shoes should be available to ensure they can be replaced when required. F3.2.3 Consumables Consideration should be given to the quantity, form of supply and flow rates of shielding gas that is required for the completion of the construction welds. F4 WELD PARAMETER MONITORING A weld parameter monitoring system can be an integrated part of the weld system or alternatively an independent external system. However, the same system used to monitor and record weld parameters during qualification may also be used during production welding. F5 WELD PROCEDURE QUALIFICATION F5.1 General At the start of weld procedure qualification three consecutive welds should be performed with the same weld equipment, consumables, and where practical project pipe. These welds should be inspected and found acceptable to the project NDT acceptance criteria. These welds may be used for pWPS mechanical testing, or alternatively, for excavation and repair welding for the purpose of qualification of repair weld procedures. F5.2 Weld bevels The dimensional accuracy of weld bevels is extremely important for automatic/mechanized welding. For this reason the weld procedure specification should contain a detailed and dimensioned joint design sketch with the major dimensions, and their tolerances clearly stated. During production welding, routine inspection of the machined weld bevels against the stated requirements of the weld procedure specification should be performed before fit up. F6 INSPECTION Consideration should be given to the type of defects typically associated with any welding process when selecting the type of NDT. In the case of GMAW/FCAW they are generally planar in nature, with fusion type indications most common. The acceptance criteria should also be the same as detailed in this Standard for manual welding, except where the use of an engineering critical assessment has been agreed. COPYRIGHT

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F7 OPERATORS Welding operators may be qualified for only part of the weld, i.e. welders used for fill and cap passes only.

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The qualification of 5G and 6G positions may be performed on half of the pipe circumference however, for the weld this should be from the 12 o’clock through to the 6 o’clock position. Welder qualification should be undertaken on the thickest nominal thickness being qualified. F8 CONSISTENCY WELDS Consideration should be given to the use of consistency welds before proceeding with qualification welds and/or production welding. Consistency welds made before production welding are recommended to be made in an environment representative of the site conditions. The number of consistency welds to be made should be— (a)

agreed/approved by the licensee; and

(b)

agreed between the welding contractor and the client.

Consideration should be given to the availability of pipe, welding wire and other consumables required for the production of consistency welds. F9 FITTINGS Consideration should be given to the welding of pipe pups onto fittings for ease of construction. Consideration should be given to the selection of welding process used for the welding of fitting into the pipeline. F10 REPAIR WELDS It is acceptable to use an alternative welding process to repair a mechanized weld. Repair weld procedures should be qualified. Where base materials are micro-alloyed or have had heat treatment to achieve the required mechanical properties, repair procedures need to physically assess the effect of multiple heat (welding) cycles.

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APPENDIX G

GUIDANCE ON ‘GMAW’ WELDING CONSUMABLES FOR MECHANIZED AND AUTOMATIC PIPELINE WELDING PROCESSES

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(Informative) The most commonly used consumables for GMA welding of pipeline steel grades below X80 is plain carbon manganese steel wire, which may have small additions of titanium and boron. These wires generally comply with the AWS A5.18 classification E70S-6 and the nearest Australian equivalent is the superseded Standard AS/NZS 2717.1 designation ES6xxW50. They are used with argon-based gas mixtures or CO 2 shielding. It is also reported that the same wires have been used successfully for fill passes on X80 pipeline steels but where overmatching yield strength is required, a nickel/molybdenum alloyed wire is preferred. It is, however, clear that within the broad classification of E70S-6 or ES6xxW50 there is scope for considerable variation in chemistry, both in the deliberate alloying additions, and in the level of residual elements. In some cases there may be deliberate but unreported additions of alloying element and this may be indicated by the use of terms such as ‘micro-alloying’. This is of some concern in mechanized girth welding since small changes in alloying element levels can have a significant effect on strength and toughness, arc stability, slag formation, inter-pass cleaning, bead profile and hot cracking susceptibility. It should also be noted that the properties achieved vary with shielding gas and operating mode. In addition, consistent feedability and low contact resistance are very important in mechanized welding, and are influenced by the surface quality and coating thickness of the wire as well as its cast (diameter of a loose turn) and helix. The operator may also specify dehydrogenation baking of the wire at an appropriate stage of processing to achieve the lowest possible levels of hydrogen in weld metal. For all of the foregoing reasons operators of GMAW girth welding systems have chosen to test and qualify specific consumables by brand name rather than relying on standard classifications. It is, therefore, important that the selected consumables be tested and qualified using a representative welding procedure and, once selected, the consumable be specified not only by standard designations but also by brand name (to avoid substitution). Regular batch testing of the consumable is recommended, and the supplier should be advised that any substitution of a wire from a different manufacturing stream will require requalification.

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APPENDIX H

AUTOMATED ULTRASONIC TESTING (AUT) SYSTEM AND OPERATOR REQUIREMENTS

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(Normative) H1 SYSTEM REQUIREMENTS The AUT system shall meet the following criteria: (a)

The AUT system shall detect flaws in accordance with the defect acceptance criteria in Section 17.

(b)

The system shall be qualified to the satisfaction of the licensee by either— (i)

previous qualification to a recognized national or company standard e.g. DNV-OS-F101; or

(ii)

undergoing a qualification to prove system suitability/capabilities, e.g. capable of 90% PoD at 95% confidence (against under-sizing). The procedure shall be verified, during which a previous qualification is verified as being applicable for a new application. NOTE: Consideration should be given to a project specific qualification.

(c)

Where the AUT system is to be used for inspecting repaired sections of weld, this shall be demonstrated during procedure qualification on typical mock-up defects (e.g. lack of side fusion and lack of root fusion), in conjunction with manual UT.

(d)

The AUT system shall also be able to detect flaws that are oriented transverse to the direction of the weld.

(e)

Calibration block(s) design in accordance with ASTM E1961-11, shall be approved (see Clause 1.6.1) before manufacture.

(f)

Calibration scans, shall be at the start of each shift or break, every 10th weld, and after every repair scan, whichever occurs first. NOTE: The maximum loss of signal should normally be no greater than the smallest allowable planar flaw in line with the specific acceptance criteria (its diminution and extent along the weld) due to reduced coupling, which can be tolerated. It is recommended that this does not exceed 6 dB.

(g)

Flaw interaction rules, shall be as per BS 7910, or project-specific rules.

H2 EQUIPMENT REQUIREMENTS H2.1 General The AUT equipment shall meet the following criteria: (a)

The ultrasonic system shall use both phased array and time of flight diffraction (ToFD), or pulse-echo and ToFD.

(b)

The system shall include probe sets specifically designed to detect the presence of any flaws transverse to the line of the weld that may be present in either the internal or external weld near-surface zones. The transverse flaw scanning unit does not require a complimentary ToFD scan.

(c)

All probe frequencies shall be advised in the approved AUT procedure/technique.

(d)

The system shall have sufficient examination channels (phased array, pulse echo and tandem channels) configured so that the complete through-wall thickness of the weld can be examined, preferably in a single circumferential scan. COPYRIGHT

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(e)

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The volume of weld examined by each channel shall be divided into primary examination zones of a height ‘typically’ not exceeding 3 mm (1/8 in) unless specifically agreed beforehand with a proven test procedure. Each examination channel shall provide the following: (i)

A linear A—scan presentation.

(ii)

Adjustable gain control with maximum 2 dB steps over a range of at least 60 dB.

(iii) One or more gates, each adjustable for start position and length. (iv)

Recording threshold between 5% and 100% of full screen height.

(v)

Signal outputs that record the signal amplitude and its time of arrival representing the beam travel distance.

(f)

Transducers used for zonal discrimination shall give signals from adjacent zones (overtrace), given that there is no shift in weld bevel angle between the zones. For adjacent zones of comparable size and with equal calibration sensitivity, the overtrace shall be within 5%–40% FSH when the peak signal from the calibration reflector representing the zone of interest is set to 80% FSH.

(g)

The system shall provide an overlap of the start and end of the scans of at least 50 mm (2 in).

(h)

The recording or marking system shall clearly indicate the location of flaws relative to the 12 o’clock position of the weld (the ‘zero datum’), with a ±10 mm (3/8 in) accuracy, or ±1%. The system resolution shall be such that each scan of recorded data from an individual inspection channel does not represent more than 1 mm (1/32 in) of circumferential weld distance.

(i)

The system shall have a fully automatic recording system to detect and display the presence and location of flaws, by reference to distance markers on the recording at intervals of 100 mm (4 in) or less.

(j)

Transducers shall couple to the surface though a layer of water. The method used shall be in accordance with DNV-OS-F101 B411. The system shall display the integrity of the acoustic coupling. An environmentally safe agent may be used to help wet the pipe surface or to prevent freezing, provided it leaves no residue after the liquid has evaporated.

(k)

The ultrasonic examination equipment performance characteristics shall meet the requirements of ISO 16828. Instrument amplitude linearity shall be within 5% of the ideal and shall be assessed before qualification and production AUT commences. Calibration certificates shall be made available to the client.

(l)

The instrument shall provide a record of the ToFD image. This shall complement the AUT system in confirming the presence, nature, and size of weld flaws. Time of flight diffraction shall be used to measure defect depth and height as required. High/low shall also be measured in ToFD. The ultrasonic instrument shall meet the requirements detailed in ISO 16828.

(m)

Reference and calibration blocks The AUT contractor shall supply the necessary reference and calibration blocks for the system. The design of the block(s) shall be specific to the geometry of the weld bevel to be used in the welding system and the pipe nominal thickness to be used on the project. At the completion of the project, calibration blocks shall be retained for a minimum of four years and the following shall apply: (i)

Separate calibration blocks shall not be required if differences in material, either from different sources or differing nominal thicknesses, are demonstrated to give beam angle differences in the test materials of less than 1.5°, for the AUT beams in use. COPYRIGHT

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(ii)

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Calibration blocks shall be identified with a hard stamped, unique, serial number that provides traceability to the examination work and the material source of supply for which the standard was manufactured.

(iii) Records of the serial number, wall thickness, bevel design, diameter, and ultrasound velocity shall be kept and be available.

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(iv)

The machining tolerances for calibration reflectors shall be tabulated as follows: Hole diameters

±0.2 mm (0.008 in)

Hole depth

±0.2 mm (0.008 in)

Flatness of flat bottomed holes

±0.1 mm (0.004 in)

Position of centres of holes

±0.1 mm (0.004 in)

Notch depth

±0.1 mm (0.004 in)

Notch length

±0.5 mm (0.020 in)

Position of reflecting face of notch

±0.1 mm (0.004 in)

All pertinent angles

±1°

All reflectors shall be protected physically from degradation. (v)

(vi)

A calibration block register shall be established: (A)

The register shall include all calibration blocks to be used, identified with the unique serial number and include the dimensional verification records, ultrasound velocity, name of the plate/pipe manufacturer, and the heat number.

(B)

The register shall be available for review.

The inspection/validation report for the calibration block(s), following manufacture, shall be from an independent third party.

(n)

Any software required to view the results shall be included on the data disc(s) that will be provided as part of the final results.

(o)

Any software licences shall be agreed before any of the production welds are examined.

(p)

The software version used in the construction shall be clearly identified.

(q)

A system preventing any unqualified alterations to agreed focal laws shall be implemented for the phased array AUT system (DNV OS-F101 2013 A-408).

NOTE: For ToFD inspection refer to ISO 10863.

(r)

Ultrasonic probes should be within a frequency range of 2–6 MHz. However, it is recognized that certain systems, such as ToFD, employ higher frequency probes (10–15 MHz).

NOTE: In certain cases, the licensee may stipulate minimum frequency for pulse echo due to reliable detection of small flaws, i.e. higher frequency = smaller wavelength = higher POD of small flaws. This is normally based on the criteria which has been defined. Time of flight diffraction at higher frequencies can also generate high noise making interpretation less reliable. Time of flight diffraction frequencies should be decided once the weld and pipe material have been received and tested by the proposed system.

H2.2 Inspection procedure The examination procedure to be used in production shall be documented and agreed prior to commencement of welding, for each nominal thickness and joint geometry (including that of repairs). This includes description of the proposed configuration of the system and how it is to be used, particularly detailing its set-up and calibration. COPYRIGHT

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H2.3 System configuration The AUT system shall be configured with the following:

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(a)

The procedure document shall fully describe the intended system configuration and shall include a description of— (i)

a functional description of the system and a detailed equipment description;

(ii)

any limitations of the system with regard to material or weld features such as sound velocity variations, geometry, size, surface finish, or material composition;

(iii) transducer numbers and configuration(s), characteristics, set-up and coverage; and (iv)

means of monitoring probe wear.

(b)

The number of examination zones and their heights.

(c)

Gate and threshold settings shall be set to meet the detection required for the minimum sized flaw, with the required, defined, PoD.

(d)

Ultrasonic instrument, number of channels, and data acquisition system.

(e)

The processing and recording of signals.

(f)

Coupling method and coupling monitoring method. Positive confirmation of acoustic coupling during the weld examination scan is required for each weld examination.

(g)

The un-inspected length and loss of signal amplitude associated with below-adequate coupling shall be specified by the contractor.

(h)

Such below-adequate acoustic coupling during a weld examination shall require a complete re-examination of the weld.

(i)

Pipe preparations, such as seam weld removal (internal and external), coating removal, and surface preparation.

(j)

The temperature range for testing and any limitations.

(k)

Maximum scanning speed and direction.

(l)

The scanning speed (Vs) shall not exceed that defined in ASTM E1961-11, repeated below, unless otherwise agreed or proven during procedure qualification: Vs = W ×

PRF 3

where W

= –6 dB beam-width at the target distance

PRF = the pulse repetition frequency to the transducers (m)

The weld scanning direction (clockwise or anti-clockwise relative to a fixed datum) shall be agreed prior to welding and shall be consistent for all production girth weld examination.

(n)

Identification means for inspection starting point and scanning direction.

(o)

Reporting of indications and the documentation of sensitivity settings.

(p)

Full description of calibration equipment, as follows: (i)

A detailed description of calibration block(s) including type, size, and location of the calibration reflectors, as per ASTM E1961-11.

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The procedure shall detail how the calibration reflectors for phased array or pulse-echo channels are suitable to give full coverage of the through-weld thickness, with an acceptable uniformity of response to flaws at the appropriate fusion face angle.

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(iii) The spacing between targets along the scan length shall be adequate to ensure that the response from one target reduces to grass level before any signal from the next target is detected in the scan. (iv)

Calibration of transverse probes shall use EDM notches.

(v)

Calibration targets for the system to detect transverse flaws, such as cracking, shall be made having regard to the non-linearity of the relationship between the signal level and the depth of the notch/slot.

(vi)

Calibration plates are in the same surface condition as that of the production welds, with whatever surface treatment is used in the field before AUT scanning.

(vii) The configuration of the system for inspection of repaired sections of weld, if AUT is agreed as the inspection means. H2.4 Mode of use The procedure document shall fully describe the way that the system shall be used. This document shall include descriptions of the following: (a)

The recording of calibration files and inspection scan files, within the requirements of the project QA/QC system.

(b)

The method for alignment of the scanner and method for maintenance of this alignment.

(c)

The method of scanner location with regard to the weld centre-line and the accuracy of location.

(d)

The application of a scribe line to the pipe ends before welding.

(e)

Transducer checks and overall functional checks and the recording of such results in the equipment log book.

(f)

The frequency of monitoring probe wear, to what specification and how it is done, and the remedial action when wear is detected.

(g)

If carbide runners are used (or similar) then the periodic monitoring of grooves in the calibration block(s).

(h)

The instructions to operators for reporting to include an example of the recorder chart and the forms to be used.

(i)

The interpretation method, including specifically— (i)

the method used to determine the height of flaws, with sufficient detail to allow replication of an assessment;

(ii)

details of the method used to determine the length of flaws;

(iii) the flaw interaction rules to be applied, e.g. API 1104 or BS 7910 or project specific rules; and (iv) (j)

the treatment of flaws near or at the intersection of the seam and girth welds.

A log book shall be maintained that conforms to the following: (i)

Identifies the instruments and transducers and details their performance characteristics. COPYRIGHT

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(ii)

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Updated as changes are made or as more information is gathered.

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(iii) Kept at the place of inspection and made available for review upon request. (k)

Each weld shall be numbered in the sequence used in the pipe tracking system, as specified and agreed by the licensee.

(l)

Welds joining pipes of different nominal thickness shall only be examined by AUT if the internal surfaces are in line, within normal offset (or high/low) tolerances. Preferred method of inspection for transition welds shall be manual phased array or ToFD and manual ultrasonics.

(m)

If AUT is required on transition joints, it may require that the thicker material is counter-bored back from the weld face (to reduce it to that of the thinner section) by a sufficient length to avoid disruption of the ultrasonic beams.

(n)

If AUT is agreed as the inspection means for the inspection of repaired sections of weld, the configuration and mode of use of the AUT system shall be fully defined for that geometry. Manual phased array ultrasonic testing or ToFD and manual ultrasonics should be used in these instances.

(o)

The performance of the transverse flaw detection channels shall be such as to guarantee detection of flaws of height greater than 10% of the nominal thickness (i.e. an N10 slot) in either the inside or the outside surface of the pipe. Alternatively, an ECA-based figure may be employed.

H2.5 Set-up and calibration H2.5.1 General The procedure document shall fully describe the intended set-up and calibration methods. This shall include a static calibration that is initially used to optimize the system, followed by dynamic calibrations. A calibration certificate shall be made available. H2.5.2 Static calibration The procedure for static calibration shall set out all aspects of the calibration, including the following: (a)

For each pulse-echo (including tandem) channel in turn, the signal from its calibration target in the calibration block shall be maximized and adjusted to be 80% of the height of the full screen. The gain level required to attain this level, the signal to noise ratio, and the ultrasonic transducer stand-off distance from the weld shall all be recorded.

(b)

The detection gates shall conform to the following: (i)

Each shall be set, in turn, as each transducer is positioned to obtain the peak signal response from its calibration target.

(ii)

The gates shall start before the theoretical weld preparation and a suitable allowance shall be included to allow for the width of the heat affected zone (HAZ), so that complete coverage of the HAZ is achieved.

(iii) The gate shall end after the theoretical weld centre-line, including a suitable allowance for offset of the actual weld centre-line after welding e.g. from shrinkage. (c)

For mapping channels (also called ‘porosity’ or ‘volumetric’ or ‘stacked A scan’ channels), the gates shall be set to encompass the full weld width at that depth in the weld section. NOTE: The ToFD channel gate should start at least 1 µs before the time of arrival of the lateral wave and should extend beyond the arrival of the first back wall echo.

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H2.5.3 Dynamic calibration

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The procedure for dynamic calibration shall set out all aspects of the calibration, including the following: (a)

During dynamic calibrations the calibration standard shall be scanned at the same travel speed as the speed for testing the production welds.

(b)

The positional accuracy of the recorded target reflectors relative to each other shall be within ±2 mm (0.08 in) and it shall be within ±10 mm (0.4 in) with respect to the zero datum over the full circumference.

(c)

Gate settings shall not deviate by more than 0.25 mm (0.01 in) from the reference positions defined during the static calibration.

(d)

No coupling loss shall be acceptable during calibration.

(e)

Calibration signals for the pulse-echo channels shall be within the range of ±2 dB (64%–99%) of the FSH.

(f)

If, during the dynamic field calibration, the signal falls outside this range, one of the following: (i)

If a calibration signal falls below 70% FSH, welds inspected since the last successful calibration scan shall be re-tested, unless otherwise agreed by the client.

(ii)

If a calibration signal is over 99% FSH, then the results for all welds scanned since the last successful calibration shall be reviewed.

H2.6 Calibration intervals The system shall be calibrated by scanning the calibration block(s) at the start and end of each work period and at any point if the nominal thickness is changed or if any system changes or adjustments are made. Calibration shall also be conducted before and after each repair is inspected. A calibration scan shall be done before or after each of the first 10 welds inspected in production and before and after every weld during qualification. H3 AUT OPERATORS Personnel engaged in AUT shall have successfully completed formal training on the specific AUT system to be used for inspection. Additionally, AUT interpreters shall hold at least UT Level 2 certification (specific to welds) and shall have undergone a period of supervised AUT interpretation in the field before assuming responsibility for weld interpretation. AUT interpreters shall hold current UT certification, specific to weld testing, to any of the following Standards or equivalent, as a minimum: (a)

AINDT Level 2.

(b)

CGSB Level 2.

(c)

CSWIP (TWI, UK) Level 2.

(d)

BGAS-CSWIP (TWI, UK)—full ultrasonic.

(e)

PCN (BINDT, UK) Level 2.

(f)

ACCP (ASNT) Level 2.

(g)

SNT TC 1A (ASNT) Level 2.

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Roles and responsibilities for each individual involved with the QC/AUT operations shall be defined, with the chain of responsibility of the operators also defined. Support shall be available to operators from a qualified Level 3 individual, throughout the construction phase of the pipeline. H4 SYSTEM QUALIFICATION Licensed to Mr Paolo Corronca on 10 June 2016. 3 concurrent user network licenses. Copying and copy/pasting prohibited. (10607402). Get permission to copy from this publication www.saiglobal.com/licensing

H4.1 General Before any system is used for the inspection of production welds on the pipeline, it shall have been previously qualified to a procedure to demonstrate that the system and operators can reliably achieve the detection, location, characterization, and sizing capability needed to support the project acceptance criteria. Systems that have not been previously qualified shall undergo a qualification/validation with a minimum of 50 flaws/seeded defects. The following apply: (a)

The flaws shall be in a number of test welds, sufficient to ensure that each flaw can be individually identified, with at least three times the flawed length of weld having no flaws present or interacting therein.

(b)

The flaw set shall include a number of each class of flaw which is of importance to the duty of the pipeline under construction. NOTE: Depending on the welding process these may include the following: (i) Lack of fusion (LF), either in the root (LR) and/or in the side wall (LS), and/or at the cap. (ii) Lack of penetration (LP). (iii) Porosity (PG cluster, scattered, and/or isolated GP). (iv) Lack of inter-run fusion (LIF). (v) Lack of cross penetration (LCP). (vi) Non-metallic inclusions, including slag inclusions (IN’s/IL’s). (vii) Burn-through (BT). (viii) Centre line cracks (KL) and transverse cracks (KT). (ix) Stacked flaws (particularly stop/start indications). (x) Others, e.g. hollow bead (HB), concave root (SRC), etc.

(c)

A flaw matrix shall be created prior to ‘seeded defect welding’ so the required flaws made of varying lengths and at varying depths from the outer surface, can be monitored and tracked based on achieving the required defect.

(d)

The welds shall be tested to confirm the presence of the defects and define their locations: (i)

The welds shall be radiographically tested (RT). The RT interpretation shall be conducted by two interpreters qualified in accordance with Clause 19.3 separately and their results combined to include all indications.

(ii)

Any areas of uncertainty from the RT and a proportion of the unflawed weld length of the welds shall be scanned by manual phased array ultrasonic testing or ToFD and manual ultrasonics at high sensitivity, to identify any sub-critical defects.

(e)

The test welds shall be scanned with the AUT equipment to the method defined in the procedure, without variation.

(f)

Following AUT interpretation, a validation report of all these results shall be presented to the client.

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(g)

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Sectioning of qualification flaws, as follows:

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Qualification flaws shall be sectioned. An agreed selection of the flaws shall be cut in section, in a defined manner to be agreed, or by maximum values (as described below) to define both the nature and size of the flaws (principally the height).The maximum sectioned flaw height may be correlated with the maximum AUT signal for each flaw, to give one sectional data point per flaw. In this case the AUT scanner should be used to identify the best location for the metallurgical section and the position marked on the weld cap in a positive manner e.g. punch mark. Additional sections may be taken nearby to give the best maximum value of the flaw height. (h)

Statistical analysis of the data shall be required to demonstrate satisfactory performance, both for the detection of flaws and for their size evaluation or assessment.

(i)

Performance shall be considered to be satisfactory if the required minimum flaw size is shown to be detectable at a 95% confidence (against undersizing).

(j)

Appropriate characterization and an acceptable accuracy of sizing shall also be demonstrated, i.e. within the bounds of project productivity.

(k)

For each flaw, the error figure shall be added to the AUT estimate of the flaw height, before it is decided if it is to be accepted or rejected to the defined acceptance criteria.

(l)

As an alternative qualification method, previous data may be used, if a qualification has been completed for an earlier project in accordance with the essential variables specified in DNV-RP-F118.

(m)

Qualification of repair weld sections shall employ an agreed number of repaired sections of weld, covering the range of variety of repair groove geometry anticipated in construction.

(n)

The qualification tests shall include repeat tests over the same test welds with the system and guide band removed and replaced between scans. The number of repeats is the subject of agreement between the parties.

(o)

The qualification tests may include repeat tests over the same test welds with the test sample temperature elevated to that expected to apply, as a maximum, in field conditions. The necessity for elevated temperature tests is the subject of agreement between the parties.

(p)

A full report of the qualification tests and/or verification tests shall be prepared for the client, and the interpretation outcomes detailed in terms of the system requirements.

H4.2 Verification Verification shall require an initial evaluation of the previous qualification data by the client representatives to confirm that the projects are similar in all the key factors, both in terms of the AUT system and the project requirements. NOTES: 1 Verification should still require a set of flaws (approximately 29–30 in number) to be made, tested with the AUT system, their character and sizes identified by the analyst and these results compared with values from sectioning the flaws. 2 This should demonstrate detection of flaws near the detection threshold with sufficient signal to support the required PoD.

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H4.3 Changes to qualification The essential variables of the AUT system shall be as per DNV-RP-F118. If there are any changes to the ‘essential variables’ of the system, the validity of the qualification of the modified system shall be demonstrated. This may be done by verification as specified in Paragraph H4.2.

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H4.4 System checks Before the ultrasonic system is used for examination of production welds, the system shall be tested. The test shall include three consecutive satisfactory scans and recalibrations are required. After calibration of the complete system, the first weld shall be scanned three times, followed by recalibrations, with the probe transport system removed and replaced between each scan. If any of the echo amplitudes from the reflectors of the calibration block deviate by more than 2 dB from the initial calibration, the system shall not be used until acceptable corrections have been made. Transducer wear shall be monitored during the course of operations as described in the procedure. H4.5 Documentation A quality assurance system shall be used, covering all aspects of the development and use of the automated ultrasonic inspection systems. Documentation shall include— (a)

an electronic copy from each weld inspection and calibration scan should be provided to the client on a daily basis;

(b)

the assessment of the weld to the defined acceptance criteria; and

(c)

hardcopy printout to the welding inspector for each weld repair.

H4.6 Weld dressing It may sometimes be necessary to dress the weld cap where it is excessively proud or wide, to allow unhindered passage of the AUT probes. The weld dressing shall only be done after consultation with the client’s welding engineer. H4.7 Welder qualification welds If AUT is to be used for production welding, then the same proposed system shall be used for welder qualification welds. H4.8 NDT of repaired areas Defective welds that have been repaired shall be re-examined visually and by non-destructive testing. If the repaired areas are examined using AUT, the support inspection shall be carried out using manual phased array or ToFD and manual ultrasonic methods. If the repair is conducted by fully removing the defective weld and re-welding, the new weld may be examined using AUT to the agreed procedure.

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