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• Eslam Soliman

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BASIC REFRESHER LEVEL 111

/

NOT MEASUlcERIENT SENSITII'E

25 Januarv 1991 SUPERSEDING MILSI7D-410D 23 JULY 1974

MILITARY STANDARD NONDESTRUClTVi? TESTING PERSONNEL QUALIFICATION AND CERTIFICATION

AMSC N/A

AREA NDTI

DISTRJBUnON STATEMENT A. Approved for public release distribution is unlimited.

.

F O R E W O R D

1. This military standard is approved for use by all Departments and Agencies of the Department of Defense. 2. Beneficial comments (recommendations, additions, deletions) and any pertinent

data which may be of use in improving this document should be addressed to ASDE3ES. Wright-Patterson Air Force Base, Ohio 454334503. by using the self addressed Standardization Document Improvement Proposal @D Form 1426) appearing at the end of this document or by letter. 3. n/m,-STD-410E specifies the qualification and certification requirements for nondestructive testing/nondestructive inspection personnel. Previous revisions of this specification addressed the requirements for personnel using penetrant, magnetic particle, ultrasonic, eddy current and radiographic nondestructive testinglnondestructive inspection methods. This revision adds detailed requirements for acoustic emission and neutron radiographic methods as well as general requirements for any other nondestructive method for determining the acceptability of a product. In addition, this revision upgrades the designation of Level I, eliminates the Level I Special, adds an instructor level of qualification and adds a recertification requirement for Level III.

MILSTD-4IOE

CONTENTS

PAGE

PARAGRAPH 1. 1.1 1.2 1.2.1 1.2.2 1.3 1.4

SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Common methods . . . . . . . . . . . . . . . . . . . . . . . . . . Other methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . Levels of qualification . . . . . . . . . . . . . . . . . . . . . . . . Levels of certification . . . . . . . . . . . . . . . . . . . . . . . .

1 1 1 1 1 1 2

APPLTCABLE DOCUMENTS . . . . . . . . . . . . . . . . . . . 2 Non-Government publications . . . . . . . . . . . . . . . . . . . 2 Order of precedence . . . . . . . . . . . . . . . . . . . . . . . . . 2 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Certifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Closed book examination . . . . . . . . . . . . . . . . . . . . . . 2 Contracting agency . . . . . . . . . . . . . . . . . . . . . . 3 Documented . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Employer ............................... 3 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 General examination . . . . . . . . . . . . . . . . . . . . . . . . . 3 Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Instructor . . . . . . . . . ; . . . . . . . . . . . . . . . . . . . . . . 3 Interpretation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 On-the-job . . training . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Organ~zatlon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Outside agency . . . . . . . . . . . . . . . . . . . . . . . . . 3 Practical examination . . . . . . . . . . . . . . . . . . . . . . . . 4 Prime contractor . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Product form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Qualification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Specific examination . . . . . . . . . . . . . . . . . . . . . . . . . 4 Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Test samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Training ......................................... 4 ;

iii

MILSTD-310E CONTENTS PARAGRAPH

PAGE

4. 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.1.7 4.2 4.3 4.4 4.5

GENERAL F?EQUlREMENTS. . . . . . . . . . . . . . . . . . . . Certification procedure . . . . . . . . . . . . . . . . . . . . . . . . Levels of qualification . . . . . . . . . . . . . . . . . . . . . . . . Perso'nnel . . duties and responsibilities . . . . . . . . . . . . . . . Tralnrng program . . . . . . . . . . . . . . . . . . . . . . . . . . . . Experience requirements . . . . . . . . . . . . . . . . . . . . . . . . Examination practices . . . . . . . . . . . . . . . . . . . . . . . . . . Records and documentation administrative practices ..... Recertification requirements . . . . . . . . . . . . . . . . . . . . . Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Outside agency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5. 5.1 5.1.1 5.1.2 5.1.3 5.1.4 5.1.5 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.3 5.3.1 5.3.2 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.4.1 5.4.4.2 5.4.4.3 5.4.5 5.4.6 5.4.7 5.5 5.6 5.6.1

DETAILED REQtJIREMENTS . . . . . . . . . . . . . . . . . . . . . 6 Levels of qualification . . . . . . . . . . . . . . . . . . . . . . . . . 6 Trainee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Level I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Level I1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Jnstructor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Level . .ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Specialist personnel . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Exams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Minimum required training hours . . . . . . . . . . . . . . . . . 7 Previous training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Previous experience . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Equivalent . . experience . . . . . . . . . . . . . . . . . . . . . . . . 10 Exam~natlons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Physical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Specific . . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Practical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Level l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Level II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 LevelIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Administxation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Re-examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Designation of instructors . . . . . . . . . . . . . . . . . . . . . 12 Certification . . . . . . . . . . . . . . : . . . . . . . . . . . . . . . . 13 Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5 5 5 5 5 5 5 5 5 5 5 6 6

MILSTD-410E

CONTENTS PARAGRAPH

Loss of certification . . . . . . . . . . . . . . . . . . . . . . . . . . Reinstatement of certification . . . . . . . . . . . . . . . . . . . . Recertification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13 13 14

NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level1 Special ..................................... Intended Use ....................................... Subject tenn (key word) listing . . . . . . . . . . . . . . . . Changes from previous issue . . . . . . . . . . . . . . . . . . . . .

14 14 14 14 15

1. SCOPE 1.1 Pumose. This standard establishes the minimum requirements for the qualification and certification for personnel involved in the application of nondestructive inspection WI) or nondestructive testing (NDT) personnel. These requirements include training, experience and examination. 1.2 ~oplicability.This standard applies to personnel using NDI or NDT methods to accept materials, products, subsystems, components or systems for the Government, prime contractors or subcontractors. It also applies to those individuals directly responsible for the technical adequacy of the NDI and NDT methods used as well as those providing the technical training or supervision for NDI or NDT personnel. This standard is not intended to apply to individuals with administrative authority only over the above identified personnel or to research personnel developing technology for use by qualified and certified NDI or NDT personnel. 1.2.1 Common methods. This standard contains detailed requirements for the applicable training, experience, and examination for the following methods: Liquid penetrant Magnetic particle Mdy current Ultrasonic Radiography Acoustic emission Neutron radiography

(pr)

0

m) m

(RT) (AE) (NRT)

1.2.2 Other methods. This standard may apply to other NDI or NDT methods such as leak testing. thermography, holography, computed tomography. or any other method that can determine the acceptability or suitability for intended service of a material, part, component, subsystem, or.system without impairment of the intended function. The requirements for personnel training, experience, and examination for these other methods shall be as established by the contracting agency and shall be in accordance with the guidelines established for the methods listed in 1.2.1. 1.3 Levels of are: Trainee Level I Level I1 hstructor Level III

The levels of qualification established by this standard

1.4 Levels of certification. The levels requiring certification in accordance with this standard are: Level I Level I1 Level Lll 2. APPUCABLE DOCUMENTS 2.1 Non-Government ~ublications.The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of the documents which are DoD adopted are those listed in the issue of-the DODISS cited in the solicitation. Unless otherwise specified, the issues of documents not listed in the DODISS are the issues of the documents cited in the solicitation (see 6.2). AMERICAN SOCIETY FOR NONDBTRUCTIVE TESTING ASNT-CP-189 - ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel AShT Recommended Practice No. ShT-TC-1A Certification in Nondestructive Testing

- Personnel Qualification

and

(Applications for copies should be addressed to the American Society for Nondestructive Testing, 1711 Arlingate Plaza, Columbus OH 43228-0518.) 2.2 Order of ~recedence.3n . the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

3.1 Activiq. One of the organizational elements of an agency of the Department of Defense.

3.2 Certification. A written statement by an employer that an individual has met the applicable requirements of this standard. 3.3 Certifier. A designated representative of the employer with the responsibility and authority to document that an individual meets the applicable'requirements of this standard. 3.4 Closed book examination. An examination administered without access to reference material except that provided with or in the examination. Questions utilizing such reference material shall require understanding of the information contained therein rather than mere location.

3.5 Contracting agency. A government activity, prime contractor or subcontractor procuring the product requiring testing or the nondestructive testing services. 3.6 Documented. The condition of being in written form. 3.7 Emplover. The government activity, prime contractor, subcontractor, or outside agency employing individuals performing NDI or NDT. 3.8 Evaluation. The determination of the significance of relevant indications. 3.9 Examination. A formal, controlled, documented interrogation conducted in

accordance with a procedure. 3.10 Ex~erience.Actual performance or observation conducted during work time resulting in the acquisition of knowledge and skill. This does not include classroom or laboratory training but does include on-the-job training. 3.1 1 ~ e n e r a examination. l A written examination addressing the basic principles of the applicable NDI or NDT method. 3.12 Indication. The response, or evidence of a response, occurring during a nondestructive inspection or test. 3.13 Instructor. An individual qualified and designated, LAW this standard, to provide classroom or laboratory training for NDTMDI personnel and to administer and grade qualification examinations. 3.14 Interoretation. The determination of whether indications are relevant or nonrelevant. 3.15 Method. One of the disciplines of nondestructive inspection or testing (e.e. .radiography) within which different techniques exist. 3.16 Qn-the-iob train in^. Training. during work time, in learning insuumentation set up, equipment operation, recognition of indications, and interpretation under the technical guidance of a designated Level I[ or Level DI individual. 3.17 Organization. The entity, Government or private, having the responsibility of complying with this standard. 3.18 Qutside aeency. The organization under contract for NDI or NDT services which may include the training and examination of personnel to the requirements of this standard. Consultants and self employed individuals are included in this definition

3.19 Practical examination. The examination used to demonstrate an individual's ability in conducting the NDI o r NDT methods that will be performed for the employer. Questions and answers need not be written, but observations and results must be documented. 3.20 Prime contractor. The organization having responsibility to the government for a system, component, or materials. 3.21 Procedure. A detailed, written instruction for conducting NDI or NDT or certifying personnel. All procedures shall be approved by a Level ID. 3.22 Product form. Materials, parts, or components having similar NDI or NDT characteristics. Examples of individual product forms are: castings. extrusions, plate, aeldments, pyrotechnics, bonded assemblies, composite materials, and printed circuit boards. 3.23 Oualification. The skills, training, knowledge and experience required for personnel to properly perform to a particular Level. 3.24 Soecific examination. The written examination to determine an individual's understanding of procedures, codes, standards, and specifications for a given method used by the employer. 3.25 Techniaue. A category within a method, for example: ultrasonic immersion testing or fluorescent dye penetrant inspection. 3.26 Test samples. Parts containing known defects and used in the practical examination to demonstrate the candidate's proficiency in using a particular method. Test samples will not be production parts unless the Level ID has previously investigated the parts and documented all abnormal or out of specification conditions within the samples. Alternatively, test samples can refer to images of actual hardware, i.e.. radiographs, when the candidate's required proficiency is in the interpretation of the image rather than the generation of the image. 3.27 Training. An organized and documented program of activities designed to impart the knowledge a n d skills t o b e qualified to this standard. This program may be a mix of classroom, laboratory, programmed self-teaching and on-the-job training as approved by the appropriate Level III.

4 . GENERAL REQUIREMENTS

4.1 Certification ~rocedure.All organizations involved in any aspect of NDI or NDT

shall develop and maintain a procedure for the qualification and certification of their NDI or NDT personnel. This procedure shall be in accordance with the requirements of this standard. The procedure shall be available for review by the organization's customers. The procedure, as a minimum, shall include: 4 . l . i Levels of aualification. This shall include identification of the levels of qualification covered by the procedure. The organization may add any additional levels that are appropriate; however, in no manner can the organization eliminate or reduce minimum requirements of this standard in its qualification and certification procedure. 4.1.2 Personnel duties and responsibilities. This shall include the identification of the duties and responsibilities for the different levels of qualification. 4.1.3 Trainine Droeram. This shall include-outlines of the instruction provided by the organization as well a s sources of outside training utilized by the organization. 4.1.4 Exoerience reauirements. This shall include the techniques within the method and the minimum amount of time for each technique. 4.1.5 Examination oractices. This shall include the designation of the individuals or organizations that will perform the examinations as well as the number of questions. and the specific types of physical tests to be used. 4.1.6 Records and documentation administrative oractices. This shall include the description of the details to be recorded for each certified individual and identification of the individuals responsible for developing, administering, and maintaining the employer's certification program. 4.1.7 Recertification requirements. This shall include the employer's requirements for recertification of personnel. It shall also include the requirements for the loss and r&nstatement of certification. 4.2 Personnel. Personnel (Government. prime contractor, subcontractor, outside agency, etc.) performing, specifying, reviewing, monitoring, supervising, or evaluating . NDI or NDT functions for the purpose of accepting items for the Government shall be qualified to the appropriate requirements of this standard. Personnel performing specialized NDI or NDT, such a s ultrasonic thickness gauging or e l e d & l conductivity tests, with equipment designed for and limited to such usage and that produces clearly recognizable output for both acceptable and unacceptable conditions, do not require qualification to this standard. 4.3 Methods. For the common methods listed in paragraph 1.2.1 of this standard, the requirements for training, experience and examination are detailed in section 5 of this standard. These requirements, as well as those requirements contained in the two publications referenced in paragraph 2.1, shall serve as guidelines for those methods not listed in paragraph 1.2.1.

4.4 Com~liance.Prime contractors shall be responsible for compliance to this standard by their subcontractors. Those organizations utilizing outside sources for training or examination of their personnel shall be responsible for assuring that the appropriate requirements of this standard are met. The employer'is solely responsible for the certification of its employees and cannot certify for another employer. Individuals cannot certify themselves.

4.5 Outside agency. An employer may utilize an outside agency to develop a certification program, train and examine NDI or NDT personnel and perform any other Level LU function. An outside agency cannot certify personnel. The employer shall document the suitability of any outside source selected to perform any function to meet the requirements of this standard. This documentation shall be sufficient to justify that the outside agency is capable of performing the required Level III functions. 5. DETAILED R E Q W S 5.1 Levels of qualification. There shall be five levels of personnel qualification. 5.1.1 Trainee. A trainee is an individual who is participating in a training program for an NDI or NDT method and is not certified. Trainees shall obtain work experience only under the direct supervision of a Level Il, Level III or Instructor in the same method. Trainees shall not independently conduct tests, make accept or reject decisions, or perform any other NDI or NDT functions. 5.1.2 Level I.Level I is the first certifiable qualification level. The Level 1 certification shall be for a specific technique in a given method. The Level I individual shall have the skills and howledge to perform specific tests, specific calibrations, and, with prior written approval of the appropriate Level III individual, specific interpretations and evaluations for acceptance or rejection, and document the results in accordance with specific procedures. The individual shall be knowledgeable of any necessary preparation of parts before or after inspection. The individual shall be able to follo\r procedures in the techniques for which certified and shall receive the necessaiy guidance or supervision from an Level II or Level E l individual. 5.1.3 Level II. Level I1 individuals shall have the skills and knowledge to set up and calibrate equipment, conduct tests, and t o interpret, evaluate, and document results in accordance with procedures approved by the appropriate k v e l LU. The individual shall be thoroughly familiar with the scope and limitations of the method in which he is certified and shall be capable of directing the work of trainees and Level I personnel. The individual shall be able to organize and document NDI or NDT results. The individual shall be familiar with the codes, standards, and other contractual documents that control the method as utilized by the employer.

.,

5.1.4 In~rrucror. Lnstructors shall have the skills and kn~wledgeto plan, organize, and present classroom, laboratory, or on-the-job training programs of instruction, in accordance with approved course outlines, in the method for which appointed. The individual shall be familiar with the codes, standards, and other contractual documents that control the method , a s utilized by the employer. C/O*

5.1.5 Level

5I'4LC

JD. Level III individuals shall have the skills and knowledge to interpret

codes, standards. and other contractual documents that control the method as utilized by the employer; select the method and technique for a specific inspection; and prepare and verify the adequacy of procedures. Only individuals certified to Level I II shall have the authority to approve procedures for technical adequacy in the method to which they are certified. The individual shall also'have general knowledge of all other NDI or NDT methods utilized by the employer. The individual shall be capable of conducting or directing the training and examination of personnel in the method certified. The individual shall nor conduct NDI or NDT for the acceptance of parts unless the demonstration of proficiency in this capability was included in the practical examination upon which, in part, the certification is based. 5.2 Training. Candidates for certification as Level I or Level II shall complete sufficient organized training to become familiar with the principles and practices of the applicable test method and techniques. The training shall be conducted in accordance with a detailed course outline approved by a Level El. The training shall cover basic principles, products, equipment, operating procedures and techniques, and the applicable specifications, codes and instructions used by the employer. The supplements to SNT-TC-IA may be used to develop the training outlines. Subjects not covered in the instruction shall not appear on the training outline. The training outlines shall include the list of references from which the training material is derived.

5.2.1 S~ecialist~ersonnel.The training shall be presented by an Irstructor or a Level IU with the exception that specialist personnel not qualified to this standard may be used to provide instruction on highly specialized topics. Selection of such pers~nnel must be approved by the Level ID. 5.2.2 Exams. An individual must pass-a final exam in order to receive credit for a block of training hours. Such examinations given in conjunction with training shall not be used to satisfy any of the qualification examination requirements of section 5.4.

5.2.3 Minimum required trainine hours. The minimum training hours for Levels I and

In are given in table I for a variety of NDIMDT methods. The minimum training hours for those methods not covered by table I shall b e as determined by the Level III and agreed upon by the facility's customer. There are no additional training requirements to transition from Level II to Level ID nor can an individual have sufficient training to allow certification to Level IU without prior certification as a Level 11 or performance equivalent to a Level II.

RIILST?)-4 IOE

TABLE I. h4WTMU4 TRAJNING HOURS. LEVELS I AND II

CONDITION ~

O

D

[I1

I21

I31

Penetrant

8

8

16

Magnetic particle

12

8

20

Eddy current

12

40

52

Ultrasonics

40

40

80

Radiography

40

40

80

Acoustic Emission

40

40

80

Neutron radiography

28

40

68

[I ] k v e l I [2] Level 11, with prior Level I Certification 131 Level 11, no prior Level I Certification

5.2.4 Previous training. Training obtained from a prior employer must be documented and verified by the previous employer in order to be accepted by the current employer. For personnel credited with training from a prior employer or those not certified within 6 months of their training, refresher training must be provided. The refresher training shall cover the following subjects with the depth of coverage of each subject determined by the Level III responsible for the employer's certification program:

Standardization and calibration Operation of applicable test or inspection equipment Specific test o r inspection procedures Interpretation and evaluation of test or inspection results Safety Applicable codes, standards and specifications

5.3 Ex~erience.Candidates for certification at Levels 1. II or IU shall have sufficient

practical experience to assure that they are capable of performing the duties of the level for which certification is sought. The minimum requirements for Levels I, II and Dl are given in Table II. TABLE II. h4NMUvl EXPERIENCE REQUIREh4ENTS ,

CONDITION

PI

PI

[I1

[21

Penetrant

130 hrs

270 hrs

400 hrs

4 yrs

2 yrs

Magnetic particle

130 hrs

400 hrs

530 hrs

4 yrs

2 yrs

1 Yr

Eddy current

130 hrs

1200 hrs

1330 hrs

4 yrs

2 yrs

1 yr

Ultrasonics

400 hrs

1200 hrs

1600 hrs

4 yrs

2 yrs

1 yi

Radiography

400 hrs

1200 hrs

1600 hrs

4 yrs

2 yrs

1 Yr

Acoustic Emission

400 hrs

1200 hrs

1600 hrs

4 yrs

2 yrs

1 Yr

Neutron radiography 800 hrs

2400 hrs

3200 hrs

4 yrs

2 yrs

1 yr

METHOD

[51

,

[61

[I] Trainee experience for Level I. Experience in method must be at least half this tine. [2] Level I experience for Le\.el II. Experience in method must be at least half this time. [3] Trainee experience for direct certification to Level II. . Evperience in method must be a t least half this time. [4] Level Il experience required for Level

III with no college degree.

[5] Level II experience required for Level degree.

III with technical associate

[6] Level II or equivalent work experience required for Level E l with technical bachelors degree. Equivalency of the work experience shall be determined and documented by the Level III responsible for the employer's certification program.

5.3.1 Previous ex~eriencc.A candidate's experience with a previous employer may be accepted by the current employer only if that experience is documented and verified by the former employer. 5.3.2 Eauivalent ex~erience.For personnel certified under previous revisions of this document or other qualification/certification programs, the equivalency of their previous experience to the requirements of table TI will be determined and documented by the Level III.

5.4 Examinations. The examinations to verify the physical and technical qualifications of candidate personnel shall consist of a physical examination. a general examination, a specific examination, and a practical examination. The requirements for the physical examinations; the questions utilized for the general and specific examinations and the checklist for the practical examination shall be available for review by the facility's customers. If the actual test questions given during certification examinations are not kept in each certified individual's records, then the listing of questions from which examinations are derived shall be available for review by the facility's customers. The questions shall be made available to certification candidates only during administration of the examinations. 5.4.1 Phvsical. The physical examination shall assure that the applicants near vision and color perception meet the following requirements. Near vision tests shall be administered annually and color perception tests shall be administered prior to certification or recertification. These tests shall be administered by an individual approved by the Level III responsible for the maintenance of the certification program or by the outside agency utilized for the examination of personnel:

Near vision - Jaeger #I test chart at not less than 12 inches, or equivalent with one eye, either natural or corrected. Color oerception - Distinguish and differentiate between the colors used in the methad for which certification is sought. 5.4.2 General. The general examination for all levels shall be a closed book

examination consisting of questions that cover the cross-section of the applicable method at the appropriate level. The questions, answers, and references in the appliixble SNT-TC-IA supplement and other publications may be used to develop the general examination. A minimum of 40 questions shall be used for the general examination at each level. For Level IlI. the general examination questions will address the general knowledge of other methods as well as the method for which certification is sought. Possession of a current ASNT NDT Level III certificate by the candidate shall be satisfactory evidence that the general examination requirement is satisfied.

5.4.3 Suecific. The specific examination for all levels shall be a closed book examination and shall cover the specifications, codes, equipment, operating procedures, and test techniques the candidate may use in the performance of his duties. A minimum of 30 questions shall be used for the specific examination at each level. 5.4.4 Practical. The practical examination shall consist of a demonstration of

proficiency by the candidate in performing tasks that are typical of those to be accomplished in the performance of his duties. Test samples used in the examination may be actual hardware, if the candidate is required to demonstrate proficiency in the application of the process as well as interpretation of results, or may be images, such as radiographs, if the candidate is only required to interpret the results and not perform the process of generating the image. Written checklists covering the topics detailed below shall be developed by the Level IJIto assure adequate coverage and to assist in the administration and grading of the examination. 5.4.4.1 b v e l I.The candidate shall demonstrate proficiency by using the appropriate

method to examine at least one test sample for each technique to b e used and document the results. The test samples shall be representative of the products to be encountered by the candidate in the performance of his duties. The checklist shall address proficiency in the use of the procedures and equipment or materials, adherence to procedural details and the documentation of the results. If the Level I candidate is to accept products, then the checklist shall also include proficiency in the interpretation and evaluation of indications. 5.4.4.2 Level Il. The candidate shall demonstrate proficiency by using the appropriate

method to examine a t least one test sample for each technique. The candidate shall interpret, evaluate and document the results of the examination of the test samples. At least two test samples shall be evaluated for each method. The test samples shall be representative of the products to be encountered by the candidate in the performance of his duties. The checklist shall include proficiency in the use of the procedures and equipment or materials. adherence to procedural details, and the accuracy and completeness of interpretations and evaluations of indications. 5.4.4.3 Level. III. The candidate shall demonstrate proficiency by preparing an

NDIMDT procedure appropriate to his employer's requirements. When the candidate's duties will include inspection or evaluation of products, then proficiency in performance of such tasks shall be demonstrated also. The checklist shall address the practical and technical adequacy of the procedures prepared by the candidate, and when applicable, the adequacy of the interpretation and evaluation of indications. In the event that the candidate has already developed satisfactory procedures, then it is not necessary to develop another one for the practical examination. The results of the practical examination shall be documented. Procedures developed for a previous employer can be used to satisfy this requirement if their adequacy can be verified and documented.

5.4.5 Administration. A Level HI, knowledgeable and familiar with the specifications,

standards, codes, techniques and products associated with the employer, and certified Level III in the method for which the examinations are given, shall be responsible for the administration of all qualification examinations. The administration and grading of those examinations using multiple choice or truelfalse type questions can be delegated by the.level III. If an outside agency is used to provide this function, then the employer shall assure that the individual who performs the administration of the examinations is fully qualified. In no case can an examination be administered by one's self or by a subordinate. 5.4.6 Grading. The candidate for certification must achieve a minimum grade of 70%

on the general and specific qualification examinations. The candidate must detect all discontinuities or conditions specified by the Level HI during the practical examination and achieve a minimum score of 70% on the remainder of the practical examination. The candidate must have an average score of no less than 80% in order to be eligible for certification. All examination scores shall be of equal weight in determining the average score. 5.4.7 Re-examination. Candidates failing any examination (general, specific or

practical) shall receive additional training or wait at least 30 days before attempting re-examination. The additional training shall be documented and shall address those areas found deficient in the candidate's skills or knowledge. The re-examination shall not utilize the same questions or specimens that were used in the initial examination.

5.5 Designation of Instructors. Instructors shall be designated by the Level JJ3 responsible for the employer's certification .program and shall meet a least one of the . following criteria: a. Be certified to Level

in the method for which they will be designated Instructors

b. Possess the equivalent of a B.S. in engineering, physical science or technology and have adequate knowledge in the method for which they will be designated Instructors. c. Possess an associate's degree in physic21 science or technology and have a minimum of 5 years experience, or equivalent, as a Level II in the method for which they will be designated ~nstructors. d. Possess a minimum of 10 years experience as a Level 11, or equivalent, in the method for which they wili be designated Instructors.

5.6 Certification. Personnel who have demonstrated that they possess the appropriate

qualifications shall be certified by their employer in accordance with the employer's certification procedure. Certification is not required for personnel who are trainees or those who are designated as Instructors. 5.6.1 Records. The employer shall maintain certification records for personnel for as long a s their certification is in effect. Such records shall be available for audit by the facility's customers. The records shall include, as a minimum:

a. Name of the individual certified. b. Level, method, and techniques for which individual is certified, c. Results of all qualification examinations, including the separate test scores, that the individual has taken. d. Date and expiration of current certification(s). e. History of all previous NDTMDI certifications with current employer. f. Training history which identifies source and dates of training, course hours and

-grades (if given after training), and instructor's name.

g. Experience history, both with current and previous employers, sufficient to justify satisfaction of experience requirements for certification. h. Results of physical examinations. i. Extent and documentation of formal education. 5.6.2 Loss of certification. Certification may expire, be suspended or be revoked. Certification shall expire when employment is terminated or when the cenification interval has lapsed with no recertification attempted. Certification shall be suspended when the periodic physical examination is overdue, the individual does not perform in the method certified for at least 12 consecutive months, or the individual's performance is found to be deficient in any manner. Certification shall be revoked when the individual does not perform in the method certified for at least 24 consecutive months or the individuals conduct is found to be unethical or incompetent. 5.6.3 Reinstatement of certification. Certifications which have been suspended may be reinstated when the cause for suspension has been corrected and the correction verified by the employer. Certifications that have expired or been revoked may not be reinstated except by recertification.

5.6.4 Recertification. Level I and I1 personnel shall be recertified ar intervals not to exceed three years. Level lIl personnel shall be recertified at intervals not to exceed 5 years. The physical and practical examinations, equivalent to those required for initial certification, shall be given prior to recertification. The extent to which the individual's knowledge of the general and specific examination subject areas is examined shall be determined by the Level III responsible for the employer's certification program and shall be documented in the individuals certification records. 6. NOTES (This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.) 6.1 Level I Soecial. The Leve! I designation in this revision is equivalenL to the Level I Special designation of MIL-STD-410D. The MIL-STD-4IOD Level I Special was limited to the ultrasonic and eddy current methods. Experience has shown that the Level I Special designation is an effective way of designating the entry level certification for nondestructive inspection and that it should be allowed a for all methods; thus the change was made in this revision. Because of the increased responsibilities assigned to the Level I, minimum required classroom training hours are no? specified (see table 1).

ur

6.2 Intended use. When invoked in a Request for Proposal (RFP),lnvitation for Bid of other similar document, the contracting agency should request that a copy of the offeror's existing qualification/certification procedure for NDI o r NDT personnel be included with the technical proposal. If the offeror has no existing procedure or if the existing procedure does not comply with this standard, then the contracting agency should request that the offeror's approach for establishing a procedure that complies with this standard b e included in the technical proposal. In addition, if the contacting agency intends that personnel using methods other than those listed in paragraph 1.2.1 be qualified and certified to this standard, then details on the offeror's approach to conducting such an effort should be requested as part of the technical proposal.

m),

6.3 Subiect term (key word) listing. Acoustic emission Certification Eddy current Liquid penetrant Magnetic particle Neutron radiography Nondestructive testing Qualification Radiography Ultrasonic

6.4 Chanees from orevious issue. Marginal notations are not used in this revision to identify changes with respect to the previous issue due to the extensiveness of the changes.

Custodians: Army.- MR Navy - AS Air Force - 11 Reviewer Activities: Army - AR

Preparing Activity: Air Force

- I1

(Project No. NDTI-0176)

INTERNATIONAL STANDARD First edition

1992-05-15

Non-destructive testing - Qualification and certification of personnel

Reierencc number

is0 9712:1992(E)

INTERNATIONAL STANDARD

I S 0 97121992(E)

Non-destructive testing personnel

- Qualification and certification of

.

;

For the purposes of this lnternational Standard, the following definitions apply:

This lnternational Standard establishes a system for the qualification and certification, by a cenlral independent body, of personnel to perform industrial nondestructive testing (NDT) using any of the following methods:

3.1 authorization: Permission to work. issued by the employer or responsible agency and based on the individual's suitability for a specific job. In addition to the certification. amongst othels the jobspecific knowledge. skill and physical ability could be assessed.

a) eddy-current testing; b) liquid-penetrant testing;

d) radiographic testing;

3.2 qualilication: A demonstration of the knowledge. skill. training and experience required to property perform NDT tasks.

e) ultrasonic testing.

3.3

c) magnetic testing;

certification: The orocedures. leading to a written testimony of the 4alification of an individual's competence in an NDT

The system described in this lnternational Standard may also apply to visual inspection. leak testing. neutron radiography, acoustic emission and other NOT methods where national certification pmgrammes exist.

L,;Cp

3.4

certificate: Written testimony of qualification.

J\ 3.5 naUonal ceNfying body: The agency that administers procedures for certification of NOT personnel in accordance with the requirements of this lnternational Standard.

,,,,/ \*

&' r2

Abbreviations qualifying body: A competent organizalion. independent of the employer or responsible agency, authorized by the national certifying body to prepare and administer examinations to qualify NOT personnel.

3.6

The following abbreviations shall be used to identify the five NDT methods covered by this International Standard: English Eddy current

f 3

CF

Liquid penetrant Magnetic Radiography

PT MT RT

RS MG RI

Ultrasonic Nondestructive testing

French Couranls de Foucault

Ressuage Magnetoscopie Rayonnements Ionisants UT US Ultrasons NOT END Essais non destructifs

candldate: The individual seeking certilication under the qualification and certification scheme.

3.7

employer or responslble agency: The organization lor which the candidate works on a regular basis. 3.8

NOTE 1

Candidates may be self-employed.

basic education: The minimum formal education required for qualification.

3.9

I1 may be used to determine duralion and level training and experience required prior to

b) The practical test lor levels 1 and 2 is to verify

'TE 2

3.10 NDT training: A process o l instruction in theory and practice in the NDT methods in which certification is being sought, which may take the form of training courses to an approved syllabus in addition to periods of practical work under qualified supervision but shall not include the use of specimens used in practical examinations.

ability to set Up and Operate test equipment, and perform the necessary settings to yield satislaclory test results. specific examination: The specific examination C-d" 4 includes both a written and a practical part for levels

3.11 experience: The period during which the candidale performed the specific NDT method as his main activity under qualified supervision. inciuding personal application ofthe NDT method to materials, parts or structures but not including tests performed during training courses. 3.12 NDT method: The application of a physical principle in nondestructive testing (for example: ultrasonic testing). 3.13 NDT technique: A specific way of utilizing an NDT method (for example: immersion ultrasonlc testing). 3.14 NDT procedure: An orderly sequence of ~ l e s which describe in detailed terms where, how and in .fhich sequence an NDT method should be applied ,o a product. 3.15 NDT inshuctions: A written document detailing the.precise steps to be lollowed in testing in accordance with an NDT procedure.

3.19

Iand 2. and only two written parts for level 3.

a) The written test is concerned with components, systems, equipment, operating procedures and test techniques commonly used in a particular industry or industrial sector. It involves the demonstration of knowledge related to the product being tested and covers the applicable specifications, codes and acceptance criteria. For level 3 only, this examination includes the writing of one or more satisfactory procedures. b) The practical test involves, for levels1 and 2. the demonstration of familiarity with and the ability to operate the necessary test equipment on prescribed mmponents and the ability to record and analyse the resultant informalion to the degree required.

&

3.20 lob-specific examination: Any additional examcnation concerned with the application of an NDT methog to a specialized product not commonly involved in a particular industrial sector. This examination. which supplements this International Standard. is carried out following written guidelines with results recorded to meet quality-assurance or customer-audit requirements.

-

This examination is outside the scope of lhis International Standard. NOTE3

3.16 industrial sector. A particular area in industry or technology where specialized NOT practices are utilized requiring specific skill. knowledge, equipment or training to achieve satisfactory performance. An industrial sector may be interpreted to mean a product (welds, castings, elc.) or an Industry (aerospace, steel, etc.). qualiIica~lonexamlnauon: An examination administered by the national certifying body or by an authorized qualifying body, which shall include a general examination and a specific examination for each level of competence.

3.17

3.18 general examinauon: The general examination includes both a written and a Practical part for levels 1 and 2. and only a written part for level 3.

3.21 bainee: An individual who works under the supervision of certified personnel but who does not conduct any tests independently. does not interpret test results and does not write reports on test results. This individual may be'regislered as being in the process of gaining appropriate experience to establish eligibility for qualilication lo level 1 or for direct access to level 2.

4 Levels of c o m p e t e n c e 4.1

Classification

An individual certified in accordance with this national Standard shall be classified in one of three levels depending upon the Individual's respective a) The written test Is mncerned with the principles whereas one who has not yet of Of the method and' at least lorlevel attained certllicallon may be registered as a trainee, level 3, covers basic knowledge of other NDT melhods. of materials and pmcesses. and of 4.2 NDT level 1 discontinuities arising through the use of various materials, manufacturing processes or service An individual certified to NDT level 1 is qualified to conditions. For level 3, the requirements for carry out NDT operalions in accordance with written certification of NDT personnel are also Included.

.

instructions and under the supervision of level 2 or level 3 personnel. The individual shall be able to set up the equipment. carry out the tests, record the resulls obtained, classify the results in accordance with written criteria, and report the results. He shall not be responsible for the choice of the test method or technique to be used. nor for the assessment of test results.

4.3

NDT level 2

An individual certified to NDT level 2 is qualified to perform and direct nondestroctive testing in accordance with established or remgnized techniques. The individual shall be competent to choose the test techniques to be used; to set up and calibrate equipment; to interpret and evaluate results i n accordance with applicable codes, standards and specifications; to carry out all duties for which a level 1 lndlvldual is qualifed and to check that they are property executed; to develop NDT procedures adapted to problems which are the subject of an NDT specification; and to prepare written instructions and organlze and report the results of nondestructive tests. The individual shall also be familiar with the scope and limitations of the method for which helshe is qualifed, and be able to exercise assigned responsibility for on-the-job tralnlng and guidance of trainees and NDT level Ipersonnel.

4.4

NDT level 3

An individual certified to NDT level 3 shall be capable of assuming full responsibility for a test facility and stall; establishing techniques and procedures; interpreting codes, standards. specifications and procedures; and designating the particular test methods, techniques and procedures to be used. The individual shall have the competence to interpret and evaluate results in anordance with existing codes. standards and specifications: have a sulficient practical background in applicable materials. labrication and product technology to select methods and establish techniques and to assist in establishing acceptance criteria where none are olherwise available: have general familiarity with other NDT methods; and have the ability to train level I and level 2 personnel.

5 5.1

G e n e r a l principles of certification Administration

The certification activity that includes ail procedures adopted to demonstrate the qualification of an individual to carry out tasks in a specific NDT method and leads to a written testimony of hislher competence shall be adminlstered in each country by the national certifying body, with the assistance. where necessary, of duly authorized qualifying bodles.

0) 5.2

(/

National certifying body

The national certifying body shall be a non-profit organization which has no direct involvement in training of NOT personnel and which is recognized by the I S 0 member body of the country Concerned. 5.2.f

Composition

The national certifying body shall be Supported by an adminislrative committee, which shall i n c l d e eminent representatives of NDT societies, cummittees, users, suppliers. government departments and other interested parties as appropriate. The NCB shall establish. In writing. the number of members of this committee, their qualifications (including education. training and experience), the means and extent of documentation of their qualifications. and their tenure. 5.22

Responsibilities

-

The national certifying body a) shall initiate, maintain and promote the national certification scheme as specified in this International Standard; b) shall administer the procedures and operations for certification in accordance with national documents meeting the minimum requirements of this International Standard, and a stringent code of ethics. including sanctions, which shall apply to committee members and certificate holders; c) may delegate, under its direct responsibility. the detailed administration of the certification pmcedure to other organizations which will act as qualifying bodies and which could represent industrial sectors: d) shall take the ultimate responsibility for the certilication scheme, including technical and adminislrative requirements; e) 'shall approve, either directly o r through a qualifying body, properly stafied and equipped examination centres which it shall monitor on a periodic basis and f)

shall keep ail appropriate records and issue, or delegate the issuing of, written testimonies. o r responslble agency --a-

The employer or responsible agency shall introduce the candidate to the national certifying body and document the validity of the personal information provided, including the declaration of educatlon.

:ng and experience needed to eslablish the el,w,lity o f (he candidate, but shall not be directly iniolved in the certification procedure itself. The employer or responsible agency shall be fully responsible for all t11at concerns the authorization to operate and the validity of the results of NDT operations.

proved by the national certifying body in that method. Table 1 and annex 8 are provided for guidance; however national certifying bodies shall lake into consideration education. certification in other methods, training facilities and other factors. Table 1 - Minimum duration of trainina Training hours

If the individual is self-employed, or introduces himself* he shall assume all responsibilites deskribed for the employer or responsible agency.

5.4

Examination c e n t r e s

Examination centres established by the national certifying body o r through authorized qualifying bodies shall, as a minimum requirement.

NDT method

1 1

Eddy-current testing Liquid-penetrant testing

1

1 1

40

l6

Radiographic testing Ultrasonic tesliog

I

use only specimens prepared or approved by the national certifying body for the practical examinations conducted at that centre.

1

80

(

40

I

Magnetic testing

a) have adequate qualified stan; premises and equipment t o ensure satisfactory qualification . . indusexaminations for the levels, methods and trial sectors concerned; b) use only those documents and .examination questionnaires established or approved by the national certifying body;

+._

.

40

80

40

80

1 Training hours include both praclical and lheoretical lrainlng courses.

I

2 Direct access to level 2 implies the total of the. hours shown lor levels 1 and 2

Whenmore than one authorized examination centre exists, each shall have specimens containing comparable defects. Under no circumstances shall examination specimens be used for training purposes.

6.3.2

6 6.1

Taking into account the scientific and technical potential of candidates for level 3 certification. it i s considered that preparation for qualification could be done in dilierent ways: by taking training courses. attending conrerences o r seminan such as organized by industrial or independent associations, and studying books. periodicals and other specialized printed matter. No training hours have therefore been specified in table 1, although references cited in annex B do suggest course content and duration.

General

Candidates shall have a combination o f education. training and experience adequate to ensure that they have the polential t o understand the principles and procedures o f the applicable NDT method.

6.2

Level 3

Eligibility for examination

Education

fvldence of education may be required to establish the eligibility o f a candidate.

6.4

6.3 T r a i n i n g

6.4.1

j.3.1 Levels 1 and 2 To be eligible to apply for certification in any NDT method. the candidate shall provide evidence of successful completion of a training programme ap-

.

Experience Levels 1 and 2

To be eligible lor certification. the candidale shall have the minimum experience Indicated i n table2 for the method in which helshe i s seeking certiSication. .

Table 2

- Minimum experience requirements

Table 3

- Minimum experience requirements lor level 3 Degree

NDT method

Experience (months)

four-year accredited science or engineering mllege or university programme

I

Successful mmpletion of at leas1 Wo years of engineering or science study at an accredited college. university or technical school

I

NOTES 1 Work experience in months Is based on a nomlnal 40 hlweek (175 h/month). When an lndivldual Is workIng more lhan 40 hlweek. helshe may be credited wilh experience based on the total hours. but helshe shall be required lo produce evidence of this experience.

I I

Direct access lo level 3 by a now ceriilied -&rator wilh experience euuivalent to level

2 For level 2 certification, lhe.intent of lhls International Standard is lhat work experience consists of time accrued as a level I . If the individual Is being qualified directly to level 2, wilh no time at level 1. the experience shall consist of the sum of the periods r e quired for level 1 and level 2

I

I

Graduate of a four-year accredited science or engineering college or university . pro. gramme Suacessful wmpletion of at least two years of engineering or xience study at an amedited college. university or technical school

3 Credit for work experience may be gained simultaneously in two or more of the NDT melhods covered by this International Standard, with the reduction i n total required experience as follows:

l

I I

a) two testing methods time by 25 %;

c) four or more testing methods - reduction of total required time by 50 %.

6.4.2

I No degree

- reduction of total required

h) three lesting methods -reduction of total required lime by 33 %:

The candidate shall be required to show Illat. for each of the testing methods for which helshe seeks certification, helshe has at least half of the lime required in labie2.

48

No degree

I

I I

Level 3

Level 3 responsibilities require knowledge beyond the technical scope of any specific NDT method. This broad knowledge may be acquired through a variety of combinations of education, training and experience. Table3 details rnlnimum experience related t o formal education. All candidates for level 3 certification in any NDT method shall have successfully completed the practical examination for level 2 i n that method.

I

NOTE - 11 the college or university degree is issued In non. deslludive testing. lhe experience required lor a m s to level 3 may be reduced by 50 %.

6.5. V l s l o n requirements

/

~

-

-

-

-

-

-

-

-

The candidate shall provide documented evidence o f satisfactory vision, in accordance with the following requirements: a) distant vision shall equal Snellen fraction 20130 o r better In at least one eye, either unmrrecled o r corrected;

b) near vislon shall permit reading a minimum o f Jaeger number 2, or equivalent type and size letters, at not less thanJ&cm on a standard Jaeger test chart for near vision, in at least one eye. corrected or uncorrected; c) colour vision shall be sumcient that the candidate can distinguish and dillerentiate contrast

between the colours used in the NDT method concerned.

b) the date of certification;

c) the date upon which certilication expires;

7 7.1

Examinations Examination content

The qualification examination shall consist of a general and a specific examination and normally m v e r a given NDT method as it is applied in one or more specific industrial sectors. For level Iand level 2. each of these two examinations shall include both a written and a practical test. For level 3, however, besides the written general examination. the specific examination shall consist of two written tests t o b e respectively designated 'specific (seclor)" and "specific (procedure)'. No level 3 practical test as such is required.

In the general examination, the candidate shall demonstrate sullicient proficiency in performing the NDT method. In the specific examination, he shall demonstrate his ability t o use the same NDT method In the industrial sector concerned.

-2

Administration o f examinations

All examinations shall b e conducted in examination centres established o r approved by the national certifying body. Detailed procedures for the s t ~ c ture, monitoring and grading of examinations by the nalional certifying body are contained in annex A.

Criteria applicable to re-examinalion with respect to (a) partial o r complete failure o f examination and (b) extension of certificalion t o other methods or sectors are described i n annex A: subclause A.l.5 refers to levels 1 and 2. and A.2.4 t o level 3.

8.1

Administration

Based o n the results of the qualification examinalions, the national certifying body, directly or through its authorized qualifying bodies, shall announce the certification. and issue cerlificates and/or corresponding wallet cards.

8.2

d) the level o f certification; e) the NDT method; I) the industrial sector(s) concerned: g) a unlque identification number; h) the siqnature of the individual certified: i) a photograph o f the individual certified and

j) the cold seal of the national certifying body o r the approved qualifying body cancelling the pholograph to avoid falsification. NOTE 4 By issuing the certilicale and/or the mrra sponding wallet card, the national certifying body or the qualifying body attests lo the qualification of the individual but does not give any authority lo operate. There may be a special space on both lhe certilicale and lhe wallet card for ihe signature of the employer or responsible agency authorizing the holder of the cwtificale lo operale and taking responsibilily for leal results. This authorization also serves as testimony of aclivity of the certified lndividual.

9 9.1

Validity and renewal Validity

The period of validity shall not exceed a maximum o f live years from the date of certification indicated on the certificate and/or wallet card. Certification shall be invalid a) i f the lndlvidual changes from one industrial sector to another. i n which case he/she shall successfully mmplete supplementary examinations lor the new industrial sector; b) at the option of tile national certifying body afler reviewing evidence of unethical behaviour; c) i f the individual becomes physically incapable of perlormlng hls/her dutles. based upon the visual examination taken at least every second year under the responsibilily of his employer o r responsible agency.

Certiflcates a n d wallet c a r d s

9.2 Zertificates and corresponding wallet cards shall bear: a) the name of the individual certified;

Renewal

ARer the first period of validity. certification may be renewed by the national certifying body, directly or through an authorized qualilying body, for a new

period of similar duration, provided the individual meets the following criteria:

national certifying body will have the option of replacing this simplified examination by an alternative. structured credit system under its control).

a) helshe provides evidence at least every second

year of satisfactory visual examination and b) heishe provides evidence of continued satisfactory work activity without significant interruption.

if the individual fails to achieve a grade of 80 % or better in the simplified examination, helshe shall apply for new certification.

NOTE 5 A significant interruption means an absence or a change of activity which prevents h e certifiedindividual

10

from practising the duties corresponding to his/her level in the method and the industrial sector(s) for which helshe is certified, for one or several periods for a total time exceeding one year.

The national certifying body or its authorized quatiwing bodies shall keep

If the criteria for renewal are not met. the individual shall apply for recertification.

9.3

Recertification

Upon completion of each second period of validity, or at least every ten years. certification shall be renewed by the national certifying body. directly o r through an authorized qualifying body, for a similar period, provided the individual meets the two criteria for renewal and successfully completes a slmplified examination to assess hislher current knowledge. This simplified examination shall consist of:

Files

a) an updated list of all Individuals certified. classified a m r d i n g to level. test melhod and industrial sector; b) an individual file for each lndividual certified and for each individual whose certification has been withdrawn, containing I)application forms.

2) examination documents, including questionnaires, answers. descriptions of specimens, records, results of tests. written procedures and/or techniques, and grade sheets, 3) renewal documents, including evidence of

physical condition and continuous activity.

a) Level I and level 2: a practical examination or. ganized in accordance with a simplified procedure:

4) reasons for any withdrawal of certification and details of any further penalty inflicted.

b) Level 3: a written examination which includes 20 questions on the application of the test method in the industrial sector concerned and 5 questions on this International Standard (the

Individual liles shall be kept under suitable conditions of safely and discretion for a period at least equal to the total of the initial period of validity plus the renewal period.

Annex A (normative)

Administration of examinations A.l

Examinations for l e v e l 1 and l e v e l 2

A.l.l

Table A.l

- Required number of questions General examination

Qualification examination

Number of questions The qualification examination administered under this International Standard shall include a general examination and a specific examination for each level of competence. Each examination shall mnsist of a written parl and a pradlcal part The pradlcal parl shall be of sullicient duration, complexity and smpe to verify adequately the candidate's ability to apply the NDT method to real test situations.

A.1.2

NDT method

Examination content

1.21 General exarnlna~on

of

basic-knowledge

questions valid at the date of examination. The candidate shall be required, as a minimum, to give anto the fixed number Of multiple-choice questions shown in tableA.1. The practical test in the general examinalion is to verify the candidate's ability to make the required settings and operate the test equipment properly in order to obtain satisfactory results and correctly interpret these results. The candidate shall therefore be required to demonstrate this ability. with mmments; using the means of verification>vailable for each test method. such as calibration blocks, Image-quality, indicators and magnetic-field lndifalOE.

For the radiographic test method, there shall be an additional examination on radiation safety.

"OTE 6

Eddycurrent testing

30

30

Liquidpenelrant testing

30

30

Magnetic testing

30

30

Radiographic testing

40

40

Ultrasonic testing

40

40

Examinations on the radiographic test method .ay indude either X- or garnrna-radiation, or both, depending upon the procedure of the national certirying MY.

Specific examlnation

In .the specilic examlnation, the candidate shall demonstrate his ability to use the relevant test method in the industrial sector concerned.

The written test in the general examination shall include only questions selected from the national cer-

collection

Level 2

A.1.22

In the genera! examlnation, the candidate shall demonstrate proficiency in performing the relevant NDT method.

body's

Level 1

'

The written test in the specific examination shall include only questions selected from the national certifying body's current mllection related to all industrial sectors or from the mllection of specific questions maintained by an authorized qualifying body related to the industrial sector concerned. During the specific examination. the candidate shall to a fixed number of be required to give questions. as defined in tableA.2. including multiple-choice questions. calculations. written procedures and questions on codes, standards and specilications. ~ h , practical test inthe specific examination is to verify the ability to perlorm testing of prescribed components relating to the industrial sector concerned, and to record and analyse the resultant information to the degree required, accurding to specific testing instructions or specifications. and to the NDT level being sought. The specimens used for the practical test shall be Selected from a ml~ection of representative specimens chosen b~the national certifying body or by its authorized qualifying body.

For level 2. the candidate shall be required to demonstrate the ability to prepare written instructions for level 1 personnel.

cedure which includes at least ten check points. 7his procedure shall be developed by the national certi. lying body o r an authorized qualifying body.

If the practical test in the specific examination covers two o r more industrial sectors, the number of specimens to be tested shall be increased proportionally to examine the candidate's competence in each of the industrial sectors concerned.

A candidate for a practical examination may use his own apparatus. The examiner shall investigate the reliability o f the test apparatus made available to the candidate. and unreliable apparatus shall be re_ placed. as well as any apparatus that may be rendered unserviceable during the course of the examination. Any item of apparatus brought by a candidate that i s unreliable o r rendered unserviceable during the examination shall be replaced by the candidate himself.

Table A.2

- Required number of questions Specific examlnation Number of questions

NDT method Level 1

Level 2

Eddy-current testing

15

15

Liquid-penetrant testing

20

15

Magnetic testing

20

15

Radiographic testing

20

20

Ultrasonic testing

20

20

A.1.4

The general examination shall be graded separately from the specific examination so that the candidate may be examined later for certification in another branch of industry without having t o take the general examination again; thus a certified operator changing from one industrial sector t o another keeps the benefit of the general examination valid for all industrial sectors. To be certified. the candidate shall obtain a grade of at least 70 % in each of tfi&ur tests I examination ana a cumnosite arade of at least

-

If the written part o f the specific examination covers two or more industrial sectors. the number of questions shall be increased proportionately t o reasonably cover each o f the industrial sectors, and evaluated accordingly.

A.1.3

The composite grade for.the respeclive level shall be determined by adding the weighted marks obtained from multiplying each of the four test marks by a weighting factor t o be selected from tableA.3. The total of the selected weighting factors shall equal 1.00.

Conduct of examinations

All examinations shall be conducted in examination centres approved and monitored by the national certifying body, either directly or through an author-' ized qualifying body. At the examination. the candidate shall have in his possession a valid proof o f identification and a n official notification o f the examination, which shall be shown to the examiner o r invigilator on request. Any candidate who, during the course of the examination, does not abide by the examination rules o r who perpetrates, o r is an accessory to, fraudulent conduct shall be excluded from further participation. The written and practical tests shall be conducted and supervised by an examiner chosen among NDT level 3 personnel and designated by the natlonal certifying body, either directly o r through an authorlzed qualifying body. The examiner may be assisted by one o r more invigilators placed under his responsibility. The examiner shall mark the written tests completed by the candidate; he shall judge and mark the results of the practical tests in accordance with a oro-

Grading

/(

Table A.3

/c,

- Weighting factors for gradlng - Levels 1 and 2

I Level

I

Weighting factor General

Speciflc

Written

Practical

Written

Practical

1

0.2 to 0.4

0.2 to 0.4

0.2 to 0.4

0.2 to 0.4

2

0.2 to 0.4

0.2 lo 0,4

0.2 to 0.4

0.2 to 0.4

1

A candidate failing for reasons of unethical behaviour shall wait at least 12 months before reapplying. A candidate who fails to obtain the pass grade for the whole examination may take one. and only one. retest in a maximum o f two parts. provided the minimum percentage (70%) was obtained i n each

-t and that retesting takes place within 12 months o f the failed examination.

A candidate for re-examination shall apply for and take the examination in accordance with the procedure established far new candidales. A certified operator wanting to extend certification in a given NOT method to new industrial sectors keeps the benefit of the general examination and shall be required to take only the related specific examination.

A2 A.21

E x a m i n a t i o n s f o r level 3

A.2.1.2

Specilic examlnation

The specific examination shall include two parts, to be marked separately. The first part is designated "specific (sector)" and the second "specific (procedure) ". The specific (sector) test shall include 20 questions on the application of the NDT method in each industrial sector concerned. The necessary questions shall be chosen from a list maintained by the national certifying body o r by an authorized qualifying body. The specific (procedure) test shall require the drafling of one or more satisfactory NOT procedures.

Examination content

The qualification examination for level 3 candidates shall consist only of a written examination. normally covering a specified test method applied in one or more industrial sectors. This examination shall cover a) basic knowledge relating to the test method applied for and to materials, processes and dis2 general-examination continuities; level questions relating to at least two other test methods covered by this International Standard and selected by the candidates themselves; and requirements for the certification of NDT personnel; b) specific knowledge relating to the application of the NOT method i n which the candidate is being examined in the industrial sector concerned. including the applicable codes. standards and specifications, plus knowledge of the product being tested. If the candidate is not certified to NOT level 2 at the time of application, then helshe shall also successfully complete the level 2 practical examination in the relevant NOT method.

The general examination shall include only l~iultiple-choice questions, selected from the national certifying body's collection of basicknowledge questions valid at the date of the examination. The number of questions shall be as follows: a) 30 questions on the main test method and materials, processes and discontinuities: b) 10 level 2 questions on each of at least two additional test methods; c) not less than 5 questions o n the personnelcertification scheme.

A.2.2

Conduct of examinations

All examinations shall be conducted in examination centres established or approved by the national certifying body. and shall be monitored by the national certifying body, directly or through an authorized qualifying body. At the examination, the candidate shall have i n his possession valid proof of identification and an official notilication of the examination, which shall be shown to the examiners o n request. Any candidale who. during the course of the exa'mination, does not abide by the examination rules o r who perpetrates, or is an accessory to, fraudulent condud, shall be excluded from further participation. Examinations shall be conducted and supervised by at least two examiners chosen among level 3 operators and designated by the national certifying body. directly or through an authorized qualifying body. Each examiner shall correct and grade separately the dillerent parts of the examination i n accordance with procedures established by the national certifying body. During a meeting, each o f the examiners shall present and explain his grades, and a n average grade shall be calculated for each part o f the examination.

The written general examination shall be graded separately so that the candidate may be examined later for certification in another branch o f industry without having to repeat the general examination. To be certified, the candidate shall obtain a grade of at least 70 % in each part of the examination and a composite grade o f at least 80 %. The composite grade for the respective level shall be determined by adding the weighted marks obtained from multiplying the test marks in each part

..

of the examination by a weighting factor to be selected from tableA.4. The total of the selected weighting factors shall equal 1.00. Table A.4

- Weighting factors for grading Level 3

minimum percentage (70 %) was obtained in each part and that retesting takes place within 12 months of the first failure. In the case of a second failure to obtain the pass grade, the candidate shall be re. examined in all three Parts. A candidate for re-examination shall apply for and take the examination in accordance with the procedure applicable to new candidates.

A certified operator changing from one industrial sector to another, but who keeps using the same NDT method, retains the benefit of the general examination and shall be required to take only the two specific (sector and procedure) examinations concerning the new industrial sector. A candidate failing for reasons of unethical behaviour shall wait at least 12 months before reapplying. A candidate who fails to obtain the pass grade for the whole examination may take one, and only one, retest in a maximum of two parts, provided the

A special procedure may be apptied in the case of a candidate taking examinations for certification in several testing methods within a period of one year. to avoid the duolication of level 2 ouestions relatino to the additiorial test methods & well as thos; questions relating to codes or standards and the certification scheme.

Annex B (informative) Technical knowledge of NDT personnel 6.1

General

This annex provides a bibliography of international publications detailing course content. The minimum hours of training recommended to confirm eligibility for examination are detailed in the main text of this International Standard.

8.2

[2] The cdrnpiete Recommendations o n international harmonization offraining qualification and cerfilication or nondestructive testing personnel. Prepared by the lnternational Cornrnittee on Non-Destructive Testing. adopted November 1985. Available from tlie Foundation lor the Qualification o f NDT Personnel. P.O. Zoetermeer. The Box 190. 27M1- AD

.'

References

C13 Technical Document IAEA-TECDOC-407 (1987). Training guidelines in nondestructive testing techniques, International Atomic Energy Agency, WagramrnerstraCe 5. P.O. Box 100. A-1400 Vienna. Austria.

[3] ASNT recommended praclice SNTITC-IA 1988 Edition. Tables I-A l o I-H (recommended training courses). Published by the American Society for Non-destructive Testing. 1711 Arlingate Lane, P.O. Box 28518. Columbus. Ohio 43228-0518. USA.

GENERAL DESCRIPTION

At.(

JpJ")'

LIQUID PENETRANT TESTING A.5

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charge

charge

. The nucleus itselfis made up of two types of paaicles of appro-Y equal mass: 'protons' which are positively charged and 'neutrons' which cany no charge.

EIelectrons are 1840 timeslighter than protons or neutrons, and have negligible. . mass.

?he total negative charge of all h e elelectrons orbiting the nucleus balances the positive m e o f theprotonsin the nucleus. The atom as a whole therefore has no e l d c a l charge.

EICC~O& the ~udens in c ~ defined y paths or shells, Each shellcontainsa catainnumbex of elechons. The oqta shall has fcwaclccwns t&anit can @kcIt'is pnpand to khan:'.the . 'vacantplaceswitfi c l c m u ~from s other atoms. This aIIows one atamto combine ch+caIIy with anotha: . . '

Thechemicalpro~ofatomsarc~odbythenumbaofelectronsindx:outn:shelL A . t m of a particuk clementhave a fixed andequal nambcrofelectrons and protons Mdanormal ciratmma The numbm of protons in the n u d w of aparthhclanent is known as tfie atomic number of the clrmcnt

...

MASS NUMBER

("A" number)

_ -,.

? h e m s of an atom is fix& by the number of protons and neutrons in the nucleus. L .

2 Neutrons

13 Protons 14 Neufrons

00 00

Hydrogen

Helium

1proton + 0 neutrons Mass number = 1

2 p ~ t o nt s 2 neutrons Mass number = 4

13protons t 14neutrons

Mass number =27

Theatomic n u m b i s the number of protons, and is a ~ c m i s t iofc thc atom of a p m m i d~nent, for example:

Hydrogen Helium AlmDinium

ISOTOPES The atoms of each elemerit kiitain aJe6nite number of protons but may have a different number of neutrons. The& atoms are called 'isotopes' and are given an identifying number related to the weight of the nucIeus. Such atoms have the same chemical properties, but have different weights and radiation properties. The three different isotopes of hydrogen are an example. These isotopes are chemically identical but are written:

.:

...

Other well known isotopes used for indastrial radiography are: 1)

Cobalt 60

Nore: the fop number represents he total number of prorons and neutrons in the nudm Ehe alorm-c weight. The bottom number representr the as~micnrunber.

-

3)

Iridium 192

1P2Ir 77

.Th& arc isot~pcswfiich;givt off some form of ionizing radiatioa In the process they may themscva be mnsfhmd into otfierelements by lmingpartides.fromthtnuclcus. 1sornpcs chat have a @eat& number of neutrons than pmmns in tfie n&cIeusan said to be 'unsta&'. Unstable isotopes try to s t a b i i themselves spontaneously by a nnmba.of diffwprocesses:

-

1)

by nlcasingneutrons .thatis ejectingneutrons frmnthe nucleos.

2)

by s p W g neutrons into anew proton plos an electron, which fIies off at hi& speed.

The isotopes which arc usefnlforradiography give offgmmaradiation as a aof some and affects of these spontaneouschanges. Gammamdiation is vay penphotographic fiIa - hence its uxfdness.

i

TYPES OF RADIATION

- . Dlning the radioactive decay process, caused by the splitting of the neutrons, radiation is released in three different forms: - '

1)

2) 3)

alphapdcles (a) betaparticles (p) gamma rays (Y)

Alpha particles - are 2 neutrons and 2 protons (helium nucleus) bound together to behave as one fundamental particle. Alpha particles are emitted from heavy nuclei containing a large number of nucleons (neutrons and protons) such as Americium 241, an anificial elment Beta particles - arc high speed elecEons which are emitted from the nucleus. Beta particles are emitted dlning the decay of Iridium 192 and Cobalt 60.

-

Gmitna rays are electromagneticradiations (as are radio waves and Light waves) that are emitted from the nucleus. After the emisdon of alpha and beta particles, the nucleus can re-adjustits ehergy still fkther by the emission of gamma rays. This emission does not ftnther change the element These gamtna rays are used for radiography.

Apart fromxntudy oarnringradioisotopes, it is also possible to produceradioactivity in n d y stable elements by the use of a nuclear reactor,or a high energy particle amelemlor. This is done by introducingenergy into the stable nucleus in the form of an energetic paaide such as a neutron. The nuc1ev.s then loses this excess energy by giving off radiation in the form of gamma rays Radioisotopes are producbi in nuclear reactors by twomethods:

1)

They can be sepaiatedout of fission hgments, ifenemfedwhen afnel element like uranium 235 is used E m m ~ l of e ~comma nidioiitopes this manner - rxoducedin . are cesium. 137, strontium90 and krypton 85.

2)

'~$ble~ents&bcmaderadi~by~adngthrmina~e~d~onina ndearreactor, shieldtd by specially designed aaxssholes. Nentrons originating f h m the mxta are used to irradiate thcsestable clancats. Examples of mdioisotopes prodnced by this m&od am cobalt60 from cobaIt59, iridium 192 fromiridium 191,'and thulium 170f r o m t h h 169.

All these radioisotopes may be used for i n d d radiography.

.

RT LESSON 102

'RADIATION SAFETY DANGERS OF IONIZLNG RADIATION It is vital thatpeople who use and operate X-ray and gamma-ray equipment obsave the proper safety standards. Radiation may damage your health and shorten your Iife. Your . safety is of utmost importance.

-

-

Ionidngradjationsarc pa&cularly dangerous becanstthey arc invisible and cannot be detected by the human senses. They can canse injury to human tissues and organs, for example those that prodnce red blood corpuscles in bone marrow.

&tcn&e dosesof ionizing mdiations can m n ~localized e damage such as radio&m&is or gangrene. They may also cause wad h& disordas, such as Ieukaunia, {cancer of

ffie bl&)

which may eventualIylead to death.

;

?he darnaee that on be done to vow

health by &nidng radiations m$ also affect future generations.

Some effects ofradiation accumulate with time. Each radiadon dose received adds to those already gained,

However. X-raysarid gamma rays used for industrialpurposes cannot make a room or an object or the air radioactivt. When m s u r e is over the radiomhed o b i a i s hamless and can be approached and handled dsafety. A m e y met& n k bc t b d after each expasme to ensure that the sourceis safe to approach.

...

CONTROL OF RADIATION EXPOSURE

Employers and employees are rcqkedto do aIl t h i s rmsonably praaicablc m restrict the extent to which people an:exposed to ionizing radiations. ?he unit of mdiation dosc is the REM Forpractical~nrposcs when measming X and gamma &on the rem can bc considered to be apvahu to the RAD or the Rocntgeo

j-j \

-:

MAXIMUM PERMISSIBLE DOSES ?he statutory regulations'sI;ecify' hsilymakcs it possible provide a liglllly collimated k x n > : ~hcrcforc.Iri~h-resolutio,, radiographs w ~ bc i produced. 5.3 Subcri~icol ~s.~e~?tb/j-Asubcritical assembly is achieved by the addition of suficienl fissionable material surrounding a moderated source oT neutrons, usually a radioisotope source. ~ l t h o ~ gtlie h total thermal neulron yield is smaller than that o f a nuclear reactor, such a systenl olTen the attractions of adequate image quality in a r-nable exposure tinie. relative eare oT licensing. adequate neutron yield Tor most industrial applications, and the possibility of tfanspomblc operation. 5.4 Acccl~~ralor So~rrces-Acceleraton used for thermal neutron radiography have generally been of the low-voltage type which utilize the 'H(d,n)'He reaction, high-energy X-ray machines in which the (x,n) reaction is applied and Van de GraalT accelerators which employ the 'Be(d,n)I0~ reaction. I n all cases, the mrgeLs are surrounded by a moderator lo reduce the neutrons to thermal energies. The total neutron yields of such can be in theorder of 1 0 1 2 . ~ . ~ -the ~ ; thermal neutron flu of such sources before collimation can be in the order of 109n.cm-2.s-', for example, the yield from a Van de Graaff a d e m o r . 5.5 ]soropic Sortrcr3-Many isotopic sources have been employed Tor neutron radiologic applications. Those that have been most widely utilized are outlined in Table 2. ~ ~ dsources i ~ the ~ best~ posibjty ~ i for pomble ~ ~ operation. However, becauie of the relatively low neutron yield. the exposure times are usually long for a given imaze quality. The isotopic soura: Z52Cf offers a number of advantages for thermal neutron radiology, namely, low neutron energy and small physical size, both ofwhich lead to eficient neutron moderation. and the posibility for high total neutron yields. 6 . imaging Methods and Conversion Screens 6.1 General-Neutrons are nonionizing particulate radiation that have little dirm effea on radiographic film. T o obtain a neutron radiographic image on film, a canversion screen is normally employed, upon neutron capture, screens emit prompt and delayed decay products in the form of nuclear radiation or light. In ail cases the screen should be placed in intimate contact with the radiographic film in order to obtain sharp images. 6.2 Direcr h4e1110d-In the direa method, a film is placed on the source side of !he conversion screen (front film) and exposed to the neutron beam together with the conversion screen. Electron emission upon neutron capture is the mechanism by which the film is exposed. The screen is generally one of the following types: ( I ) a free-standing gadolinium metal screen accessible to film on both sides; ( 2 ) a sapphirei-oated, vapordeposited gadolinium screen on a substrate such as aluminum; or (3) a light-emitting fluorescent screen such as gadolinium oxysulfide or 6LiF/ZnS.

Thermal Neutron Sources Radlagiaphc Resdutlar

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s W opaabm. px!amy dfollt ar-dlopenthn st* openm w l t y pos~lble

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opaaucn ml pcrtable

TABLE 2

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TYW

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i

~Sources ~ ~ t Employed i ~ e lor Thermal Neulron Radiography

1i.n)

60 days

"OPo-ae

lo.")

2"Am-Be

(=."I

138 days 458 yea's 163 days 2.65 years

251c(

11l.n)

SPonlanMuS lissl~n

mese comments canpare w r c e s m

Commmls'

Iiail.Llle

"'Sb-Qe

219~m.212 Cm.Be

A

~

s h m hait.LIe and high ~~bachground.low rieulian energy is advanlaqe lor modcrallan. high yield source shed hattJde. ww 7-background long hall4fe. easily shieldca ,-bachgrouna shEn hallJ8le. high nculron yvcld long hallJile. hjgh neulrw yield. nmall slle and low energy oncr advanIa~e5in moderalsan

lne table

Exposure of an additional film (without object) is often useful to resolve anifacts that may app&r in radiographs. Such anifam could result from screen marks, excess pressure, light leaks, developmen\ or nonuniform film. In the case of light-emitting conversion screens, it is recommended that the spectral response of the light emission be matched as closely as possible to that of the film used for optimum results. The direct method should be employed whenever high-resolution radiographs are required, and high beam contamination of low-energy gamma rays or highly radioactive o b j w do not preclude its use. 6.3 Indirecf Merhod-This method makes use of conversion screens that can be made temporarily radioactive by neutron capture. The conversion screen is exposed alone to the neutron-imaging beam; the film is not present. Candidate conversion materials include rhodium, gold, indium, and dysprosium. Indium and dysprosium are recommended with dysprosium yielding the greater speed and emitting less energetic gamma radiation. It is recommended that the conversion xreens be activated in the neutron beam for a maximum of three half-lives. Further neutron irradiation will result in a negligible amount of additional induced activity. ffier irradiation, the conversion sueens should be placed in intimate contad with a radiographic film in a vacuum cassette, or other light-tight assembly in which good contact can be maintained between the radiographic film and radioactive screen. X-ray intensification screens may be used to increase the speed of the autoradiographic p r o m if desired. For the indirect type of exposure, the material from which the cassette is fabricated is immaterial as there are no neutrons to be scatIered in the exposure process. In this case, as in the activation process, there is litde to be gained for conversion screen-film exposures extending beyond three half-lives It is recommended that this method be employed whenever the neutron beam is highly contaminated with gamma rays, which in turn cause fdm fogging and reduced contran sensitivity, or when highly radioactive objects are to be radiographed. In shorf this method is beam gammainsensitive. 6.4 Orher Imaging Sysrems-The scope of these practices is limited to fdm imaging (see 1.3). However, other imaging systems such as track-etch or real-time are available. 7. Neutron Collimators 7.1 General-Neutron sources for thermal neutron radiology generally involve a sizeable moderator region in which the neutron motion is highly multidirectional. Collimators are required to produce a beam and thereby produce adequate image raolution capability in a neutron radiology facility. It should be noted that in the definitions of collimator parameters, it is assumed that the object under

Fast Neutron Source

ol Diameler 0

/

Moderator

Film

I

Diverging

Gamma Ray

Neutron

Filler

FIG. 2

Object

Beam

Pinhole Catlimatar

examination is placed as close to the imaging system as possible to decrease both magnification and image unsharpnes due to the finite neutron source s'm.Several types of collimators are available. These include the widely used divergent type, multichannel, pinhole, and slraight collimators. The image spatial resolution properties of the beams are generally set in part by the diameter or longest dimension of the collimator entrance port (D) and the distance behyeen that apetture and the imaging system (L). An exception is the multichannel collimator in which D is the diameter of a channel and L is the length of the collimator. It should be noted that the detection system used in conjunction with a multichannel collimator will register the collimator pattern. Registry can be eliminated by empirically adjusting the distance between the collimator and the imaging system until the pattern disappears. Ratios of LID as low as 10 are not unusual for low neutron yield sources, while higher resolution capability systems ohen will display LID values of several hundred or more. The actual spatial resolution or image unsharpness in a particular radiologic examination will depend, of course, on factors additional to the beam characterinics. Thex include the object size, the geometry of the system. and scatter conditions. The size of the X-radiologic source. F. would be replaced by the size of the eReaive thermal neutron radiologic source (D) in the calculation of geometric unsharpness. The geometrical aspects ofthe problem are discussed in Guide E 94. 7.2 Divcrgcnr Collimaror-The divergent collimator is a tapered reentrant porl into the point of highest thermal neutron flux in the moderator. The walls of the collimator are lined with a thermal neutron absorbing material to permit only unscattered neutrons from the source to reach the object and the image plane. This type of collimator is preferred when larger objects will be radiographed in a single exposure. It is recommended that the divergent collimator be lined with a neutron absorber which produces neutron

capture decay products that \\.ill ,I 56)

*

-

Phase Lag Eddy currents experience a linear phase lag with depth as depth increases, eddy current activity is progressively delayed phase lag in the test material proceeds at the rate of one radian (57.3") per standard depth of penetration

Test Output

-

During an eddy current test, a primary circuit (the test coil) induces eddy currents into a secondary circuit (the test material)

-

The test material behaves the same as a single turn secondary coil

-

Variations in the test material change the test coil's inductive reactance and effective resistance, producing indications on the instrument display

Copyright 1993 Hcllier Associntcs. Inc.

21

-

Note the use of the term effective resistance the resistance of the coil's wire does not change however, the eddy currents circulating in the test material cause friction and dissipate a part of their energy as heat thus the secondary acts as a load on the primary, causing a resistance change on the display

Copyright 1993 Hellicr Associ;ltes. Inc.

*

Impedance

-

When resistance and inductive reactance are combined they produce a quantity called impedance

-

Impedance amplitude is the magnitude of the vector "* .,-sum of inductive .reactance andFsl3Eice

impedance amplitude is the coil's total opposition to current flow as inductive reactance and/or resistance increases, impedance amplitude increases

-

Impedance phase angle is the proportional relationship between inductive reactance a n d resistance

as inductive reactance increases relative to resistance, impedance phase angle increases as resistance increases relative to inductive reactance, impedance phase angle decreases

Copyright 1993 Hcllicr Associntcr. Inc.

-

With most eddy current instruments, the coil assembly is connected to the instrument via a bridge circuit

at the start of the test, the instrument operator balances the bridge to provide a reference signal during testing, the display provides a readout of bridge imbalance caused by interaction of the coil with the test material -

When an instrument is balanced during test setup, it is balanced for impedance values at a particular point on the impedance plane

-

the balance point serves as a display reference during testing

Copyright 1993 Hellicr Associates. hc.

Impedance Plane Display -

The impedance plane is a graphic plot of values present in the test coil

-

The total voltage affecting coil current consists of two components voltage across the coil's resistance induced back voltage that causes inductive reactance.

-

The voltage across the coil's resistance is in phase with the current

-

The induced back voltage is 90 degrees out of phase with the current

-

A graph of these two voltages would therefore place them on axes that are 90 degrees opposed

-

Likewise, a plot of the impedance components associated with these voltages, inductive reactance and resistance, would require axes that are 90 degrees opposed -

Resistance values are shown on the X axis

-

Inductive reactance values on the Y axis

-

Such a plot is called an impedance plane and is used for displaying eddy current test data.

-

Impedance plane display instruments present both impedance amplitude and phase angle simultaneously on a CRT screen

Copyright 1993 Hellicr Associalcs. Inc

Signal Analysis

-

Test information on an impedance plane instrument is interpreted by observing the movement of the display dot on a cathode ray tube screen while the test coil interacts with the test material

-

Each type of condition that an eddy current test can detect is characterized by a certain pattern of display dot movement

-

Test variables are arranged along curves or "loci" on the impedance plane

-

Generally, there are separate curves for each variable

-

Distribution of information on the impedance plane can be altered by changing test frequency

-

Redistribution of information on the impedance plane by adjustment of frequency is a key technique in optimizing test performance

Copyright 1993 Hellicr Associalcs. Inc.

Lift-Off Curves

-

The zero conductivity point, also called the coil in air or empty coil point is typically located at a position of low resistance, but high inductive reactance

Resi s t a n c e

-

This is the impedance point for a coil whose flux is not near any conductive material

Copyright 1993 Hcilier Associatrr. Inc.

-

As a coil is moved toward a conductor, secondary flux changes the coil's impedance and the display dot moves

Res i s t a n c e

-

The position where movement terminates depends on the conductivity of the test material

Copyright 1993 Hellier Asxrciatcs. Inc.

-

The more conductive the test material, the greater the cancellation of primary flux

-

Thus, the greater the drop in inductive reactance, the further downward the display dot moves

-

In addition, since the coil and test material are mutually coupled, the test material acts as a load on the coil and the effective resistance of the coil changes

-

The movement of the display dot is therefore a combination of variations in both inductive reactance and effective resistance.

I Resistance

Copyright 1993 Hcllicr Associates. Inc.

Conductivity Curve

-

The conductivity curve originates at the zero conductivity point and terminates at the infinite conductivity point

counterclockwise extreme represents zero conductivity clockwise extreme represents infinite conductivity sometimes called the comma curve because of its shape

Copyright 1993 HcUier Associntes. Inc.

-

Different positions along this curve represent nonferromagnetic materials of different conductivities whose thicknesses are infinite relative to electromagnetic penetration i.e., the flux lines entering the material, as well as the eddy currents that they generate are not touching the bottom surface of the material

d U

Rir Point

C

t i v 8

R 8

a C

t a

n

C

Resistance

Capyight 1993 Hcllicr Associatcs. Inc.

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As frequency is increased, the impedance points for the various conductivities move clockwise along the curve

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Thus, as frequency is increased, the lower conductivity materials spread apart along the curve while the higher conductivity materials become compressed at the bottom end of the curve

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Higher frequencies provide greater separation fdr conductivity tests on lower conductivity materials

Copyright 1993 HeUicr Associntes. Inc.

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As test frequency is decreased, the impedance points for the various conductivities move counter-clockwise along the curve

I

$ U

R i r Point

C

t I

v

e

R e a C

t a n C

Resistance

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And, as frequency is decreased, the higher conductivity materials spread apart while the lower conductivity materials become compressed at the top end of the curve

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Lower frequencies provide greater separation for conductivity tests on higher conductivity materials

Copyright 1993 Hellicr Associntes. Inc.

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Frequency adjustment also helps separate the lift-off and conductivity variables At low frequencies, lift-off curves for low conductivity materials are almost parallel to the conductivity curve As frequency is increased, the operating point moves clockwise along the coaductivity curve, increasing the angle between the lift-off curve and conductivity curve

Maximum separation is achieved at the so-called "knee" of the conductivity curve, where the lift-off curve approaches it almost perpendicularly

Coil Diameter

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Increases in coil diameter move the display dot clockwise on the conductivity curve

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Decreases in coil diameter move the display dot counter-clockwise on the conductivity curve

Copyright 1993 Hcllier Associarcs. Inc.

Thickness Curves -

As stated above, the conductivity curve consists of impedance points for materials whose thicknesses are infinite, relative to electromagnetic penetration

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At lesser thicknesses, eddy current flow in the material becomes restricted and the impedance point spirals away from the conductivity curve

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As thickness.approaches.zero, the impedance point approaches the zero conductivity point

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One standard depth of penetration is approximately located on thickness curves at a point slightly to the right of initial intersection with the conductivity curve

Copyright 1993 Hellier Associates. Inc.

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Frequency adjustment is again available to optimize performance

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As frequency is decreased, material penetration increases, but thickness resolution on thinner materials decreases

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As frequency is increased, material penetration decreases, but thickness resolution on thinner materials increases

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4

. - .,

Resistance

Copyright 1993 Hcllier Associntcs. Inc.

Discontinuitv Signal Displav

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A discontinuity causes an interruption of current flow

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The magnitude of an eddy current discontinuity signal depends on the quantity of interrupted current flow

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Eddy current density decreases exponentially with depth

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Discontinuity volume, shape, and position all affect signal magnitude

The depth of the disturbance, however, causes a linear phase lag of the signal

Copydghl 1993 Hellier Associntcs. Inc.

Test Variables a

Test Performance Parameters

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Eddy current test performance is generally defined by the following criteria: Sensitivitv: The minimum size of discontinuity that can be displayed from a given material depth Penetration: The maximum depth from which a useful signal can be displayed for a particular application Resolution: The degree to which separation between signals can be displayed

Copyright 1993 Hellicr Associnm, Inc.

Control of Test Performance

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Test performance is primarily influenced by conductivity, permeability, frequency, and coil design

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In that only test frequency and coiI design are selectable, these two are the primary controls over test performance

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Conductivitv: The greater the conductivity of the test material, the greater the sensitivity to surface discontinuities, but the less the penetration of eddy currents into the material Explanation: As the coil's flux field expands, voltage is induced first on the surface and then at increasing depths in the test material

In high conductivity materials, a considerable eddy current flow and thus a strong secondary flux field is developed at the surface This results in a substantial cancellation of primary flux Because the primary flux has been greatly weakened, less primary flux is available to develop eddy currents at greater depth

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Permeability: As material permeability increases, signals resulting from permeability variations increasingly mask eddy current signal variations this effect becomes more pronounced with increased depth permeability thus limits effective penetration of eddy currents

Copyright 1993 Hcllicr Associates. Inc.

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Freauencv: As test frequency is increased, sensitivity to surface discontinuities is increased, permitting increasingly smaller surface discontinuities to be detected as frequency is decreased, material penetration is increased the test frequency for obtaining standard depth penetration in.a given material can be estimated from a Penetration Chart because of the number of variables affecting eddy current behavior, standard depth should only be used as a starting point the optimum frequency is best determined by experimentation

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Coil Desi~n: Penetration and sensitivity are affected by coil geometry penetration: larger coils produce flux fields that extend further in both the lateral and depth dimensions. Rule of thumb: eddy current penetration is limited to coil diameter sensitivity: since a small surface defect would cause a proportionally greater disturbance in the field of a smaller coil, smaller coils are preferred for detection and localization of small surface defects Rule of thumb: coil diameter should not exceed the length of he discontinuity that is to be detected

Copyright 1993 Hcllicr Associarcs, Inc.

*

TEST MATERIAL VARIABLES

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Response of the test system to the test material can be classified according to three types of test material variable: J I. Conductivity

2. Geometry J

3. Permeability ! ,

Copyright 1993 Hellier Associates. Inc.

Conductivitv

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Conductivity is the ease with which electrons pass ihrough a given material Conductivity depends on relative ability of a material's atoms to allow electron flow Each metal is assigned a conductivity value on a scale called the International Annealed Copper Standard (IACS) G . . : :,.:.>,,,zd..

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