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SHELL NIGERIA EXPLORATION AND PRODUCTION COMPANY Ltd

Bonga FPSO Plant Operating Procedures Manual Volume 4 OIL STORAGE, HANDLING AND BALLAST SYSTEMS

OPRMOPRM-20032003-0304

Version: 1.2

This document is not confidential. The Copyright of this document is vested in Shell Nigeria Exploration and Production Company Limited. All rights reserved. Neither the whole nor any part of this document may be reproduced, stored in any retrieval system or transmitted in any form or by any means (electronic, mechanical, reprographic, recording or otherwise) without the prior written consent of the copyright owner.

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Document Status Information 1.0. DOCUMENT CONTROL CONTROL 1.1. Change History Date

Version

Author

Ref Indicator

01/03/04

1.0

ODL

–

Issue of document for signature.

31/08/05

1.1

ODL

–

Amendment to Part 1 Section 2 Paragraphs 2.2 and 2.3, and Section 5 Paragraphs 2.1 and 4.

Change Description Description

Part 2 Section 1 Procedure No 1/001 Valve Checklist 1 restructured; Valve Checklist 2 and its procedure updated; Valve Checklist 3 restructured. Part 2 Section 2 Procedure No 2/003 Danger notices and Step 4 altered. Part 2 Section 3 Procedure No 3/001 Step 10 altered; Procedure No 3/002 Introduction altered; Procedure No 3/004 Preamble and Step 22. 30/04/06

1.2

ODL/SNEPCO

–

Amended throughout to address outstanding HOLDs and to reflect the latest PFS (Rev 00). Amendments to Part 1 Section 5 Tables 5.2 and 5.3.

OPRM-2003-0304

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PURPOSE The purpose of this document is to provide guidance on the safe, efficient and environmentally aware operation of the Oil Storage, Handling and Ballast Systems. It is one Volume within an overall suite of Volumes, which comprise the Bonga FPSO Plant Operating Procedures Manual (POPM). The full listing of Volumes is as follows: Volume 1 Volume 2A Volume 2B Volume 2C Volume 2D Volume 3 Volume 4 Volume 5 Volume 6 Volume 7 Volume 8 Volume 9 Volume 10 Volume 11 Volume 12 Volume 13 Volume 14 Volume 15 Volume 16 Volume 17 Volume 18 Volume 19 Volume 20 Volume 21 Volume 22 Volume 23 Volume 24 Volume 25 Volume 26 Volume 27 Volume 28 Volume 29 Volume 30 Volume 31 Volume 32 Volume 33 Volume 34 Volume 35

OPRM-2003-0304

Field and Facilities Overview Subsea Production System Subsea Waterflood System Subsea Control System Flow Assurance Guidelines Oil Separation and Treatment Oil Storage, Handling and Ballast Systems Oil Metering and Export System Vapour Recovery Compression System Field Gas Compression System Gas Dehydration/Glycol Regeneration Systems Gas Export/Import/Lift Systems Flare and Vent Systems Produced Water Treatment Systems Waterflood System Chemical Injection and Methanol Injection System Fuel Gas System Heating Medium System Drainage Systems Sewage Treatment Systems Bilge and Oily Water Separation Systems Inert Gas System Nitrogen Generation System Seawater System Fresh and Potable Water Systems Diesel Fuel System and Incinerator Aviation Fuel System Instrument and Utility Air System Deck Hydraulic Systems Fire Protection Systems and Equipment Safety and Lifesaving Equipment PSCS and ESS Power Generation and Distribution Systems Black Start Procedures HVAC Systems Deck Machinery and Mechanical Handling Systems (Cranes, etc) Telecommunications Ancillary Living Quarters (ALQ)

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SCOPE This document provides a detailed description of the plant and equipment, which comprise the Oil Storage, Handling and Ballast Systems, and includes step-by-step guidance on the operation of the system and its equipment, under both normal and abnormal operation.

4.0

TARGET READERSHIP All SNEPCO staff, contractors and other third-party personnel who may be involved in the operation of the Oil Storage, Handling and Ballast Systems onboard the Bonga FPSO.

5.0

SPECIAL NOTE Not applicable.

6.0

ABBREVIATIONS The abbreviations used within this document are listed at the end of these introductory pages.

7.0

REFERENCE INFORMATION/SUPPORTING DOCUMENTATION The primary reference/supporting documents, which have been either used or referred to in the development of this document, are listed at the end of these introductory pages. These are part of the available Operational Documentation which SNEPCO Offshore Operations (OO) has in place to support its day-to-day operations. These and many other documents are available within the SNEPCO Livelink System. Where appropriate, these documents have been cross-referenced within this document.

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Abbreviations AC ANSI API APWBT

Alternating Current American National Standards Institute American Petroleum Institute Aft Peak Water Ballast Tank

BA bara barg BASEEFA BBL BOPD BPD BS&W BWPD

Breathing Apparatus Bar Absolute Bar Gauge British Approvals Service for Electrical Equipment in Flammable Atmospheres Barrel Barrel of Oil per Day Barrels per Day Base Sediment and Water Barrel of Water per Day

CCR CI CIGM CIV COT COW CV

Central Control Room Chemical Injection Clean Inert Gas Main Chemical Injection Valve Crude Oil Tank Crude Oil Washing Production Choke Valve

DC DCS DE DIGM

Direct Current Distributed Control System Drive End Dirty Inert Gas Main

ESD ESR 1 ESR 2 ESR 3 ESS

Emergency Shutdown Process Shutdown Surface Process Shutdown Total FPSO Shutdown Emergency Support System

F&G FBHP FC FCV FG FIC FLA FO

Fire and Gas Flowing Bottomhole Pressure Fail Closed Valve Flow Control Valve Flow Indicating Gauge Flow Indicating Controller First Line Ashore Fail Open Valve

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FPSO FPWBT FT FTP

Floating Production, Storage and Offloading Forward Peak Water Ballast Tank Flow Transmitter Flowing Tubing Pressure

GA GOR

General Alarm Gas/Oil Ratio

H HH HCU HCV HMI HOV HP HPI HPU HSE HVAC Hz

High Alarm High Trip Hydraulic Control Unit Hand Control Valve Human Machine Interface Hand-operated Valve High Pressure High Performance Insulation Hydraulic Power Unit Health, Safety and Environment Heating, Ventilation and Air Conditioning Hertz (Frequency)

ID IG IGF IMO IP IS ISO

Internal Diameter Inert Gas Induced Gas Flotation International Maritime Organisation Intermediate Pressure Intrinsically Safe International Standards Organisation

kW

Kilowatt

L LAT LC LCV LEL LG LIC LL LNG LO LOS LP LPG LS LSA

Low Alarm Lowest Astronomical Tide Locked Closed Level Control Valve Lower Explosive Limit Level Gauge Level Indicating Controller Low Trip Liquefied Natural Gas Locked Open Line of Sight Low Pressure Liquified Petroleum Gas Level Switch Low Specific Activity (Scale)

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LT LU

Level Transmitter Level Unit

m3 MAC MCC MEG MIV MMSCFD MOV m/s MSDS MW

Cubic Metres Manual Alarm Callpoint Motor Control Centre Mono Ethylene Glycol Methanol Injection Valve Millions of Standard Cubic Feet per Day Motor Operated Valve Metre per Second Material Safety Datasheets Megawatt

NB NC NDE NDT NGL NO NPSHA NRV

Nominal Bore Normally Closed Non-drive End Non-destructive Testing Natural Gas Liquid Normally Open Net Positive Suction Head Available Non-return Valve

OD ODMS OLI

Outside Diameter Oil Discharge Monitoring System On-line Inspection

P&ID PCV PDR PDS PDT PFD PG PIC PIL PIV PM PMV ppm v/v ppm wt/wt PT PTW

Piping and Instrument Diagram Pressure Control Valve Pressure Difference Ratio Differential Pressure Switch Differential Pressure Transmitter Process Flow Diagram Pressure Gauge Pressure Indicator Controller Process Interlocks Pigging Isolation Valve Production Manifold Production Master Valve Part per Million by Volume Parts per Million by Weight Pressure Transmitter Permit to Work

RTJ RV RVP

Ring Type Joint Relief Valve Reid Vapour Pressure

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Abbreviations (cont’ d) SCSSV SCU SDV SI SIL Sm3/hr SSDS STIL SWL SWP SWV

Surface Controlled Subsea Safety Valve Subsea Control Unit Shutdown Valve Statutory Instrument Shutdown Interlocks Standard Cubic Metres per Hour Safety Shutdown System Startup Interlocks Safe Working Load Safe Working Pressure Sacrificial Wing Valve

TC TCV TEG TG TIC T/T TT TVP

Tank Cleaning Temperature Control Valve Tri-ethylene Glycol Temperature Gauge Temperature Indicating Controller Tangent to Tangent (Vessel Length) Temperature Transmitter True Vapour Pressure

UEL UPS UV

Upper Explosive Limit Uninterruptible Power Supply Ultraviolet

VDU VRU

Visual Display Unit Vapour Recovery Unit

WBT WI WSV

Water Ballast Tank Water Injection Well Switching Valve

XOV

Crossover Valve

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Reference Information/Supporting Documentation Project Data Document No/Ref No/Ref

Document Title

BON-AME-3GN-J-15658-005 Rev A03

Ballast Tanks – PFS

BON-AME-3GN-J-15626-007 Rev A01

Cargo Storage and Handling – PFS (NAPA)

BON-AME-3GN-J-15626-013 Rev A01

PFS Cargo Storage and Handling

BON-SHI-P-00002-001/002/00300

Ballast System (Sheets 1, 2 and 3)

BON-SHI-P-00002-004/005-00

Air Sounding System (Sheets 1 and 2)

BON-SHI-P-00002-007-00

Position of Tank Gauging

BON-SHI-P-00002-008-00

Crude Oil Headers

BON-SHI-P-00002-009 to 016-00

Storage Compartments (1 to 8)

BON-SHI-P-00002-017-00

Storage Compartments 8 (Tank Utilities)

BON-SHI-P-00002-08-00

Tank Cleaning and Nitrogen Headers

BON-SHI-P-00002-019 to 024-00

Storage Compartments 1 to 7 (Utilities)

Vendor Data Vendor

Document Number

Document Title

FRAMO

FRAMO doc 1008 dated 2/7/2002/TS

Service Manual for Cargo Pumping System

SAAB

BON/1DA2617/SAAB/000001

Load Computer

FRANK MOHN

BON/1JA0980/FRANK/000003

Ballast Pump

NIASCO

BON/1YA1151/NIASCO/000001

Valve Remote Control System Ballast Valves

SAAB

BON/1DA2177/SAAB/000002

COT Level Gauging System

CONSILIUM

BON/1DA2160/CONSILIUM/0000 01

Remote Sounding System (Ballast, FO)

SAAB

BON/1DA2177/SAAB/000002

COT Level Gauging System

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GUNCLEAN

BON/1FA1108/GUNCLEAN/0000 01

Fixed Tank Cleaning Machine

FRANK MOHN

BON/1JA0980/FRANK/000001

Cargo Oil Pump

SEIL

BON/1SA1043/SEIL/000001

Oil Disch Monitoring System

SAAB

BON/1DA2177/SAAB/000002

COT Level Gauging System

CONSILIUM

BON/1DA2160/CONSILIUM/0000 01

Remote Sounding System (Ballast, FO)

HEMP Actions No

Description

Control Measure

1

Portable Cargo Pump (Part 2 Section 2 Procedure No 2/004).

Steps for hooking up the hoses need to give details about the minimum requirements such as pressure ratings, connection types, material of construction etc.

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Main Table of Contents

Document Status Information Abbreviations Reference Information/Supporting Documentation Part 1 – Technical Description Section 1

System Overview

Section 2

Detailed Description – Cargo Loading

Section Section 3

Detailed Description – Ballast System

Section 4

Detailed Description – Crude Oil Washing

Section 5

Detailed Description – Slops System

Part 2 – Operating Procedures Section 1

System Operating Procedures

Section 2

Equipment Operating Procedures

Section Section 3

Supplementary Operating Procedures

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PART 1 TECHNICAL DESCRIPTION Section 1

System Overview

Section 2

Detailed Description – Cargo Loading

Section 3

Detailed Description – Ballast System

Section 4

Detailed Description – Crude Oil Washing

Section 5

Detailed Description – Slops System

Part 1 Technical Description

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Part 1 Technical Description Section 1 System Overview

Table of Contents 1.0

INTRODUCTION............................................................................................................. 2

2.0

PROCESS DESCRIPTION ............................................................................................. 2

3.0

2.1

Crude Oil Loading and Storage ........................................................................... 2

2.2

Ballast System..................................................................................................... 4

2.3

Tank Cleaning Systems....................................................................................... 4

2.4

Slop Tank System ............................................................................................... 7

2.5

Crude Oil Offtake................................................................................................. 8

HEALTH, SAFETY AND ENVIRONMENT (HSE) .......................................................... 8 3.1

General................................................................................................................ 8

3.2

Specific Hazards.................................................................................................. 9

3.3

Environmental Issues .......................................................................................... 9

FIGURES Figure 1.1 – Oil Storage and Offloading Facilities Overview.................................................. 10 Figure 1.2 – Ballast Facilities Overview ................................................................................. 11

Part 1 Section 1 System Overview

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INTRODUCTION Bonga FPSO is a spread moored barge shaped vessel at the Bonga field offshore Nigeria. It is moored with a 12-anchor spread in 1000m water depth and produces from a network of remote subsea wells connected to Bonga FPSO by a system of seabed pipelines and risers. Well fluids are treated in the topside processing facilities and dry crude oil is stored in the hull cargo tanks. Associated gas is exported by pipeline to the Liquefied Natural Gas (LNG) terminal at Bonny and any produced water is treated before being disposed of overboard. Treated seawater is pumped into the reservoir to maintain reservoir pressure and thus enhance oil recovery. The Cargo and Ballast System can be broken down into the following five sub-sections: •

Crude Oil Loading and Storage

•

Ballast System

•

Crude Oil Washing

•

Crude Oil Slops System

•

Crude Oil Offtake

These systems are primarily concerned with the safe storage of crude onboard Bonga FPSO, and counter-action of the effects of the crude on the vessel stability and structural integrity.

2.0

PROCESS DESCRIPTION Refer to Figure 1.1.

2.1

Crude Oil Loading and Storage The crude oil, recovered from the well fluids, is stabilised before passing through the crude coolers to storage. The coolers reduce the temperature of the crude product to below 43.3°C. Isolation valves are fitted to the crude outlet line from the coolers upstream of the tie-in point of the produced oil line to provide topside isolation from storage. Stabilised crude oil at a maximum flowrate of 1450m3/hr from the oil processing facilities can be loaded through a loading header and drop lines, fitted with hydraulically operated isolation valves, into selected Cargo Tanks as required in accordance with the pre-calculated loading plan. Each tank spur feeds the port centre and/or starboard cargo tank through a manual isolation and a hydraulically operated valve. Loading into the cargo tanks is carried out on a continuous basis from the topsides processing module through the loading header and into the selected cargo tanks, normally the reception tank COT 3C. In the reception tank, some separation will take place to further reduce the water content. From COT 3C the oil overflows a standpipe and the crude oil is cascaded by gravity to COT 2C and COT 4C from where it can be transferred via bottom transfer valves into adjacent tanks, or pumped to any other tank via the crude oil transfer header in accordance with the loading plan. As an alternative, COT 5C can be used as reception tank if COT 3C is out of service.

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Crude capacity of the 15 Crude Oil Tanks is 2,039,200 barrels (324,233m3), however it is unlikely that all tanks will be completely filled as the crude is offloaded prior to reaching this point. If there is any delay in offloading due to problems with the tanker or offloading facilities it may be necessary to reduce and, in extreme cases, stop oil production. A submerged, hydraulically driven, Cargo Oil Pump is provided in each COT to deliver crude from the associated tank to the discharge header for export (refer to Volume 5 Oil Metering and Export System (OPRM-2003-0305)) or to the transfer header when being decanted to another COT. The Framo hydraulic system is designed for simultaneous operation of five submerged cargo pumps and two water ballast pumps. The cargo piping system is configured to permit loading of crude oil into the cargo tanks and simultaneously offloading to the export tanker, using a combination of manual and remote hydraulically operated valves. Each cargo tank and the two slop tanks are provided with a Saab radar tank level gauge, a Metritape backup level gauge, pressure sensors and temperature sensors that provide information to the DCS System and the Load Computer. In addition to these sensors, oil-water interface level sensors are provided in the slop tanks and the reception tank COT 3C. Manual sounding points are also provided for each tank. These allow the operator to monitor the filling or emptying of each tank through tank dips as planned in a manually controlled loading or offloading programme in order to meet the design operational and safety requirements of Bonga FPSO. Export of crude oil to the offtake tanker is normally via the offloading cargo system and the topsides SPM booster pumps to the calm buoy, or via the stern offloading facility if the calm buoy is unavailable. Stripping facilities are provided on the cargo pumps to permit the operation of the cargo pumps when pumping from a tank when the level is very low, such as during the removal of any residual fluids from the tank prior to tank cleaning. During the stripping process the submerged pump is operated under local control from the Framo control panel. Compressed nitrogen is injected at the base of the pump discharge column to lift the oil up through the column. Stripping ensures that the tank can be totally emptied prior to, and during, cleaning operations. It is not envisaged that the tanks will be stripped on the completion of every discharge, as Bonga FPSO storage capacity is much greater than the anticipated offloaded parcel size. Oily water mixtures from the topsides equipment are normally routed to the port (dirty) slop tank but can, if required, be routed to the primary reception tank, COT 3C. Generally the liquid to these tanks is from drains or overflows in the process systems. When the produced water quality is such that it cannot be disposed of directly overboard, it is directed to one of these tanks.

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Gravity separation of the liquid phases in the port slop tank occurs allowing the oil and emulsion to be drawn off and returned to storage using the skimming pump. Clean water is then passed to the starboard slop tank, where it is polished prior to disposal overboard. The oil content of water to overboard disposal from the starboard slop tank is continually monitored to ensure it is below the maximum oil-in-water content. Note: No transfer of crude oil, ballast or other significant weight transfer should be performed without first simulating the weight transfer on the loading computer, in compliance with the Cargo Planning Procedure.

2.2

Ballast System Refer to Figure 1.2. A segregated Ballast System, in compliance with MARPOL 73/78, is used to adjust draft, trim and list of the hull to control transverse stability and structural loading. Ballast water is stored in 12 Water Ballast Tanks (WBTs), six down each side of the vessel outside of the crude oil tanks. A ballast main runs through each set of six wing tanks, allowing the distribution of ballast to and from each tank. Two further ballast tanks, the fore peak tank and the aft peak tank, can also be used to take ballast if required. The arrangement of the ballast wing tanks and crude oil tanks provides protection to the crude tanks in the event of a rupture of the ship’s hull. A certain amount of ballasting and de-ballasting can be carried out under gravity using the draught differential to fill or empty the tanks, although normally adjustment of ballast is carried out using the two ballast pumps located in BWT 4 Port and BWT 4 Starboard. Level monitoring in the ballast tanks uses a Metritape System as primary and RF Admittance Probe type for backup and independent high-level indication, which provides level indication to the DCS and the Load Computer. The Ballast System can also be used to supply seawater to the Tank Cleaning System when water washing is to be carried out. An emergency inert gas connection to the Ballast System allows the ballast mains and tanks to be purged and inerted with inert gas should hydrocarbons leak into the tanks. Seawater for ballasting is taken onboard via the port and starboard sea chests. The sea chests are manually treated with sodium hypochlorite for the control of marine growth. Ballasting and de-ballasting operations are carried out from the DCS.

2.3

Tank Cleaning Systems Crude oil washing is carried out to ensure the vessel is operated in accordance with the requirements of Regulation 13B of the Protocol of 1978 to the International Convention for the Prevention of Pollution from Ships 1973 (MARPOL 73/78). Crude Oil Washing Systems should be operated in accordance with the IMCO Revised Specifications for the Design, Operation and Control of Crude Oil Washing Systems (A.446 (XI)).

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Bonga FPSO is equipped with fixed tank cleaning machines served by fixed piping that can be used with either crude oil or seawater as a washing medium. Although it is possible to crude oil wash several tanks simultaneously, the normal practice is to clean one cargo oil tank at a time. Normal tanker practice is to crude oil wash during discharge; on Bonga FPSO, crude oil washing will be performed between offtakes, thus avoiding reducing the pumping rate to the export tanker. The deck-mounted programmable washing machines can be selected to do a full clean or a bottom clean. If bottom clean is selected, the nozzle of the machine is elevated to no higher than 30° so that only the lower section of the walls and base of the tank are cleaned. A crude oil tank containing dry crude is used to supply the washing media to clean an empty tank. The standard washing cycle is one full cycle followed by one bottom cycle on the programmable machines, while at the same time running the bottom-mounted machines. The time required for a full-cycle wash is approximately 60 minutes and the time duration of a tank bottom wash is approximately 30 minutes. The residues and any sediment from the cargo oil tank being washed is pumped out using the submerged cargo pump of that tank discharging into the transfer header. From the transfer header it can be routed back to any cargo tank but normally to the tank which is supplying the wash fluid. It must never be routed to the slop tanks. The contents of the supply tank are then exported at the next offtake. The manual isolation valves fitted on the individual feed lines to the cleaning machines should not be throttled to control the pressure of the crude oil supply to the machines. Tank cleaning is normally followed by water washing if entry to the cargo tank is required. Crude oil washing has the major benefit that cargo residues, which mainly consist of settled-out waxy and asphaltic substances, are dissolved and subsequently discharged with the rest of the cargo. This substantially reduces the amount of residues left in the cargo tanks. Crude oil washing can only be practised on vessels fitted with an Inert Gas System. Tank cleaning, by cold or hot seawater washing, is normally only carried out on a tank when access is required for inspection or repair. The tank will normally be cleaned using the same fixed tank cleaning machines that are used for crude oil washing. Movement of water at high velocity can generate static electricity, therefore water washing is always performed in an inert atmosphere.

IT IS ESSENTIAL THAT THE OXYGEN LEVEL IN THE VAPOUR SPACE OF THE TANK IS MAINTAINED BELOW 5% (VOLUME) AT ALL TIMES DURING TANK WASHING. FOR THIS REASON THE INERT GAS SYSTEM MUST BE AVAILABLE PRIOR TO THE COMMENCEMENT OF TANK WASHING.

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During seawater washing operations, a closed or open cycle method may be used. In either case, tank washings are returned to the dirty slop tank for separation prior to disposing overboard via the Slop Tank System. Seawater for tank washing is supplied to the tank cleaning header either from the clean slop tank or from the tank cleaning pump which is supplied from one of the starboard ballast pumps. 2.3.1

Closed Cycle Wash If the slop tanks are to be used, before seawater washing operations commence, the port and starboard slop tanks are charged with seawater to an ullage of approximately 15m, sufficient to cover the outlet from the decant line in the clean slop tank. The Slop Pump P-2605A submerged in the starboard slop tank is then started and utilised to pump clean seawater from the slop tank to the COW/TC header and thence to the tank cleaning machines on the tank to be washed. At the same time, the submerged cargo pump located in the cargo oil tank being washed, strips the tank and returns the oily water from the tank to the port slop tank for separation. Following separation in the port slop tank, the recovered crude oil can be directed to a cargo tank using the skimmer pump. The cleaned wash water from the port slop tank is decanted to the starboard slop tank then pumped overboard, monitored by the Oil Discharge Monitoring System (ODMS).

2.3.2

Open Cycle Wash Open cycle washing is normally only used where there is insufficient clean seawater in the slop tanks, the starboard slop pump is not available or when washing the slop tanks. During an open cycle wash, clean seawater is supplied by one of the starboard Ballast Pumps P-5804C/D from the starboard sea chest to the Tank Cleaning Pump P-2604 (refer to Part 1 Section 3). There is a Filter P-2604-S-01 fitted with a differential pressure alarm on the suction side of the tank cleaning pump. A removable spool is fitted on the discharge side of the pump that must be fitted before the line is used. As this is a hydrocarbon/non-hydrocarbon system interface it is important that this spool is removed when not in use to avoid the possibility of contaminating the ballast system. The tank cleaning pump discharges into the COW/TC header. The procedure for stripping the tank being washed back to the port slop tank and subsequent treatment of the washings is the same as for a closed cycle wash. The slop tanks can only be water washed using the open cycle method. The clean slop tank can be washed and the washings pumped to the port slop tank via the transfer main. The port (dirty) slop tank can be similarly washed to the starboard (clean) slop tank, however, in order to avoid contaminating the starboard slop tank it is preferable to direct the port slop tank washings via the transfer main to the cargo reception tank, 3C.

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The minimum operating parameters for any system during seawater washing are as follows: •

Seawater pressure at cleaning machine – 8barg

•

Flowrate deck-mounted machines – 87m3/hour

•

Flowrate bottom-mounted machines – 39m3/hour

A suitable number of closed ullage stations are provided for each cargo oil tank and slops tank to check the tank before and after cleaning. Two stands fitted with a vapour seal valve for use with appropriate 2in portable measuring instrument are provided for each cargo oil tank and slop tank. Two stands fitted with a vapour seal valve for use with appropriate 1in portable measuring instrument are provided for each cargo oil tank and one in each slop tank. Tank washings are returned to the dirty slop tank for disposal whether open or closed cycle washing is employed.

2.4

Slop Tank System The slop tanks are designed to treat mixtures of water and entrained oil from crude oil processing, cargo handling, cargo tank washings, open and closed drains and bilge systems. The port (dirty) Slop Tank T-2603 receives the mixtures to allow time for settling out before transfer of the water to the starboard (clean) Slop Tank T-2602. Oil is removed from the upper part of the dirty slops tank by a Dirty Slops Tank Oil Skim Pump P-2603 which delivers the wet oil to a selected cargo tank, normally the reception tank 3C. Water is decanted to the starboard slop tank to allow further separation of oil before being pumped overboard. The hydraulically driven skimming pump has a capacity of 100m3/hour. The suction of the pump is set approximately 10m from the top of the tank. Both slop tanks have a hydraulically driven slop pump installed in a similar manner to the cargo pumps. The pumps each have a capacity of 400m3/hour and can discharge to either the transfer header or tank-cleaning header. After confirmation by sampling that the oil-in-water content of the starboard clean slop tank is below 29ppm, water can be discharged overboard by the clean water overboard pump. The overboard discharge is monitored for quality by the ODMS and, if oil content is above specification, the flow is directed to the dirty slop tank. If a significant amount of oil collects on the surface of the clean starboard slop tank it can be skimmed from the surface by filling the tank with water. When the oil/water interface level is above the upper oil skim pipe inlet (70% tank height) the top level can be run off back into the port tank by hydrostatic head via the Remote-operated Valves 26-ZCV-108 and 26-ZCV-109. There are also facilities to isolate the flow to the transfer header and pump to the Flare Scrubber V-4640 for disposal to the LP Separator V-2340A via the Flare Scrubber Pumps P-4640A/B/C.

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Crude Oil Offtake The Offtake System is designed to offload the crude cargo from the vessel to an export tanker safely and efficiently, whilst also maintaining loading into the storage tanks from the production facilities. The export of crude oil from Bonga FPSO to the offtake tanker can be either via the SPM buoy or via the stern discharge system. A cargo pump is located in each of the cargo tanks and can be lined up to the discharge header or to the transfer header. The cargo pumps are powered by variable speed hydraulic motors and have their suction 100mm above the base of the tank. Each pump can deliver crude to the discharge header at 1500m3/hour. The design export rate is 7500m3/hour, requiring up to five cargo tanks to be pumped out simultaneously. Nitrogen is injected at the base of the pump discharge column, this then lifts the oil in the column on a pocket of gas during stripping. Stripping ensures that the tank can be totally emptied prior to and during cleaning operations. It is not envisaged that the tanks will be stripped on the completion of every discharge, as Bonga FPSO storage capacity is larger than the anticipated offloaded parcel size. From the discharge header, the oil flows through the LACT metering package (fiscal meter) topsides before being directed to the topsides CALM booster pumps or to the stern discharge system. Note: For details and operation of the Cargo Offloading and LACT Metering Systems reference should be made to Volume 5 Oil Metering and Export System.

3.0

HEALTH, SAFETY AND ENVIRONMENT (HSE)

3.1

General The Cargo and Ballast System is located mostly in the vessel hull with some pipework on the vessel topsides, which is part of the main topside operating area. All personnel in the areas must have received training in, and be fully conversant with, the following: •

Location and use of fire and safety equipment in the area

•

Recognition and response to all the vessel’s visual and audible alarms

•

Muster and evacuation procedures

•

Escape routes

•

Location and use of lifesaving equipment

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Specific Hazards The Cargo and Ballast System handles crude oil and separated water at relatively low temperature (below 43°C) and pressure. Hazards are therefore low compared with other processing systems. The oil storage tanks are inert gas blanketed. However, it is incorrect to assume that no hazards exist. Potential hazards include the following: •

If storage tank levels containing water/crude oil mix are left static for a period of time there is a real danger of large quantities of H2S being generated when the tanks are disturbed

•

Most of the pumps and actuated valves used in operation of the system are driven from a high-pressure hydraulic system

•

The cargo tanks are inerted using inert gas supplied from the inert gas system. The inert gas is an asphyxiant and may contain toxic gases such as carbon dioxide and carbon monoxide

•

The Cargo and Ballast System employs various items of rotating equipment which must have all moving parts securely guarded at all times

•

Excessive list, trim and hull stress causing structural integrity concerns

•

Oil pollution/spills to ballast tanks or to outside directly

All personnel must wear the appropriate protective clothing (overalls, safety helmet, gloves, goggles etc) when in the area, and wear hearing protection if noise levels in the area are high.

3.3

Environmental Issues

3.3.1

Overboard Discharge Since the Cargo, Slops and Ballast System discharges effluent overboard, environmental issues could arise if the discharge fails to meet the target requirement of less than 29ppm monthly average, with a maximum single occurrence of 40ppm. The water effluent is continuously monitored for oil at the discharge point and if its quality deteriorates below the acceptable value, the off-specification water is automatically diverted to the dirty slops tank for further treatment.

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FI

FROM CRUDE COOLER NOTE 1: ACTUAL ARRANGEMENT (TYPICAL FOR ALL CARGO PUMPS)

AFT CARGO HOSE CLEANING MANIFOLD

TRANSFER HEADER

FROM FROM I/G OIL DEGASSING FLOTATION SEPARATOR TANK

FROM PRODUCED WATER TANK

DISCHARGE HEADER

CRUDE OIL LOADING HEADER

STERN OFFLOADING

P-2061C

TRANFER HEADER

DRAIN TANK P-2061B P-2061A

SEE NOTE 1 TANK T-2601 O(5P)

T-2603 SEAL LOOPS DIRTY SLOP TANK

TANK T-2601 L(4P)

TANK T-2601 I(3P)

TANK T-2601 F(2P)

ESD

TANK T-2601 C(1P)

AFT HEADER DRAIN

FORWARD HEADER DRAIN

P-2603 SLOP OIL SKIMMING PUMP

BACKFLUSH/METER PROVING HEADER P-2061C CARGO PUMP

P-2061F CARGO PUMP

P-2061I CARGO PUMP

P-2061L CARGO PUMP

P-2061O CARGO PUMP

ESD

REMOVABLE SPOOL

P-2605B SLOP TANK PUMP

A-2740 LACT METER ESD

A-2741 METER PROVER

ESD

SEAL LOOPS P-2061N CARGO PUMP

PC

DISCHARGE HEADER

P-2061H CARGO PUMP

P-2061K CARGO PUMP

P-2061D CARGO PUMP T-2601 N(5C) BACK-UP RECEPTION TANK

P-2061M CARGO PUMP

P-2605A SLOP TANK PUMP

T-2603 CLEAN SLOP TANK

P-2602 CLEAN WATER DISCHARGE PUMP

TANK T-2601 M(5S)

T-2601 H(3C) BACK-UP RECEPTION TANK

T-2601 K(4C) TANK

T-2601 D(2C) TANK

P-2061G CARGO PUMP

P-2061J CARGO PUMP

TANK T-2601 J(4S)

P-2061E CARGO PUMP

TANK T-2601 G(3S)

TANK T-2601 E(2S)

P-2061B CARGO PUMP A-5401 CARGO PUMP HPU A TO F L/C

T-2601 B(1C) TANK

P-2061A CARGO PUMP

TO PRODUCTION FLARE HEADER

TO SUBSEA FLOWLINE WARMUP PIGGING EXCHANGE

FROM FLARE SCRUBBER TO FLARE SCRUBBER FROM OIL DEGASSING TANK

INERT GAS

PC

TANK T-2601 A(1S) P-2741A SPM BOOSTER PUMP

A-0821A SPM BUOY LAUNCHER RECIVERS

CRUDE OIL WASH AND TANK CLEANING HEADER

FROM INDUCED GAS FLOTATION SEPARATOR

P-2741B SPM BOOSTER PUMP

FC

A-0821B SPM BUOY LAUNCHER RECIVERS

FROM PRODUCTION SUMP AND COLLECTION TANKS

P-0821A CIRCULATION PUMP

P-2741C SPM BOOSTER PUMP

PC

OVERBOARD VIA ODME REMOVABLE SPOOL

PC

A-2742 LACT SAMPLE CABINET

PC

TO SUBSEA FLOWLINE WARMUP PIGGING EXCHANGE

P-2604 TANK CLEANING BOOSTER PUMP

FC

A-0821C SPM BUOY LAUNCHER RECIVERS

FC

P-0821B CIRCULATION PUMP

FROM BALLAST SYSTEM (FOR TANK CLEANING)

DERIVED FROM PFD BON-AME-3GN-B-21192-006-C02

AC91003_VOL_004_001.ai

Figure 1.1 – Oil Storage and Offloading Facilities Overview

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FROM CLEAN INERT GAS SYSTEM

FROM SEA CHEST

CHLORINE DOSING TO ATMOSPHERE

UPPER DECK LOAD WATER LINE

P-5804A/B SUBMERGED BALLAST PUMPS SLOP OIL TANK (P)

SLOP OIL TANK (S) P-5804C/D SUBMERGED BALLAST PUMPS

A.P.T

No 6 WBT (P&S)

No 5 WBT (P&S)

No 4 WBT (P&S)

No 3 WBT (P&S)

No 2 WBT (P&S)

No 1 WBT (P&S)

FPT

T-6501(P)

T-5801(P) T-5801(S)

T-5801(P) T-5801(S)

T-5801(P)

T-5801F(P)

T-5801D(P)

T-5801B(P)

T-5801A

T-5801G(S)

T-5801E(S)

T-5801C(S)

T-5801(S) FROM SEA CHEST

CHLORINE DOSING

LOAD WATER LINE

TO CARGO TRANSFER HEADER

TO TANK CLEANING PUMP

FROM CLEAN INERT GAS SYSTEM

DERIVED FROM P&IDs BON-SHI-008-P-000002-001/002-00

AC91003_VOL_004_002.ai

Figure 1.2 – Ballast Facilities Overview

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Part 1 Technical Description Section 2 Detailed Description – Cargo Loading

Table of Contents 1.0

INTRODUCTION............................................................................................................. 3

2.0

EQUIPMENT DETAILS .................................................................................................. 3

3.0

4.0

2.1

Loading Facilities................................................................................................. 3

2.2

Cargo Oil Storage Tank T-2601C (Typical) ......................................................... 4

2.3

Cargo Reception Tank T-2601H (COT 3C) ......................................................... 6

2.4

Cargo Transfer Header........................................................................................ 7

CONTROL AND INSTRUMENTATION.......................................................................... 8 3.1

Control Overview ................................................................................................. 8

3.2

Tank Level Gauging ............................................................................................ 9

3.3

NAPA Loading Computer .................................................................................. 12

3.4

Cargo Loading Control ...................................................................................... 15

3.5

Cargo Transfer .................................................................................................. 15

3.6

Operator Interface for Loading Operations........................................................ 17

3.7

Cargo Pump Interlocks ...................................................................................... 18

SAFEGUARDING ......................................................................................................... 19

TABLES Table 2.1 – Crude Oil Tank Capacities .................................................................................... 6 Table 2.2 – Cargo Tank Alarm and Trip Settings ................................................................... 10 Table 2.3 – Associated Tag Numbers for COT ...................................................................... 16 Table 2.4 – Startup Interlocks (STIL) – Cargo Pumps P-2601A to O..................................... 18 Table 2.5 – Process Interlocks for Cargo Pumps P-2601A to O ............................................ 18

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Table of Contents (cont’d) FIGURES Figure 2.1 – Graphical Interface – Cargo Headers ................................................................ 20 Figure 2.2 – Graphical Interface – Cargo Storage ................................................................. 21 Figure 2.3 – Hull Tanks – Level System Schematic............................................................... 22

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INTRODUCTION The purpose of the Cargo Loading System is to allow, in conjunction with the ballast system, crude oil cargo to be distributed to the cargo oil tanks to maintain the vessel’s stability within the specified design envelope to avoid causing excessive stresses or bending moments in the hull. The cargo storage tanks are used to store the treated and stabilised crude oil production for regular offloading, approximately every 5 days, to the tankers via the single point buoy mooring system or the Stern Discharge System (when the single point mooring buoy is not available). The cargo loading facilities consists of the following pieces of equipment: •

Loading Header

•

Cargo Storage Tanks

•

Transfer Headers

Loading into the cargo tanks is carried out on a continuous basis from the topsides processing module through the loading (rundown) header and into the selected cargo tanks. Refer to the following P&IDs: •

BON-AME-3SP-B-21425-001 Crude Cooler

•

BON-SHI-008-P-00002-008 Crude Oil Headers

•

BON-SHI-008-P-00002-011 Storage Compartment 3

•

BON-SHI-008-P-00002-012 Storage Compartment 4

•

BON-SHI-008-P-00002-013 Storage Compartment 5

•

BON-SHI-008-P-00002-014 Storage Compartment 6

•

BON-SHI-008-P-00002-015 Storage Compartment 7

•

BON-SHI-008-P-00001-012 Position of Tank Gauging and Hand Dipping System

2.0

EQUIPMENT DETAILS

2.1

Loading Facilities Refer to Figure 1.1 or P&IDs BON-SHI-008-P-00002-011 Storage Compartment 3, BON-SHI-008-P-00002-008 Crude Oil Headers and BON-AME-3SP-B-21425-001 Crude Cooler. Equipment Description Processed oil from the crude oil coolers flows down the rundown line through the Isolation Valve 25-MOV-401 into the 20in (500mm) loading header. The loading header runs the length of the main deck to allow oil to be distributed to the 15 cargo tanks as required.

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There are five sets of cargo tanks numbered one to five from the forward end of the vessel. Above each set of tanks there is a 20in (500mm) (Nos 1 and 2 Tanks are 14in (350mm)) transverse manifold running, connected to the loading header through a remotely operated, hydraulically actuated butterfly valve. The manifold delivers oil to each of the three tanks in each set, Port, Centre and Starboard, through a drop line that extends almost to the bottom of each tank. The drop line is isolated from the manifold by a manual butterfly valve and a remotely operated, hydraulically actuated butterfly valve. Each drop line has a removable spool to provide positive isolation of the tank from processed crude. Each of the five manifolds also have a connection to the transfer header, described in the following paragraphs, complete with a remotely operated, hydraulically actuated butterfly valve.

2.2

Cargo Oil Storage Tank T-2601C (Typical) Equipment Details Tag Number:

T-2601C

Capacity:

18,740m3

Maximum Operating Pressure:

1400mm WG (1.4barg)

Minimum Operating Pressure:

400mm WG (0.4barg)

Refer to Figure 1.1 and P&IDs BON-SHI-008-P-00002-015 Storage Compartment 7, and BON-SHI-008-P-00002-024 Storage Compartment 7 Tank Cleaning and Utilities. Equipment Description The following paragraphs describe Crude Oil Tank T-2601C (COT 1P). The other crude oil storage tanks have similar facilities. Crude enters the tank via a 14in (350mm) nominal bore drop line from the loading header/manifold. The tank drop line incorporates Valve 26-ZCV-011 on the main deck. The valve is hydraulically actuated controlled from the DCS. Open and closed position signals are provided to the DCS by position switches. In normal operation the tank is connected to the dirty inert gas header through Three-way Valve 55-SV-001 to maintain a positive pressure in the tank under all conditions. Pressure in the dirty inert gas header is controlled by Pressure Control Valve 55-PCV-104, set at 800mm WG (0.8barg), that relieves pressure to the vent riser. During offloading operations, pressure in the dirty inert gas header is maintained by operation of the inert gas generators. Alternatively, during inerting and gas freeing operations Three-way Valve 55-SV-001 is used to connect the tank to the clean inert gas header. Venting in this operation is provided through a 10in (250mm) line which extends down to the bottom of the tank and connects to the crude oil purge main. Isolation of this line is provided by a manual Butterfly Valve 55-BUV-003. Refer to POPM Volume 19 Inert Gas System (OPRM-2003-0319).

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The tank is protected against over-pressurisation or vacuum conditions through Pressure/Vacuum Valve 55-RV-003 located on the 10in (250mm) connection to the vent main. This valve has two settings, 1600mm WG (1.6barg) to relieve over pressure conditions and -200mm WG (-0.2barg) to relieve vacuum conditions. Pressure relief is to the crude vent header. For tank isolation, a spectacle blind is provided in the connection to the clean and dirty inert gas headers and the crude oil purge main. A removable spool is provided below the Relief Valve 55-RV-003 and on the oil loading line. Communication with tanks in the next set is provided through the lower transfer valves, for example COT 1P can be connected to COT 2P by opening 26-ZCV-071 located in COT 1P and 26-ZCV-070 in COT Number 2P. The valves can be used to transfer oil in either direction between tanks when filling tanks or to allow both tanks to be offloaded using one pump if the other is out of service. The valves are operated from the DCS and position of the valves is indicated on the DCS by measuring the flow of hydraulic oil to the valve actuator. In the cargo oil tank Sets 2 and 4, lower transfer valves are provided for transfer fore and aft, and between adjacent tanks in the set. Offloading from the tank is carried out using the dedicated Cargo Pump P-2601C which takes suction from the bottom and towards the aft end of the tank. The pump is a hydraulically driven submersible Framo pump controlled from the DCS. In exceptional circumstances it can be controlled locally from the Framo panel. The pump discharges into the common manifold for the No 1 cargo tanks and on into either the discharge or transfer headers. Each pump has a discharge capacity of 1500m3/hr, at 150nlc. Refer to POPM Volume 5 Oil Metering and Export System (OPRM-2003-0305). As a backup there is one portable cargo pump which can be inserted into the tank through a Butterworth hatch in the tank top. A tie-in to the hydraulic supply is provided at each cargo tank to drive the pump. The portable pump discharges through a flexible hose to a 6in (150mm) connection at each cargo pump discharge valve. This is an abnormal operation and the risks involved should be assessed via the PTW System. For details of the operation refer to Part 2 Section 2 Procedure No 2/005. Level in each tank is measured by a SAAB radar type level measuring transmitter 26-LIT-002 installed in the top of the tank. The transmitter also measures tank pressure and temperature at three levels within the tank. A second system, 26-LZT-001, using Metritape provides an alternative level measurement. The second system also provides a shutdown capability. Three fixed tank washing machines are fitted to the roof of the tank allowing it to be washed with either crude oil or water. The washing machines are isolated from the crude oil washing header by manual Isolation Valves 26-GTV-001/002/035. In the centre tanks there are additional washing machines, located on the tank bottom, to provide additional cover in areas not accessible to the main machines.

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Facilities are provided to allow manual tank dips to be performed using the closed tank portable gauging system. The portable instrument can be mounted on 2 x 2in and 2 x 1in valves at deck level so that access is gained without venting the tank. This portable system can measure the oil level, the oil/water interface level and temperature at any point over the depth of the tank. The cargo tanks are coated with coal tar epoxy for the top 2m and the bottom 3m, plus the upper side of all horizontal stringers. The remainder of the tank is uncoated. Sacrificial anodes are fitted based on the assumption that the bottom 1m of the tank being in contact with water 100% of the time.

COT No

100% Capacity (m3)

98% Capacity (m3)

Pump Dry (m3)

1P&S: T-2601C&A

18,740.2

18,365.4

0.5

1C: T-2601B

23,771.1

23,295.7

0.5

2P&S: T-2601F&E

21,086.4

20,664.7

0.5

2C: T-2601D

14,862.0

14,564.8

0.5

3P&S: T-2601I&G

21,086.4

20,664.7

0.5

3C: T-2601H

26,751.6

26,216.6

0.5

4P&S: T-2601L&J

21,086.4

20,664.7

0.5

4C: T-2601K

26,751.6

26,216.6

0.5

5P&S: T-2601O&M

21,082.7

20,661.0

0.5

5C: T-2601N

28,742.7

28,167.8

0.5

Table 2.1 – Crude Oil Tank Capacities

2.3

Cargo Reception Tank T-2601H (COT 3C) Equipment Details Tag Number:

T-2601H

Capacity:

26,751.6m3

Max Operating Pressure:

1400mm WG (1.4barg)

Minimum Operating Pressure:

400mm WG (0.4barg)

Refer to Figure 1.1, P&IDs BON-SHI-008-P-00002-013 Storage Compartment 5 and BON-SHI-008-P-00002-022 Storage Compartment 5 Tank Cleaning and Utilities. Equipment Description Two cargo reception tanks are provided, T-2601H (COT 3C) nominated as the primary and T-2601N (COT 5C) nominated as the backup if T-2601H is out of service.

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The tanks have all the same equipment as the cargo tanks described above in addition to facilities required to perform reception duties. Oil is loaded through the 20in (500mm) drop line which deposits the freshly processed oil in the bottom of the tank. Oil leaves the tank to adjacent tanks (COT 2C and 4C in the case of primary reception, and COT 5P and 5S in the case of backup reception) through a 20in (500mm) cascade line which is 70% (24m) of the height of the tank. The cascade line has a remotely operated Butterfly Valve 26-ZCV-101 controlled through the DCS. The valve position is indicated on the DCS. The two centre tanks either side of the primary reception tank have lower transfer valves that will permit the free flow of crude oil from either centre tank into the adjacent wing tanks. It is intended that such an arrangement permit the ‘free flow’ loading of crude and can minimise deep well pumping. Process drains and overflow lines can flow to either the dirty slop tank or to the reception tank. Initially these will be routed such that the drains will be routed to the dirty slop tank and the overflow routed to the reception tank. During later field life when produced water rates increase it is likely that they will both be routed to 3C as the ability of the dirty slop tank to handle them diminishes. In the reception tank the process drains and overflow lines terminate at the bottom of the tank in seal pots 3m and 10m high respectively. Separated water from the reception tanks is pumped by the Cargo Oil Pump P-2601H directly into the dirty slop tank via a dedicated oily water transfer line, for eventual disposal overboard. In the event of a reception tank cargo oil pump failure, drain/free-flow transfer valves 26-ZCV-086/087 connected to the bottom transfer header are used to free flow the reception tank crude into an adjacent tank. The bottom header is kept as low as possible to facilitate this transfer. The primary reception tank is fully coated with pure epoxy. Sacrificial anodes are fitted based on the bottom 3m of the tank being in contact with water 100% of the time. Number 5 COT centre tank is designated as the ‘backup’ reception tank with similar piping and valve arrangements, coating and anodes.

2.4

Cargo Transfer Header Oil from the crude oil pumps can be diverted from the transverse discharge manifold for a set of tanks through an isolation valve into the 20in (500mm) transfer header. The transfer header runs the length of the main deck to allow oil to be transferred between any tanks during loading and tank cleaning operations.

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3.0

CONTROL AND INSTRUMENTATION

3.1

Control Overview Refer to Figures 2.2 to 2.4, and P&IDs BON-SHI-008-P-00001-012 Position of Tank Gauging and Hand Dipping System, and BON-SHI-008-P-00001-024 Storage Compartment 7 Tank Cleaning and Utilities. Cargo loading and associated de-ballasting operations are carried out in several stages. For loading and offtake, the Trim and Stability Book places the cargo tanks in two groups. Group A comprises Crude Oil Tanks 2 and 4, and Group B comprises Crude Oil Tanks 1, 3 and 5. However, any combination of tanks can be used as dictated by operational requirements, provided trim and stress requirements are met. The loading sequence for the FPSO is dictated by the maximum available production rate of crude oil and the expected offloading schedule from the FPSO to the offtake tanker. Following offtake, the cargo tanks are not normally completely stripped empty and will have a remaining level of around 1%. Cargo Offtake takes place when at least 75% of the one million barrel (159,000m3) parcel is available. Variation in the weight of consumables, such as diesel and freshwater, stored at the aft end of the vessel, also affect the trim and to a lesser extent stability of the vessel. Changes to the weight of consumables is balanced by adjusting the weight and distribution of ballast. Tank loading valves are remotely controlled from the Central Control Room (CCR) with the tank levels monitored by the SAAB radar system. Tanks should normally be loaded with the production initially going to the reception tank and the oil then being distributed to the other tanks either by pumping or through a network of inter-tank sluice valves. Prior to each loading/unloading operation, a loading or unloading plan will be issued by the Marine Supervisor. The cargo oil tanks are provided with SAAB radar level gauges fitted to the main deck in the respective tanks. The analogue signals from the radar beams reflecting off the liquid within the cargo tanks are passed from the local instrumentation to the DCS and NAPA System in the control room. The cargo tanks are additionally provided with deck-mounted temperature transmitters. The temperature transmitters consist of three temperature probes of lengths corresponding to lower, middle and upper levels of each cargo tank. A pressure transmitter is incorporated within the SAAB unit, giving a read out of the pressure within the individual tanks. The temperature and pressure transmitter signals are linked with the radar ullage signals from each cargo tank and pass jointly back to the DCS System. It is essential that cargo loading and de-ballasting is accomplished in the correct sequence to maintain vessel stability and provide for acceptable bending moments and shear forces on the FPSO. The loading computer interfaces with the DCS to ensure that the cargo loading program or discharge program is monitored safely and will alarm if the actual operation differs significantly from the plan.

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In general, the cargo tanks will be loaded to a maximum 95% capacity but in exceptional circumstances this can be increased to 98%, in which case it must be carefully monitored.

3.2

Tank Level Gauging The cargo, slop, chemical and diesel tanks are provided with SAAB tank radar level gauge system as the ‘primary’ level sensing system. This integral system consists of radar level transmitter, IG pressure transmitter and three sets of temperature sensors for each tank (eg 26-LIT-002, 26-PT-001 and 26-TT-001-003 for COT 1P). These signals are interfaced to the DCS via a serial link and used for monitoring/alarming. The tank radar is an intrinsically safe system with a narrow beam parabolic antenna located on the tank top, which measures the ullage distance from the transmitter to the liquid surface. It is hardwired to the central Level Unit (LU), which is located in the CER and communicates via a serial interface connection to the DCS. The LU serial link transmits level, pressure and temperature data to the DCS, as well as the status of the equipment for alarm purposes. Using the SAAB radar transmitters, the level in the storage tanks is measured as ullage, which is the distance from the top of the tank to the top of the liquid measured in metres. All tank levels will be displayed in ullage on the tank monitoring screens. The same data is also to be used to display the level (0 to 100%) on the process screens. Level is the measured linear value as a percentage of the measured range ie 0 to 100%. The SAAB system provides a high level alarm when the tank level exceeds 95% and a low level alarm when the tank level falls below 5%. The Pt100 Temperature Detectors are installed in a stainless steel guide pipe. To provide accurate data, three separate temperature elements are installed per guide pipe. Each tank therefore has three temperature readouts: at the top (27.3m), middle (16.8m) and bottom (5.8m). All cargo and slop tank temperatures are displayed on the DCS. A pressure transmitter is fitted on the top of each cargo tank and both slop tanks to monitor the operating pressure of the tanks. All individual cargo and slop tank pressure readouts can be displayed on the DCS though normally the common system pressure only will be displayed. A Metritape liquid level sensor (eg 26-LZT-001 for COT 1P) is fitted, mounted in a tube with the termination on the top of the tank. The system uses a pressure sensitive tape that varies in resistance according to submerged length. The resistance signal provides a level indication which gives a high level alarm when the tank level exceeds 95% and a high-high level (safety) alarm when the tank level exceeds 98% of capacity. This system is totally independent of the radar gauges and is connected directly to the SSDS. Signals from the level transmitter are also fed to the load computer which calculates volume and makes corrections for list and trim.

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When the tank level reaches 98%, a high level alarm is initiated in the DCS and the tank loading valve will close to prevent further loading into the tank. The valve cannot be re-opened until the level is below 94%. Reception tank COT 3C is equipped with a Halla Oil/Water Interface Level Transmitter 26-LZT-037. This provides interface level indication and a high level alarm on the DCS to an accuracy of +/-0.5%.

Instrument Tag Number

Low Low Trip

Low Alarm

High Alarm

High High Trip

Controller Set Point

Cargo Tank No 1 Port 26-LIT-002

4%

96%

26-PT-001

-100mmwg

1200mmwg

26-LZT-001

95%

98%

Cargo Tank No 1 Centre 26-LIT-004

4%

96%

26-PT-002

-100mmwg

1200mmwg

26-LZT-003

95%

98%

Cargo Tank No 1 Starboard 26-LIT-006

4%

96%

26-PT-003

-100mmwg

1200mmwg

26-LZT-005

95%

98%

Cargo Tank No 2 Port 26-LIT-008

4%

96%

26-PT-004

-100mmwg

1200mmwg

26-LZT-007

95%

98%

Cargo Tank No 2 Centre 26-LIT-010

4%

96%

26-PT-005

-100mmwg

1200mmwg

26-LZT-009

95%

98%

Table 2.2 – Cargo Tank Alarm and Trip Settings

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Instrument Tag Number

Low Low Trip

Unrestricted

Low Alarm

High Alarm

High High Trip

Controller Set Point

Cargo Tank No 2 Starboard 26-LIT-012

4%

96%

26-PT-006

-100mmwg

1200mmwg

26-LZT-011

95%

98%

Cargo Tank No 3 Port 26-LIT-014

4%

96%

26-PT-007

-100mmwg

1200mmwg

26-LZT-013

95%

98%

Cargo Tank No 3 Centre 26-LIT-016

4%

96%

26-PT-008

-100mmwg

1200mmwg

26-LZT-015

95%

98%

Cargo Tank No 3 Starboard 26-LIT-018

4%

96%

26-PT-009

-100mmwg

1200mmwg

26-LZT-017

95%

98%

Cargo Tank No 4 Port 26-LIT-020

4%

96%

26-PT-010

-100mmwg

1200mmwg

26-LZT-019

95%

98%

Cargo Tank No 4 Centre 26-LIT-022

4%

96%

26-PT-011

-100mmwg

1200mmwg

26-LZT-021

95%

98%

Table 2.2 – Cargo Tank Alarm and Trip Settings (cont’d)

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Instrument Tag Number

Low Low Trip

Unrestricted

Low Alarm

High Alarm

High High Trip

Controller Set Point

Cargo Tank No 4 Starboard 26-LIT-024

4%

96%

26-PT-012

-100mmwg

1200mmwg

26-LZT-023

95%

98%

Cargo Tank No 5 Port 26-LIT-026

4%

96%

26-PT-013

-100mmwg

1200mmwg

26-LZT-025

95%

98%

Cargo Tank No 5 Centre 26-LIT-028

4%

96%

26-PT-014

-100mmwg

1200mmwg

26-LZT-027

95%

98%

Cargo Tank No 5 Starboard 26-LIT-030

4%

96%

26-PT-015

-100mmwg

1200mmwg

26-LZT-029

95%

98%

Table 2.2 – Cargo Tank Alarm and Trip Settings (cont’d)

3.3

NAPA Loading Computer Refer to P&ID BON/1DA2617/SAAB/000001 Load Computer. The ‘Onboard NAPA’ software allows loading and unloading plans to be developed by the Marine Supervisor. The plans detail the magnitude of liquid volumes and sequencing transfer to and from the tanks, eg loading from the topsides process and unloading to the offtake tanker with concurrent ballasting/de-ballasting as required. Onboard NAPA is run in two separate locations; on a standalone PC situated in the Marine Supervisor’s office and on an identical online PC located in the CCR. The NAPA software does not perform control functions and is only used for monitoring, alarm generation and reporting. The same software version is loaded in both PCs and in the event of failure of the CCR PC it can be replaced by the other one.

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Unrestricted

The loading and unloading plans are developed on the standalone copy of the software and transferred, by disk, to the DCS server mounted in the CCR engineering console. The ‘Onboard NAPA’ program in the CCR PC monitors the vessel draft, the levels, pressures and temperatures in the cargo, ballast, clean and dirty slops, methanol, chemical, diesel and freshwater storage tanks. The vessel dimensions, lightweight values and capacities of all of the tanks are built into the loading computer software. The software uses these values as inputs to a vessel model and calculates the various stability and stress values for the ship at all times. It is essential that the operator maintains each of these parameters within safe limits at all times. The ‘Onboard NAPA’ is a computerised version of the Class Approved Stability and Strength Manuals and is always consulted prior to moving cargo or ballast volumes. The ‘Onboard NAPA’ is frequently referred to during the execution of these operations to ensure that the operation is going to plan with respect to structural limitations and stability. The Trim and Stability Book provides calculation data and methodology for manual calculation of the data, which the loading computer provides. The booklet also contains a number of standard conditions, which Bonga FPSO will often load and must always be referred to in the event of non-availability of the loading computer. Although the same software configuration runs on both machines, the NAPA generated alarms from the online system in the CCR are displayed on the CCR PC only. The standalone PC in the Marine Supervisor’s office is updated every 30 minutes from the CCR PC. The measured tank level data is provided over a serial link from the SAAB tank gauging system; the SAAB unit also sends the tank level data to the DCS via a separate data link. Alarms generated within NAPA are routed via the SAAB unit to the DCS for annunciation and logging. Although tank level measurements are normally online inputs, it is possible to input tank levels manually in the event of a communication or equipment failure. For this purpose manual dips can be taken on deck through the closed hand dipping system using a portable tank gauging tape. The aft MMC 2in dipping point on each cargo tank is designated as the tank datum point, and all SAAB and Metritape readings are corrected to this datum. Values obtained in this way can then be entered manually into the load computer. Note: Prior to commencing the loading sequence, all crude oil loading and discharging operations must be fully simulated on the loading computer. A safe loading plan must be drawn up, agreed and fully understood by all personnel involved in loading operations. The cargo loading operation is carried out from the control room.

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3.3.1

Unrestricted

NAPA Operator Interface The NAPA PC located on the operator console in the CCR is the primary operator interface for the loading computer and allows access to all NAPA displays provided including the following: NAPA controls on the PC: •

Develop Loading Plan

•

Initiate Stability Calculations

•

Start Loading Plan Monitoring

•

Access Menus for Tank Loading, 3D model etc

Indication from NAPA on the PC: •

Load Tanks

•

Load Stores

•

Draft Survey

•

GM Required

•

Grade Database

The DCS replicates the displays used in the SAAB cargo monitoring system which includes: •

Tank ullage, corrected for trim and list

•

Tank temperatures, top, middle and bottom

•

Ship trim and list

The following NAPA vessel monitoring alarms are available: •

GM

•

Bending Moment

•

Shear Force

•

Trim

•

Mean Draft

Reports generated in the NAPA software package are available for printing on the report printer on the LAN. The following reports are available from the package: •

Tank Report

•

Stability Report

•

Longitudinal Strength Report

•

Cargo History Report

•

Tank Inspection Report

•

Damage Case Report

All displays provided with the NAPA package are available for viewing via the server interface to the DCS.

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3.4

Unrestricted

Cargo Loading Control Cargo from the topside process is normally loaded from 25-MOV-401 to the loading header through 26-ZCV-009 and 26-ZCV-018/020 into the reception tank COT 3C or through 26-ZCV-022 and 26-ZCV-027/029 to the alternate reception tank COT 5C. The cargo normally flows from the 3C reception tank out the overflow line at 70% tank level through 26-ZCV-101 to the required tanks through the cascade lines into 2C (via balancing Valves 26-ZCV-087/088) or 4C (via 26-ZCV-085/084). The path from the alternate reception tank 5C (when used) is out its overflow line at 70% tank level through 26-ZCV-102 to the required tanks through cascade lines into 5P via balancing valves 26-ZCV-103/104 or 5S via 26-ZCV-105/106. The hydraulically actuated valves are controlled from the DCS, where valve status is also displayed. During startup, valves in the loading header between topsides production facilities and the hull storage tanks must be aligned to provide an open flow path. Opening of routing valves such as the Main Inlet Header Valve 25-MOV-401 must be co-ordinated with the overall production startup procedure and control sequences. The operator must ensure that at least one valid combination of open valves to at least one cargo tank. When the loading operation is in progress, the Isolation Valve 25-MOV-401 between the Topsides Crude Coolers E-2540A/B/C and the loading header must be open. If the operator attempts to close this valve, a message ‘Closing this valve will shut down production’ will appear. The operator must confirm the action before the close command will be sent to the valve. The operation of the cargo tank balancing valves will be a manual operator action from the CCR, which will allow transfer of cargo between the tanks. There are no interlocks identified for these valves.

3.5

Cargo Transfer

3.5.1

Pump Operation The cargo pumps can be used to transfer from any tank directly into the transfer header, and then into any other tank, pigging system, slop system, crude oil washing and tank cleaning system. Operation of the pumps when used for cargo transfer is from the individual pump overlay on the DCS. Note: The tag numbers in the descriptions below are for cargo tank 1P. Refer to P&IDs for equivalent tags for other tanks. To start the pump from the individual pump overlay, after pressing the ‘Pump Start’ for P-2601C, the DCS will start the pump and set the pump speed to 5% through 54-SY-202. When the pump is confirmed running determined from the Discharge Line Pressure Transmitter 26-PIT-018 being greater than 0.5barg (initially setting configurable) the Pump Discharge Valve 26-ZCV-031 will be opened. If the pump fails to start the discharge valve will stay closed. Stopping the pump will close the discharge valve and ramp the pump speed down to 0% after a time period. When a pump has been selected to start from the overlay, the relevant discharge valve is put into ‘auto’ without prompting the operator for confirmation.

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3.5.2

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High Tank Level When the level in a tank, eg COT 1P 26-LIT-002, reaches 98%, a high level alarm is initiated in the DCS and the Tank Loading Valve 26-ZCV-011, will be closed by the application to prevent further loading into that tank. The valve cannot be reopened until the level falls below 94%. Note: A 2% hysteresis (configurable) is included to prevent cycling of the valve around the alarm set point. Cargo Oil Tank No

Cargo Pump Discharge Valve

Cargo Pump Discharge Pressure

Cargo Pump Speed Control

Inlet Valve Transfer/Load Line

1P

ZCV-031

PIT-018

SIC-202

ZCV-011

1C

ZCV-032

PIT-019

SIC-203

ZCV-012

1S

ZCV-033

PIT-020

SIC-204

ZCV-012

2P

ZCV-034

PIT-021

SIC-205

ZCV-015

2C

ZCV-035

PIT-022

SIC-206

ZCV-016

2S

ZCV-036

PIT-023

SIC-207

ZCV-017

3P

ZCV-037

PIT-024

SIC-208

ZCV-019

3C

ZCV-038

PIT-025

SIC-209

ZCV-020

3S

ZCV-039

PIT-026

SIC-210

ZCV-021

4P

ZCV-043

PIT-027

SIC-213

ZCV-024

4C

ZCV-044

PIT-028

SIC-214

ZCV-025

4S

ZCV-045

PIT-029

SIC-215

ZCV-026

5P

ZCV-046

PIT-030

SIC-216

ZCV-028

5C

ZCV-047

PIT-031

SIC-217

ZCV-029

5S

ZCV-049

PIT-032

SIC-218

ZCV-030

Table 2.3 – Associated Tag Numbers for COT

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3.6

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Operator Interface for Loading Operations The DCS HMI located in the CCR is the primary operator interface. Figures 2.2 and 2.3 at the end of this section illustrate cargo handling graphical interface screens. A list of operator controls and indicators is shown below: •

•

•

Control from the HMI −

Control and feedback setting of each pump hydraulic valve

−

Starting of pump (set output to 5%)

−

Stopping of pump (set output to 0%)

−

Open and close commands for each on/off valve

−

Position setting and indication for proportional control valves

−

Manual override facility

−

Activate synchronisation

−

Cascade control from topsides booster pumps suction (27-PIC-407)

Indication on the HMI −

Interlock status of each valve

−

Interlock status of each pump

−

Level indication of each cargo and slop tank

−

Valve position indication

−

Pump running indication

−

Discharge pressure (used as pump running indication) for each pump

−

Interface level in slop tanks and reception tank 3C

−

Indication of IGG clean and dirty header pressures

−

Indication of N2 header pressure

−

Transfer and discharge header pressure

Local Control (at the Framo Control Unit) −

Start and stop of the pumps by setting pump flow control valve to a position between 0 to 100%

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3.7

Unrestricted

Cargo Pump Interlocks Tag No/Pop-up Message

Function Description

P-2601A to O

Pumps will not start if any one of the following four interlocks are present.

Oil Transfer/ Discharge Valve Routing

The discharge or transfer header isolation valves relevant to the pump are closed, eg pumps P-2601A/B/C = 26-ZCV130 or 131 (refer to Part 1 Section 3 Table 3.2 for equivalent valves for other pumps).

Hydraulic HPU

All power packs are stopped (54-YS-201A to 209A), eg the pump HPU is not running.

Valve HPU

When both (54-YA-001 and 54-YA-002) are failed or any one of the common system alarm 54-YA-003 to 007 is present, eg the Valve HPU is not healthy.

Header Isolation Valves

26-SDV-122 to 125 are not closed.

Table 2.4 – Startup Interlocks (STIL) – Cargo Pumps P-2601A to O

Tag No/Pop-up Message

Function Description

54-YZC-101(1)

P-2601A to C – Pump trip immediately stops pumps (54-SY-202 to 204 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2601D to F – Pump trip immediately stops pumps (54-SY-205 to 207 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2601G to I – Pump trip immediately stops pumps (54-SY-208 to 210 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2601J to L – Pump trip immediately stops pumps (54-SY-213 to 215 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2601M to O – Pump trip immediately stops pumps (54-SY-216 to 218 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2603 – Pump trip immediately stops pumps (54-SY-219 output = 0%) and prevents pump from starting.

Table 2.5 – Process Interlocks for Cargo Pumps P-2601A to O

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Tag No/Pop-up Message

Unrestricted

Function Description

54-YZC-101(1)

P-2605B – Pump trip immediately stops pumps (54-SY-220 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2605A – Pump trip immediately stops pumps (54-SY-221 output = 0%) and prevents pump from starting.

54-YZC-101(1)

P-2602 – Pump trip immediately stops pumps (54-SY-222 output = 0%) and prevents pump from starting.

Notes: (1)

54-YZC-101 is the trip signal from the SSDS to the HPU to trip the hydraulic supply feeding the cargo/slop pumps, this signal will also be used to drive the pumps to 0%.

(2)

Low Low Pressure 55-PZLL-101 and 55-PZLL-102 on the CIGM and DIGM, respectively, trips the cargo, slop and skimming pumps and shuts the main oil export ESD Valve 26-SDV-121 (tandem offloading) and ESD Valves 27-SDV-454/464/474 (SPM offloading). During periods when the CIGM is not in use, the output from 55-PZT-101 should be inhibited from taking any executive action. Table 2.5 – Process Interlocks for Cargo Pumps P-2601A to O (cont’d)

4.0

SAFEGUARDING Protection against potential overfilling of the cargo oil tanks and slop tanks is provided by the high level alarm and trip signal from the Metritape system. The set points for all of the cargo and slop tank high level alarms is 95% and the trip signal is provided at 98% of the tank capacity. The activation of the high level alarm is annunciated in the DCS. The activation of the high level trip is annunciated in the DCS and initiates closure of the Tank Loading Valve (26-ZCV-011 for COT 1P) and stops the cargo oil pump being used in the case of cargo transfer. The loading valve cannot be re-opened until the level is below 94%. The transfer and discharge headers are shut in on an ESD. To ensure that pressure in the headers does not increase in this situation due to a heat source or fire in the vicinity of the lines, each header has a Fail Open Valve 26-SDV-122 and 26-SDV-123, for the transfer and discharge headers respectively located at the aft end of the headers. The valves drain the headers to either the reception tank COT 5C or the dirty slop tank. A similar arrangement is provided at the forward end of the headers with 26-SDV-124 and 26-SDV-125, for the transfer and discharge headers respectively. The valves drain the headers to either the COT 1P or COT 1S.

Part 1 Section 2 Detailed Description – Cargo Loading

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Shell Nigeria E&P Company Limited Bonga FPSO Plant Operating Procedures Manual Volume 4 – Oil Storage, Handling and Ballast Systems

Unclassified

(E2540_SD)

Crude Cooler

(Cargo_Str_SD) 25-MOV-401

5P TOPSIDES BOOSTER PUMPS (P2741ABC_SD)

S/P Mooring SPM Launcher XXX

5S

barg

SDV-121

P

(Cargo_Str_SD)

4P 028

029

27-P-371

PZT-039

(A0821ABC_SD)

5C

030

4C

024

(Cargo_Str_SD)

4S

025

3P

3C

3S (Cargo_Str_SD)

026 019

XXX

020

021

2P

2C

015

Stern O/L P

016

2S

(Cargo_Str_SD) 017

1P 011

XXX

1C

1S

012

Slops Tnks

013

(Slops_SD)

27-P-372 (Slops_SD) 056

Slop Tanks

115

LACT FISCAL METERING (LACT_UNIT_SD)

023

027

014

018

010

058

Hydraulic HPU

Hydraulic Valve HPU

Running/ Stopped

Running/ Stopped

Loading Header 022 (Slops_SD)

068

Dirty Slop

116

009

052

055

053 054

PIT-037 XXX

051 barg

Transfer Header

(V4640_SD)

057

126

Flare Scrbr 118

139

137

135

133

SDV-124

131

PIT-038 127

SDV-122

XXX

050

barg Discharge Header

SDV-123 138

136

134

132

130 (Cargo_Str_SD)

(COW_SD)

1P/1C/1S

COW &T/O Hdr SDV-125

(Cargo_Str_SD)

(SS_FL_HTNG_SD)

5P/5C/5S

Pigging

4P/4C/4S

129

3P/3C/3S

(COW_SD)

COW &T/O Hdr

2P/2C/2S 061

1P/1C/1S

128

Slop Tanks

(Slops_SD)

(Slops_SD)

Slop Tanks

Figure 2.1 – Graphical Interface – Cargo Headers Part 1 Section 2 Detailed Description – Cargo Loading OPRM-2003-0304

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Unclassified

Pick box to Cargo_Hdr_SD

(5P) T-2601O LZT-025

Dirty IGG Header XXX

barg

XXX

55-PIT-104

XXX%

XXX

XXX%

PIT-027

barg

XXX

XXX

barg

LIT-008

LZT-007

XXX%

PIT-024

(1P) T-2601C

(2P) T-2601F

LIT-014

LZT-013

LIT-020

PIT-021

barg

XXX

LIT-002

LZT-001

XXX%

XXX%

PIT-018

barg

XXX

barg

barg

55-PIT-103

046

043

N 2 Header XXX

LIT-026

PIT-030

Clean IGG Header

(3P)T-2601I

(4P) T-2601L LZT-019

P-2601O

xxx

54-SIC-216

barg

037

xxx

54-SIC-213

031

034

P-2601I

P-2601L

P-2601C

P-2601F

xxx

54-SIC-208

54-SIC-205

xxx

54-SIC-202

xxx

55-PIT-001 Hydraulic HPU

Running/ Stopped

104

Hydraulic Valve HPU

077

092 095

Running/ Stopped

082

096

080

083

091

103

081

070

071

076

(3C) T-2601H

(5C) T-2601N LZT-027

(Slops_SD)

(4C) T-2601K

LIT-028

XXX%

Slop Tanks 042

XXX

barg

XXX

047

048

041

PIT-025

040

XXX

xxx 54-SIC-217

54-SIC-214

107

105

038

xxx

035

70% 101

xxx

54-SIC-203

072

088

085

0% 087

093

xxx

073

078

098

LIT-030

LIT-024

LZT-023

XXX%

LIT-018

LZT-017

XXX%

PIT-032

barg

XXX

barg

XXX

045

049

P-2601M

xxx

54-SIC-215

100

XXX

barg

54-SIC-210

089

090

barg

XXX

54-SIC-207

119

120

barg

033

P-2601E

xxx

XXX%

PIT-020

036

P-2601G

xxx

LIT-006

LZT-005

XXX%

PIT-023

039

P-2601J

LIT-012

LZT-011

XXX%

PIT-026

PIT-029

(1S) T-2601A

(2S) T-2601E

(3S) T-2601G

(4S) T-2601J

(5S) T-2601M

099

P-2601B

079 084

106

54-SIC-218

barg

032

54-SIC-206

086

XXX

XXX

xxx 54-SIC-209

0%

LZT-029

barg

P-2601D

094

097

PIT-019

barg P-2601H

P-2601K

XXX%

XXX%

PIT-022

XXX

LIT-004

LZT-003

LIT-010

LZT-009

Slops

barg

(1C) T-2601B

(2C) T-2601D

(Slops_SD)

044

70% 102

XXX%

XXX%

PIT-028

P-2601N

LIT-016

LIT-022

LZT-021

PIT-031

LZT-015

LZT-037

P-2601A

xxx

54-SIC-204

074

xxx

075

Figure 2.2 – Graphical Interface – Cargo Storage Part 1 Section 2 Detailed Description – Cargo Loading OPRM-2003-0304

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Unclassified

NAPA LOAD COM PUTER #1

SAAB PRIM ARY

PRIM ARY

PRIM ARY

SAAB W ORK STATION

NAPA LOAD COM PUTER #2

SAAB PRIM ARY Note 3

BACK-UP

CARGO

CHEM ICAL M ETHANOL

DIESEL

SLOP

FRESH W ATER

BALLAST

DRAFT SENSORS (4)

DCS (LOAD COM PUTER SOFTW ARE)

Note 2

PRIM ARY

SSDS 15 TANKS

2 TANKS

2 TANKS

4 TANKS

4 TANKS

14 TANKS

Note 1

BACK-UP

BACK-UP

BACK-UP

BACK-UP

PRIM ARY

PRIM ARY

M ETRITAPE API-14C TANKS

NON-API-14C TANKS & DRAFT

PRIMARY SYSTEM - SAAB

PRIMARY SYSTEM - METRITAPE (VIA SAAB)

BACK-UP SYSTEM METRITAPE

BACK-UP SYSTEM - DREXEL BROOKS NOTE THAT METRITAPE SIGNALS TO SAAB VIA SERIAL LINK ARE "CORRECTED" SIGNALS.

Notes 1) The hardwired signals between the Metritape Vangaurd system & SSDS are the back-up signals from the Cargo/Slops/Diesel/Chem ical tanks. 2) The serial signals between the Metritape Vangaurd system & SAAB are the prim ary signals from the Draft Readings/Fresh W ater/ Ballast tanks. 3) Drexel Brooks (4-20MA)

M ETRITAPE VANGUARD

RS-485 Modbus RTU RS-232 SAAB Protocol Hard W ired

Figure 2.3 – Hull Tanks – Level System Schematic

Part 1 Section 2 Detailed Description – Cargo Loading OPRM-2003-0304

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Unrestricted

Part 1 Technical Description Section 3 Detailed Description – Ballast System

Table of Contents 1.0

INTRODUCTION............................................................................................................. 3

2.0

EQUIPMENT DETAILS .................................................................................................. 3

3.0

4.0

2.1

Ballast Tanks ....................................................................................................... 3

2.2

Ballast Pumps P-5804A to D ............................................................................... 6

2.3

Ballast Valves ...................................................................................................... 7

CONTROL AND INSTRUMENTATION.......................................................................... 8 3.1

General................................................................................................................ 8

3.2

Ballast Tank Gauging .......................................................................................... 8

3.3

Ballast System Controls .................................................................................... 10

3.4

De-ballasting...................................................................................................... 13

3.5

Ballasting ........................................................................................................... 15

3.6

Ballast Line Surge Protection ............................................................................ 16

3.7

Manual Override ................................................................................................ 17

3.8

Header Isolation Valves..................................................................................... 17

3.9

Ballast Pump Discharge Valves ........................................................................ 18

3.10

Hydraulic System Capacity................................................................................ 18

3.11

Tank Cleaning/Transfer Main ............................................................................ 18

3.12

Interlocks ........................................................................................................... 19

3.13

Logic Conditions ................................................................................................ 22

SAFEGUARDING ......................................................................................................... 23

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Table of Contents (cont’d) TABLES Table 3.1 – Ballast Tank Details............................................................................................... 5 Table 3.2 – Ballast Water Tank Alarm and Trip Settings ......................................................... 9 Table 3.3 – Ballast Water Pump Alarm and Trip Settings ...................................................... 12 Table 3.4 – Tag Nos for Ballast Pump Valves and Instrumentation....................................... 14 Table 3.5 – Ballast Water Header Alarm and Trip Settings.................................................... 17 Table 3.6 – Common Start Interlocks for Ballast Pumps (P-5804A/B/C/D)............................ 20 Table 3.7 – Start-up Interlocks – Ballasting or De-ballasting (P-5804A and B)...................... 20 Table 3.8 – Start-up Interlocks – Ballasting or De-ballasting (P-5804C and D) ..................... 21 Table 3.9 – Start-up Interlocks – Tank Cleaning (P-5804C and D)........................................ 21 Table 3.10 – Process Shutdown Logic................................................................................... 22 Table 3.11 – Header Flooding Logic ...................................................................................... 22 Table 3.12 – Abnormal Conditions Logic ............................................................................... 22 FIGURES Figure 3.1 – Graphical Interface – Ballast Facilities ............................................................... 24

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1.0

Unrestricted

INTRODUCTION The Ballast System provides the distribution of seawater ballast throughout the FPSO, under varying load conditions. To comply with IMO requirements the segregated seawater Ballast System is completely separate from the Crude Oil Storage System. The stress and bending moments applied to the vessel hull and the FPSO trim are affected by cargo oil loading, offloading, bunkering, fuel oil transfer and consumption. The Ballast System consists of a ring main, hydraulically driven pumps and tank isolation valves. Vessel ballast level is remotely controlled from the PSCS operator workstations located in the CCR. Operation/control can also be achieved from the Framo control panel located in the valve cabinet room in ‘A’ deck of the accommodation. The Loadmaster Computer is used to simulate changing loading conditions and predict ballast requirements. Refer to P&IDs: •

BON-SHI-008-P-00002-001 Ballast System (1/3)

•

BON-SHI-008-P-00002-002 Ballast System (2/3)

•

BON-SHI-008-P-00002-003 Ballast System (3/3)

•

BON-SHI-008-P-00002-004 Air and Sounding System (1/2)

2.0

EQUIPMENT DETAILS

2.1

Ballast Tanks Refer to Figure 1.2 and P&ID BON-SHI-008-P-00002-001/2/3 Ballast System. Equipment Details The Ballast Wing Tanks are located along the outside of the Crude Oil Tanks thus affording some collision damage protection for the containment of the hazardous crude cargo. Six tanks down each flank of the vessel store varying volumes of ballast to help maintain the trim, list and stress condition of the vessel. In addition, there are two ballast tanks located at the forward and aft ends of the vessel, which are the Fore and Aft Peak Tanks. The peaks are used as normal ballast tanks, holding various quantities of water at different stages of the loading and unloading sequences. Submerged Ballast Pumps are located in the Water Ballast Tanks No 4 Port and Starboard. Each group of six ballast tanks, either port or starboard, has a ballast main running through them fore to aft which can draw suction from all six tanks in the group. The fore and aft peak tanks are served by both port and starboard ballast mains. The piping system allows ballast water to be pumped or flowed by gravity into the tanks. The ballast mains are interconnected in the forepeak tank, which will also allow the pumps on one side of the vessel to pump via the ‘ring main’ from/into a tank on the opposite side of the vessel. The internals of all ballast tanks are fully coated with tar-free epoxy paint and fitted with cathodic protection based on the bottom 3m of the tank being submerged 100% of the time and the remainder of the tank being submerged 70% of the time. To minimise corrosion, all ballast piping located in the ballast wing tanks is manufactured from reinforced glass-fibre piping, except for the tank penetration pieces.

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In order to control trim, list and stability, it is necessary to discharge and refill the ballast tanks with seawater as the quantity of cargo changes. Before the start of oil production and after each shuttle tanker offloading, the water ballast tanks will normally contain water and will be discharged (de-ballasted) as the cargo tanks are gradually filled. Ballast is taken onboard again during the offloading operation. Ballast Wing Tanks 4S and 4P each contain two ballast pumps which are used to move ballast around the system via the ballast mains. The ballast system is used to supply water to the suction of the tank cleaning pump when water washing of tanks is required. The system can also supply water into the transfer main if water is required to put into the cargo or slop tanks. The port side and starboard side ballast system has an emergency inert gas connection, from the clean inert gas main for filling the ballast mains and any damaged tanks with inert gas. The above three connections have removable spool pieces that are normally only fitted when required and removed after use. All normal ballasting and de-ballasting operations can be carried out from the DCS, using the remotely operated hydraulic valves. Seawater level in the ballast tank is measured using a metritape type system as primary and RF capacitive probes system as backup. Level transmitters provide level signals to the DCS and loading computer, and are equipped with high level alarm set at 95% volume and a trip set at 98% volume. Activation of either alarm is annunciated on the DCS. Deck standpipes are provided for manual tank soundings to be obtained using the portable tank gauging tape in the event of failure of the metritape type and RF capacitive probes system. Any pressure buildup in the tank is vented to atmosphere via four sets of ball float vent valves.

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Ballast Tank

Valves

Capacity

Fore Peak WBST T-5801A

58-ZCV-139 Main 58-ZCV-140 Main 58-ZVC-141 Port Crossover 58-ZVC-142 Stbd Crossover 58-ZCV-151 Ballast Main Vent Valve

28699.6

No 1 WB Tank Port T-5801B

58-ZCV-115 Main 58-ZCV-116 Stripping

6905.5

No 1 WB Tank Starboard T-5801C

58-ZCV-117 Main 58-ZCV-118 Stripping

6905.5

No 2 WB Tank Port T-5801D

58-ZCV-119 Main 58-ZCV-120 Stripping

7767.6

No 2 WB Tank Starboard T-5801E

58-ZCV-121 Main 58-ZCV-122 Stripping

7767.6

No 3 WB Tank Port T-5801F

58-ZCV-123 Main 58-ZCV-124 Stripping

17107.4

No 3 WB Tank Starboard T-5801G

58-ZCV-125 Main 58-ZCV-126 Stripping

17107.4

No 4 WB Tank Port T-5801H

58-ZCV-127 Main 58-ZCV-128 Stripping 58-ZVC-147 Port Main Isolation 58-ZVC-101 Sea Chest Valve 58-ZVC-102, 105 Sea Chest to Pump Suct 58-ZVC-103, 106 Pump Suction 58-ZVC-104, 107 Discharge to Main 58-ZVC-145 Pump Disch Overboard 58-ZCV-149 Discharge to Main

7761.4

No 4 WB Tank Starboard T-5801J

58-ZCV-129 Main 58-ZCV-130 Stripping 58-ZVC-148 Stbd Main Isolation 58-ZVC-108 Sea Chest Valve 58-ZVC-109, 112 Sea Chest to Pump Suct 58-ZVC-110, 113 Pump Suction to Main 58-ZVC-111, 114 Discharge 58-ZVC-146 Pump Disch Overboard 58-ZCV-150 Discharge to Main

7761.4

No 5 WB Tank Port T-5801K

58-ZCV-131 Main 58-ZCV-132 Stripping

7735.3

No 5 WB Tank Starboard T-5801L

58-ZCV-133 Main 58-ZCV-134 Stripping

7735.3

No 6 WB Tank Port T-5801M

58-ZCV-135 Main 58-ZCV-136 Stripping

2428.5

Table 3.1 – Ballast Tank Details

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Ballast Tank

Valves

Capacity

No 6 WB Tank Starboard T-5801N

58-ZCV-137 Main 58-ZCV-138 Stripping

2428.5

Aft Peak Tank T-5801P

58-ZCV-143 Main 58-ZCV-144 Main

9891.8

Note: The atmosphere of all Ballast Tanks is automatically sampled by the Omnicron sampling system to detect hydrocarbon gas. This gives an indication of oil contamination of the ballast system. Table 3.1 – Ballast Tank Details (cont’d)

2.2

Ballast Pumps P-5804A to D Equipment Detail Type:

SB600

Capacity:

2000m3/hr

Discharge Pressure:

3bar(g) (Differential)

Head/Specific Gravity:

30m at rated speed/1.025

Motor:

Hydraulic high-pressure motor

Tank Depth/Pump Length:

Approximately 32/31.639m

Pump housing Material:

Stainless Steel AISI 316

Pump shaft Material:

Mild Steel (protected from seawater)

Material Impeller:

Seawater-resistant Bronze

Material Cofferdam Pipe Stack:

Stainless Steel AISI 316 Mechanical Type

Equipment Description Refer to Figure 1.2 and P&IDs BON-SHI-008-P-00002-002 Ballast System and BON/1JA0980/FRANK/000003 Ballast Pump. Seawater for ballasting is taken onboard the FPSO via the Port and Starboard sea chests. Both independent sea chests are manually treated with sodium hypochlorite from Steel Drum Tank T-5804A/B located on the main deck port and starboard, for the control of marine growth. Refer to POPM Volume 21 Seawater System (OPRM-2003-0321) for details of the sodium hypochlorite system. Port and Starboard Ballast Lines are used to distribute the ballast water to the six sets of Wing Ballast Tanks, the Aft and Fore Peak Tanks. The vertically mounted centrifugal water Ballast Pumps P-5804A/B/C/D are submerged pumps located in No 4 Starboard (P-5804C/D) and No 4 Port (P-5804A/B) Ballast Tanks. The Ballast Pumps are self-priming pumps driven by hydraulic motors in the Ballast Tank. Downstream of the suction valves, an inline filter, P-5804A/B/C/D-S-01 is fitted on the pump suction line to remove any extraneous material from the seawater passing to the pump suction.

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All submerged pump controllers are calibrated from a minimum output where the hydraulic supply pressure to the pump motor is 0bar(g) to a maximum output of 260bar(g). In practice the submerged Ballast Pumps are never operated with the hydraulic supply pressure for the pump motor set below 60barg. If the ballast pumps are controlled from the DCS System, the set point from the DCS Console is used by the PLC logic incorporated in the Framo Control Panel to adjust the hydraulic supply to the pump motor. To ensure a smooth start-up of the ballast pumps, the set point is limited to 60barg for 45 seconds. When this time period has elapsed, the hydraulic supply pressure will increase to match the required set point. A manually operated flow control valve is provided for the hydraulic supply to the submerged pump motor. The valve is mounted on the top-plate of the ballast pumps. The flow control valve is always set to the fully closed position of the ballast pumps and controlled from the DCS Console. During ballasting operations, the ballast pumps are normally operated from the DCS Console but during an emergency the pumps can be operated locally at the Framo Control Panel. Pressure transmitters are installed on the pump suction line either side of the inline filters to warn of impending filter blockage. The readings from the pressure sensors are processed by the DCS and a high Differential Pressure alarm given at 1bar. Seawater is passed from/to the discharge lines of the Ballast Water Pumps at up to 5.0barg during Ballasting/De-ballasting Operations.

2.3

Ballast Valves The Ballast Main, and dedicated lines to/from the ballast tanks, ensures that seawater may be passed into any of the Ballast Tanks for ballasting, or pumped overboard during de-ballasting operations. A crossover line installed in the Fore Peak Water Ballast Tank enables the port and starboard mains to be made common. The crossover line is fitted with the Isolation Valves 58-ZVC-141 and 58-ZVC-142, which are normally in the closed position. All wing ballast tanks are fitted with one 20in main suction and one 10in stripping suction valve. The Fore and Aft peak tanks each have two 20in main suctions. With the exception of Nos 5 and 6 port and starboard, all suction valves are located in tanks adjacent to the ones they serve. This is in order to enable access to the valves for maintenance in the event of failure with ballast in the tank, when the adjacent tank can be emptied to allow access to the valve. All the valves used in normal ballasting operations can be remotely operated from the CCR through the DCS and, if necessary, operated manually by portable hydraulic hand pumps or remotely at the solenoid valve cabinets in the valve control cabinets on ‘A’ deck. The valves are of the butterfly type (rubber lined) with rotary hydraulic actuators mounted directly on the valve bodies, with position feedback through flowmeters in the individual hydraulic lines. All remote valves are potentially submerged in the ballast tanks.

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3.0

CONTROL AND INSTRUMENTATION

3.1

General The ballast adjustment requirements for Bonga FPSO is determined by the Marine Supervisor when developing the loading or discharging plans. These plans are developed on the loading computer using the levels on the 15 Cargo Oil Tanks from the Saab radar-based Cargo Monitoring System and the level in the ballast water tanks measured by the Metritape level monitoring system.

3.2

Ballast Tank Gauging Refer to Figure 3.1 and P&IDs BON/1DA2177/SAAB/000002 COT Level Gauging System and BON/1DA2160/CONSILIUM/000001 Remote Sounding System (Ballast FO). The 14 ballast tanks are provided with the Metritape Vanguard system as the primary sensor. These are connected through a serial link to the Saab system, which provides level and draft correction, and then by serial link from Saab to the DCS to provide all Metritape data to DCS. All tank levels are displayed in ullage (the distance from the bottom of the tank to the top of the liquid in metres) on the tank monitoring screens. The same data will also be used to display the level (0 to 100%) on the process screens. The level is the measured linear value as a percentage of the measured range, ie 0 to100%. The ballast tanks are provided with RF capacitance type Drexell Brooks transmitters. These transmitters are back-up sensors for the primary Metritape sensors and provide the high level alarms independently of the Metritape. They are directly wired to SSDS. The Aft Peak Tank is provided with DP type Rosemount level transmitter as a back-up to the primary Metritape sensor to provide an independent high level alarm and for the SSDS.

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Instrument Tag Number

Unrestricted

Low Low Trip

Low Alarm

High Alarm

High High Trip

Controller Set Point

Fore Peak Ballast Tank 58-LT-125

0.1m

0.2m

31.5m (sounding)

32.5m

58-LZT-126

98% Ballast Wing Tank No 1 Port

58-LT-101

0.1m

0.2m

30.61m

31.58m

58-LZT-102

98% Ballast Wing Tank No 1 Starboard

58-LT-103

0.1m

0.2m

30.61m

31.58m

58-LZT-104

98% Ballast Wing Tank No 2 Port

58-LT-105

0.1m

0.2m

30.61m

31.58m

58-LZT-106

98% Ballast Wing Tank No 2 Starboard

58-LT-107

0.1m

0.2m

30.61m

31.58m

58-LZT-108

98% Ballast Wing Tank No 3 Port

58-LT-109

0.1m

0.2m

31.5m

32.5m

58-LZT-110

98% Ballast Wing Tank No 3 Starboard

58-LT-111

0.1m

0.2m

31.5m

32.5m

58-LZT-112

98% Ballast Wing Tank No 4 Port

58-LT-113

0.1m

0.2m

30.61m

31.58m

58-LZT-114

98% Ballast Wing Tank No 4 Starboard

58-LT-115

0.1m

0.2m

58-LZT-116

30.61m

31.58m 98%

Table 3.2 – Ballast Water Tank Alarm and Trip Settings

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Instrument Tag Number

Unrestricted

Low Low Trip

Low Alarm

High Alarm

High High Trip

Controller Set Point

Ballast Wing Tank No 5 Port 58-LT-117

0.1m

0.2m

30.61m

31.58m

58-LZT-118

98% Ballast Wing Tank No 5 Starboard

58-LT-119

0.1m

0.2m

30.61m

31.58m

58-LZT-120

98% Ballast Wing Tank No 6 Port

58-LT-121

0.1m

0.2m

30.61m

31.58m

58-LZT-122

98% Ballast Wing Tank No 6 Starboard

58-LT-123

0.1m

0.2m

30.61m

58-LZT-124

31.58m 98%

Aft Peak Water Ballast Tank 58-LT-127

0.1m

0.2m

58-LZT-128

22.64m

23.35m 98%

Table 3.2 – Ballast Water Tank Alarm and Trip Settings (cont’d)

3.3

Ballast System Controls

3.3.1

Primary Operation The DCS Human Machine Interface (HMI) is the operator’s primary means of operation for the ballast pumps and valves. It is used to send speed control commands to the pumps and open/close signals to the valves, as well as monitoring the level in the ballast tanks and main header lines. The HMI also displays the current status of each pump and valve, ie running/stopped or open/closed, alarms are reported in the CCR if feedback status does not match the selected state of the pump or valve. Open and closed position limit switches are used on all valves except the proportional control valves, which have position transmitters to indicate 0 to 100%. Each ballast pump has a dedicated hydraulic control valve, which dictates the speed of the pump and can be set from the CCR. Under normal operation, main line isolation valves ZCV-141/142 will be closed so that pumps P-5804A/B supply the port/aft/forward ballast tanks and pumps P-5804C/D supply the starboard/aft/forward tanks, thus giving two separate ballast systems one for each side of the vessel. However, if the ballast pipework is damaged or maintenance is being carried out then these valves can be opened allowing the port and starboard tanks to be supplied from any of the pumps.

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A degree of semi-automation is provided to assist the operator in some of the routine tasks associated with ballasting, de-ballasting and flooding. A sequence overlay is provided to allow selection of ballasting/de-ballasting operation and to select the pump for this duty. The operator manually selects and opens the ballast tanks and routing valves from the CCR in advance of initiating this sequence. A sequence to aid the flooding (surge protection) of the header is also provided. Note: The application will not allow simultaneous selection of ballasting/ de-ballasting. There is no automatic control when loading or unloading the ballast tanks, however, information is provided by the loading computer regarding the ship’s current and predicted hull stresses, trim and list. To enable the ballast system to operate, the pump HPU and valve HPU must be started and available for operation. Once these have been confirmed, the operation will depend on whether the tanks are being emptied (de-ballasting) or filled (ballasting). For each wing ballast tank there are two isolation valves, the 20in main valve and the 10in stripping valve. Under normal operation the main valves will only be used. This main line will allow lowering of the level in the ballast tank to a minimum value. The stripping valves are only used when the tank has to be emptied as much as possible, ie during tank entry for inspection/maintenance. The smaller stripping line reduces the available flowrate from the tank and allows better internal draining before the pump starts to draw air and thus loses suction. The Fore Peak and Aft Peak Tanks have 20in main valves from the port and starboard section of the ballast header and do not have the 10in stripping valves. If the HPU is in local control, through 54-YS-214, all of the pump starts are ‘greyed out’ on the display. The ballast pumps will not overpressure the discharge pipework, but excess pressure indicates a flow problem. 3.3.2

Operator Interface The HMI located in the CCR is the primary operator interface. The operator controls and indicators are as follows: •

Control from the DCS HMI

•

Control and feedback setting of each pump hydraulic valve (to start/stop pump)

•

Open and close commands for each on/off valve

•

Position setting and indication for proportional control valves

•

De-ballast button

•

Ballast button

•

Flooding button

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•

Pump sequence start button (1 for each pump)

•

Manual override button (available at Operator Access Level 3 (OAL3) only)

Indications on the DCS HMI:

3.3.3

•

Interlock status of each valve

•

Interlock status of each pump

•

Level indication for each ballast tank

•

Liquid indication in ballast lines

•

Valve position indication

•

Pump running indication

•

Suction strainer differential pressure

•

Suction and discharge pressure for each pump (discharge pressure is used as pump running indication)

Local Pump Control (at the Framo Control Unit) Local operation of the ballast pumps is not envisaged. However, these pumps can be operated from the Framo Control panel located in the Hydraulic Power Unit room, and the respective suction/discharge valves can be operated from the Nakakita Solenoid valve cabinet. Start, Stop and Speed Control of the pumps can be performed by setting the pump motor hydraulic fluid flow control valve to a position between 0 to 300barg. If the pumps are operated from the Framo Control panel, they must be stopped before the unit is switched to ‘local’ control.

Instrument Tag Number

Low Low Trip

Low Alarm

High Alarm

High High Trip

Controller Set Point

Ballast Pump P-5804A 58-PT-102

0.5barg

58-PT-103

6.8barg

58-PT-101/102

1barg Ballast Pump P-5804B

58-PT-105

0.5barg

58-PT-106

6.8barg

58-PT-104/105

1barg

Table 3.3 – Ballast Water Pump Alarm and Trip Settings

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Instrument Tag Number

Low Low Trip

Unrestricted

Low Alarm

High Alarm

High High Trip

Controller Set Point

Ballast Pump P-5804C 58-PT-108

0.5barg

58-PT-109

6.8barg

58-PT-107/108

1barg Ballast Pump P-5804D

58-PT-111

0.5barg

58-PT-112

6.8barg

58-PT-110/111

1barg

Table 3.3 – Ballast Water Pump Alarm and Trip Settings (cont’d)

3.4

De-ballasting The de-ballasting operation can be activated either by pumping or gravity and in many cases will be a combination of the two. The operator chooses to carry out a semi-automated operation by selecting the ‘De-ballasting’ button and then a ‘Pump Sequence’ button. Manual operation is chosen by selecting the ‘Manual Override’ button, which is only selectable at OAL3, opening the associated isolation valves and starting the pump from the relevant overlay. The tag numbers referred to in this description are for Ballast Pump P-5804A, refer to Table 3.1 for the equivalent tag numbers for the other pumps. To allow the pump to start, either the main or stripping valves for at least one tank associated with that set of pumps and an overboard discharge valve must be open to remove the interlocks. If all the interlocks are not met, the letter ‘I’ will be displayed next to the pump on the display and the valve routing should be checked by the operator. The pump cannot be started and the Start button on the overlay and Pump Sequence button will be greyed out. When the De-ballasting button is pressed and the Pump Sequence button is selected for the pump, the associated valves 58-ZCV-103/104/145, will be opened and the pump will be automatically started and run up to 5% (configurable). The overboard discharge valve 58-ZCV-145 associated with the set of pumps will be confirmed open and the sea chest valve 58-ZCV-101 will be confirmed closed by the application before starting the pump. Once the pump is confirmed to be operating from the discharge line pressure transmitter 58-PIT-103 greater than 0.5barg (configurable), the discharge valve 58-ZCV-104 will be opened to 5% (configurable). The valve may be opened further from the valve overlay as required to meet the demand. The pump speed can be changed from the pump overlay. The DCS sends an analogue output to the pump hydraulic valve located in the Cargo HPU control panel, feedback to the DCS confirms that the pump speed has changed to the new setting through 58-SI-211.

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When the pump output is set to 5% by 54-SY-211 and the required discharge pressure (58-PIT-103) is not achieved after a preset time delay (initially 5 seconds (configurable)), an alarm is raised ‘Pump Failed to Start’, the associated valves (58-ZCV-103/145/104) will be closed and the pump output will be driven to 0%. This alarm will only be raised when the pump is started using the Pump Sequence button and not when the Manual Override is selected. When the pumps are stopped from the display overlay, the starting sequence is reversed, stopping the pumps and then closing the isolation valves 58-ZCV-103/104/145. If the sequence is manually overridden and the pump is stopped, the valves shall remain in the open position until they are selected closed by the operator. If the pump fails to stop, the valves will still be closed and an alarm raised. The output of the pump is a combination of the hydraulic set point and the position of the discharge valve (58-ZCV-104). A discrepancy alarm is generated if the difference between the pump position output and feedback (54-SY-211 and 54-SI-211) is greater than ±5% (configurable). This alarm is inhibited if the HPU is in local control. Note: The hydraulic supply transmitter is ranged 0 to 253barg and the return is ranged 0 to 300barg. To allow a meaningful display, a 0 to 100% scale is used. To prevent unnecessary discrepancy alarms, the output display is 0 to 253 = 0 to 100% and the feedback display is 0 to 300 = 0 to 119%. Normal operation of the pumps will be from the CCR, if the pumps are operated from the local control panel located in the valve equipment room, the pumps must first be stopped before the unit is switched to ‘Local’ control.

P-5804A

P-5804B

P-5804C

P-5804D

58-ZCV-103

58-ZCV-106

58-ZCV-110

58-ZCV-113

54-SY-211

54-SY-212

54-SY-223

54-SY-224

54-SI-211

54-SI-212

54-SI-223

54-SI-224

58-PIT-103

58-PIT-106

58-PIT-109

58-PIT-112

58-ZCV-104

58-ZCV-107

58-ZCV-111

58-ZCV-114

58-ZCV-145

58-ZCV-145

58-ZCV-146

58-ZCV-146

58-ZCV-101

58-ZCV-101

58-ZCV-108

58-ZCV-108

58-ZCV-102

58-ZCV-105

58-ZCV-109

58-ZCV-112

Table 3.4 – Tag Nos for Ballast Pump Valves and Instrumentation

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3.5

Unrestricted

Ballasting The ballasting operation can be activated either by pumping or gravity and in many cases will be a combination of the two. The operator will choose to carry out a semi-automated operation by selecting the Ballasting button and then a Pump Sequence button. Manual operation is chosen by selecting the Manual Override button (selectable only at OAL3) then opening the associated isolation valves and starting the pump from the relevant overlay. The tag numbers referred to in this description are for Ballast Pump P-5804A. Refer to Table 3.1 for the equivalent tag numbers for the other pumps. To allow the pump to start, either the main or stripping valve for at least one tank associated with that set of pumps and the sea chest valve must also be open. If all of the interlocks are not met, the letter ‘I’ will be displayed next to the pump on the display and the valve routing checked by the operator. The pump cannot be started and the Start button on the display overlay and Pump Sequence button will be ‘greyed out’. When the Ballasting button is pressed and the Pump Sequence button is selected for a pump, the associated valves 58-ZCV-101/102/149 will be opened and the pump will be automatically started and run up to 5% (54-SY-211 will be set to 5% (configurable)). The overboard discharge valve associated with the set of pumps will be confirmed closed 58-ZCV-145 and the sea chest valve 58-ZCV-101 shall be confirmed open by the logic before the pump is started. Once it is confirmed that the pump is operating, from the discharge line pressure transmitter 58-PIT-103 being greater than 0.5barg (configurable), the discharge valve 58-ZCV-104 will be opened to 5% (configurable). The valve may be opened further from the valve overlay as required. When the output is set to 5% (54-SY-211) and the discharge pressure 58-PIT-103 does not reach the required pressure after a preset time of 5 seconds (configurable) an alarm is raised ‘Pump Failed to Start’, and the associated valves 58-ZCV-101/102/149 will be closed and the pump will be stopped by driving the output to 0%. This alarm will only be raised when the pump is started using a Pump Sequence button and not when the Manual Override is selected. When the pumps are stopped from the display overlay, the starting sequence is reversed, stopping the pumps and then closing the isolation valves 58-ZCV-101/102/104/149. If the pump fails to stop, the valves will still be closed and an alarm raised. If the sequence is manually overridden and the pump is stopped, the valves will remain in the open position until they are closed by the operator. Once the pump has been started, the speed can be changed from the display overlay. The DCS sends a signal to the pump hydraulic valve located in the Cargo HPU control panel and feedback is provided to the DCS by 58-SI-211 to confirm that the pump speed has moved to the new setting.

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A discrepancy alarm is generated if the difference between the required and actual pump speed (54-SY-211 and 54-SI-211) is greater than ±5% (configurable). This alarm is inhibited if the HPU is in local control. Normal operation of the pumps is from the DCS in the CCR, if the pumps are to be operated from the local control panel located in the valve equipment room, the pumps must first be stopped before the unit is switched to ‘Local’ control.

3.6

Ballast Line Surge Protection Both the port and starboard ballast lines are fitted with capacitance level probes 58-LZT-133/34/35/36 near the forward and aft ends of the lines. These are to provide an indication if the ballast line, in its vicinity of the sensor, is flooded. On sensing a non-flooded condition, eg pipe less than 90% full, an alarm in the DCS is raised on any of the sensors. If any ballast pumps are running, identified by 58-PIT-103 output being greater than 0.5bar and the lines are not flooded, the stopping of the pumps and closing of the tank isolation valves 58-ZCV-115 to 140 and 143/144 is delayed for 10 seconds (configurable). The logic also prevents the opening of any further valves, with the exception of 58-ZCV-101/108, 58-ZCV-102/112 (limited to 5% open), 58-ZCV-103/113, 58-ZCV-147/148, 58-ZCV-141/142 and 58-ZCV-151, and also prevents pumps from starting until the condition is reset. This is to allow adequate stripping of any tank. Note: When stripping a tank, some air is likely to be sucked into the main header after the water level falls below the bottom of the suction pipe. Manual closing of the valves is not affected. This sequence and the associated interlocks operate irrespective of the selection of the ‘Manual Override’. The ballast line is flooded by gravity filling through the following valves: •

58-ZCV-101/108

•

58-ZCV-102/112 (limited to 5% open)

•

58-ZCV-103/113

•

58-ZCV-147/148

•

58-ZCV-141/142

•

58-ZCV-151

These valves are permitted to open either under Sequence control or Manually while the low level in the header exists. To ‘re-flood’ the system, the Flooding button can be pressed which will automatically open the following valves in this sequence when the pumps have been confirmed as stopped. (1)

58-ZCV-151 – Ballast line vent.

(2)

58-ZCV-141/142 – Forward ring main isolation valves.

(3)

58-ZCV-147/148 – Middle ring main isolation valves.

(4)

58-ZCV-103/113 – Pump ‘A/D’ ballast lines suction.

(5)

58-ZCV-102/112 – Pump ‘A/D’ sea suction (proportional to 5%).

(6)

58-ZCV-101/108 – Sea chest isolation valves.

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If the Flooding button is not used, all of the above mentioned valves will not be interlocked and may be opened individually. After the header has been flooded above 90%, the interlocks are removed automatically and the ballast pumps can operate as normal, and the tank isolation valves can be re-opened. When any of the pumps are started, the ballast line vent isolation valve (58-ZCV-151) will automatically be closed after a configurable time set initially at 1 minute. Instrument Tag Number

Low Low Trip

Low Alarm

High Alarm

High High Trip

Controller Set Point

Port Water Ballast Header 58-LZT-133

40%

90%

58-LZT-134

30%

90% Starboard Water Ballast Header

58-LZT-135

40%

90%

58-LZT-136

30%

90%

Table 3.5 – Ballast Water Header Alarm and Trip Settings

3.7

Manual Override The Manual Override button is only accessible under OAL3. If the Manual Override button is activated some of the start interlocks will be overridden, except when the level in the header detected by 58-LZT-133/34/35/36 is below 90%. Note: Process interlocks or valve opening interlocks due to flooding will not be overridden by this facility.

3.8

Header Isolation Valves For normal operation, main line isolation valves 58-ZCV-141/142 will be closed so that pumps P-5804A and B supply the port/aft/forward ballast tanks, and pumps P-5804C and D supply the starboard/aft/forward tanks. Thus giving two separate ballast systems, one for each side of the vessel. When the two separate systems are no longer required, the header isolation valves 58-ZCV-141/42 can be opened so that any pump can operate on any tank. This condition is taken into account in the pump start interlocks.

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Ballast Pump Discharge Valves The operator can limit maximum output command for the discharge valve by using software pushbuttons. When a proportional discharge valve is selected to Manual mode, the operator can give ‘Fully Open’ or ‘Fully Close’ command and stop the output signals when the required setting, as indicated by the position feedback, is achieved. Alternatively, the operator can give an ‘Open’ or ‘Close’ pulsed output command. The open command will always be limited to the maximum value defined by the operator from the mimic.

3.10

Hydraulic System Capacity The HPU for the hull pumps is designed to operate five cargo and two ballast pumps at maximum design head pressure. Any combination of pumps can be run depending on the hydraulic demand on the HPU. Ballasting operations normally only require two ballast pumps and an interlock is provided to restrict the number of pumps in use to this number. The HPU system supply pressure, which drives the ballast pumps, will depend on the number of power packs running. It is the operator’s responsibility to ensure there is a sufficient number of power packs running to meet the demand required for ballasting/cargo operations. An override button, accessible at OAL3, is provided on the pump overlay to allow the simultaneous operation of more than two ballast pumps. The use of +2 pump operation will only be required in exceptional circumstances, such as a casualty situation. An interlock has been inserted to prevent more than two pumps running in normal operations.

3.11

Tank Cleaning/Transfer Main Ballast pumps P-8804C/D can also be used for tank cleaning of the cargo storage tanks or transferring seawater to the cargo or slop tanks via the transfer main. Both operations use local manual valves and require the removal of spools. These spools must be placed when not in use. Water is pumped from the ballast pump via 26-BUV-101 to the cargo transfer header and via 26-BUV-102 through the tank cleaning pump P-2604 and into the tank cleaning header. A dedicated button ‘Tank Cleaning’ is located on the ballast system functional buttons overlay. When selected the application will only allow pumps C or D to be used for tank cleaning. Pumps A and B can still be used for ballasting in the other tanks. The operator will initiate a semi-automated operation by selecting the Tank Cleaning button and then a Pump Sequence button. Before the pump is started, the operator must ensure that the relevant manual routing valves have been opened. When the semi-automated operation is selected, the associated valves will be opened (58-ZCV-108/109) and the pump will be automatically started and run up to 5% through 54-SY-223 (configurable). Once confirmation that the pump is operating from the discharge line pressure transmitter 58-PIT-109 being greater than 0.5barg (configurable) the discharge valve 58-ZCV-111 will be opened (initially to 5% (configurable)) then the valve may be opened further from the valve overlay as required.

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Once the pump has been started the pump speed can now be changed from the overlay, the DCS will send a signal from 54-SY-223 via the serial link to the pump hydraulic valve, located in the Cargo HPU control panel. Feedback is provided to the DCS by 58-SI-223 to confirm that the pump has moved the desired amount. A discrepancy alarm is generated if the difference between the pump position output and feedback 54-SY-223 and 54-SI-223 is greater than ±5% (configurable). This alarm is inhibited if the HPU is in local control. When the pump output is set to 5% and no discharge pressure is seen on 58-PIT-111, after 5 seconds (configurable) an alarm is raised ‘Pump Failed to Start’, the associated valves 58-ZCV-108/109 will be closed and the pump output will be driven to 0%. This alarm will only be raised when the pump is started using a sequence button and not when the ‘Manual Override’ is selected. If all the interlocks are not met the letter ‘I’ will be displayed next to the pump on the display and the valve routing should be checked by the operator. The pump cannot be started and the start button on the overlay and ‘Pump Sequence’ button will be ‘greyed out’. Manual operation is performed by selecting the ‘Manual Override’ button, which is only selectable at OAL3, then opening the associated isolation valves and starting the pump from the relevant display overlay. The tag numbers referred to in this section are for Pump No P-5804-C. Refer to Table 3.1 for the equivalent tag numbers for pump ‘D’. When the pump is stopped from the overlay, the starting sequence is reversed, stopping the pumps first and then closing the isolation valves 58-ZCV-108/109. If the sequence is manually overridden and the pump is stopped, the valves remain in the open position until closed by the operator. Normal operation of the pumps is from the CCR, if the pumps are operated from the local control panel located in the valve equipment room, the pumps must first be stopped before the unit is switched to ‘local’ control.

3.12

Interlocks Status of all Start-up Interlocks (STIL), Process Interlocks (PIL) and Shutdown Interlocks (SIL) are displayed on the ‘Interlocks’ pop-up, accessible from the pump overlay. The overlay also provides facilities to override STILs and PILs at operator access Level 3 (OAL3). The interlock pop-up can be accessed from the overlay from each pump/valve. In Tables 3.6 to 3.12, where a message is shown in the ‘Tag No/Pop-up Message’ column, this text is displayed as a message on the interlock pop-up. Tables 3.6 to 3.9 list the interlocks and conditions for various control scenarios on the Ballast System.

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The pumps will be prevented from starting when the conditions listed below apply. Tag No/Pop-up Message

Function Description

Two pumps * already running

If two pumps are already running (reading on 58-SI-103/06/09/12 greater than 0.5bar).

No pump HPU running

No power packs running (54-YS-201A to 209A).

Valve HPU Fault *

If either (54-YA-001 or 54-YA-002) are in alarm or any one of the common system alarms 54-YA-003 to 007 – valve HPU has failed.

All tanks isolated *

When 58-ZCV-141 and 142 are open and none of the isolation valves (58-ZCV-115 to 140 and 143/144) is open.

*Not valid if ‘Manual Override’ button is selected. Table 3.6 – Common Start Interlocks for Ballast Pumps (P-5804A/B/C/D) Tag No/Pop-up Message

Function Description

Check valve routing

Pump A – If valves 58-ZCV-103 and 58-ZCV-102 are both closed or both open, or 58-ZCV-104 is open (58-ZT-104 ≠ 0%).

Check valve routing

Pump B – If valves 58-ZCV-106 and 58-ZCV-105 are both closed or both open, or 58-ZCV-107 is open (58-ZT-107 ≠ 0%).

Check valve routing *

Pumps A and B – When 58-ZCV-141 is closed and 58-ZCV-147 is open and all of the valves 58-ZCV-115/116/119/120/123/124/127/ 128/131/132/135/136/139/143 are closed.

Check valve routing *

Pumps A and B – When 58-ZCV-141 and 58-ZCV-147 are closed and all of the following valves 58-ZCV-115/116/119/120/123/124 are closed.

Check valve routing *

Pumps A and B – 58-ZCV-145 and 58-ZCV-149 are open.

* Not valid if ‘Manual Override’ button is selected. Table 3.7 – Start-up Interlocks – Ballasting or De-ballasting (P-5804A and B)

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Tag No/Pop-up Message

Function Description

Check valve routing

Pump C – If valves 58-ZCV-110 and 58-ZCV109 are both closed or both open, or 58-ZCV-111 is open (58-ZT-111 ≠ 0%).

Check valve routing

Pump D – If valves 58-ZCV-113 and 58-ZCV112 are both closed or both open, or 58-ZCV-114 is open (58-ZT-114 ≠ 0%).

Check valve routing *

Pumps C and D – When 58-ZCV-142 is closed and 58-ZCV-142 is open, and all of the following valves 58-ZCV-117/118/121/122/125/126/129/130/133/135/137/ 138/140/144 are closed.

Check valve routing *

Pumps C and D – When 58-ZCV-148 and 58-ZCV-142 are closed, and all of the following valves 58-ZCV-117/118/121/122/125/126 are closed.

Check valve routing *

Pumps C and D – 58-ZCV-150 and 58-ZCV-146 are open.

*Not valid if ‘Manual Override’ button is selected. Table 3.8 – Start-up Interlocks – Ballasting or De-ballasting (P-5804C and D) Tag No/Pop-up Message

Function Description

Check valve routing

Pump C – If valves 58-ZCV-110 and 58-ZCV-109 are both closed or both open, or 58-ZCV-111 is open (58-ZT-111 ≠ 0%).

Check valve routing

Pump D – If valves 58-ZCV-113 and 58-ZCV-112 are both closed or both open, or 58-ZCV-114 is open (58-ZT-114 ≠ 0%).

Check valve routing *

Pumps C and D – When 58-ZCV-146 is open.

*Not valid if ‘Manual Override’ button is selected. Table 3.9 – Start-up Interlocks – Tank Cleaning (P-5804C and D)

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Logic Conditions The following logic is applied to pump control through the control facilities. Tag No/Pop-up Message

Function Description

P-5804A

Pump trip 54-YZC-103# immediately stops pump (set 54-SY-211 – output = 0%) and prevents pump from starting.

P-5804B

Pump trip 54-YZC-103# immediately stops pump (set 54-SY-212 – output = 0%) and prevents pump from starting.

P-5804C

Pump trip 54-YZC-103# immediately stops pump (set 54-SY-223 – output = 0%) and prevents pump from starting.

P-5804D

Pump trip 54-YZC-103# immediately stops pump (set 54-SY-224 – output = 0%) and prevents pump from starting.

# 54-YZC-103 is the trip signal from the SSDS to the cargo control system to drive all ballast pumps to 0%. The HPU (hydraulic supply) will still be available for other end users. Table 3.10 – Process Shutdown Logic Tag No/Pop-up Message

Function Description

P-5804A/B C/D

Pump outputs (54-SY-211/212/223/224) will be held at 0% until 58-LZT-133/134/135/136 have returned below trip state.

58-ZCV-102/112

Valves can only be opened 5% until 58-LZT-133 to 136 have returned below trip state and been reset. Table 3.11 – Header Flooding Logic

Tag No/Pop-up Message

Function Description

P-5804 A/BC/D

All four ballast pumps can be run at the same time, if the Manual Override from the overlay is selected.

P-5804 A/B/C/D

When not in Manual Override Mode – Interlock to stop simultaneous ballasting and de-ballasting operation, ie the ballast button shall be greyed out when de-ballasting is taking place. Table 3.12 – Abnormal Conditions Logic

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SAFEGUARDING Protection against potential overfilling of the Ballast Water Tanks is provided by the High Level alarm signal from the Metritape system, and the High High alarm signal from the capacitive probes. The set points for all of the Ballast Water Tank High Level Alarms is 95% and the High High alarm signal is provided at 98% of the tank capacity. The activation of the Level Alarm is annunciated in the DCS. If hydrocarbons should leak into a ballast tank, inert gas can be provided to inert the tanks from the clean inert gas header through either of the ballast/de-ballast lines or through flexible connections to the tank lid.

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6P T-5801M

5P T-5801K

58-LZT-122

58-LIT-121

xxx%

58-LIT-117

HH

ZCV-135

xxx%

ZCV-136

ZCV-131

4P T-5801H

58-LZT-118

HH

xxx%

ZCV-132

3P T-5801F

58-LZT-114

58-LIT-113

58-LIT-109

HH

ZCV-127

xxx%

ZCV-128

2P T-5801D

58-LZT-110

HH

ZCV-123

58-LIT-105

xxx% ZCV-119

ZCV-124

ZCV-119

1P T-5801B

58-LZT-106

58-LIT-101

HH ZCV-120

xxx%

HH

ZCV-120

ZCV-115

ZCV-116

58-LZT-102

LZT-134

LZT-133

xxx%

xxx%

ZCV-147 PIT-103 ZCV-104

PDI-101

xxx barg

P

58-LIT-130

xxx bar

PIT-102

ZCV-139

P

PIT-106

Atm osphere Sea Chest

PDI-104

xxx barg

xxx bar

PIT-105

PIT-104

ZCV-101

xxx barg

xxx barg

Aft Tank T-5801P

P

ZCV-107

ZCV-145

ZCV-102

xxx %

xxx %

SIC-211

Overboard

ZCV-105

Forward Tank T-5801A

xxx % ZCV-106

P-5804-B

xxx%

Port Draft

xxx % P-5804-A

58-LIT-127

xxx%

ZCV-103

xxx barg PIT-101

xxx barg ZCV-143

ZCV-141

58-LIT-132

58-LZT-128

xxx %

ZCV-149

SIC-212

58-LIT-129

xxx%

HH

58-LIT-125

xxx%

Aft Draft

xxx%

58-LZT-126

ZCV-151

HH

Fwd Draft PIT-109 ZCV-111 P

PDI-107

xxx barg

xxx bar

PIT-108

PIT-107

ZCV-110

xxx barg

xxx barg xxx % P-5804-C

SIC-223

ZCV-146 ZCV-114 P

ZCV-144

ZCV-109

xxx %

xxx barg

Sea Chest

PDI-110

PIT-112

PIT-111

xxx bar

xxx barg

PIT-110

xxx barg

H_COW _SD COW

ZCV-112 xxx %

58-LIT-131

xxx%

xxx %

ZCV-113

P-5804-D

xxx %

LZT-136

ZCV-140

ZCV-108

P

Overboard

Starboard Draft

ZCV-150

SIC-224

LZT-135

xxx%

xxx%

ZCV-148

ZCV-142

ZCV-137

58-LIT-123

xxx%

ZCV-138

58-LZT-124

ZCV-133

58-LIT-119

HH

6S T-5801N

xxx%

ZCV-134

58-LZT-120

HH

5S T-5801L

ZCV-129

58-LIT-115

xxx%

ZCV-130

58-LZT-116

HH

4S T-5801J

ZCV-125

58-LIT-111

xxx%

ZCV-126

58-LZT-112

HH

3S T-5801G

ZCV-121

58-LIT-107

xxx%

ZCV-122

58-LZT-108

HH

2S T-5801E

ZCV-117

58-LIT-103

xxx%

ZCV-118

58-LZT-104

HH

1S T-5801C

Figure 3.1 – Graphical Interface – Ballast Facilities

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Part 1 Technical Description Section 4 Detailed Description – Crude Oil Washing

Table of Contents 1.0

INTRODUCTION............................................................................................................. 2

2.0

EQUIPMENT DETAILS .................................................................................................. 3

3.0

2.1

COW and Tank Cleaning Header........................................................................ 3

2.2

Tank Washing Machines ..................................................................................... 3

CONTROL AND INSTRUMENTATION.......................................................................... 5 3.1

General................................................................................................................ 5

3.2

Crude Oil Washing .............................................................................................. 5

3.3

Water Washing Open/Closed Cycle .................................................................... 6

TABLES Table 4.1 – Crude Oil Washing Machine Locations ................................................................. 4

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INTRODUCTION Tank cleaning should only be undertaken when there is a specific and justifiable reason to do so. In general, tank cleaning is used for the removal of residues, wax and clingage from all cargo tank and slop tank surfaces that could result in unsafe conditions for tank entry or unacceptable build-up of residues. The tank washing methods available are as follows: Crude Oil Washing (COW) The cargo and slop tanks are equipped with fixed tank cleaning machines served by fixed piping which can use crude oil as a washing medium. By this method, some of the crude oil from the cargo oil pumps discharge is directed to the fixed tank cleaning machines. This is the normal method used to clean the Cargo Tanks. On a standard tanker COW is only performed during Cargo Offloading Operations, whereas on an FPSO it is normal to Crude Oil Wash between offtakes. Doing this avoids reducing the discharge rate, thus reducing exposure to demurrage claims, and allows flexibility in the timing of the operation, which will be done during daylight hours where possible. Seawater Washing This process is carried out prior to tank entry and is used to thoroughly clean all internal surfaces of the Cargo Tanks, using hot or cold water, before gas-freeing procedures commence. The use of cold seawater (up to 35°C) has been found to be adequate for most in-service tank cleaning and it is preferred to hot water. It is possible that when a very high standard of cleanliness is needed (hot work repairs) it may be necessary to use hot water. When to use hot water will be identified from experience. When washing with hot water it is essential that the temperature is well above the melting point of the wax in the cargo residues. If residues are first liquidised in this way but then allowed to cool they will solidify into a hard and rigid substance which is very difficult to remove. For this reason the temperature of hot wash water should be at least 85°C while temperatures between 35°C and 65°C must be scrupulously avoided as washing in this temperature range causes an emulsion. As no tank cleaning heater is fitted and the slop tank coating temperature is limited to about 70°C for short periods, hot water washing will be done only under exceptional circumstances. Refer to the following P&IDs: •

BON-SHI-008-P-00002-018 Tank Cleaning and Nitrogen Headers

•

BON-SHI-008-P-00002-019 Storage Compartment 1 and 2 Tank Cleaning and Utilities

•

BON-SHI-008-P-00002-020 Storage Compartment 3 Tank Cleaning and Utilities

•

BON-SHI-008-P-00002-021 Storage Compartment 4 Tank Cleaning and Utilities

•

BON-SHI-008-P-00002-022 Storage Compartment 5 Tank Cleaning and Utilities

•

BON-SHI-008-P-00002-023 Storage Compartment 6 Tank Cleaning and Utilities

•

BON-SHI-008-P-00002-024 Storage Compartment 7 Tank Cleaning and Utilities

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2.0

EQUIPMENT DETAILS

2.1

COW and Tank Cleaning Header Refer to P&ID BON-SHI-000002-018-00. A COW/Tank Cleaning (COW/TC) Header is provided on the Upper Deck of Bonga FPSO and this facility is used for both Crude Oil Washing and Seawater Washing. Crude oil for washing purposes is directed to the COW/TC Header through crossover isolation valves 26-ZCV-113/114 at the forward end and 26-ZCV-061/128 at the aft end of the Discharge Header. The manual in-line filter isolation valves, 26-BUV-074 and 26-BUV-075 (aft) and 26-BUV-076 and 26-BUV-077 (forward), are fitted either side of the aft and forward in-line filters, S-2601A/B. An isolation valve, 26-BUV-070, can be used to isolate the forward and aft sections of the COW/TC Header. The submerged Cargo Oil Pumps (refer to POPM Volume 5 Oil Metering and Export System (OPRM-2003-0305)) are operated as necessary to direct crude oil to the Discharge Header. Once the crossover valves on the selected supply line, forward or aft, from the Discharge Header to the COW/TC Header is opened, crude oil is available from the header for tank cleaning. In-line filters S-2601A/B are located in both crude oil supply lines to remove any particulate matter. Each is provided with a differential pressure transmitter 26-PDIT-042/043. The filters can be cleaned when the Crude Oil Washing System is shut down and the supply line isolated. A spur with an isolation valve connects each tank cleaning machine, programmable and submerged, to the COW/TC Header to permit the crude oil or water for washing to be directed to the tank cleaning machines in the Cargo Oil Tank to be cleaned. The spurs to the individual tank cleaning machines are fitted with coarse in-line strainers. The COW/TC Header supplies the fixed Tank Cleaning Machines provided in the Cargo Oil Tanks with crude oil at a minimum pressure of 8barg.

2.2

Tank Washing Machines Refer to P&ID BON-SHI008-P-000002-024-00 Storage Compartment 7 Tank Cleaning and Utilities and BON/1FA1108/GUNCLEAN/000001 Fixed Tank Cleaning Machine. Single nozzle, programmable, fixed Tank Cleaning Machines mounted on deck and in the larger centre tanks twin-nozzle submerged non-programmable Tank Cleaning Machines, located in the tank bottom, are provided for all Cargo Oil Tanks in compliance with MARPOL regulations. These facilities are suitable for Crude Oil Washing and Seawater Washing. The Slops Tanks are also provided with fixed, deck-mounted Tank Cleaning Machines and submerged Tank Cleaning Machines. A complete listing of the Tank Cleaning Machines and their locations is provided in Table 4.1.

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Deck-mounted Gunclean 270FT

Submerged TZ-65

COT No 1 Port/Starboard

3 off

–

COT No 1 Centre

3 off

2 off

COT No 2 Port/Starboard

3 off

–

COT No 2 Centre

2 off

1 off

COT No 3 Port/Starboard

3 off

–

COT No 3 Centre

3 off

2 off

COT No 4 Port/Starboard

3 off

–

COT No 4 Centre

3 off

2 off

COT No 5 Port/Starboard

3 off

–

COT No 5 Centre

3 off

2 off

Port Slops Tank

2 off

1 off

Starboard Slops Tank

2 off

1 off

Tank No

Table 4.1 – Crude Oil Washing Machine Locations The deck-mounted, fixed tank cleaning machines are Toftejorg Gunclean 270FT units fitted with 30mm nozzles and integral controllers. The units are 3.5m and 4.0m long and can be operated with a supply pressure in the range of 7 to 12barg. The nozzle angle, range and time duration for any set washing programme can be selected by choosing the suitable programme located on top of the turbine housing. The programme selector for the Toftejorg machines is mounted on the cover plate fitted to the unit. This allows the controller settings and nozzle angle to be checked at any stage during the tank washing sequence. The nozzle is designed to operate with a slow vertical movement, while simultaneously rotating about its vertical axis. This produces a helical spraying effect pattern inside the tank that ensures that the interior walls are thoroughly cleaned. The time taken to complete one full tank washing cycle is approximately 60 minutes with nozzle revolution set between 1.5 to 2.5rpm. A full cycle consists of one complete nozzle pass through the designed vertical arc of rotation from 0° to 120°; these actions are summarised in the following table.

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Cycles/Rotation/Time

Units of Measurement

One Full Cycle

120° – 0° – 120° – 0°

Time (T)

Approximately 60 minutes

Horizontal rotations (rpm)

1.5rpm

One Bottom Cycle

30° – 0° – 30° – 0°

Time (T)

Approximately 30 minutes

Horizontal rotations (rpm)

1.5rpm

The submerged Tank Cleaning Machines are Toftejorg TZ-65 units. These cleaning units are non-programmable and are fitted with twin nozzles. The units are situated 3m above the tank bottom. The asymmetrically opposed nozzles are driven by an integral turbine to achieve stable speed control. Once the manual isolation valve on the Tank Wash Line is opened, the nozzles rotate around 360° at a fixed speed to produce the maximum wash effect in the tank.

3.0

CONTROL AND INSTRUMENTATION

3.1

General During the normal operation of Bonga FPSO, oil sludge, wax and sediment will build up in cargo oil tanks. Thus all cargo tanks and the slop tanks require to be washed periodically. There are two mediums for washing these tanks, crude oil and water. The most frequently employed method is crude oil washing. Water washing of the tanks is usually only carried out prior to tank entry for inspection purposes. Crude Oil washing and Tank Cleaning are manual operations performed using manual valves and local controls at each tank washing machine. The following information describes the manual processes.

3.2

Crude Oil Washing Cleaning of the cargo tanks will normally be undertaken between cargo discharges. One or more cargo pumps require to be used to maintain the COW/TC Header at least at 8bar. The valves connecting the discharge header to the Tank Cleaning Header must be opened. This can either be hydraulically-operated valves 26-ZCV-061 and 26-ZCV-128 along with manual valves 26-BUV-074 and 26-BUV-075, or hydraulically operated valves 26-ZCV-113 and 26-ZCV-114 along with manual valves 26-BUV-076 and 26-BUV-077. Manual valve 26-BUV-070 is situated in the middle of the Tank Cleaning Header and is to allow the header to be split for maintenance or if damage has occurred.

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The distribution to an individual set of tanks is through a series of manual valves. The isolation valve to the set of cross tanks must be opened and then the individual tank cleaning machine valves opened. The oil used to wash the tank is returned to the transfer header by the individual cargo pump in each tank. When carrying out crude oil washing a large volume of vapour is produced and the cargo tank pressure must be monitored closely.

3.3

Water Washing Open/Closed Cycle Water washing of the cargo tanks is normally carried out prior to entry into the tank for routine inspection or maintenance. This allows any residual oil or sludge to be removed to allow safe entry. This water washing can be carried out by either hot or cold water.

3.3.1

Hot Washing Seawater is placed in the clean slop tank via the ballast pump, transfer header and the tank cleaning return line. This water is heated in the slop tank by the installed heating coils. These heating coils use waste heat from the topside. It will take approximately 24 hours to raise the temperature to 65°C. The temperature must not be below this for hot washing. Note: The temperature must no exceed 65°C during hot washing to prevent damage to the tank coating. This hot water is delivered by the clean slop pump to the COW/Tank Cleaning Header via manual valves 26-BUV-042, 26-BUV-049 and 26-BUV-070 as required, and 26-BUV-074 and 26-BUV-078. The hot water will be distributed to the individual tank cleaning machines as mentioned above. The water used to clean the tank is returned by the tank cargo pump to the transfer header and hence to the dirty slop tank.

3.3.2

Cold Wash Open Cycle With a Ballast Pump P-5804D/C in operation, water is supplied to the Tank Cleaning Booster Pump P-2604. This booster pump increases the seawater pressure up to 10barg before discharging into the tank cleaning header via manual valve 26-BUV-066. Distribution to the individual machines and drainage of the tanks is as above. Closed Cycle As for hot wash, but without the use of the heating coils.

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Part 1 Technical Description Section 5 Detailed Description – Slops System

Table of Contents 1.0

INTRODUCTION............................................................................................................. 2

2.0

EQUIPMENT DETAILS .................................................................................................. 2

3.0

4.0

2.1

Slop Tanks........................................................................................................... 2

2.2

Slop Pumps ......................................................................................................... 4

2.3

Dirty Slop Tank Oil Skim Pump P-2603............................................................... 5

2.4

Clean Slop Tank Clean Water Pump................................................................... 6

2.5

Overboard Discharge Monitoring System............................................................ 6

CONTROL AND INSTRUMENTATION.......................................................................... 8 3.1

Slop Tank Level Gauging .................................................................................... 8

3.2

Pump Controls and Interlocks ............................................................................. 9

3.3

Oil Discharge Monitoring System ...................................................................... 10

SAFEGUARDING ......................................................................................................... 12

TABLES Table 5.1 – Slops Tank Alarm and Trip Settings...................................................................... 8 Table 5.2 – Start Interlocks (STIL) – Slop Tank Pumps ......................................................... 10 Table 5.3 – Process Interlocks – Slop Tank Pumps............................................................... 10 FIGURES Figure 5.1 – Graphical Interface – Slops................................................................................ 13

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INTRODUCTION The slop tanks are designed to treat mixtures of water and entrained oil from crude oil processing, cargo handling, cargo tank washings, open and closed drains and bilge systems. Refer to the following P&IDs: •

BON-SHI-008-P-00002-008 Crude Oil Headers

•

BON-SHI-008-P-00002-009 Storage Compartment 1 (Dirty Slop Tank)

•

BON-SHI-008-P-00002-010 Storage Compartment 2 (Clean Slop Tank)

•

BON-SHI-008-P-00002-033 Cargo Heating System

•

BON-SHI-008-P-00002-007 Position of Tank Gauging and Hand Dipping System

2.0

EQUIPMENT DETAILS

2.1

Slop Tanks Equipment Details Tag Number:

T-2603, T-2602

Capacity:

5129.3m3 each

Maximum Operating Pressure:

1600mm WG (1.6barg)

Minimum Operating Pressure:

-200mm WG (-0.2barg)

Maximum Operating Temperature:

66oC

Refer to Figure 5.1 or P&IDs BON-SHI-008-P-00002-009 Storage Compartment 1 (Dirty Slop Tank) and BON-SHI-008-P-00002-010 Storage Compartment 2 (Clean Slop Tank). Equipment Description The slop tanks are rectangular compartments built into the hull of Bonga FPSO and are located on the port and starboard sides of the vessel aft of the cargo tanks. Each tank has a storage capacity of 5129.3m3. Both tanks are fitted with heating coils that can be used to assist oil/water separation and to heat clean seawater prior to water-washing of cargo tanks. When using the heating coils, it is important to check the heating medium return to the WHRU for oil contamination by sampling from the return line bleed valves 57-GBV-009/011/013/022/024/026. The two slop tanks are designated as Dirty (port) and Clean (starboard). During normal operations the port slop tank receives the mixtures to allow time for settling out before the water is transferred to the starboard clean tank.

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When time has been allowed for settling, separated water near the bottom of the port slop tank is allowed to flow through the lower decanting line driven by the hydrostatic head into the adjoining starboard clean slop tank. The decanting line is directed upwards in the clean slop tank in order to direct any entrained oil towards the surface. Oil is removed from the upper part of the dirty slops tank by a Dirty Slops Tank Oil Skim Pump P-2603, which delivers the wet oil to a selected cargo tank, normally the reception tank 3C, via the transfer header. There are also facilities to isolate the flow to the transfer header and pump to the Flare Scrubber V-4640 for disposal to the LP Separator V-2340A via the Flare Scrubber Pumps P-4640A/B/C. Level Controller 46-LC-301 controls the level in the flare scrubber. As the level rises, the lead Flare Scrubber Pump is started at 550mm and pump discharge valve 46-PDCV-320 is enabled. If the liquid level continues to rise to 700mm, the standby pump is started. If the level continues to rise, Level Control Valve 46-LCV-301 is opened to dump liquid to the dirty slop tank or Reception Tank 3C at a level of 1100mm. When the liquid level falls to its low setting of 450mm, the pumps are stopped and 46-LCV-301 is closed. At a level of 300mm, Shutdown Valve 46-SDV-310 upstream of 46-LCV-301 is closed, preventing gas blowby to the slop oil tank. The port slop tank should be more than 50% full to give the differential head required. Remote Operated Valves 26-ZVC-110 (Proportional) and 26-ZVC-111 can be opened to allow flow into the starboard slop tank. Subject to operational requirements, the proportional valve should be used to make the flow between the two tanks as slow as practical. After confirmation by sampling that the oil-in-water content of the starboard slop tank is below 29ppm, water can be discharged overboard. The last few metres contain higher oil contamination levels so pumping should be stopped before stripping occurs. The overboard discharge from the starboard slop tank must be visually monitored whilst the Clean Water Overboard Pump is running. If a significant amount of oil collects on the water surface of the starboard slop tank, it can be skimmed from the surface by filling the tank with water. When the level is above the upper oil skim pipe inlet approximately 70% height from the bottom of the tank, the top level can be run off, back into the port tank by hydrostatic head via Remote Operated Valves 26-ZVC-109 (proportional) and 26-ZVC-108. The proportional valve should be used to slow the flow to the port slop tank. To prevent the possibility of a hazardous atmosphere forming in the tank, inert gas is used to fill the tank ullage space at a slight positive pressure. Inert gas normally enters or is released from the slop tanks via a 250mm line from the dirty inert gas headers. The dirty and clean inert gas headers connect to the tank via a three-way valve that ensures one inert gas header is always aligned to the tanks. Tank pressure is controlled by venting inert gas through the dirty Inert Gas Header pressure control system. For details of the Inert Gas System refer to POPM Volume 19 Inert Gas System (OPRM-2003-0319). Each slop tank is provided with two fixed Tank Cleaning Machines fitted to the roof of the tank and one submerged in the tank to enable the tank to be cleaned.

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To aid separation of the oil and water and in breaking emulsions, heating coils are installed in the bottom of the slop tanks. The coils have three individual passes in each tank that are supplied with heating medium at 204°C and at a pressure of 16barg from the topside facilities. The topsides overflow is normally routed to the primary reception tank COT 3C through Locked Open Manual Isolation Valve 26-BUV-048. There are also facilities to route the topside overflow to the Dirty Slop Tank via normally Locked Closed Manual Isolation Valve 26-BUV-047. If the configuration is required, 26-BUV-047 must be opened and Locked Open Manual Isolation Valve 26-BUV-048 should be closed. The topsides drain passes to the dirty slops tank through Locked Open Manual Isolation Valve 26-BUV-045. There is also a facility to route the topside drain to the primary reception tank COT 3C via normally Locked Closed Manual Isolation Valve 26-BUV-046. If this configuration is required, 26-BUV-045 must be opened and Locked Open Manual Isolation Valve 26-BUV-046 should be closed.

2.2

Slop Pumps Equipment Details Tag Number:

P-2605A and P-2605B

Type:

SD200

Capacity:

400m3/hr

Discharge Pressure:

12 to 13barg

Head/Specific Gravity:

150m at rated speed/0.89

Viscosity:

8.2cst

Motor:

Hydraulic high-pressure motor

Tank Depth/ Pump Length:

Approximately 32/33.32m

Refer to Figure 5.1 or P&IDs BON-SHI-008-P-00002-009 Storage Compartment 1 (Dirty Slop Tank), BON-SHI-008-P-00002-010 Storage Compartment 2 (Clean Slop Tank) and BON/1JA0980/FRANK/000001 Cargo Oil Pump. Equipment Description Slop pumps P-2605A/B are fitted taking suction from the bottom of the clean and dirty slop tanks, which can discharge the contents of the tank into either the transfer or COW/TC headers. Although they both share a common discharge line, two spectacle pieces are provided which provide positive isolation to allow the starboard slop pump, P-2605A, to be utilised as a back-up clean water pump. It is essential that one of these spectacle pieces is always closed in order to maintain the cleanliness of the clean water overboard line. The pumps are submersible, single-stage, centrifugal pumps driven by a hydraulic motor, close-coupled to the pump. Each pump has a rated capacity of 400m3/hr. The submerged slop pumps are supported and positioned in the tank by means of a deck flange resting on the deck trunk and supported by an intermediate support ring and a bottom support. The pump impeller is driven by a built-in high-pressure hydraulic motor via a short shaft. The shaft is supported by bearings, which are lubricated and cooled by the hydraulic oil drain from the submerged pump motor.

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The pump pipe stack consists of two separate lines, the discharge line and hydraulic oil line. The hydraulic oil line is made up of three concentric pipes. The inner pipe transfers the high-pressure hydraulic oil which drives the pump motor and the low-pressure hydraulic oil returning from the pump motor passes through an annulus formed between a second concentric pipe and the supply line. A second annulus between the return pipe and a third concentric pipe acts as a cofferdam between the cargo on the outside and hydraulic pipes on the inside. This cofferdam space is filled with hydraulic fluid and the hydrostatic head is maintained by a Header Tank fitted with a gauge glass, which allows the level to be monitored. The slop pumps are fitted with the same stripping arrangement as the cargo pumps. Shaft seals are arranged to prevent any leakages between the cargo and cofferdam and between the cofferdam and hydraulic oil returns from the pump motor. Any leakages getting past the shaft seals or any other seal will migrate to the cofferdam, which always operates at the lowest pressure. The pump motors are powered by high-pressure hydraulic oil supplied at a maximum pressure of 260barg by the Framo Hydraulic System. The Slop Pump capacity is controlled by adjusting the hydraulic supply pressure to the pump motor. Full details on the Framo Hydraulic System are provided in POPM Volume 26 Deck Hydraulic Power Systems (OPRM-2003-0326). The Slops Pumps are operated from the Framo Control Panel or remotely from the DCS System.

2.3

Dirty Slop Tank Oil Skim Pump P-2603 Equipment Details Tag Number:

P-2603

Capacity:

100m3/h

Discharge Pressure:

15barg

Speed:

4458rpm

Refer to Figure 5.1 or P&IDs BON-SHI-008-P-00002-009 Storage Compartment 1 (Dirty Slop Tank), BON-SHI-008-P-00002-010 Storage Compartment 2 (Clean Slop Tank) and BON/1JA0980/FRANK/000001 Cargo Oil Pump. Equipment Description Skimming Pump P-2603 is a submersible, single-stage, centrifugal pump located in the port Slop Tank driven by a hydraulic motor. The pump has a discharge flow capacity of 100m3/hr and discharges directly to the transfer header. When the oil/water interface in the Port Slop Tank is at or below 70% of the tank level, oil floating at the top can be removed by the Skimming Pump. While this is being done, careful monitoring of the operation is required to ensure that oil and not water is pumped into the cargo tanks. The pump will be stopped and inhibited from starting if either the interface level 26-LZT-036 is above the pump suction or the tank level 26-LIT-032 reading is below the pump suction. The technical description and operation of the pump is as described for the Slop Pumps.

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Clean Slop Tank Clean Water Pump Equipment Details Tag Number:

P-2602

Capacity:

240m3/h

Discharge Pressure:

15barg

Speed:

2550rpm

Refer to Figure 5.1 or P&IDs BON-SHI-008-P-00002-009 Storage Compartment 1 (Dirty Slop Tank), BON-SHI-008-P-00002-010 Storage Compartment 2 (Clean Slop Tank) and BON/1JA0980/FRANK/000001 Cargo Oil Pump. Equipment Description Clean Slop Tank Clean Water Overboard Pump (P-2602) is a submersible, single-stage, centrifugal pump located in the bottom of the starboard Slop Tank driven by a hydraulic motor. The pump has a discharge flow capacity of 240m3/hr. The pump is used to deliver water from the clean slop tank into the Slop Pump discharge header for disposal overboard. The pump discharges into the slop tank common discharge header, however a spading arrangement keeps the overboard section of the header positively isolated from the rest of the system. The same spading arrangement can allow the clean slop tank pump to pump overboard in the event of failure of the clean water pump.

UNDER NO CIRCUMSTANCES MUST THE TWO SPECTACLE BLINDS IN THIS SPADING ARRANGEMENT BE SIMULTANEOUSLY IN THE OPEN POSITION OTHERWISE THERE IS A SERIOUS RISK OF CONTAMINATING THE OVERBOARD DISCHARGE PIPEWORK. The technical description and operation of the pump is as described for the Slop Pumps.

2.5

Overboard Discharge Monitoring System Refer to BON/1SA1043/SEIL/000001 Oil Discharge Monitoring System. The Overboard Discharge Monitoring System (ODMS) equipment is distributed between hazardous and safe areas according to its certification. The unit comprises the following major items: •

Hydraulic Panel

•

Sample Pump

•

Measuring Vessel

•

Oil-in-water Analyser

•

Remote Control Panel

The monitoring system is controlled from the local and remote control panels and must be started and stopped whenever clean water is being discharged from the slop tanks.

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The sample is drawn through a sample probe on the overboard discharge line and flows through a strainer to the hydraulic panel. In addition to the sample probe on the line there is a flow measurement device, which feeds a signal to the remote control panel (calculator) in the control room, to be used in computing the actual quantity of oil passing through the overboard line. In normal operation, the sample flows to the suction of the sample pump where the pressure is increased to 5barg to deliver the sample to the measuring vessel. Routing of the sample to the pump is performed by the pneumatic valves in the hydraulic panel which are controlled by air signals from the Oleometer cabinet. There are four pneumatic valves in the cabinet to enable the following functions to be performed: •

Test Running

•

Backflushing

•

Calibration

•

Monitoring

A clean water supply is provided at the hydraulic panel to flush the measuring vessel and sample line during backflushing and for use as calibration media. The pneumatic valves are used to switch between the sample and water supply and to direct the water from the measuring vessel outlet. Control of the valves is by solenoid valves in the Oleometer cabinet, which switch the air signals on commands from the remote control panel. LEDs inside the cabinet indicate when solenoids are energised. The sample pump is a mono pump driven by 415V electric motor with a power rating of 1.5kW. The pump discharges at a maximum pressure of 5barg at a flowrate of 750 litres/hr. The measuring vessel is an ODME S663 MKIII photometer manufactured by Seres. This part of the analyser is bulkhead-mounted and has no electrical components so it can be located in a hazardous area. The electrical components are located in the Oleometer cabinet in a safe area on the opposite side of the bulkhead. The sample flows upwards through a glass tube where it is exposed to light from a lamp. There are two detector cells, one offset by 30° and one set 90° from the axis of the light source. Any oil in the water flowing through the tube will fluoresce and be detected by the detector set at 90°. The amount of fluorescence produced is dependent upon the amount of oil in the sample. The detector set at 30° to the light path is used to measure the turbidity of the water. To monitor the intensity of the light source there is a compensating cell located diametrically opposite the light source, which adjusts the power to the light source. The light source and detector cells are actually located in the Oleometer cabinet and connect to the measuring vessel through optical fibre connectors passing through the bulkhead. As the sample will contain some oil, this may collect on the inside of the glass tube and affect the operation of the instrument. The measuring vessel is equipped with a pneumatically-operated cleaning device, which drives a wiper up and down the inside of the glass tube.

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3.0

CONTROL AND INSTRUMENTATION

3.1

Slop Tank Level Gauging Slop tanks are provided with a Saab Tank Radar level gauge system. This is used as the primary level sensing system. The system installed on each slop tank consists of a radar level transmitter 26-LIT-032/034, tank pressure transmitter 26-PT-016/017, and three sets of temperature sensors for each tank 26-TT-046/47/48 and 26-TT-049/50/051. The temperature in each tank is measured at three levels; 15%, 50% and 85%. These signals are interfaced to DCS via a serial link. The Saab system provides high and low level, high and low pressure and high Temperature Alarms on DCS. In addition to the Saab system, a Metritape Vanguard back-up level transmitter 26-LZT-031/033 is installed which provides high-high level trip signals. The trip signal closes all inlet valves to the tank and shuts down the cargo pumping system when the tank level exceeds 98% of capacity (volume). This system is totally independent of the radar gauges and is connected directly to the SSDS. The two slop tanks are also provided with Halla Oil/Water Interface Level Transmitters, 26-LZT-035 and 036. These provide interface level indication and a low-level alarm on the DCS to an accuracy of +/-0.5%. Instrument Tag Number

Low Low Trip

Low Alarm

High Alarm

High High Trip

Controller Set Point

Dirty Slop Tank (Port) 26-LIT-032

32.322m

1.701m

26-PT-016

40mbar

120mbar

26-LZT-031 26-LZT-036

0.68m 33.002m Clean Slop Tank (Starboard)

26-LIT-034

32.12m

1.69m

26-PT-017

40mbar

120mbar

26-LZT-033 26-LZT-035

0.676m 32.796m

Note: These settings are fed to the DCS and the levels are measured as ullage in metres. Table 5.1 – Slops Tank Alarm and Trip Settings

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The two slop tanks are each equipped with three Temperature Transmitters, as follows: •

Clean Slop Tank T-2602 – 26-TT-049/050/051

•

Clean Slop Tank T-2603 – 26-TT-046/047/048

These provide temperature indication and high temperature alarms on the DCS at 15%, 50% and 85% tank levels respectively.

3.2

Pump Controls and Interlocks Refer to Figure 5.1 and P&IDs BON-SHI-008-P-00002-009 Storage Compartment 1 (Dirty Slop Tank) and BON-SHI-008-P-00002-010 Storage Compartment 2 (Clean Slop Tank).

3.2.1

Clean and Dirty Slop Tank Slop Pumps P-2605A/B Control Slop pumps are fitted in the bottom of the clean P-2605A and dirty P-2605B slop tanks, which can discharge the contents into either the transfer or tank cleaning headers. Although they both share a common discharge line, spectacle pieces are provided which allow the starboard slop pump to be utilised as a back-up clean water overboard pump. The Slops Pumps are operated remotely from the DCS System or from the Framo Control Panel. Individual controllers for all submerged pump motors are provided on the Framo Control Panel installed in the CER. All submerged pump controllers are calibrated from a minimum output where the hydraulic supply pressure to the pump motor is 0barg to a maximum output of 260barg. When the Slop Pumps are controlled from the DCS System, the set point from the DCS Console is used by the PLC logic incorporated in the Framo Control Panel to adjust the hydraulic supply to the pump motor. To assume a smooth start-up of the Slop Pumps, the set point is limited to 60barg for 45 seconds. When this time period has elapsed, the hydraulic supply pressure will increase to match the required set point. When stripping is in progress, the pumps are operated locally. For local operation at the pump top, the manual flow control valve at the pump top plate is opened, the pump started from the DCS or Framo control panel and the system hydraulic pressure set to approximately 150barg. Pump control is then by manually closing the flow control valve to raise the hydraulic pressure at the pump as required.

3.2.2

Oil Skimming Pump P-2603 Control After being allowed to settle out in the port slop tank, and once the oil/water interface level is below about 10m ullage, oil is removed from the upper part of the tank by an Oil Skimming Pump into a cargo tank, via the Transfer Header. Control of the pump is as described for the slop pumps in Paragraph 3.2.1. The interface detector 26-LZT-036 and port slop tank level 26-LIT-032 readings show the operator when the skimming pump can be used to transfer oil, and when the water interface is at or below pump suction. Start inhibit and pump trips are provided at a preset level of 70% on 26-LIT-032 in the Slop Tanks in case of tank low level. Start inhibit and pump trips are provided at a preset interface level of 70% on 26-LZT-036 in the Slop Tank to prevent water carryover to the cargo tanks.

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Clean Slop Tank Clean Water Overboard Pump P-2602 Control of the pump is as described for the slop pumps in Paragraph 3.2.1.

Tag No/Pop-up Message

Function Description

ODME unit unavailable

Clean Water Pump P-2602 – ODME unit is unavailable (26-YZA-001) and 26-ZCV-056 is closed.

Low tank level

Skimming Pump P-2603 – Inhibit start if tank level 26-LIT-032 is less than 70%.

Dirty tank level

Clean Water Pump P-2602 – Inhibit start if 26-ZCV-056 is not open and 26-LIT-032 high alarm is active.

HPU not running

All power packs are stopped.

Table 5.2 – Start Interlocks (STIL) – Slop Tank Pumps

Tag No/Pop-up Message

Function Description

High interface level

Skimming Pump P-2603 – Stop pump if interface level 26-LZT-036 is greater than 70%.

Tank level below pump inlet 26-LZHH-035

Skimming Pump P-2603 – Stop pump if level 26-LI-032 is less than 70%. Stop Pumps P-2602 and P-2605A if interface level is high.

Hydraulic tank low level 54-LALL-209

Aux Hydraulic Unit A-5401 oil level low 54-LALL-209 trips Pumps P-2602, P-2603 and P-2605A/B.

Table 5.3 – Process Interlocks – Slop Tank Pumps Note: Low Low Pressure 55-PZLL-101 and 55-PZLL-102 on the CIGM and DIGM, respectively, trips the cargo, slop and skimming pumps and shuts the main oil export ESD Valve 26-SDV-121 at 200mm WG. During periods when the CIGM is not in use, the output from 55-PZT-101 should be inhibited from taking any executive action.

3.3

Oil Discharge Monitoring System

3.3.1

Control Panel The ODME unit is used to analyse the oil content of the water pumped from the clean slop tank to check if the oil-in-water is below the regulatory amount, so that it can be discharged overboard or, if off-specification, returned to the dirty slop tank. The ODMS provides high and high high oil-in-water alarms and a unit abnormal 26-YZA-001 alarm, which is sent to the SSDS.

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Control of the ODMS is through the control panel located in the control room. This panel is microprocessor based and uses a number of sub-programmes to interrogate and control the analyser, then process and store the data received. The unit also provides the interface with the operator through an LED display and keypad. Data logging is performed by printing out time-tagged key values and events. The control panel receives input from the Oleometer cabinet, and from the overboard flowmeter. If the oil-in-water content exceeds 39ppm, the control panel provides a signal to the valve control panel to open the Remote Operated Valve 26-ZCV-067 and close Overboard Discharge Valve 26-ZCV-066 to prevent out-of-specification water being discharged overboard. The dirty water is diverted back to the port slop tank through 26-ZCV-067. 3.3.2

Control Logic When the transfer line isolation valve 26-ZCV-056 is closed and the Clean Water Pump P-2602 is started and confirmed to be running, and 26-PIT-036 is greater than 0.5bar, the application will open the ODME recirculation valve 26-ZCV-067 and start the ODME unit. If the valve fails to open or the ODME unit fails to start, the application will stop the ODME unit, close the valve, stop the pump and raise an alarm. When the oil/water ratio falls below the preset value configured in the ODME unit, the ODME unit sends a low oil content signal (26-YZ-001) to the DCS, which will start the overboard discharge sequence. The application then opens the overboard discharge valve 26-ZCV-066 and closes the recirculation valve 26-ZCV-067. If either of the valves fails to reach its requested position, the application will stop the ODME unit, close the discharge valve, stop the pump and raise an alarm. The overboard discharge valve 26-ZCV-066 will be inhibited from opening for a period of 60 seconds (configurable) after the ODME unit has started even if the oil/water ratio falls below the required set point. If the oil/water ratio rises above the unit set point, an alarm will be generated by the ODME unit 26-YZA-001 and the application will stop the ODME unit. The clean water pump is stopped (54-YZC-221 driven to 0%), the recirculation valve (26-ZCV-067) opens and the overboard discharge valve 26-ZCV-066 closes. The application will stop the clean water pump and the ODME unit if the ODME unit detects a high oil content and the dirty slop tank high-high level 26-LZT-031 is detected. The status of the ODME unit is displayed on the DCS. The ODME unit can be manually started and stopped by the operator and the running status, unit abnormal alarm 26-YZA-001 and the overboard discharge status can also be seen on the HMI.

Part 1 Section 5 Detailed Description – Slops System

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SAFEGUARDING Protection against potential overfilling of the Slop Tanks is provided by the high-level trip signal from the Saab Radar System and the high high trip signal from the Metritape. The set points for all of the Slop Tank high level alarms is 95% and the high high trip signal is provided at 98% of the tank capacity. The activation of the level alarm is annunciated in the DCS. The slop tanks are protected against overpressurisation or vacuum conditions through Pressure/Vacuum Valves 55-RV-018 and 55-RV-019 for the port and starboard tanks respectively, connected to the Vent Main. The relief valves each have two pressure settings, 1600mm WG to prevent overpressurisation conditions and -200mm WG (-0.2barg) to prevent vacuum conditions. An inert atmosphere is maintained in the slop tanks by connection to the dirty inert gas header that maintains a positive pressure on the tanks. To prevent pollution when water from the slop tanks is dumped overboard, the ODME is provided to monitor water quality and automatically divert water for disposal to the dirty slop tank if water quality does not meet the regulatory requirements or on failure of the ODME.

Part 1 Section 5 Detailed Description – Slops System

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Dirty IGG Header

Clean IGG Header

XXX

XXX

barg

55-PIT-104

(3C) T-2601H (5C) T-2601N

barg

55-PIT-103

LZT-027

LIT-028

N2 Header XXX

XXX% 041

barg

55-PIT-001

Running/ Stopped

Hydraulic Valve HPU Running/ Stopped

XXX

XXX%

PIT-025 barg

barg 038 047

040 P-2601H

048

P-2601N

54-SIC-209

xxx

54-SIC-217

LIT-016

XXX

PIT-031 Hydraulic HPU

LZT-015 LZT-037

xxx

042

26-LIT-038 XXX%

117

T-2604

Pick box to cargo_Hdr_SD

Start/Stop

Overboard 059

067

068

DIRTY SLOP T-2603 XXX I/F% LZT-036

XXX%

LZT-031

PIT-035 XXX barg

LIT-032

54-SIC-219

CLEAN SLOP T-2602 LZT-035

LIT-034

XXX I/F%

XXX%

LZT-033

PIT-036 XXX barg

065

xxx

PIT-033 XXX barg

COW_SD

T/C COW Hdr

YZ-001 A-5801

063

P-2603

056

YZC-004 Unit Abnormal YZA-001 Running/ Stoppped YZ-003 High Oil Content

066

PIT-034 barg XXX

P-2602 xxx

062

54-SIC-222

064 109

P-2605B (Slop) xxx

108

P

110

P-2605A

P xxx XXX

%

54-SIC-221

111

54-SIC-220 XXX

%

112

Figure 5.1 – Graphical Interface – Slops

Part 1 Section 5 Detailed Description – Slops System

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PART 2 OPERATING PROCEDURES Section 1

System Operating Procedures

Section 2

Equipment Operating Procedures

Section 3

Supplementary Operating Procedures

Part 2 Operating Procedures

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Part 2 Operating Procedures Section 1 System Operating Procedures Procedure Number CARGO LOADING AND BALLAST SYSTEMS OPERATING PROCEDURES PROCEDURE NO 1/001:

LOADING FACILITIES OPERATIONS (INITIAL)

PROCEDURE NO 1/002:

BALLAST OPERATIONS

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OIL STORAGE, HANDLING AND BALLAST

PROCEDURE NO 1/001: LOADING FACILITIES OPERATIONS (INITIAL)

THE WHOLE OF THIS PROCEDURE MUST BE READ THROUGH AND FULLY UNDERSTOOD BEFORE CARRYING OUT ANY OF THE FOLLOWING ACTIONS.

INTRODUCTION This procedure details the operator actions required to be carried out on the Cargo System prior to and during start-up of loading operations. In the procedure it is assumed that Crude Oil Tanks (COT) 2 and 4 in Group A are to be filled first. Loading can be by two methods – via the reception tank or directly to the individual Cargo Tanks. The reception tank is the preferred method as it gives less likelihood of stopping production due to erroneous-manipulation of valves and ensures that any water entrained in the crude oil is contained in a single tank. Checklist No 1 indicates all the system valves that are required to be shut prior to loading at start-up. Checklist No 2, together with a small written procedure, indicates loading valve positions for loading via reception tank 3C to group A tanks. Checklist No 3, together with a small written procedure, indicates loading valve positions for loading directly to group A tanks.

PRECONDITIONS Supporting Drawings The procedure utilises the following P&IDs: •

BON-SHI-008-P-00002-008 Crude Oil Headers

•

BON-SHI-008-P-00002-012 Storage Compartment 3

•

BON-SHI-008-P-00002-012 Storage Compartment 4

•

BON-SHI-008-P-00002-013 Storage Compartment 5

•

BON-SHI-008-P-00002-014 Storage Compartment 6

•

BON-SHI-008-P-00002-015 Storage Compartment 7

•

BON-SHI-008-P-00002-018 Tank Cleaning and Nitrogen Headers

•

BON-SHI-008-P-00002-019 to 24 Storage Compartments 1 to 7 Tank Cleaning and Utilities

Supporting Document •

Framo Doc 9242-0169-4 – Service Manual for Cargo Pumping

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Interface Systems Before cargo loading can take place the following systems are required to be operational: •

Inert Gas System. Refer to POPM Volume 19 (OPRM-2003-0319)

•

Seawater System. Refer to POPM Volume 21 (OPRM-2003-0321)

•

Fresh and Potable Water Systems. Refer to POPM Volume 22 (OPRM-2003-0322)

•

Instrument and Utility Air System. Refer to POPM Volume 25 (OPRM-2003-0325)

•

Power Generation and Distribution System. Refer to POPM Volume 30 (OPRM-2003-0330)

•

Deck Hydraulic Systems. Refer to POPM Volume 33 (OPRM-2003-0333)

Pre-requisites •

No Work Permits are in force that will prohibit any part of this Procedure and all relevant Hot Work Tags have been returned to the Installation Control Centre

•

Fire, Gas and Safety Systems are commissioned and are in readiness for operation

•

Special Safety considerations: Shell Export Safety Manual of Safe Handling of Chemicals for the use of all chemicals added to the upstream Crude Oil Production Facilities

•

If the loading sequence for the Cargo Oil Tanks is following a Tank Inspection, the status of the tanks is as follows:

•

•

−

All Cargo Oil Tanks are totally empty, oxygen free and charged with inert gas at approximately 800mm WG

−

All submerged Cargo Oil Pumps are available for operation

−

The bottom transfer mains interconnecting adjacent Cargo Oil Tanks are unrestricted and available for use

Assuming all Cargo Tanks are empty, the status of the Ballast Tanks is as follows: −

The Aft Peak Water Ballast Tank (APWBT) is empty but available for use

−

The Port and Starboard Water Ballast Tanks (WBTs) 1 to 6 contain seawater

−

The Forward Peak Water Ballast Tank (FPWBT) is empty but available for use

−

The Port and Starboard Submerged Ballast Pumps are available for operation

−

The Port and Starboard Ballasting lines interconnecting all WBTs are available for use

−

The Port (Dirty) and Starboard (Clean) Slop Tanks are available for use

−

The Cargo Oil Transfer Main is available for use

The following tank systems are isolated: −

Nitrogen Header

−

Clean Inert Gas Main

PLANT STATUS Initially the system isolation valves are all closed as indicated in Valve Checklist No 1.

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 Tag No

Function

Setting

Checked

Pre-start Positions: Cargo Oil Tank Nos 1P, C&S Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-130

Isolation Valve on Cargo Pump common discharge to Discharge Header

CLOSED

26-ZCV-131

Isolation Valve on Cargo Pump common discharge to Transfer Header

CLOSED

No 1 Port Cargo Tank Refer to P&ID BON-SHI-008-P-000002-015 26-ZCV-031

Cargo Pump P-2601C discharge isolation valve

CLOSED

26-BLV-001

Cargo Pump P-2601C stripping isolation valve

CLOSED

26-BUV-018

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-071

Lower transfer line to No 2P COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-018 26-BUV-073

COTs 1P, 1C and 1S Isolation valve from COW Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-024 26-GTV-001

COT 1P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-002

COT 1P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-035

COT 1P Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-009

COT 1P Isolation Valve for portable tank cleaning pump

CLOSED

No 1 Centre Cargo Tank Refer to P&ID BON-SHI-008-P-000002-015 26-ZCV-032

Cargo Pump P-2601B discharge isolation valve

CLOSED

26-BLV-002

Cargo Pump P-2601B stripping isolation valve

CLOSED

26-BUV-019

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-073

Lower transfer line to No 2C COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-018 26-GTV-037

COT 1C Isolation Valve from COW line to submerged machine

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-024 26-GTV-038

COT 1C Isolation Valve from COW line to submerged machine

CLOSED

26-GTV-003

COT 1C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-004

COT 1C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-036

COT 1C Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-010

COT 1C Isolation Valve for portable tank cleaning pump

CLOSED

No 1 Starboard Cargo Tank Refer to P&ID BON-SHI-008-P-000002-015 26-ZCV-033

Cargo Pump P-2601A discharge isolation valve

CLOSED

26-BLV-003

Cargo Pump P-2601A stripping isolation valve

CLOSED

26-BUV-020

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-075

Lower transfer line to No 2S COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-024 26-GTV-005

COT 1S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-006

COT 1S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-039

COT 1S Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-011

COT 1S Isolation Valve for portable tank cleaning pump

CLOSED

Pre-start Positions: Cargo Oil Tank Nos 2 P, C&S Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-132

Isolation Valve on Cargo Pump common discharge to Discharge Header

CLOSED

26-ZCV-133

Isolation Valve on Cargo Pump common discharge to Transfer Header

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

No 2 Port Cargo Tank Refer to P&ID BON-SHI-008-P-000002-014 26-ZCV-070

Lower transfer line to No 1P COT

CLOSED

26-ZCV-077

Lower transfer line to No 2C COT

CLOSED

26-ZCV-081

Lower transfer line to No 3P COT

CLOSED

26-ZCV-034

Cargo Pump P-2601F discharge isolation valve

CLOSED

26-BLV-004

Cargo Pump P-2601F stripping isolation valve

CLOSED

26-BUV-021

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

Refer to P&ID BON-SHI-008-P-000002-018 26-BUV-072

COTs 2P, 2C and 2S Isolation valve from COW Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-023 26-GTV-007

COT 2P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-008

COT 2P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-040

COT 2P Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-012

COT 2P Isolation Valve for portable tank cleaning pump

CLOSED

No 2 Centre Cargo Tank Refer to P&ID BON-SHI-008-P-000002-014 26-ZCV-035

Cargo Pump P-2601D discharge isolation valve

CLOSED

26-BLV-005

Cargo Pump P-2601D stripping isolation valve

CLOSED

26-BUV-022

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-BUV-061

Cargo Pump P-2601D discharge isolation valve of diesel during start-up

CLOSED

26-ZCV-072

Lower transfer line to No 1C COT

CLOSED

26-ZCV-076

Lower transfer line to No 2P COT

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

26-ZCV-079

Lower transfer line to No 2S COT

CLOSED

26-ZCV-088

Lower transfer line to No 3C COT

CLOSED

Checked

Refer to P&ID BON-SHI-008-P-000002-023 26-GTV-010

COT 2C Isolation Valve from COW line to submerged machine

CLOSED

26-GTV-009

COT 2C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-041

COT 2C Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-013

COT 2C Isolation Valve for portable tank cleaning pump

CLOSED

No 2 Starboard Cargo Tank Refer to P&ID BON-SHI-008-P-000002-014 26-ZCV-036

Cargo Pump P-2601E discharge isolation valve

CLOSED

26-BLV-006

Cargo Pump P-2601E stripping isolation valve

CLOSED

26-BUV-023

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-074

Lower transfer line to No 1S COT

CLOSED

26-ZCV-120

Lower transfer line to No 3S COT

CLOSED

26-ZCV-078

Lower transfer line to No 2C COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-023 26-GTV-011

COT 2S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-012

COT 2S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-042

COT 2S Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-014

COT 2S Isolation Valve for portable tank cleaning pump

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

Pre-start Positions: Cargo Oil Tank Nos 3 P, C&S Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-134

Isolation Valve on Cargo Pump common discharge to Discharge Header

CLOSED

26-ZCV-135

Isolation Valve on Cargo Pump common discharge to Transfer Header

CLOSED

No 3 Port Cargo Tank Refer to P&ID BON-SHI-008-P-000002-013 26-ZCV-037

Cargo Pump P-2601I discharge isolation valve

CLOSED

26-BLV-007

Cargo Pump P-2601I stripping isolation valve

CLOSED

26-BUV-024

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-080

Lower transfer line to No 2P COT

CLOSED

26-ZCV-083

Lower transfer line to No 4P COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-018 26-BUV-071

COTs 3P, 3C and 3S Isolation valve from COW Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-022 26-GTV-013

COT 3P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-014

COT 3P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-043

COT 3P Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-015

COT 3P Isolation Valve for portable tank cleaning pump

CLOSED

No 3 Centre Cargo Tank Refer to P&ID BON-SHI-008-P-000002-013 26-ZCV-038

Cargo Pump P-2601H discharge isolation valve

CLOSED

26-ZCV-040

Cargo Pump P-2601H discharge isolation valve

CLOSED

26-ZCV-041

Cargo Pump P-2601H discharge isolation valve to dirty slop tank

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

26-BLV-017

Cargo Pump P-2601H stripping isolation valve

CLOSED

26-BUV-025

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-101

Upper cascade line on 3C COT

CLOSED

26-ZCV-085

Lower transfer line to No 4C COT

CLOSED

26-ZCV-086

Lower transfer line to 3C suction

CLOSED

26-ZCV-087

Lower transfer line to No 2C COT

CLOSED

Checked

Refer to P&ID BON-SHI-008-P-000002-022 26-GTV-015

COT 3C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-016

COT 3C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-044

COT 3C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-045

COT 3C Isolation Valve from COW line to submerged machine

CLOSED

26-GTV-046

COT 3C Isolation Valve from COW line to submerged machine

CLOSED

26-SV-016

COT 3C Isolation Valve for portable tank cleaning pump

CLOSED

No 3 Starboard Cargo Tank Refer to P&ID BON-SHI-008-P-000002-013 26-ZCV-039

Cargo Pump P-2601G discharge isolation valve

CLOSED

26-BLV-008

Cargo Pump P-2601G stripping isolation valve

CLOSED

26-BUV-026

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-BUV-060

Cargo Pump P-2601G Isolation Valve on tie-in for discharge of diesel during start-up

CLOSED

26-ZCV-090

Lower transfer line to No 4S COT

CLOSED

26-ZCV-119

Lower transfer line to No 2S COT

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-022 26-GTV-017

COT 3S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-018

COT 3S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-047

COT 3S Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-017

COT 3S Isolation Valve for portable tank cleaning pump

CLOSED

Pre-start Positions: Cargo Oil Tank Nos 4 P, C&S Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-136

Isolation Valve on Cargo Pump common discharge to Discharge Header

CLOSED

26-ZCV-137

Isolation Valve on Cargo Pump common discharge to Transfer Header

CLOSED

No 4 Port Cargo Tank Refer to P&ID BON-SHI-008-P-000002-012 26-ZCV-043

Cargo Pump P-2601L discharge isolation valve

CLOSED

26-BLV-009

Cargo Pump P-2601L stripping isolation valve

CLOSED

26-BUV-027

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-082

Lower transfer line to No 3P COT

CLOSED

26-ZCV-096

Lower transfer line to No 5P COT

CLOSED

26-ZCV-092

Lower transfer line to No 4C COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-018 26-BUV-069

COTs 4P, 4C and 4S Isolation valve from COW Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-021 26-GTV-019

COT 4P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-020

COT 4P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-048

COT 4P Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-018

COT 4P Isolation Valve for portable tank cleaning pump

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

No 4 Centre Cargo Tank Refer to P&ID BON-SHI-008-P-000002-012 26-ZCV-044

Cargo Pump P-2601K discharge isolation valve

CLOSED

26-BLV-018

Cargo Pump P-2601K stripping isolation valve

CLOSED

26-BUV-028

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-098

Lower transfer line to No 5C COT

CLOSED

26-ZCV-084

Lower transfer line to No 3C COT

CLOSED

26-ZCV-091

Lower transfer line to No 4P COT

CLOSED

26-ZCV-094

Lower transfer line to No 4S COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-021 26-GTV-021

COT 4C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-022

COT 4C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-049

COT 4C Isolation Valve from COW line to Tank Top

CLOSED

26-GTV-050

COT 4C Isolation Valve from COW line to submerged machine

CLOSED

26-GTV-051

COT 4C Isolation Valve from COW line to submerged machine

CLOSED

26-SV-019

COT 4C Isolation Valve for portable tank cleaning pump

CLOSED

No 4 Starboard Cargo Tank Refer to P&ID BON-SHI-008-P-000002-012 26-ZCV-045

Cargo Pump P-2601J discharge isolation valve

CLOSED

26-BLV-019

Cargo Pump P-2601J stripping isolation valve

CLOSED

26-BUV-029

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-089

Lower transfer line to No 3S COT

CLOSED

26-ZCV-100

Lower transfer line to No 5S COT

CLOSED

26-ZCV-093

Lower transfer line to No 4C COT

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-021 26-GTV-023

COT 4S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-024

COT 4S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-052

COT 4S Isolation Valve from COW line to Tank Top machine

CLOSED

26-SV-020

COT 4S Isolation Valve for portable tank cleaning pump

CLOSED

Cargo Oil Tank Nos 5 P, C&S Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-138

Isolation Valve on Cargo Pump common discharge to Discharge Header

CLOSED

26-ZCV-139

Isolation Valve on Cargo Pump common discharge to Transfer Header

CLOSED

No 5 Port Cargo Tank Refer to P&ID BON-SHI-008-P-000002-011 26-ZCV-046

Cargo Pump P-2601O discharge isolation valve

CLOSED

26-BLV-010

Cargo Pump P-2601O stripping isolation valve

CLOSED

26-BUV-030

Manual Isolation Valve for Portable Cargo Pump discharge

CLOSED

26-ZCV-095

Lower transfer line to No 4P COT

CLOSED

26-ZCV-104

Lower transfer line to No 5C COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-018 26-BUV-067

Isolation Valve on COW Header to No 5 COTs PC&S

CLOSED

Refer to P&ID BON-SHI-008-P-000002-020 26-GTV-025

COT 5P Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-026

COT 5P Isolation Valve from COW line to Tank Top

CLOSED

26-GTV-053

COT 5P Isolation Valve from COW line to Tank Top

CLOSED

26-SV-021

COT 5P Isolation Valve for portable tank cleaning pump

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

Checked

No 5 Centre Cargo Tank Refer to P&ID BON-SHI-008-P-000002-011 26-ZCV-047

Cargo Pump P-2601N discharge isolation valve

CLOSED

26-ZCV-048

Cargo Pump P-2601N discharge isolation valve

CLOSED

26-ZCV-042

Cargo Pump P-2601N to dirty slop tank

CLOSED

26-BLV-011

Cargo Pump P-2601N stripping isolation valve

CLOSED

26-BUV-031

Manual Isolation Valve on tie-in for Portable Cargo Pump discharge

CLOSED

26-ZCV-097

Lower transfer line to No 4C COT

CLOSED

26-ZCV-102

Upper cascade line from 5C COT

CLOSED

26-ZCV-103

Lower transfer line to No 5P COT

CLOSED

26-ZCV-105

Lower transfer line to No 5C COT

CLOSED

26-ZCV-107

Lower transfer line to 5C COT

CLOSED

Refer to P&ID BON-SHI-008-P-000002-020 26-GTV-027

COT 5C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-028

COT 5C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-054

COT 5C Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-055

COT 5C Isolation Valve from COW line to submerged machine

CLOSED

26-GTV-056

COT 5C Isolation Valve from COW line to submerged machine

CLOSED

26-SV-022

COT 5C Isolation Valve for portable tank cleaning pump

CLOSED

No 5 Starboard Cargo Tank Refer to P&ID BON-SHI-008-P-000002-011 26-ZCV-049

Cargo Pump P-2601M discharge isolation valve

CLOSED

26-BLV-012

Cargo Pump P-2601M stripping isolation valve

CLOSED

26-BUV-032

Manual Isolation Valve on tie-in for Portable Cargo Pump discharge

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 1: PRE-START POSITIONS CARGO TANKS 1 TO 5 (cont’d) Tag No

Function

Setting

26-ZCV-099

Lower transfer line to No 4S COT

CLOSED

26-ZCV-106

Lower transfer line to No 5C COT

CLOSED

Checked

Refer to P&ID BON-SHI-008-P-000002-020 26-GTV-029

COT 5S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-030

COT 5S Isolation Valve from COW line to Tank Top machine

CLOSED

26-GTV-057

COT 5S Isolation Valve from COW line to Tank Top machine

CLOSED

Part 2 Section 1 System Operating Procedures

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PRE-START CHECKS AND CONDITIONS Step

Action

1

CHECK that all Instrument Isolating Valves are OPEN.

2

CHECK that all Sample Point Isolation Valves are CLOSED and blanked.

3

CHECK that the ESS System is healthy, with any previous ESS being RESET.

4

CHECK that Isolation Valves are in the closed position as indicated in the following Valve Checklist 1 Pre-start Positions: •

Cargo Oil Tank No 1 Port, Centre and Starboard

•

Cargo Oil Tank No 2 Port, Centre and Starboard

•

Cargo Oil Tank No 3 Port, Centre and Starboard

•

Crude Oil Tank No 4 Port, Centre and Starboard

•

Cargo Oil Tank No 5 Port, Centre and Starboard

Note: The initial line-up of closed valves are itemised in Valve Checklist 1. Where indicated in the text, Checklists 2 and 3 are used in the separate procedures for tank filling which follow. 5

ENSURE that the Nakakita Hydraulic System is operating normally and high-pressure hydraulic oil is available at 90barg. The Nakakita Local Control Panel must be SET to Remote control to allow the Isolation Valves to be OPENED and CLOSED from the DCS Console in the DCS.

6

CONFIRM that the oxygen concentration in the Inert Gas System is less than 5% (Volume).

7

CONFIRM that the Dirty Inert Gas Main (DIGM) is connected and open to all Cargo and Slop Tanks.

CARGO LOADING MUST NOT PROCEED UNTIL ALL CARGO OIL TANKS ARE FILLED WITH INERT GAS. THIS IS TO PREVENT ANY INGRESS OF OXYGEN THAT COULD RESULT IN A POTENTIALLY HAZARDOUS ATMOSPHERE WITHIN THE TANKS. 8

ENSURE that the overflow from the Flare Scrubber V-4640 is lined up to either the dirty slop tank or the primary reception tank.

9

Prior to commencement of Cargo Loading or any Ballasting adjustments, a complete simulation of the Loading Sequence must be completed by the Loading Computer.

10

The Loading Plan has been issued by the Marine Supervisor and approved by the OIM.

Part 2 Section 1 System Operating Procedures

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PROCEDURE FOR LOADING VIA RECEPTION TANK 3C TO GROUP A TANKS NOS 2 AND 4 The system isolation valves are positioned as indicated in the following Valve Checklist No 2. VALVE CHECKLIST No 2: PRE-START POSITIONS: LOADING VIA RECEPTION TANK 3C TO GROUP A TANKS (NOS 2 AND 4) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-008 26-BUV-001

Fwd Isolation Valve on loading header

OPEN

26-ZCV-009

Isolation Valve on loading header Fwd of Import

OPEN

26-GBV-023

Drain Valve between 26-BUV-001 and 26-ZCV-009

CLOSED

26-BUV-011

Aft Isolation Valve on loading header

OPEN

26-ZCV-022

Isolation Valve on loading header Aft of Import

OPEN

26-GBV-024

Drain Valve between BUV-011 and ZCV-022

CLOSED

26-ZCV-010

Master Isolation Valve on No 1 COTs loading header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-015 26-ZCV-011

COT 1P Loading Valve

CLOSED

26-BUV-002

COT 1P Manual Isolation Valve

OPEN

26-ZCV-012

COT 1C Loading Valve

CLOSED

26-BUV-003

COT 1C Manual Isolation Valve

OPEN

26-ZCV-013

COT 1S Loading Valve

CLOSED

26-BUV-004

COT 1S Manual Isolation Valve

OPEN

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-014

Master Isolation Valve No 2 COTs loading Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-014 26-ZCV-015

COT 2P Loading Valve

CLOSED

26-BUV-005

COT 2P Manual Isolation Valve

OPEN

26-ZCV-016

COT 2C Loading Valve

CLOSED

26-BUV-006

COT 2C Manual Isolation Valve

OPEN

26-ZCV-017

COT 2S Loading Valve

CLOSED

26-BUV-007

COT 2S Manual Isolation Valve

OPEN

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 2: PRE-START POSITIONS: LOADING VIA RECEPTION TANK 3C TO GROUP A TANKS (NOS 2 AND 4) (cont’d) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-018

Master Isolation Valve No 3 COTs Loading Header

OPEN

Refer to P&ID BON-SHI-008-P-000002-013 26-ZCV-019

COT Loading Valve

CLOSED

26-BUV-008

COT 3P Manual Isolation Valve

OPEN

26-ZCV-020

COT 3C Loading Valve

OPEN

26-BUV-009

COT 3C Manual Isolation Valve

OPEN

26-ZCV-021

COT 3S Loading Valve

CLOSED

26-BUV-010

COT 3S manual Isolation Valve

OPEN

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-023

Master Isolation Valve No 4 COTs Loading Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-012 26-ZCV-024

COT 4P Loading Valve

CLOSED

26-BUV-012

COT 4P Manual Isolation Valve

OPEN

26-ZCV-025

COT 4C Loading Valve

CLOSED

26-BUV-013

COT 4C Manual Isolation Valve

OPEN

26-ZCV-026

COT 4S Loading Valve

CLOSED

26-BUV-014

COT 4S Manual Isolation Valve

OPEN

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-027

Master Isolation Valve No 5 COTs Loading Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-011 26-ZCV-028

Actuated Valve on loading header to No 5P COT

CLOSED

26-BUV-015

Manual Valve on loading header to No 5P COT

OPEN

26-ZCV-029

Actuated Valve on loading header to No 5C COT

CLOSED

26-BUV-016

Manual Valve on loading header to No 5C COT

OPEN

26-ZCV-030

Actuated Valve on loading header to No 5S COT

CLOSED

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 2: PRE-START POSITIONS: LOADING VIA RECEPTION TANK 3C TO GROUP A TANKS (NOS 2 AND 4) (cont’d) Tag No

Function

Setting

Checked

Before Reception Tank 3C Reaches 70% Full Refer to P&ID BON-SHI-008-P-000002-013 26-ZCV-101

Skim valve 70% line in 3C

OPEN

26-ZCV-084

Lower transfer line to No 4C COT (in 4C)

OPEN

26-ZCV-085

Lower transfer line to No 4C COT (in 3C)

OPEN

26-ZCV-086

Lower transfer line 3C suction (0%)

CLOSED

26-ZCV-087

Lower transfer line to No 2C COT (in 3C)

OPEN

26-ZCV-088

Lower transfer line to No 2C COT (in 2C)

OPEN

Refer to P&ID BON-SHI-008-P-000002-014 26-ZCV-076

Valve 2C – 2P levelling (2C)

OPEN

26-ZCV-077

Valve 2C – 2P levelling (2P)

OPEN

26-ZCV-078

Valve 2C – 2S levelling (2S)

OPEN

26-ZCV-079

Valve 2C – 2S levelling (2C)

OPEN

Refer to P&ID BON-SHI-008-P-000002-012 26-ZCV-091

Valve 4C – 4P levelling (4C)

OPEN

26-ZCV-092

Valve 4C – 4P levelling (4P)

OPEN

26-ZCV-093

Valve 4C – 4S levelling (4S)

OPEN

26-ZCV-094

Valve 4C – 4S levelling (4C)

OPEN

Part 2 Section 1 System Operating Procedures

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PROCEDURE FOR LOADING VIA RECEPTION TANK C TO GROUP A TANKS NOS 2 AND 4

THE WHOLE OF THIS PROCEDURE MUST BE READ THROUGH AND FULLY UNDERSTOOD BEFORE CARRYING OUT ANY OF THE FOLLOWING ACTIONS.

THE CARGO LOADING OPERATION CANNOT COMMENCE UNTIL THE DECK HYDRAULIC SYSTEMS ARE PRESSURISED AND THE INERT GAS SYSTEM IS OPERATING NORMALLY.

PREAMBLE This Procedure covers the start-up of the Cargo System after a major planned shutdown. After completion of the Procedure, the cargo of crude oil may be offloaded to the Offtake Tanker, as detailed in POPM Volume 5 Oil Metering and Export System (OPRM-2003-0305). Ballast changes are required as cargo is taken onboard. The Procedure for Ballast Changes is detailed in Procedure No 1/002. As an example the general outline for the start-up of the Cargo System is as follows: •

Fill Reception Tank 3C to 70%

•

Cascade to No 2C and 4C COTs

•

Simultaneously transfer by gravity to No (Port and Starboard) wing COTs (Group A tanks)

•

Further transfer of cargo may be either by gravity or pumped from No 2C and 4C

•

Reduce Ballast in accordance with the approved Loading Plan

•

Offload to export tanker when sufficient cargo is available

2

(Port

and

Starboard)

and

4

Pre-requisites The Crude Oil Production facilities are PREPARED for start-up. (The level control valve for the Oil Degassing Tank V-2344 located downstream of Crude Cooler E-2540C regulates the flowrate of stabilised crude oil from the production facilities to the crude oil loading header.) The Loading Header is lined up to fill Cargo Tank 3C. The Water Ballast System is PREPARED for operation as described in Procedure No 1/002. The Port and Starboard Slop tanks are AVAILABLE for use. ENSURE de-ballasting is carried out as per loading plan.

Part 2 Section 1 System Operating Procedures

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PROCEDURE Step

Action

1

START UP the Oil Production System.

2

MONITOR the rising oil level in the reception tank from the DCS console.

3

MONITOR the operating pressure in the cargo tanks and DIGM.

4

OPEN the cascade system to Nos 2C and 4C COT by OPENING valves 26-ZCV-084/085/087/088 and 26-ZCV-101. Note: As the level reaches 70% oil will flow to Cargo Tanks 2C and 4C.

5

OPEN levelling valves between No 2C and No 2 Port and Starboard Wing COTs, and No 4C and 4 Port and Starboard Wing COTs, as shown below.

Levelling Valves

Port

Starboard

No 2 Cargo Tanks

26-ZCV-076/077

26-ZCV-078/079

No 4 Cargo Tanks

26-ZCV-091/092

26-ZCV-093/094

Group A Tanks are now being loaded: 6

MONITOR the rising oil level in the Group A Tanks COT 2 and 4 Port, Centre and Starboard.

7

DE-BALLAST as required in line with the loading plan.

8

CONTINUE to monitor individual tank levels in Group A.

9

CLOSE the levelling valves as the level approaches 90% to the individual wing tanks as listed above. Note: The reception tank level will rise above 70% and lead the levels in the other tanks. The wing tanks will be later topped off to 95% using a suitable cargo pump and the transfer header.

10

CONTINUE to load by gravity. When the wing tanks are at 90%:

11

CLOSE the levelling valves to the corresponding centre tank and OPEN the levelling valves between adjacent Centre Tanks 2C to 1C, and 4C to 5C as shown below.

Levelling Valves

2C – 1C

4C – 5C

26-ZCV-072/073

26-ZCV-097/098

12

If it is intended to continue loading by pumping from 2C and 4C COT it should be started by topping up COT 2 and 4 Wing Tanks to 95%, then fill COT 2C and 4C to 90%.

13

Pump from 2C and 4C to the Group B tanks, in general to the Centre COTs (1C and 5C) first followed by the wing tanks.

Part 2 Section 1 System Operating Procedures

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Step

Action

14

This will be an intermittent operation as crude oil becomes available in COTs 2C and 4C, FILL 2C and 4C to 70%.

15

PUMP crude to the selected Group B tanks until 2C and 4C are reduced to 10%.

16

REPEAT until Group B tanks are full or until discharge to an export tanker starts. Notes:

17

(1)

At this stage there is enough crude onboard to export if a tanker is available.

(2)

It is possible to open the levelling valves between Nos 1 and 2 across COT and Nos 4 and 5 across COT; it is good operating practice to restrict the number of tanks common to each other.

CONTINUE loading by gravity. WHEN COTs 2C/1C and 4C/5C are at a level of 85%:

18

OPEN the levelling valves between COT 2 and 1 wings (26-ZCV-070/071/074/075) and between COT 4 and 5 wings (26-ZCV-095/096/099/100) until the tanks are level, CLOSE the valves. WHEN COTs 2C and 4C reach 90%:

19

OPEN (simultaneously) the levelling valves between 2C and 2 wings, and CLOSE the levelling valves between COTs 2C an 1C. WHEN COTs 4C and 5C reach 90%:

20

OPEN (simultaneously) the levelling valves between COTs 4C and 4 wings, and CLOSE the levelling valves between COTs 4C and 5C. Note: When the tanks reach 90%, any remaining cargo transfer and topping off tanks will be by cargo pump. WHEN COTs 2C and 4C reach 90%:

21

LEVEL COTs 1 and 2 (and 4 and 5) wing tanks via the levelling valves (to 90%).

22

Close the levelling valves.

23

CONTINUE to fill COTs 2C and 4C to 90%.

24

FILL all other tanks via the cargo pumps to the required level.

Part 2 Section 1 System Operating Procedures

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PROCEDURE FOR DIRECT LOADING TO GROUP A TANKS, NOS 2 AND 4 The system isolation valves are positioned as indicated in the following Valve Checklist. VALVE CHECKLIST No 3: PRE-START POSITIONS: DIRECT LOADING TO GROUP A TANKS (NOS 2 AND 4) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-008 26-BUV-001

Fwd Isolation Valve on loading header

OPEN

26-ZCV-009

Isolation Valve on loading header Fwd of Import

OPEN

26-GBV-023

Drain Valve between 26-BUV-001 and 26-ZCV-009

CLOSED

26-BUV-011

Aft Isolation Valve on loading header

OPEN

26-ZCV-022

Isolation Valve on loading header Aft of Import

OPEN

26-GBV-024

Drain Valve between BUV-011 and ZCV-022

CLOSED

26-ZCV-010

Master Isolation Valve on No 1 COTs Loading Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-015 26-ZCV-011

COT 1P Loading Valve

CLOSED

26-BUV-002

COT 1P Manual Loading Valve

OPEN

26-ZCV-012

COT 1C Loading Valve

CLOSED

26-BUV-003

COT 1C Manual Loading Valve

OPEN

26-ZCV-013

COT 1S Loading Valve

CLOSED

26-BUV-004

COT 1S Manual Loading Valve

OPEN

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-014

Master Isolation Valve on No 2 COTs Loading Header

OPEN

Refer to P&ID BON-SHI-008-P-000002-014 26-ZCV-015

COT 2P Loading Valve

OPEN

26-BUV-005

COT 2P Manual Loading Valve

OPEN

26-ZCV-016

COT 2C Loading Valve

OPEN

26-BUV-006

COT 2C Manual Loading Valve

OPEN

26-ZCV-017

COT 2S Loading Valve

OPEN

26-BUV-007

COT 2S Manual Loading Valve

OPEN

Part 2 Section 1 System Operating Procedures

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VALVE CHECKLIST No 3: PRE-START POSITIONS: DIRECT LOADING TO GROUP A TANKS (NOS 2 AND 4) (cont’d) Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-018

Master Isolation Valve on No 3 COTs Loading Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-013 26-ZCV-019

COT 3P Loading Valve

CLOSED

26-BUV-008

COT 3P Manual Loading Valve

OPEN

26-ZCV-020

COT 3C Loading Valve

CLOSED

26-BUV-009

COT 3C Manual Loading Valve

OPEN

26-ZCV-021

COT 3S Loading Valve

CLOSED

26-BUV-010

COT 3S Manual Loading Valve

OPEN

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-023

Master Isolation Valve on No 4 COTs Loading Header

OPEN

Refer to P&ID BON-SHI-008-P-000002-012 26-ZCV-024

COT 4P Loading Valve

OPEN

26-BUV-012

COT 4P Manual Loading Valve

OPEN

26-ZCV-025

COT 4C Loading Valve

OPEN

26-BUV-013

COT 4C Manual Loading Valve

OPEN

26-ZCV-026

COT 4S Loading Valve

OPEN

26-BUV-014

COT 4S Manual Loading Valve

OPEN

Refer to P&ID BON-SHI-008-P-000002-008 26-ZCV-027

Master Isolation Valve on No 5 COTs Loading Header

CLOSED

Refer to P&ID BON-SHI-008-P-000002-011 26-ZCV-028

COT 5P Loading Valve

CLOSED

26-BUV-015

COT 5P Manual Loading Valve

OPEN

26-ZCV-029

COT 5C Loading Valve

CLOSED

26-BUV-016

COT 5C Manual Loading Valve

OPEN

26-ZCV-030

COT 5S Loading Valve

CLOSED

26-BUV-017

COT 5S Manual Loading Valve

OPEN

Part 2 Section 1 System Operating Procedures

OPRM-2003-0304

Page 23 of 38

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PROCEDURE FOR DIRECT LOADING TO GROUP A TANKS NOS 2 AND 4

THE WHOLE OF THIS PROCEDURE MUST BE READ THROUGH AND FULLY UNDERSTOOD BEFORE CARRYING OUT ANY OF THE FOLLOWING ACTIONS.

THE CARGO LOADING OPERATION CANNOT COMMENCE UNTIL THE DECK HYDRAULIC SYSTEMS ARE PRESSURISED AND THE INERT GAS SYSTEM IS AVAILABLE.

PREAMBLE This Procedure will be used if the Reception Tank 3C that is normally used is out of service.

PROCEDURE Step

Action

1

ENSURE the Crude Oil Production facilities are PREPARED for start-up. The Level Controller on the Crude Oil Cooler will REGULATE the flowrate of Stabilised Crude Oil from the Production Facilities to the Crude Oil Loading Header.

2

ENSURE the Water Ballast System is PREPARED for Cargo Loading as described in Procedure No 1/002.

3

ENSURE the Primary and Secondary Slop Tanks are AVAILABLE for use.

4

START UP the Oil Production System. Once Crude Oil production is established in the Stabilised Crude, oil will be passed from the topside process system through the Crude Coolers to the Loading Header. The Loading Header then directs the crude oil through the Crude Oil Loading Mains to the Group A Cargo Tanks. Note: If the produced oil/water content is high, the crude should be directed to Reception Tank 3C until the produced oil has a BS&W of less than 0.5%.

5

MONITOR the rising oil level in the Group A tanks, COT 2 and 4 Port, Centre and Starboard from the DCS Console. Also OBSERVE the operating pressure in the Cargo Tanks and DIGM.

6

As the level in Group A COT approaches 50%, start pumping out ballast as described in Procedure No 1/002 and in accordance with the Loading Plan.

7

CARRY OUT a daily TANK SOUNDING to determine the amount of water in the Cargo Tanks. If there is sufficient to justify removal, pump out the water from the tank to the port slop tank using a cargo pump and the transfer line.

Part 2 Section 1 System Operating Procedures

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Step

Action

8

CONTINUE to monitor individual tank levels in Group A as the level approaches 95% in the tanks. Open the valves on the headers and drop lines to Group B COTs and isolate each Group A tank as it reaches 95% level by closing the respective tank valve. When all Group A tanks are complete, close the isolation valves on the loading headers to those tanks. Isolation Valves Cargo Tanks and Headers Group A No 2 PC&S Cargo Tank

26-ZCV-015

No 2 loading header isolation

26-ZCV-014

No 4 PC&S Cargo Tank

26-ZCV-024

No 4 loading header isolation

26-ZCV-023

26-ZCV-016

26-ZCV-017

26-ZCV-025

26-ZCV-026

26-ZCV-012

26-ZCV-013

26-ZCV-020

26-ZCV-021

26-ZCV-029

26-ZCV-030

Group B No 1 PC&S Cargo Tank

26-ZCV-011

No 1 loading header isolation

26-ZCV-010

No 3 PC&S Cargo Tank

26-ZCV-019

No 3 loading header isolation

26-ZCV-018

No 5 PC&S Cargo Tank

26-ZCV-028

No 5 loading header isolation

26-ZCV-027

9

Perform Tank Sounding to determine water level in the Group A COTs. Remove excess water as described in the Procedure in Offloading Facilities in POPM Volume 5 Oil Metering and Export System (OPRM-2003-0305).

10

When water is removed from the Group A COTs, top-off the COTs by opening the individual tank drop lines and closing when the level reaches 95%.

11

The Group A tanks are now ready for transfer to an export tanker as described in POPM Volume 5 Oil Metering and Export System (OPRM-2003-0305), Group B tanks are filling and further ballast adjustments should be made as identified in the Loading Plan.

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OIL STORAGE, HANDLING AND BALLAST

PROCEDURE NO 1/002: BALLAST OPERATIONS

THE WHOLE OF THIS PROCEDURE MUST BE READ THROUGH AND FULLY UNDERSTOOD BEFORE CARRYING OUT ANY OF THE FOLLOWING ACTIONS.

INTRODUCTION This Procedure details the operator actions required to be carried out on the Ballast System prior to and during loading/offloading operations. In the procedure it is assumed that Group A Cargo Tanks (COT 2 and 4) are to be filled first and offloaded first. Similar Procedures will be required when loading via the reception tank. The Ballast System has a semi-automatic function for ballasting, de-ballasting and line flooding. This function can be overridden to give manual control. Interlocks on the DCS ensure only two ballast pumps can be operated at a time, normally one each port and starboard. The ballast ringmain is constructed of GRP and, under some circumstances, could be susceptible to surge damage if not completely filled with seawater. Whilst a system is fitted to warn of an empty ringmain, it is good operating practice when starting to ballast empty tanks to start by either using the flooding procedure or restricting the pump speed until the tank level is seen to start rising.

PRECONDITIONS Supporting Drawings The procedure utilises the following P&IDs: •

BON-SHI-008-P-00002-001 and 002 Ballast System

•

BON-SHI-008-P-00002-004 Air and Sounding System (1/2)

Interface Systems Before ballast operations can take place, the following systems are required to be operational: •

Sludge and Bilge Systems. Refer to POPM Volume 18 (OPRM-2003-0318)

•

Seawater System. Refer to POPM Volume 21 (OPRM-2003-0321)

•

Fresh/Potable Water System. Refer to POPM Volume 22 (OPRM-2003-0322)

•

Instrument and Utility Air System. Refer to POPM Volume 25 (OPRM-2003-0325)

•

Power Generation and Distribution System. Refer to POPM Volume 30 (OPRM-2003-0330)

•

Deck Hydraulic Systems. Refer to POPM Volume 33 (OPRM-2003-0333)

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Pre-requisites No Work Permits are in force that will prohibit any part of this Procedure and all relevant Hot Work Tags have been returned to the Installation Control Centre. Fire, Gas and Safety Systems are commissioned and are in readiness for operation.

PLANT STATUS The system isolation valves are positioned as indicated in the following Valve Checklists. Valve Checklist No 1 indicates that all main Ballast Ringmain Valves are closed. •

Valve Checklist No 1: Start-up positions: Ballast Pumps (indicates initially all Ballast Pump Valves are closed)

•

Valve Checklist No 2: Start-up positions port Ballast Main (indicates initially all port Ballast Main Valves are closed with the exception of 58-ZCV-147)

•

Valve Checklist No 3: Start-up positions starboard Ballast Main (indicates initially all starboard Ballast Main Valves are closed with the exception of 58-ZCV-148)

Assuming all Cargo Tanks are empty, the status of the Ballast Tanks at start of loading is as follows: •

The APWBT is empty but available for use

•

The Port and Starboard WBTs 1 to 6 contain seawater

•

The FPBT is empty but available for use

•

The Port and Starboard submerged Ballast Pumps are available for operation

•

The Port and Starboard Ballast Lines interconnecting all WBTs are available for use

Assuming all Group A Cargo Tanks are full, the status of the Ballast Tanks at start of offloading is as follows: •

The APWBT is empty but available for use

•

The Port and Starboard WBTs 1 and 4 are empty, No 3 WBTs are reduced to 6100 tonnes and No 6 WBTs are reduced to 1700 tonnes

•

The FPBT is empty but available for use

•

The Port and Starboard submerged Ballast Pumps are available for operation

•

The Port and Starboard Ballast Lines interconnecting all WBTs are available for use

•

Cargo offloading main is available for use

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VALVE CHECKLIST No 1: START-UP POSITIONS: BALLAST PUMPS Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-000002-001 Port Ballast Pump 58-ZCV-103, 106

Actuated Valves on suction from port ballast main

CLOSED

58-ZCV-101

1st in-line Actuated Valve on suction from port sea chest

CLOSED

58-ZCV-102, 105

2nd in-line Actuated Valves on suction from port sea chest

CLOSED

58-ZCV-104, 107

Actuated Valves on discharge from port ballast pump

CLOSED

58-ZCV-145

Actuated Valve on pump discharge overboard

CLOSED

58-ZCV-149

Actuated Valve on pump discharge to port ballast main

CLOSED

Starboard Ballast Pump 58-ZCV-110, 113

Actuated Valve on suction from starboard ballast main

CLOSED

58-ZCV-108

1st in-line Actuated Valve on suction from starboard sea chest

CLOSED

58-ZCV-109, 112

2nd in-line Actuated Valve on suction from starboard sea chest

CLOSED

58-ZCV-111, 114

Actuated Valve on discharge from starboard ballast pump

CLOSED

58-ZCV-146

Actuated Valve on pump discharge overboard

CLOSED

58-ZCV-150

Actuated Valve on pump discharge to starboard ballast main

CLOSED

58-BUV-102

Manual Valve on pump discharge to tank cleaning line

CLOSED

58-BUV-101

Manual Valve on pump discharge to cargo transfer header

CLOSED

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VALVE CHECKLIST No 2: START-UP POSITIONS: PORT BALLAST MAIN Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-000002-001/002 58-ZCV-147

Port ballast main actuated section isolation valve at No 4 WBT

OPEN

58-ZCV-141

Port ballast main actuated section isolation valve at FPT

CLOSED

58-ZCV-139

Actuated Valve at FPT Suction/Discharge nozzle

CLOSED

58-ZCV-115

Actuated Valve at 1st No 1 P WBT Suction/Discharge nozzle

CLOSED

58-ZCV-116

Actuated Valve at 2nd No 1 P WBT Suction/Discharge nozzle

CLOSED

58-ZCV-119

Actuated Valve at 1st No 2 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-120

Actuated Valve at 2nd No 2 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-123

Actuated Valve at 1st No 3 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-124

Actuated Valve at 2nd No 3 WBT Suction/Discharge nozzle

CLOSED

58-ZCV-127

Actuated Valve at 1st No 4 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-128

Actuated Valve at 2nd No 4 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-131

Actuated Valve at 1st No 5 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-132

Actuated Valve at 2nd No 5 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-135

Actuated Valve at 1st No 6 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-136

Actuated Valve at 2nd No 6 port WBT Suction/Discharge nozzle

CLOSED

58-ZCV-143

Actuated Valve at Aft peak tank Suction/Discharge nozzle

CLOSED

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VALVE CHECKLIST No 3: START-UP POSITIONS: STARBOARD BALLAST MAIN Tag No

Function

Setting

Checked

Refer to P&ID BON-SHI-008-000002-001/002 58-ZCV-148

Stbd ballast main actuated section isolation valve at No 4 WBT

OPEN

58-ZCV-142

Stbd ballast main actuated section isolation valve at FPT

CLOSED

58-ZCV-140

Actuated Valve at FPT Suction/Discharge Nozzle

CLOSED

58-ZCV-117

Actuated Valve at 1st No 1S WBT Suction/Discharge nozzle

CLOSED

58-ZCV-118

Actuated Valve at 2nd No 1S WBT Suction/Discharge nozzle

CLOSED

58-ZCV-121

Actuated Valve at 1st No 2 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-122

Actuated Valve at 2nd No 2 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-125

Actuated Valve at 1st No 3 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-126

Actuated Valve at 2nd No 3 WBT Suction/Discharge nozzle

CLOSED

58-ZCV-129

Actuated Valve at 1st No 4 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-130

Actuated Valve at 2nd No 4 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-133

Actuated Valve at 1st No 5 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-134

Actuated Valve at 2nd No 5 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-137

Actuated Valve at 1st No 6 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-138

Actuated Valve at 2nd No 6 Stbd WBT Suction/Discharge nozzle

CLOSED

58-ZCV-144

Actuated Valve at Aft peak tank Suction/Discharge nozzle

CLOSED

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PRE-START CHECKS AND CONDITIONS Step

Action

1

CHECK that Isolation Valves are positioned as indicated in the following Valve Checklists: •

Valve Checklist 1 Pre-start Positions: Ballast Facilities

•

Valve Checklist 2 Pre-start Positions: Port Ballast Main and Tanks

•

Valve Checklist 3 Pre-start Positions: Starboard Ballast Main and Tanks

2

ENSURE that the Nakakita Valve Hydraulic System is operating normally and high-pressure hydraulic oil is available at 90barg for the operation of the isolation valves. The Nakakita Local Control Panel must be set to Remote control to allow the Isolation Valves to be OPENED and CLOSED from the DCS Console in the CCR.

3

Prior to commencement of Cargo Loading or any Ballasting adjustments, a complete simulation of the Loading Sequence must be completed on the Loading Computer.

4

The Loading/Ballast Plan has been issued by the Marine Supervisor and approved by the OIM.

5

ENSURE that the Framo Hydraulic System is operating normally and high-pressure hydraulic oil is available for operation of the Ballast Pump Motors. The Framo Control Panel must be set to Remote control to allow the Ballast Pumps to be operated from the DCS Console.

6

ENSURE that the set points for the Ballast Pump Speed Controllers are set to zero on the DCS Console.

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THE WHOLE OF THIS PROCEDURE MUST BE READ THROUGH AND FULLY UNDERSTOOD BEFORE CARRYING OUT ANY OF THE FOLLOWING ACTIONS.

NORMALLY BALLAST WATER WILL BE TRANSFERRED EITHER INTO THE HULL, OUT OF THE HULL, OR GRAVITATED BETWEEN TANKS (ONE OPERATION AT ANY ONE TIME).

BALLAST WATER CANNOT BE PUMPED FROM TANK TO TANK.

THE CARGO PLANNING PROCEDURE MUST BE COMPILED AT ALL TIMES WHEN TRANSFERRING WEIGHTS WITHIN THE HULL. PROCEDURE FOR DE-BALLASTING (MANUAL OPERATION) Step

Action

1

When the requirement to de-ballast is identified in the loading plan, check on the Load Computer that during the intended ballast changes the vessel is and will remain within permissible trim, stability and stress limits. For this procedure it is assumed that de-ballasting will take place using ballast pumps P-5804A and C, initially from No 2 WBT followed by No 4, No 3 and No 6 P&S WBTs during the loading of the Group A Cargo Tanks. Only the 20in suction valves in each Ballast Tank are used during normal de-ballasting operations.

2

OPEN the Isolation Valves 58-ZCV-103 from the Port Ballast Main to Port Ballast Water Pump P-5804A suction.

3

OPEN the Isolation Valve ZCV-104 and 145 on the Port Ballast Water Pump P-5804A Discharge to overboard.

4

OPEN the Isolation Valves ZCV-110 from the Starboard Ballast Main to Port Ballast Water Pump P-5804C suction.

5

OPEN the Isolation Valve ZCV-111 and 146 on the Starboard Ballast Water Pump P-8504C Discharge to overboard.

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Step

Action

6

OPEN the Tank Valves ZCV-119 and ZCV-121 on the Port and Starboard No 2 WBTs respectively.

7

SET pump outputs to 5% then START Ballast Water Pumps P-5804A and P-5804C. ENSURE the level in the Port and Starboard No 2 WBTs is decreasing. ENSURE that the levels in all other Ballast Tanks are not changing.

8

Record the time of commencement and the Ballast volume onboard at that time. Total ballast onboard from the Load Computer display will normally suffice.

9

Adjust the ballast pump speed to reduce the ballast at the correct rate to meet the requirement of the loading plan.

10

Monitor the surface of the sea around the overboard discharges at intervals to ensure that any cargo or hydraulic oil leakage into the Ballast Tank is detected as soon as possible.

11

Monitor hull criteria on the Load Computer during the transfer. List may develop rapidly, particularly during the start and end of the de-ballast transfer. MAINTAIN the port and starboard tank levels approximately equal at all times by adjusting the speed of the port or starboard pumps.

12

When required in the loading plan, OPEN the Tank Valves ZCV-127 and ZCV-129 on the Port and Starboard No 4 WBTs respectively.

13

Open and close as required the tank suction valves on No 2 and No 4 WBTs to control the de-ballasting from each tank at the correct rate to meet the requirement of the loading plan.

14

When No 2 WBT Port and Starboard are empty, CLOSE the tank valves ZCV-119 and ZCV-121 on the Port and Starboard No 2 WBTs respectively.

15

ADJUST the ballast pump speed to control the de-ballasting from each tank at the correct rate to meet the requirement of the loading plan.

16

As further de-ballasting is required, OPEN the tank valves on the tanks to be emptied, ADJUSTING the rates for other tanks (via opening and closing the appropriate valves) already de-ballasting accordingly. This is necessary to maintain the de-ballasting schedule in accordance with the loading plan simulation.

17

When the ballast operation is complete, SET pump outputs to zero, STOP and ISOLATE the ballast pumps and CLOSE all WBT Tank valves.

18

Log the time of completion of ballast and record the Ballast Tank levels and volumes.

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PROCEDURE FOR DE-BALLASTING (SEMI-AUTOMATIC OPERATION) Step

Action For this procedure it is assumed that de-ballasting will take place using ballast pumps P-5804A and C, initially from No 2 WBTs followed by No 4, No 3 and No 6 P&S WBTs during the loading of the Group A Cargo Tanks. Only the 20in suction valves in each Ballast Tank are used during normal de-ballasting operations.

1

OPEN the Tank Valves ZCV-119 and ZCV-121, on the Port and Starboard No 2 WBTs respectively.

2

On the DCS screen, SELECT the ‘de-ballasting’ button and SELECT the ‘sequence’ button for pumps P-5804A and C. The associated valves will be opened (58-ZCV-103/145 and 58-ZCV-110/146) and provided all the interlock conditions are met, the pump will be automatically started with pump output set to 5%. Once confirmation that the pump is operating (from the discharge line pressure transmitter 58-PIT-103/109), the discharge valves (58-ZCV-104/111) will be automatically opened to 5% initially, then the valve may be opened further from the valve overlay on the DCS screen and the pump speed increased as required.

3

FOLLOW Steps 8 to 16 under De-ballasting (Manual Operation).

4

When the pumps are stopped from the DCS overlay, the starting sequence shall be reversed – stopping the pumps and then closing the isolation valves (58-ZCV-103/145 and 58-ZCV-110/146). If the sequence is manually overridden and the pump is stopped, the valves will remain in the open position until closed by the operator.

5

CLOSE all WBT tank valves and log the time of completion of Ballast and record the Ballast tank levels and volumes.

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PROCEDURE FOR BALLASTING (MANUAL OPERATION) Step

Action

1

When the requirement to increase ballast is identified in the loading plan, check on the Load Computer that during the intended ballast changes the vessel is and will remain within permissible trim, stability and stress limits. For this procedure it is assumed that water ballast will be increased using ballast pumps P-5804A and C, initially filling No 3 and No 6 WBTs followed by No 4 P&S WBTs during the offloading of the Group A Cargo Tanks. Only the 20in suction valves in each Ballast Tank are used during normal de-ballasting operations.

2

OPEN the Isolation Valves ZCV-101/102 from the sea chest to Port Ballast Water Pump P-5804A suction.

3

OPEN the Isolation Valve ZCV-104 and ZCV-149 on the Port Ballast Water Pump P-5804A. Discharge to the port ballast main.

4

OPEN the Isolation Valves ZCV-108/109 from the sea chest to Starboard Ballast Water Pump P-5804C suction.

5

OPEN the Isolation Valve ZCV-111 and ZCV-150 on the Starboard Ballast Water Pump P-5804C Discharge to the Starboard Ballast Main.

6

OPEN the Tank Valves ZCV-123, ZCV-125, ZCV-135 and ZCV-137 on the Port and Starboard No 3 and No 6 WBTs respectively.

7

SET pump output to 5% and START Ballast Water Pump P-5804A and P-5804C. Bring pump speeds up to a maximum speed of 10% and ENSURE the level in the Port and Starboard No 3 and No 6 WBTs is increasing. Speed up the ballast pumps to achieve the desired ballasting rate. ENSURE that the levels in all other Ballast Tanks are not changing.

8

Record the time of commencement and the Ballast volume onboard at that time. Total Ballast onboard from the Load Computer display will normally suffice.

9

Open and close as required the tank suction valves to reduce the ballast at the correct rate to meet the requirement of the loading plan.

10

Monitor hull criteria on the Load Computer during the transfer. List may develop rapidly, particularly during the start and end of the De-ballast transfer. MAINTAIN the port and starboard tank levels approximately equal at all times by adjusting the speed of the port or starboard pumps.

11

When required in the loading plan, OPEN the Tank Valves ZCV-127 and ZCV-129 on the Port and Starboard No 4 WBTs respectively.

12

Adjust the tank valves on No 3, No 6 and No 4 WBTs to control the ballasting to each tank at the correct rate to meet the requirement of the loading plan.

13

When No 3 and No 6 WBTs Port and Starboard are full, CLOSE the tank valves ZCV-123, ZCV-125, ZCV-135 and ZCV-137 on the Port and Starboard WBTs respectively.

14

ADJUST the speed of the ballast pumps to control the ballasting of No 4 WBTs at the correct rate to meet the requirement of the loading plan.

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Step

Action

15

As more ballast is required, OPEN the tank valves on the tanks to be filled, ADJUSTING the rates for other tanks (via opening and closing the appropriate valves) already receiving ballast accordingly. This is necessary to maintain the ballast schedule in accordance with the loading plan.

16

When the ballast operation is complete, STOP and ISOLATE the ballast pumps and CLOSE all WBT Tank valves.

17

Log the time of completion of Ballast and record the Ballast tank levels and volumes.

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PROCEDURE FOR BALLASTING (SEMI-AUTOMATIC OPERATION) Step

Action

1

For this procedure it is assumed that water ballast will be increased using ballast pumps P-5804A and C initially filling No 3 and No 6 WBTs followed by No 4 P&S WBTs during the offloading of the Group A Cargo Tanks. Only the 20in suction valves in each Ballast Tank are used during normal de-ballasting operations.

2

OPEN the Tank Valves ZCV-123, ZCV-125, ZCV-135 and ZCV-137 on the Port and Starboard No 3 and No 6 WBTs respectively.

3

On the DCS screen, SELECT the ‘ballasting’ button and SELECT the ‘sequence’ button for pumps P-5804A and C. The associated valves will be opened (58-ZCV-101/102/149 and ZCV-108/109/150) and provided all the interlock conditions are met, the pump will be automatically started to 5%. Once confirmation that the pump is operating (from the discharge line pressure transmitter 58-PIT-103/109), the discharge valves (58-ZCV-104/111) will automatically be opened, initially to 5%, then the valve may be opened further from the valve overlay on the DCS screen as required and the pumps speeded to meet the demand.

4

FOLLOW Steps 8 to 15 under Ballasting (Manual Operation).

5

When the pumps are stopped from the DCS overlay, the starting sequence shall be reversed – stopping the pumps and then closing the isolation valves (58-ZCV-101/102/104/149 and 58-ZCV-108/109/111/150). If the sequence is manually overridden and the pump is stopped, the valves shall remain in the open position until closed by the operator.

6

CLOSE all WBT Tank valves, log the time of completion of Ballast and record the Ballast tank levels and volumes.

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PROCEDURE FOR BALLAST LINE FLOODING Both the port and starboard ballast lines are fitted with capacitance level probes near the forward and aft ends of the lines (58-LZT-133/34/35/36). These are to give an indication if the ballast line in its vicinity is flooded. On sensing a non-flooded condition (pipe less than 90% full) on any of the sensors, an alarm will be raised in the DCS. Re-flooding of the ballast line will normally be sequenced automatically from the DCS. If any ballast pump is running and the above condition occurs, the stopping of the pump(s) and closing of the tank isolation valves will be delayed for a configurable time (0 to 60 seconds initially set at 10). The DCS programme will also prevent the opening of any further valves (except those mentioned below) and pumps from starting until the non-flooded condition is reset. This is to allow adequate stripping of any tank (when stripping a tank some air is likely to be sucked into the main header after the water level falls below the bottom of the suction pipe). Manual closing of the valves is not affected. This sequence and interlocks will operate irrespective of the selection of the ‘Manual Override’. The ballast line will be flooded by gravity filling through the following valves: ZCV-101/108, ZCV-102/112 (limited to 5% open), ZCV-103/113, ZCV-147/148, ZCV-141/142 and ZCV-151. These valves will be permitted to open either under sequence control or manually while the low level in the ballast lines exists. Step

Action

1

To ‘re-flood’ the system, PRESS the ‘flooding’ button which will automatically open the following valves in this sequence (the pumps must be confirmed as stopped): •

58-ZCV-151 – Ballast line vent

•

58-ZCV-141/142 – Forward ringmain isolation valves

•

58-ZCV-147/148 – Middle ringmain isolation valves

•

58-ZCV-103/113 – Pump A/D ballast lines suction

•

58-ZCV-102/112 – Pump A/D sea suction (proportional to 5%)

•

58-ZCV-101/108 – Sea chest isolation valves

2

If the flooding button is not used, all of the above mentioned valves will not be interlocked and may be opened individually.

3

After the ballast lines have been flooded (above 90%), the interlocks will be automatically removed, the ballast pumps can now operate as normal and the tank isolation valves can be re-opened. When any of the pumps are started, the ballast vent valve (58-ZCV-151) will automatically be closed after 1 minute.

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