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CATHODIC PROTECTIONOF ONSHORE PIPELINES

FOSTER WHEELER ENERGY LTDPROJECT SPECIFICATIONEQUIPMENT ENGINEERING

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1. SCOPE

This specification covers the technical requirements for cathodic protection to beapplied to the onshore sections of buried pipelines for the Refinery.

The precise scope of pipelines to be protected is described in project document 3550-8440-SP-0004, Scope Definition for Cathodic Protection. Generally, the requirementsof this specification apply to the onshore buried sections of the twin 48 crude importlines into the refinery.

2. REFERENCED DOCUMENTS

2.1 Project Documentation

3550-8820-SP-0001 Basic Engineering Design Data (BEDD)

3550-8210-SP-0005 Specification for Pipeline 3LPE External Coating

3550-8310-SP-0013 Specification for Earthworks

3550-8440-SP-0005 Technical Specification for Cathodic Protection of In-Plant

Facilities

3550-8440-SP-0004 Scope Definition for Cathodic Protection

3550-8531-SP-0001 Electrical Design Specification

3550-8531-SP-0011 Electrical Installation Specification

2.2 International Standards, Codes & Specifications

The latest revisions of the following international standards apply:

ASTM B 80 Specification for Magnesium Alloy Sand Castings

ASTM B 338 Specification for Seamless and Welded Titanium andTitanium Alloy Tubes for Condensers and HeatExchangers

ASTM B 418 Specification for Cast and Wrought Galvanic Zinc Anodes

ASTM D 3359 Test Methods for Measuring Adhesion by Tape Test


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BS 1377-3 Soils for Civil Engineering Purposes. Chemical and

Electrochemical Tests

BS 5467 Electric Cables Thermosetting Insulated, ArmouredCables for Voltages 600/1000V and 1900/3300V.

BS 6121-5 Mechanical Cable Glands. Code of Practice for Selection,Installation and Inspection of Cable Glands and ArmourGlands.

BS 7361: Part 1 Cathodic Protection, Part 1, Code of Practice for Land andMarine Applications

BS EN 60076-3 Power Transformers, Insulation Levels, Dielectric Testsand External Clearances in Air

BS EN 60529 Degrees of Protection Provided by Enclosures (IP Code)

US Mil-A-1800I Anodes, Sacrificial Zinc Alloy

NACE RP0169 Control of External Corrosion of Underground orSubmerged Metallic Piping Systems

NACE SP0177 Mitigation of Alternating Current and Lightning Effects onMetallic Structures and Corrosion Control Systems

NACE SP0286 Electrical Isolation of Cathodically Protected Pipelines

NACE SP0572 Design, Installation, Operation and Maintenance ofImpressed Current Deep Groundbeds

3. ABBREVIATIONS

3LPE 3 Layer Polyethylene

3LPP 3 Layer Polypropylene

CP Cathodic Protection

FBE Fusion Bonded Epoxy

MMO Mixed Metal Oxide

NACE National Association of Corrosion Engineers

T/R Transformer Rectifier


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4. SURVEY REQUIREMENTS

4.1 Survey Objectives

The objective of the soils survey is to obtain data and determine soil conditions alongthe pipeline routes for the purpose of designing a suitable cathodic protection system.The soils survey shall be carried out such that sufficient data is provided to enabledesign of a permanent cathodic protection based on an impressed current system

and, due to the anticipated corrosive nature of the soils, a temporary system forprotection during the construction phase by the use of sacrificial anodes.

4.2 Survey Scope

General soils appearance, weather conditions (current and recent) and date of surveyshall all be recorded.

Foreign metallic structures within 150m of the pipeline route may significantly affectthe performance of the CP system. The location and crossing points of all metallic

pipelines, buried cables and overhead high voltage power lines shall be establishedduring the survey.

The suitability of selected areas within 300m of the pipeline (depending uponorientation) for location of groundbeds shall be confirmed.

AC sources (with rating) and provisional access routes shall be identified for thepurpose of locating new transformer rectifier units.

The four pin (Wenner) method shall be used for measurement of soil resistivity as

described in BS 7361 Part 1. Pin spacing shall be 1m, 2m and 3m for each set ofreadings. Larger pin spacing shall also be used to take measurements for suitabledeepwell groundbed locations, typically 5m, 10m, 20m, 30m, 45m and 60m.

Soil resistivity readings shall be taken in the following specific areas, plus any othersdictated by site conditions pertaining during the survey:-

Within 20m of the start of the pipeline and at the end of the pipeline at its entrypoint to the plant area.

Within 20m of road and track crossings

Where there are major changes in rock/soil types


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In the vicinity of foreign service crossings, including metallic/reinforced

concrete pipelines

In the vicinity of power lines.

Where bore holes or standing water is available, the resistivity of the water shall betaken to aid the design of deep groundbeds.

Where pipelines share a common corridor, the soil resistivity readings taken will berepresentative of soil conditions for all. Any change in conditions within the corridorshall be noted and additional data collected.

In the pH range 5.5 to 8.5, redox potential measurements shall be taken to determine

soil susceptibility to the production of sulphate reducing bacteria. The soil shall beconsidered to be corrosive at redox potentials below 400mV (BS 7361-1). Testingshall be carried out in accordance with BS 1377-3.

The location and potential of all metallic structures or pipes observed crossing thepipeline routes or at the terminal areas shall also be reported. Measurements shallbe taken with any existing CP systems switched on and normally adjusted.

5. DESIGN REQUIREMENTS

5.1 Protection Potentials

It is a requirement that instant off potentials shall be measured at each pipeline CPmonitoring test point.

The following instant off IR free potentials shall apply for all buried, coated carbonsteel pipelines:

Aerobic conditions -0.850 to -1.150 volts versus Cu/CuSO4reference electrode

-0.800 to -1.100 volts versus Ag/AgCl reference electrode

Anaerobic conditions -0.950 to -1.150 volts versus Cu/CuSO4reference electrode

-0.900 to -1.100 volts versus Ag/AgCl reference electrode

Values significantly more negative than those above should not be allowed to occur.

Pipeline attenuation calculations shall be performed to confirm the spacing of pipelineCP stations required to maintain pipe-to-soil potentials within the above ranges.

5.2 Design Current Densit ies

A minimum current density value of 0.025mA/m2shall be used based on 3LPE forpipelines operating at 30 C or below and inclusive of expected coating breakdown


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over 30 years. For the protection of pipelines operating at temperatures above 30 C,

the above minimum design current density for coated linepipe shall be increased by25% per 10 C rise in temperature above 30 C.

5.3 Pipeline Bonding

Pipelines installed in a common pipeline corridor shall be electrical continuity bondedvia above ground bond boxes located at the groundbed drain points, pipeline corridorends and all potential measuring stations located at 1000 metre intervals.

5.4 Temporary Cathodic Protection

Temporary cathodic protection will be required since the pipelines are likely to beinstalled through areas of corrosive, low resistivity soils. In soils of resistivities of lessthan 20 ohm.m, sacrificial zinc anodes shall be used having a typical open circuitpotential of -1.10 volts versus Cu/CuSO4(i.e. within the polarised protective potentialrange), sized to protect the structures and pipelines for a period of up to 1 year priorto energisation of the permanent system. In soils of higher resistivity, magnesiumanodes shall be used with in-circuit resistors to minimise the possibility of potentialshift outside of the approved range.

Anodes shall be installed as construction proceeds with pipeline backfilling allowedonly when adequate temporary anodes are available, installed and ready for

immediate connection to the pipelines. Ideally, permanent cable connections to thepipelines at designated test points shall be available for temporary connection of thesacrificial anodes. Installation shall be such that sacrificial anodes may be readilydisconnected during commissioning of the permanent impressed current CP system.

Temporary cathodic protection by the use of new or existing impressed currentsystems shall not be permitted whilst construction is in progress, except for pre-commissioning testing purposes.

5.5 Electrical Isolation of Pipelines

Each new pipeline shall have a monolithic isolation joint installed above ground andfield tested to establish their functionality in accordance with NACE RP 0286.

Isolating joints shall be protected from transient voltages by means of explosion-proofover voltage protectors to ensure that voltages do not rise above levels which wouldcause the isolation joint to breakdown or cause tracking across the isolation jointsurface. Joints shall be manufactured with lugs for overvoltage protection deviceinstallation and test cable attachment and to facilitate direct and resistive bonding atlocal monitoring stations.


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5.6 Road Crossings

Sleeved steel casings and/or concrete culvert crossings may be necessary.

Steel casings shall not be coated but electrically insulated from the carrier pipe usingnon-metallic insulators and end seals and provided with vent pipes at both ends.

Pipelines inside concrete culverts shall be provided with continuous zinc ribbonanodes along the section inside the culvert, attached to the pipeline by cablesterminating in a test post. A permanent Cu/CuSO4 reference electrode provided withelectric mud/gel shall be installed inside the culvert with its cable terminating in thesame test post.

Steel cased crossings greater than 10m in length and all culvert crossings shall havetest facilities provided at each side of the road.

5.7 Interactions and Interference

5.7.1 Foreign Services

Provision shall be made for testing (and the installation of resistive bonds comprisingfixed resistors and current measuring shunts) at all locations where pipelines cross

and where other interactions or electrical interference is likely. Resistive bonds shallbe made where the structure-to-potential of the foreign service becomes anodic by20mV or more when the new CP system is switched on and operated at maximumdrain point potential. A maximum positive swing of 20mV shall be allowed.

5.7.2 Power Transmission Lines

Stray currents and electrical interference may arise from various sources includingoverhead AC power lines.

Interaction testing shall be carried out in accordance with BS 7361 Part 1. Ifdetermined by survey and test, suitable zinc earthing ribbon, earthing rods or earthinggroundbeds may be installed with polarisation cells at AC power line crossings and atthe start and end of parallelisms. Remedial measures to reduce the effects ofinduced AC current and voltage on the cathodic protection system shall beimplemented in accordance with NACE RP0177. A safety study shall be performedand a maximum 15V AC (RMS) open circuit criterion shall also be observed inrelation to safety of personnel.

5.7.3 Other Testing

Testing of cased crossings (if used) and isolation joints shall be carried out and

corrective measures taken to alleviate any interference effects.


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5.8 Monitoring

5.8.1 Pipeline Potential

Pipe to soil potential test measurement facilities shall be provided along the pipelineroute at a minimum of 1000 metre intervals using Big Fink type (or similar) test posts.The drain point(s) and pipeline end potential test stations shall also be pre-wired forpermanently installed permanent reference electrodes and polarisation coupons.

5.8.2 Bare Steel Polarisation Coupons

To assist with commissioning and routine monitoring of the polarised potentials of the

pipelines, without the need for synchronised switching of transformer rectifiers,polarisation coupons shall be installed at the drain points and at the extremities of thepipelines. The coupons will also provide information on the distribution of current andthe ability of the CP systems to polarise holidays of known surface area.

The coupons shall be installed in circuit with the pipelines and capable of temporarydisconnection for testing and monitoring by means of a magnetic reed switchassembled inside the test post. A permanent reference electrode shall be installedadjacent to each coupon to permit polarised potentials representative of the pipelinesto be measured.

6. MATERIALS & INSTALLATION

Materials and equipment shall be suitably designed and manufactured for operationfor prevailing conditions described in project document 3550-8820-SP-0001 BasicEngineering Design Data (BEDD) and have a design life of 25 years.

Minimum requirements for CP equipment, materials and installation shall be asfollows:

6.1 Transformer Recti fiers

Transformer rectifiers shall be naturally air-cooled units suitable for continuousoperation at maximum rated output under ambient site conditions. Preferredlocations are in non-hazardous areas but where this is not possible, T/Rs shall besuitably certified for hazardous area operation. Units not oil-immersed shall beinstalled inside a concrete block shelter suitably designed to achieve adequate aircirculation and cooling and of such design to discourage non-authorised entry.Transformer tappings using relocation of jumpers shall not be used.

Transformers shall meet the requirements of BS EN 60076-3.

Transformer rectifiers shall be sized to deliver a minimum of 25% excess outputover requirements calculated at detailed design.


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The equipment shall include over voltage and current surge protection, output DC

voltmeter and ammeter and a facility to relay TR output voltage, current and ACpower failure to a control room.

Full rated continuously variable DC output shall be obtainable with a 400 V AC, 3phase, 50 Hz input voltage at 5% below the nominal value. Continuous AC inputvoltage at 10% above the nominal value shall not damage the transformer, thediode bridge assembly, or exceed any component ratings.

The transformer rectifier shall be capable of withstanding a short circuit of up to 15seconds duration at the output terminals without damage to any of its devices.

A hinged, lockable door shall allow access to the controls. The door shall have a

window to allow DC output current and voltage meter readings to be taken withoutthe need to open the door.

The control enclosure shall have a hinged, lockable door and fitted with a suitablegasket to prevent ingress of moisture or dust/sand. Hinges and assembly boltsshall be type 316 stainless steel. The main power components, rectifier, fuses,shunts and terminals shall be mounted on a separate panel.

Oil tanks and enclosures shall be IP65, weatherproof and suitable for outdooroperation in accordance with BS EN 60529.

Cable entry shall be made via glands fitted to a removable gland plate suitable to

accommodate up to 70mm2

cable. A minimum of two anode header and twonegative cable terminals shall be provided.

6.2 Deepwell Groundbeds

Anodes shall be of the Mixed Metal Oxide (MMO) type for deepwell groundbedapplication. Each CP station groundbed shall be designed to dissipate a minimumof 110% of the maximum design current output of the transformer rectifier.

Impressed current anodes for buried pipeline CP shall be of the Mixed Metal Oxide(MMO) iridium/tantalum type on a titanium tube substrate (Grade 1 ASTM-B-338).

The prepared titanium substrate shall have an electrocatalytic or arc-plasma spraycoating applied. Total coating loading requirements shall be coordinated with themanufacturers proprietary information to achieve the required performance. Theaverage gain rate for catalyst application shall not exceed 1.7 g/m2 and maximumgain rate for any single coat shall not exceed 2.7 g/m2. Coating loading shall bemeasured using an X-ray gauge which is calibrated at least once per shift for thespecific coating type. This test directly measures precious metal loading. Simpleweight gain is not an acceptable measure. Adhesion of the catalytic coating shall betested according to ASTM D3359. The manufacturer shall certify conformance withthe requirements.

All anodes shall be suitable for installation in calcined petroleum coke backfillmaterial and shall deliver up to 100 A/m2 in coke.


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All anodes shall be sealed tubular, centre connected with individual cable tails

terminating in positive junction boxes. Cable-to-anode connection resistance shallbe less than 0.001 ohm at 10A.

Cable shall be single core stranded tinned copper conductor, HMWPE/Kynarinsulated with 300mm long PTFE reinforcement sleeve adjacent to each anode.Heat shrink tubing shall be applied to seal the end of the tube where the anode leadexits. Cable tails shall be continuous from each anode to junction box. Splicingshall not be permitted.

The supplier shall submit the following information for approval:

Composition of MMO and method of coating

Anode-to-cable connection and encapsulation detailsManufacturers published data on consumption rates and current densityratings in specified conditions

Confirmation of approved cable tail specification

Anode quantity per groundbed, lengths, diameter and cable tail length and backfillproerties shall be determined and calculations submitted for approval by Contractorand Employer.

Deepwell groundbeds shall be constructed to have a resistance to earth of less than0.5 ohms. Groundbeds shall be designed such that their resistance to earth allowsthe maximum rated current outputs to be met at 80% or less of the voltage capacity

of the transformer rectifier during the design life of the system.

Deepwell groundbeds shall be provided with adequate venting pipes to prevent gasblocking of the well. Vent pipe shall be chlorine resistant. Filter gravel shall beused to avoid blockage of the vent pipe by the calcined petroleum coke backfill.

Deepwell groundbeds shall be installed remote from the pipelines to be protected, aminimum of 75 metres away from existing pipelines and 35 metres minimum fromexisting groundbed installations.

6.3 Temporary Protection Anodes

6.3.1 General

Based on soils resistivity, packaged magnesium or zinc anodes, surrounded byrapid wetting backfill and packaged in cotton bags, shall be used for temporarypipeline protection during the construction phase.

Anodes shall be cast with a galvanised steel core and supplied with 10m cabletails,10mm2XLPE/PVC.

Anode weight and dimensions requirement shall be based on latest site resistivitydata.


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6.3.2 Magnesium Anodes

Magnesium anodes shall exhibit an open circuit potential no more negative than -1.5V with respect to Cu/CuSO4 reference electrode.

Standard magnesium anodes shall be used with a capacity of 1200 Amp hrs/kg andhaving the following composition:

Aluminium 5.3 6.7%

Zinc 2.3 3.5%

Silicon 0.3% max.

Co er 0.08% max.

Man anese 0.25% max.

Iron 0.005% max.

Nickel 0.003% max.

Lead 0.03% max.

Ma nesium Remainder

6.3.3 Zinc Anodes

Zinc anodes shall exhibit an open circuit potential of -1.1V with respect to Cu/CuSO4reference electrode.

Standard zinc anodes shall be used with a capacity of 980 Amp hrs/kg and havingthe following composition:

Aluminium 0.1 0.5%

Silicon 0.125% max.

Cadmium 0.025% - 0.15%

Iron 0.005% max.

Lead 0.006% max.

Co er 0.005% max.

Others 0.02% max. each

Zinc Remainder


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6.3.4 Prepackaged Sacrificial Anode Backfill Material

Backfill material shall comprise gypsum, bentonite and sodium sulphate inproportions chosen to suit the specific soil and groundwater resistivities.Proportions shall be submitted to COMPANY for approval.

6.3.5 Ribbon Anodes

Extruded zinc ribbon anodes shall comply with ASTM B-418 Type II with a capacityof 780 amp.hrs/kg.

The steel core shall be exposed at each end and crimped to 16mm2XLPE/PVCtinned copper anode cables terminated in the test facilities. Crimped connectionsshall be encapsulated with self-amalgamating rubber tape and PVC tape.

6.4 Reference Electrodes

Cu/CuSO4 permanent reference electrodes shall be used at all test points.(Ag/AgCl in chloride contaminated soil and sabkah.) Permanent buried referenceelectrodes shall be guaranteed for a minimum period of 25 years operation inalternating water saturated and dry soil conditions and shall be supplied with anelectric mud/gel system to prevent drying out.

Where IR free potentials are required, polarisation coupons shall be used inconjunction with the permanent reference electrodes. Coupons shall be fabricatedfrom pipeline grade steel having an exposed coupon area of 50 x 50mm. Two10mm2XLPE/PVC cables (one bonding, one monitoring) shall be attached to theback of each coupon and encapsulated in epoxy resin within a PVC box. Thesecables shall be terminated in standard test/monitoring boxes.

6.5 Cables & Connections

Low voltage AC requirements for CP transformer rectifiers are 400V, 3-phase,50Hz, 4-wire with neutral solidly earthed.

All DC cables shall be unarmoured, single core, multi-stranded copper, suitable forcathodic protection.

Impressed current anode cables shall be tinned copper with HMWPE sheath andKynar insulation. All other cables shall be tinned copper XLPE/PVC insulated.

The minimum rating for all cables shall be 600/1000 volt grade to BS 5467.

Specific cable sizes shall be determined during detailed design but as a minimum,


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25mm2for DC power and negative drain cables

16mm2for anode leads and bonding cables

10mm2for test leads

Colour coding shall be by coloured heat shrink sleeves. In all cases, cables shall beidentified with cable markers in an approved manner.

All connections shall be made in approved junction/bond/distribution/test boxescertified for the hazardous area in which they are to be installed. Big Fink (orsimilar) test stations shall be used for permanent reference electrode/test leadtermination and for sacrificial anode/structure connection to buried pipework and

buried vessels. Test stations shall have UV resistant housings and metallic posts.

Junction, bond and distribution box enclosures shall be IP65, hinged and lockable,made from 316L stainless steel. Boxes shall not be installed in Zone 1 hazardousareas.

All cables brought above ground shall enter junction/bond/distribution boxes viacable glands. Cable glands shall be indoor/outdoor made of Ni-Cd plated brass.The glands shall be minimum certified as Ex.e, IIB manufactured and tested to therequirements of BS 6121-5. The minimum ingress protection shall be IP65.

All cable lugs shall be copper or high conductivity brass, suitably sized, and finished

with an electrodeless nickel-plating for superior corrosion resistance.

All buried cables shall be protected by cable tiles and marked by early warning tapein congested areas. Buried cables shall not be spliced.

Negative drain cables and other cables of size greater than 16mm2 shall beconnected to pipelines via cable lugs secured to 6mm welded pads with hex boltsusing a Contractor approved procedure. The pads shall be of similar material gradeas the pipeline steel to permit welding in accordance with the approved weldingprocedure. Welding shall be carried out prior to hydrotesting.

Connections for test, bonding and other cable up to and including 16mm2may be by

means of drawn arc pin brazing using proven kit which shall be stored and used inaccordance with the manufacturers instructions. A pin brazing qualificationprocedure shall be submitted to the Purchaser for approval.

Thermit welding shall not be permitted.

6.6 Isolating Joints

Monolithic isolating joints shall be installed at Refinery boundary limits upstream ofthe slug catcher(s) and above ground at the subsea/onshore transition at the beach.Each assembly shall be provided with two terminal connecting lugs on each side of

the joint suitable for M10 bolted cable connection to permit electrical measurementand surge diverter installation. Surge diverters shall be explosion proof spark gapsof the tungsten copper electrode type housed in a die cast zinc body with macralon


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cover and galvanised steel mount bracket. The pre-assembled surge diverter cable

shall be of minimum size 25mm2

and of sufficient length to reach across theisolating joint terminal connecting lugs.

6.7 AC Interference

Zinc to ASTM B-418 Type II, of calculated length, shall be installed in ribbon formparallel to the pipeline at locations where induced AC interference is possible. Theearthing ribbon shall be connected to 25mm2XLPE/PVC tinned copper cable by acrimped connector. Crimped connections shall be encapsulated with selfamalgamating rubber tape and PVC tape. Alternatively, zinc earthing rods orearthing groundbeds may be proposed for Employer approval.

Solid state polarisation devices inside 316L stainless steel enclosures shall beinstalled as required to mitigate AC voltage on the pipelines arising from local powerlines. The devices shall permit continuous earthing for pipelines through the zincearthing ribbon whilst maintaining high DC impedence. The devices shallautomatically reset and fail safe.

7. TESTING & COMMISSIONING

Installation supervision, testing and commissioning of CP systems shall be carriedout by a NACE qualified CP Specialist approved by the Employer.

Equipment testing & system commissioning procedures shall be prepared forapproval to demonstrate that the installed cathodic protection system is inaccordance with this specification and the system design.

Prior to energising the CP systems, temporary anodes shall be disconnected andnatural pipe-to-soil potentials shall be measured at all monitoring stations usingburied reference electrodes cross-checked where possible using a calibratedportable reference electrode.

The CP systems shall be energised and adjustments made to balance thedistribution of current to satisfy the protective potential criteria. On and InstantOff potential measurements shall be made at the same locations as the naturalpotentials.

Outputs from the transformer rectifiers shall be measured and recorded locally andremote signalling of T/R input voltage and DC current and voltage outputs checked.

Any observed effects due to stray current and interference shall be noted andcorrected as necessary.


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8. DOCUMENTATION

The following documents shall be produced and submitted for approval:

8.1 Detailed Design Report

Results and analysis of the site survey

Development & justification of the chosen system, system and componentsizing calculations

Influence on or by any existing CP systems

Comprehensive schedule of protected pipelines including sizes, lengths,

materials, coatings, burial depth and operating conditions List and identification of monitoring stations and junction boxes

System layout drawings

Component data sheets

Installation specifications and groundbed installation checklist

8.2 Testing & Commission ing Procedures

Procedure for transformer rectifier checks & tests Procedure for portable reference electrode checks & calibration

Procedure for permanent reference electrode checks and calibration

Procedure for testing the pipeline isolation joints

Procedure for cased crossing/pipeline isolation (if any) testing

Procedure for disconnection of temporary CP

Procedures for natural and on/off potential surveys at all CP test posts

Procedure for instant off polarization coupon potential measurements

Procedure for energising and trial operation of the permanent system

Procedure for interference testing

Required format of the commissioning report

8.3 Testing & Commiss ioning Report

Results of all checks and tests identified in the above procedures, recorded onstandard forms


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8.4 Operating & Maintenance Manual

Inspection & maintenance procedures for all equipment items withrecommended schedules

Safe operating guide for the CP system

Schedule of recommended spares for 5 years operation

3550-8440-sp-0006 rev d1-thanh thao

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