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KUWAIT OIL COMPANY (K.S.C.)

Engineering Group

Specifica tion Number

075- WH- 7006

Cathodic Protection ICP) Design Requirements

I CONTENTS I

SpdficaHon Numbec

01 5-WH-1006

1.0 SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.0 STANDARD SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Rev

1

3.0 SERVICECONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4.0 TECHNICAL REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.2 Construction Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.3 Adjacent Pipeline Crossings. Parallelisms. Other CP Systems . . . . . . 5

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Soil Conditions 6 4.5 Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Protection Potential Range 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Protection Current Demand 6

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 Attenuation 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9 Power Source 7

4.10 Groundbed Design and Current Distribution . . . . . . . . . . . . . . . . . 7 4.1 1 Electrical Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.12 Cabling 9 4.13 Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.14 Test Points 10 4.15 Stray Current Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.16 Protection From Transients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.17 Precommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.1 8 Calculations and Documentation . . . . . . . . . . . . . . . . . . . . . . . . . 12

Date

19-9-94

Sheet

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1.1 This specification covers the design requirements for CP systems for installation at the Facility in Kuwait.

1.2 CP systems shall fully comply with all relevant contractual requirements specified in the Scope of Work and Technical Specification of the Contract.

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1 2.0 STANDARD SPECIFICATIONS I

Date

19-9-94

2.1 CP equipment shall conform in design, materials and performance, except where otherwise specified, with the current issue and amendments of the following standards prevailing on the effective date of the Contract:

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Sp.cMcation N u m b

01 5-WH-1006

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I 2.1.1 International Standards I

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NACE RP 01 77 Mitigation of Alternating Current and Lightning Effects on Metallic Structures and Corrosion Control Systems

I 2.1.2 British Standard I BS 7361 Cathodic Protection, Code of Practice for Part 1 Land and Marine Applications

I 2.1.3 Engineering Group Specifications I CP equipment and accessories covered by this specification shall comply with all relevant Engineering Group Specifications of which the following are specifically referenced in this specification:

I 01 5-AH-1 001 Basic Design Criteria I I 01 5-AH-1 002 International Codes and Standards I I 01 5-NH-1003 Thermal and Acoustic Insulation I I 01 5-NH-1004 Passive Fireproofing Materials and Application

I 01 5-PH-1910 Cathodic Protection (CP) Transformer Rectifier Unit I I 01 5-XH-1005 Shop and Field Painting I

2.2 Compliance with this specification shall not relieve the Contractor of its responsibility to supply equipment suited to meet the specified service conditions and applicable regulations.

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2.3 Where conflicts exist between this specification and other Drawings, standards, codes and specifications, the most stringent shall

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I 3.0 SERVICE CONDITIONS I

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3.1 The equipment shall be suitable for continuous operation at a desert location under high ambient temperatures and humidity. The atmosphere at the Facility is generally dusty and corrosive and may contain traces of hydrogen sulphide.

3.2 CPequipment shall in all respects be suitable for continuousoperation in the service conditions stated in the Engineering Group Specification entitled "Basic Design Criteria" (Number 01 5-AH-1001 ).

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1 4.0 TECHNICAL REQUIREMENTS I 4.1.1 Corrosion control of buried and coated steel is to be achieved by

coating, supplemented by CP. 1

Rev

1

4.1.2 These design requirements describe the general strategy and specific parameters to be applied to the CP systems together with the associated control, commissioning and monitoring facilities. The CP systems shall cause minimum interference to foreign structures.

I 4.1.3 The overall CP systems shall apply to the following: I

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I a. Brackish water tanks. I

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I b. Firewater tanks.

I c. Crude oil storage tanks.

I d. Desalters. I I e. Buried piping. I I f. Pipelines.

I 4.2 Construction Featurag I I 4.2.1 Tanks and Vessels I

a. At tanks and vessels, a substantial amount of buried piping may be installed. Due to overall electrical continuity, the following can also drain current from the terminal CP systems and a current allowance shall be included for them: I 1. Armouring of power cables.

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2. Pipe rack footings.

E4lI-w Qw - 3. Earthing systems, e.g., earth rods and interconnecting

cables.

4. Steel reinforcement within concrete equipment bases.

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01 6-WH-1006

5. Module bases.

6. The rebar in reinforced concrete should be electrically continuous to avoid problems with preferential corrosion at discontinuities. Typically, tightened binding wire used

Rev

1

in assembling cages will generally provide sufficient connection (BS 7361). In addition. with no deliberate electrical isolation between pipework and other items, interferenceeffects between cathodically protected items and rebar, etc. should be minimal.

Date

19-9-94

4.2.2 Pipelines and Piping Systems

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a. All underground piping systems shall be installed by open cut and shall be buried to a minimum cover in the region of 1.0 m. Intimate backfill shall be graded and nominally free of stones. At points where lines pass beneath other lines in the immediate vicinity, depth of burial shall be greater.

b. At road crossings, sleeves shall be used.

4.3 Bdiacent Pl~ellne Crossinas. Parallelisms. Other CP Svstema

4.3.1 Other lines may be close to the area where the new piping systems are to be installed. There is therefore a strong likelihood of numerous pipe crossings. To evaluate the potential of interaction between the new and existing lines, the following information shall be sought:

a. Age of line, type and condition of pipeline anti-corrosion coating.

b. Electrical continuity and location of isolation devices.

c. Operational status of existing CP systems, current output of associated rectifiers and potential data.

d. Location and type of electrical bonding.

e. Possibility of use of existing systems to protect the new pipelines by resistive bonds and control circuits.

I 4.3.2 Parallelisms

a. Interaction at points where lines may run parallel with other services should also be considered and, where necessary, resistive bonding equipment provided as a precaution to interaction.

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b. Where lines run parallel and are protected by an existing CP system, consideration should also be given to joint schemes at these points.

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1

SprdRcation Number

01 5-WH-1006

I 4.3.3 Overhead Power Transmission Lines

Where overhead power transmission lines run parallel to the pipeline route, testing shall be required to evaluate the effects of induced AC current. Consideration shall be given in the detailed design to the installation of zinc electrolytic grounding cells at points of inflection and at the ends of each parallel section to ensure mitigation of these effects.

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4.4 Soil Conditions

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Soil resistivity along the pipe routes is the subject of a separate and independent survey, the results of which will be made available to the Contractor.

4.5 Environmental Conditions

The environmental conditions shall be as specified in the Engineering Group Specification entitled "Basic Design Criteria" (Number 01 5-AH-1 001 ).

I 4.6 Protection Potential Range

4.6.1 The value of protection potential for steel (I R corrected value) used shall be -0.95 V, copperlcopper sulphate electrode (CulCuS04) or more negative.

4.6.2. Excess overprotection should not be allowed to occur. The most negative value permissible will be taken as -1.5 V CulCu SO4 for design purposes.

I 4.7 Protection Current Demand

4.7.1 The use of coal tar enamel and cold-applied tape wraps should result in low protection current demand for the equipment. However, any damage to the coating during construction cannot be repaired. Damage caused to the coating during life, e.g., by soil creep and progressive deterioration cannot be repaired without testing and excavation. The protection current density elect a P

for design of the pipelines, piping and tanks shall be based on the maximum design temperature of the system 85'C and BS 7361.

EwIMw Group - 4.7.2 For applications where bare steel may be exposed, e.g., at areas

where thin coatings are applied to buried piping or vessels, a higher current density shall be used for CP design plus a coating breakdown factor, where appropriate.

For well-coated pipelines, the distribution of current shall be good and is controlled largely by the electrical resistance per metre run of steel pipe. As the length of any one run of pipe is relatively short, except for pipelines, it is not envisaged that any more than one groundbed will be required. It is desirable for reasons of power supply that the groundbed be placed in close proximity to the pipeline.

SwcMeafon Number

01 5-WH-1006

I 4.9 power Source

The direct current power supply for the impressed current system shall be provided by an oil-immersed transformer rectifier in accordance with the

Rev

1

Engineering Group Specification entitled "Cathodic Protection (CP) Transformer Rectifier Units" (Number 01 5-PH-1910). As each line enterino and leaving the gathering centre shall be individual& isolated, then curren'i shall be drained from each line individually through a free-standing resistor control box. This will provide the means of controlling the current flow and so the potential of each line. The current output and voltage rating of the control box shall be determined by the Contractor.

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I 4.10 Groundbed Desian and Current Distribution ;

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4.10.1 Groundbed construction shall be a conventional shallow vertical or horizontal beds comprising electrographite anodes, carbonaceous backfill and associated DC cables.

a. The above approach is dependent upon soil resistivity survey results and there being sufficient space in which to install the groundbedat a required minimum distance of 100 m from the nearest cathode or foreign structure.

b. Groundbed length and resistance are governed primarily by resistivity. Measured soil resistivities shall be determined and groundbed dimensions calculated.

c. If surface soil resistivities prove to be outside the values where conventional shallow vertical horizontal groundbed technology can be utilised or if available space is a constraining factor, then deep or distributed vertical anode arrays should be considered.

d. Initially, high electrographite anodes shall be considered.

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01 5-WH-1006

4.10.2 Crude Oil and Water Storage Tanks and Vessels

a. External Surfaces

Rev

1

1. If Isolation devices are not used within station, a distributed anode system should be used in which the anodes are placed sufficiently close to the items to be protected such that the item is within the potential gradient of the anode.

2. Impressed current CP systems shall be considered only for protecting the buried metallic asset against corrosion.

Date

19-9-94

3. Anodes shall not be placed beneath concrete or paved road.

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b. lnternal Surfaces

1. Sacrificial anode systems shall be provided and shall be based on continuous operation of 10 years.

2. The anodes shall be made of aluminum alloy.

3. Anodes shall be installed on the internal surface with metal fittings. The anodes shall be installed in the zones containing free water andlor those containing mixed waterlhydrocarbon.

4. The desalter vessels shall be lined internally with 1 %-in.- thick cement using the gunite process as per the Engineering Group specification. Sacrificial anodes are not required in the desalter vessels.

5. Since the wet crude tanks are to be lined with fibre glass and to be internally painted with epoxy, no sacrificial anodes are required.

6. The following equipment shall be provided with sacrificial anodes for internal corrosion protection:

a. Degassing boots.

b. Drain flash drums.

c. Internal surfaces of any other vesselltank containing formationlwaste water.

I 4.1 1 ~ l c a l Isolation

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d. Internal surfaces of all vesselltanks associated with waste water treatment system.

Electrical isolation at each end of the pipeline is not required. All buried metallic assets benefitting from the CP network shall be dealt with as one entity, and any case of suspected interference shall be studied separately and rectified during commissioning.

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015-WH-1006

4.12.1 Where current-carrying cables run outside the pipe trench or adjacent to the tank, they shall be buried in a narrow excavation and laid on a bed of soft sand, be marked with cable warning tape and their route marked with concrete cable markers at each point where there is a change of direction and at a minimum of every 50 m.

4.12.2 The electrical current rating of a cable shall not be exceeded for the temperature of use. Cable cross-section shall be selected to suit the condition of use.

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4.12.3 Cables connected to pipelines shall be wound loosely around the pipeline, and secured by several turns of tape such that the strain on the connection point is kept to a minimum during backfilling.

I 4.12.4 All cables shall be clearly identified and numbered such that no confusion exists as to their purpose or point of origin or termination.

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I 4.13 Electrical Connecti-

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19-9-94

4.13.1 The cable and all connections, e.g., bolted or drawn arc (pin) brazed, are critical. Complete electrical isolation between the cable/splice/connection and the environment is essential. Water ingress or soil contact must not occur.

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4.13.2 All cables shall be laid in single runs. No cable-to-cable splicings connections shall be made.

4.13.3 The method of connection to foreign lines shall be agreed to with the Company. No connections shall be made without the express permission of the Company.

I 4.13.4 When pipe anti-corrosion coating shall be removed to facilitate i \ 1 electrical connections, the coating shall be fully restored

afterwards to an approved procedure. All connections to pipe and structures shall be profiled and tape-wrapped after installation

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4.14 Test Pointg

4.14.1 Storage Tanks and Piping

a. Test point locations within the Facility shall be limited and to the extremities of any buried piping and at storage tank bases. When selecting test post locations within the station, consideration shall be given to area classification and the potential hazards.

b. To facilitate data collection, lengths of PVC tube shall be installed through grade at those points where data collection shall take place on a routine basis. This will facilitate repeat readings at fixed locations with portable reference electrodes.

4.15 Strav Current Interference

4.1 5.1 It is a requirement that the pipeline CP does not significantly affect the structure to soil potential of existing services.

4.15.2 Remedial actions for stray current interaction shall be carried out by the specialist CP installation Subcontractor following commissioning.

4.16 Protection From Transient?

4.16.1 Harmful voltages may be induced in the pipe during fault conditions, e.g., from high-voltage AC running close to and parallel with the pipe. Protective measures to offset these voltages shall be installed, for instance, by the placement of magnesium or zinc earthing electrodes to conduct the transient currents to ground.

4.16.2 Extraneous voltagelcurrent shall be conducted to earth by an appropriate system selected by the Contractor and submitted to the Company for approval.

Precommissioning works shall be carried out under the following procedure:

4.1 7.1 Natural Potential

Natural as found pipe to soil, casing to soil potential along the pipeline shall be measured at all the measuring points, at all the insulating joints and on all foreign installation crossings or adjacent to the pipeline. The "off" on potential of the pipelinelvessel shall be measured.

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4.1 7.2 Preliminary Adjustment

All impressed current groundbeds shall be energised initially to give 2 V at their drain points. Midpoint potentials between stations shall then be measured. It is required that the midpoint potentials shall not be less negative than 1.0 V, and the station current outputs shall then be adjusted to achieve the required midpoint potential. The current output shall not be increased, however, to produce a more negative potential at the drain point greater than 2.5 V.

4.17.3 Potential Measurement

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Following the adjustment of CP station outputs to meet the midpoint and end of pipelines pipe-to-soil potentials, a complete set of potentials shall be recorded at all the measuring points and other positions measured before. Should the potential of metallic casings be more negative than their natural potential previously recorded, then the Contractor shall investigate the reason for the low resistance between casing and carrier pipe.

4.17.4 Interference Testing

a. The Contractor shall carry out all interference testings. He shall be responsible for contacting all the authorities concerned and arranging for their presence at such tests if they desire.

b. Should any interference test results show a positive change \ in potential of a foreign installation or structure of more than / 50 mV, the Contractor shall take remedial action to eliminate

the interaction. It is preferable to overcome the interference by the use of a variable resistance installed inside a proper enclosure in the measuring points between the potential cable from the pipeline and that from the foreign installation.

c. The Contractor shall be responsible for confirming the results of interference testing with the authorities concerned and obtaining written confirmation from them that they have no objection to the operation of the CP system.

4.1 7.5 Final Precommissioning

a. On completion of interference testing and remedial action, final adjustment necessary shall be made to the current output at the CP stations to achieve pipe-to-soil potential

/ throughout the system of between -1.0 and -1.5 V with respect to CulCuSO,.

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01 5-WH-1006

Rev

1

Date

19-9-94

Sheet

110f 12

b. The final precommissioning shall consist of: I 1. Measuring pipe-to-soil potentials at all measuring points

by an approved method.

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2. Measuring total current output from each station and the current in each direction where current measurements are possible.

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3. Measuring settings of power sources: transformer - rectifiers.

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4. Measuring current and resistance if remedial bond fitted. I( \

5. Calibrating all current measurement points. I.

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4.18 ~ l c u l a t i o n s and Documentation

The following documentation and Drawings shall be submitted for approval:

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4.1 8.1 Anode specification (ICCP). I 4.18.2 Anode specification sacrificial.

4.1 8.3 Cable specification.

4.18.4 Permanent reference electrode specification. I 4.1 8.5 Junction box and marshalling box specification.

4.18.6 Anode groundbed calculations.

4.18.7 Installation procedures. I 4.1 8.8 Equipment Drawings. I 4.1 8.9 Electrical schematic and detailed wiring diagrams. I 4.18.10 Details of temporary protection measures. I 4.18.1 1 Schematic of the entire CP system.