Cathodic Protection Case Study: Padma Bangladesh. Corrosion is usually defined as the deterioration of a metal or its properties caused by a reaction with its environment. Most metals occur naturally in the form of oxides and are usually chemically stable. When exposed to oxygen and other oxidizing agents, the refined metal will try to revert to its natural oxide state. In the case of iron, the oxides will be in the form of ferrous or ferric oxide, commonly known as rust. Metallic corrosion generally involves the loss of metal at a particular location on an exposed surface. Corrosion occurs in various forms, ranging from a generalised attack over the entire surface to a severe concentrated attack. In most cases, it is impossible or economically impractical to completely arrest the corrosion process; however, it is usually possible to control the process to acceptable levels. The basic terms and definitions of corrosion are covered under ISO 8044:1999, “Corrosion of metals and alloys — Basic terms and definitions“.

Read more about EPCM

1 Cathodic Protection Case Study: The Corrosion Process

Metallic corrosion is caused by the flow of direct current from one part of the metal surface to another. This flow of direct current causes the loss of metal at the point where current discharges into the environment (oxidation or anodic reaction). Protection occurs at the point where current returns to the metal surface (reduction or cathodic reaction). The rate of corrosion is proportional to the magnitude of the corrosion current. One ampere of direct current removes approximately nine kilograms of steel in one year. Where corrosion occurs and to what extent depends upon the environment the metal is exposed to. Read more on EPCM’s Cathodic Protection.

Four conditions must be met for corrosion to occur. Eliminating any of them will halt the corrosion reaction.

  1. Anode: This is where the oxidation reaction occurs. Current is discharged into the environment, and metal loss is associated with this reaction.
  2. A Cathode. This is where the reduction reaction occurs. Current “acceptance” and metal protection are associated with this reaction if the current density is sufficient.
  3. An Electrolyte. The environment to which both the cathode and the anode are exposed. The electrolyte must be able to conduct electrical current through the flow of ions, i.e. ionic flow/current.
  4. A metallic path. The anode and the cathode must be electrically connected via a metallic connection that permits the electrical current to flow, i.e. the flow of electrons between the anode and cathode (electric current as opposed to ionic current in the electrolyte). To better understand corrosion and the process involved, the following standards should be consulted:

BS EN 12501-1

Protection of metallic materials against corrosion. Corrosion likelihood in soil. General

BS EN 12501-2

Protection of metallic materials against corrosion. Corrosion likelihood in soil. Low alloyed and non-alloyed ferrous materials

DIN 50292-3

The probability of corrosion of metallic materials when subjected to corrosion from the outside, Buried and underwater pipelines and structural components.

2 Cathodic Protection Case Study: Forms of Corrosion

Corrosion exhibits itself in several ways. Below is a brief description of certain forms of corrosion.

  1. General Corrosion is the most common form of corrosion. It exhibits itself as an overall attack of the metal surface with no apparent concentrations. An example is the effect of atmospheric corrosion on above-ground structures.
  2. Pitting Corrosion results in a localized, concentrated attack and has the appearance of holes or craters. The latter may result from a specific attack by an aggressive ion, such as chlorine (Cl), or by bacteria, such as Sulphate-Reducing Bacteria (SRB).
  3. Crevice Corrosion occurs in shielded areas where stagnant corrosive electrolyte accumulates. This corrosion occurs under bolt heads, gasket surfaces, and overlapping metal connections in buried and submerged conditions.
  4. Erosion-corrosion is a combination of electrochemical and mechanical damage in environments of high fluid velocities or mechanical movement between two metals.
  5. Selective Leaching results in one constituent of an alloy being selectively removed, leaving a porous replica of the original alloy. An example is the dezincification of brass or bronze and the graphitisation of cast iron, where iron is removed selectively, leaving a replica composed of carbon or graphite.
  6. Microbial Influenced Corrosion (MIC) has become one of the most important forms of corrosion. At the same time, it is one of the most complex and less-known processes. In high resistivity soils where water may become entrapped in the bottom of the pipe trench, particularly where the pipe is installed in rocky areas, the entrapped water stagnates and becomes anaerobic (no oxygen), which permits micro-organisms to proliferate and attack the exposed steel at coating defects. The latter is also important in anaerobic clay soils, where MIC occur. The latter often results in severe damage to buried pipes.

3 Cathodic Protection Case Study: Causes of Corrosion

Corrosion is a natural process. The primary driving force of corrosion is the transformation of iron from its natural state to steel. The refining of iron ore into steel requires the addition of energy. Steel is essentially an unstable state of iron, and corrosion is the process of iron returning to its natural state. The energy used in the refining process is the driving force of corrosion.

Corrosion cells are established on underground pipelines for a variety of causes. A primary cause of corrosion is due to an effect known as galvanic corrosion. All metals have different natural electrical potentials. When two metals with different potentials are connected in a common environment, the current will flow, causing corrosion. The latter form of corrosion will occur when the same material is located in a different environment, for example, a steel pipeline buried in aerated and unaerated soil.

Another classic example is pipelines connected to the reinforcing steel of thrust blocks and chambers. The coupling of steel to a different metal, such as copper (earthing material), will cause a corrosion circuit to be established. Direct coupling of copper to steel will cause the steel to corrode much faster than normal. Another form of this is coupling a rusty pipe to new, clean steel. The natural difference in potential causes the new steel to corrode more rapidly than the old steel. Other causes of pipeline corrosion cells include the effect of different soil types, oxygen availability, stray current interference and microbiological growth.

Two other unique causes (and sometimes related) are stress and hydrogen, but these are not applicable to the steel grades to be used on this project.

4 Cathodic Protection Case Study: Control of Corrosion

The five general methods used in the control of corrosion are ;

  1. Coating
  2. Cathodic Protection (CP)
  3. Material selection
  4. Environmental modification
  5. Design practices

Control of underground corrosion is primarily achieved by combining two of the aforementioned methods: a coating system and CP. An effective external coating can provide corrosion protection to over 99% of the exposed pipe surface. The protective coating is usually applied to the pipe before burial.

The coating electrically insulates the metal from the soil. If the metal could be completely isolated, then the establishment of corrosion cells would be prevented, and no corrosion current would flow. However, no coating can be considered perfect. Damage to the coating due to handling, transportation, installation, thermal stress, and soil stress will eventually create defects or “holidays” that expose the underlying steel to the environment.

Cathodic protection is an electrochemical technique for preventing corrosion of a metal exposed to an electrolyte. The process involves the application of DC electrical current from an external source to the metal surface. By forcing the metal surface to accept current from the environment, the underground metal becomes a cathode, and protection occurs. The external source can use outside AC power through a rectifier and ground bed or by attaching sacrificial metals such as magnesium or aluminium to protect the structure. It is used extensively to prevent corrosion in underground and submerged steel structures such as pipelines, production well casings, and tanks.

Effective cathodic protection can completely protect any exposed areas for the structure’s life. Combining an external coating and cathodic protection provides the most economical and effective choice for protecting underground and submerged pipelines. For bare or ineffectively coated existing pipeline systems, cathodic protection often becomes the only practical alternative for corrosion protection on the proviso that the pipe bedding, padding and backfill permit the adequate flow of CP currents. Stones, rock and other poor backfills often permit the ingress of water and bacteria onto the exposed steel but obviate the flow of CP currents, exacerbating the corrosion process.

Therefore, correctly sized selective material must be used for the bedding and padding so that the exposed steel can receive CP and mitigate corrosion.

4.1 Pipeline Coatings – Primary Protection System

The protective coating is fundamentally the most important aspect of buried pipeline corrosion protection; hence, it is referred to as the primary corrosion protection system.

Pipeline anti-corrosion applications represent the market with probably the largest volume of coating products worldwide. This market potential naturally draws the focus of every coatings manufacturer, distributor and applicator. For these companies, the successful penetration of this market segment represents large product sales and volume increases over an extended period of time. Since large volume sales are the primary goal of every manufacturer, the end-user is bombarded with product marketing information, all claiming that their product alone is best suited for pipeline anti-corrosion applications. The sheer volume of information available on this subject can be overwhelming for the end-user who decides to select a specific product that is difficult to reach.

The ISO 21809-1 system and mill needs to be qualified, as per Clause 9. The latter qualification considers the various coating systems available, the skill levels regarding the application, environmental and mill/site-specific conditions controlling its application, and its efficacy regarding Cathodic Protection and its resilience to Cathodic Disbondment.

The Field Joint Coating (FJC) also needs to be duly qualified; otherwise, the FJC repair becomes the weakest link and the highest risk of corrosion due to the welding and Heat Affected Zones (HAZ)

4.2 Qualifying the Coating Applicator Facilities – Clause 9 (Preci)

Pipeline production and coating may not occur without a client-approved Inspection and Testing Plan (ITP) document providing an overview of the sequence of inspections and tests, including appropriate resources and procedures. The client shall approve the ITP and Quality Control Procedure (QCP) in writing before coating production begins.

A Procedure Qualification Trial (PQT) should take place after the approval of the documentation detailed above. It should be witnessed by the client or the duly appointed and authorised person appointed by the client to witness the application of the coating and subsequent inspection/testing of its properties to confirm that the Application Procedure Specification (APS) is adequate to produce a coating with the specified properties, carried out before the start of production.

5 Cathodic Protection Case Study: Cathodic Protection

CP is an electrochemical technique for preventing corrosion of a metal exposed to the electrolyte.

5.1 The Process of Cathodic Protection

CP is covered by numerous international specifications, which most would apply to the 8″ and 6″ MI-BAF-SAIA pipeline project, such as;

  1. EN 14505 “Cathodic protection of complex structures
  2. EN 13509/SANS 53509 “Cathodic protection measurement techniques”
  3. EN 12954 “Cathodic protection of buried or immersed metallic structures. General principles and application for pipelines.”
  4. EN 12474 “Cathodic protection for submarine pipelines.”
  5. EN 12068 “Cathodic protection. External organic coatings for the corrosion protection of buried or immersed steel pipelines are used in conjunction with cathodic protection. Tapes and shrinkable materials.”
  6. BS 7361-1 “Cathodic Protection”

To many people unfamiliar with the principles of corrosion, Cathodic Protection (CP) is a rather dubious method of corrosion control that has been commercialised since the 1920s. CP essentially means reducing or eliminating corrosion on a metal surface by forcing the metal to become a cathode.

The two general types of cathodic protection systems are impressed current and sacrificial. Both systems can effectively transfer the corrosion reaction (oxidation) from the metal surface to an external anode. If all exposed parts of a structure become cathodic concerning the electrolyte, corrosion of the structure is eliminated. Cathodic Protection is by no means new or of doubtful effectiveness in controlling corrosion.

The CP system is generally required to operate effectively and efficiently for 30 years.

Coatings (e.g. paints) applied to metal surfaces can be extremely effective in containing the corrosion of the steel substrate in many environments. However, no freshly applied coating is entirely free from defects, so there will always be small steel areas exposed directly to the corrosive environment. It is possible to reduce, but not eliminate, these defects by paying attention to workmanship. In practice, it becomes increasingly expensive to achieve fewer and fewer defects due to the need for high-quality inspection, detection and repair of individual defects.

The coating provides the initial barrier against the corrosive environment, and cathodic Protection protects against coating defects. Ideally, this complementary behaviour occurs due to the defects’ low resistance path, as opposed to the coating’s high resistance path.

A coating will deteriorate chemically and mechanically during its lifetime. This results in an increase in the number of defects and the current required to protect the newly exposed steel surface areas (defects).

The defects will once again provide a low path of resistance, and the cathodic protection current will flow to it and provide protection, provided that it is of sufficient magnitude. This naturally implies that the Cathodic Protection system must be designed with sufficient reserve to provide the necessary additional current.

Cathodic Protection (CP) may be achieved using Impressed Current Cathodic Protection (ICCP) or Sacrificial Anode Cathodic Protection (SACP). The choice of system is based on technical and economic factors.

5.2 Cathodic Protection Definitions

Several frequently used CP definitions are detailed below :

Cathodic Protection: Reduction of corrosion rate by shifting the corrosion potential of the electrode toward a less oxidizing potential by applying an external electromotive force.

Sacrificial/Galvanic Anode: A metal which, because of its relative position in the galvanic series, provides sacrificial protection to metals that are nobler in the series when coupled in an electrolyte.

Sacrificial Anode Cathodic Protection (SACP): A cathodic protection system in which a galvanic anode supplies the external electromotive force.

Impressed Current Cathodic Protection (ICCP): A cathodic protection system in which an external DC power source provides the external electromotive force.

Anode Groundbed: One or more anodes installed below the earth’s surface to supply the protective CP current

Transformer Rectifier Unit (TRU): A device which converts alternating current to direct current.

Horizontal Groundbed: A group of anodes installed close (2 to 5m) together and installed in a long trench (structure) some 2,5m deep and located far from the structure requiring protection (pipeline or tank).

Deep Vertical Anode Groundbed (DW): One or more anodes installed vertically at a nominal depth of 50m or more below the earth’s surface in a drilled hole.

Shallow Vertical Anode Groundbed (SV): One or more anodes installed vertically at a nominal depth of 20m or less below the earth’s surface in a drilled or augured hole.

Distributed Anode System: Several anodes are distributed in close proximity to the structure requiring protection to concentrate the current in a specific area only.

6 Methods of Applying: Cathodic Protection

6.1 Sacrificial Anode Cathodic Protection

Galvanic anodes are most efficiently used on electrically isolated coated structures. However, this matter will not be discussed further, as it does not apply to the MI-BAF-SAIAF PADMA Project.

6.2 Impressed Current Cathodic Protection System

An ICCP system protects large bare and coated structures and structures in “high” resistivity electrolytes. The design of any ICCP system must consider the potential for causing coating damage and the possibility of creating stray currents, which adversely affect other structures. Typically, Mixed Metal Oxide (MMO), Precious Metal Oxide (PMO), Silicon Iron (Fe-Si), and Graphite are used as anode materials.

Cathodic Protection Case Study

An ICCP system will offer the following advantages:

  • Flexibility
  • Applicable to a variety of applications and structures
  • Current and voltage output may be controlled
  • Not constrained by low driving voltages
  • Effective in high resistivity soils

An ICCP system will also offer the following disadvantages:

  • Regular and increased maintenance
  • Higher operating costs
  • May cause interference with other structures

7 Background Information

The proposed MI-BAF-SAIA Pipelines traverse corrosive to mildly corrosive and generally non-corrosive soils, for which Cathodic Protection (CP) is required.

The following important aspects of the CP Design.

  • Every effort must be made to ensure that the new underground piping is constructed without damaging the coating system.
  • All of the above-ground piping and above-ground metallic structures must be electrically isolated from the below-ground piping, as well as any other extraneous piles of earth, such as man-hole reinforcing, hard-surfacing reinforcing, above-ground pipes, tank farm and pump station (plant) earth, etc.,
  • To ensure electrical isolation from other above-ground metallic structures, such as piping and tank farm/Pump Station steel structures, which are all earthed, the below-ground piping must be electrically isolated where it comes above ground using Insulating Flanges (IF) and, if possible, Monolithic Insulating Joints (IJ).
  • All IJ/ IFs must, in turn, be protected to mitigate the formation of sparks resulting from stray currents, static, and lightning effects, as defined in API RP2003. This is of particular importance where IJ/IFs are located in Zone 1 and 2 areas.
  • Pipes located adjacent to one another or at crossings require at least 250mm separation to prevent electrical shielding.

The essential purpose of the CP Design is to ensure that Cathodic Protection can protect the new pipeline(s). The proposed pipeline route is detailed below.

Cathodic Protection Case Study

8 Cathodic Protection Case Study: Proposed Design

8.1 Cathodic Protection (CP) System Design

It is extremely important that the correct type of CP system is installed and that the anode ground beds are located suitably in a congested petrochemical environment. If the anodes are not correctly located, an incorrect system may result in poor or no protection or overprotection, which can give rise to problematic and costly maintenance, etc.

8.1.1 Impressed Current Cathodic Protection (ICCP) System

A small Impressed Current Cathodic Protection (ICCP) consisting of a shallow horizontal anode groundbed and automatic CP controller will be the most commercially viable system based on the prevailing conditions.

8.2 Boundary Element Methods (BEM) Cathodic Protection Modelling

8.2.1 Introduction

Failures in oil or gas pipelines can have severe environmental and economic consequences. Therefore, large investments have been made in studies relating to preventing the corrosion of these buried pipelines. Important research has been and continues to be conducted in order to determine and predict the corrosiveness of soil in which the pipeline is buried, together with the corrosion mechanisms and the effective protection techniques required, such as protective coating systems. In addition to this, because the pipeline is buried and the location, size and overall geometry of the bare metal areas (coating defects/holidays) are unknown, as are the local soil conditions (resistivity and chemical composition), to obtain this data would require costly and often unreliable above-ground surveys. However, many of these coating defect surveys are intricate, elaborate and expensive and often do not yield all required data without substantial excavations, at great risk and expense.

Optimizing the cathodic protection (CP) system (s) design was necessary to ensure a highly efficient and low-cost CP system for pipelines, particularly in a congested petrochemical facility. This requires an understanding of the electrical/electrochemical process’s behaviour in terms of the current and potential distribution at the electrodes and in the electrolytic medium (soil).

Therefore, it is very important to have an adequate model that describes the performance of the CP system(s) and uses powerful software to simulate the electrical/electrochemical processes.

When designing a CP system, the aim is to obtain a pipe-to-soil potential (P\S) along the developed length of the pipeline network that is more negative than a certain minimum protection level. In soils, this minimum level is normally taken at -0.95V versus a copper-sulphate reference electrode (CSE). The CSE must be placed directly adjacent to the pipeline to reduce the IR- drop in the soil and across the coating to the coating defect. The value obtained in this situation is called the “Off” potential or P\S Off.

In practice, however, due to the unknown location of the defect and its unknown characteristics, it is often impossible to place the CSE directly adjacent to the pipeline coating defect. Instead, the CSE is placed at the soil surface, directly above the pipeline, which can result in significant IR errors. The value in this instance is referred to as the “On” potential or P\S On. In normal operating conditions, this value is more negative than the (true) “Off” potential, overestimating the obtained protection level.

In order to simulate and model pipeline cathodic protection systems, one needs to understand the basic ideas behind the “external” world (the soil) and the “internal” world (the metallic pipeline). The essential basics of the Boundary Elements Model (BEM) are detailed below.

The soil, together with the pipe(s) and anode(s), both of which are ostensibly cylindrical in nature, is essentially considered an electrical/electrochemical system in which the earth acts as the electrolytic solution (conducting medium) and the outer metallic pipe surface(s) (coating defects) act as the electrodes.

Boundary Element Methods (BEM) have been proven to closely follow the more precise yet time-consuming and costly Finite Element Methods (FEM) models. The latter is corroborated in the attached literature, “A Numerical Model for Cathodic Protection of Buried Pipes“.

8.2.2 Boundary Element Methods (BEM) Results

The output models, which are also detailed individually below and in Appendix A, provide the complete level of protection afforded to the proposed BAF, SAIA, and Hydrants.

The piping model is summarised below, where L is the length, and S is the surface area.

Pipeline Detail

Length (m)

Surface Area (m²)
BAF Pipe2

1556.00

822.40
BAF-Spur

55.20

29.18
BAF-H1

116.90

61.80
BAF-H2

13.86

7.33
PADMA8

5773.00

3973.00
SAIA 10

637.80

547.10
Total

8152.76

5440.809

The BEM model indicates that all “Off” potentials are more negative and -950mV CSE.

The “On” potentials indicate that no substantial over-protection will take place, based upon the “On” and “metal potential”. The metal potential is the pipe potential located directly at the coating interface but remote to the coating defect, thereby limiting the “IR Error” to a better degree. It is more valid in terms of judging the level of overprotection that could occur if the “Off” potentials are more negative than -1100mV CSE (EN 12954 Clause 4.2) than using the “On Potential”.

The current density is indicated to be the highest and closest to the Cp Station. It will also become higher in areas of low soil resistivity (lowest resistance to earth of defects), as the most current will be required in these areas to polarise the pipeline and prevent corrosion.

However, the total current is 10A for the 30-year end-of-life design, which is attainable from the new 50V 25A Transformer Rectifier Unit (TRU) when coupled to a single 50m long 2.5m deep horizontal anode ground bed.

The summary of the current (I) balance and current density (J) is detailed below:

Pipeline Current (A) Current Density (A/m²)
BAF Pipe2 -1.43 -0.00174
BAF-Spur -0.06 -0.00193
BAF-H1 -0.12 -0.00189
BAF-H2 -0.01 -0.00091
PADMA8 -7.90 -0.00199
SAIA 10 -0.50 -0.00091
Groundbed1 10.00 6.30300
Current Balance of All Branches 0.00011

Appendix A details the complete BEM Output Model Data and indicates that the proposed ground’s location is acceptable.

9 Proposed MI-BAF-SAIA Pipeline (PADMA) Project ICCP Installation

The proposed PADMA ICCP system shall comprise of the following, as a minimum:

  • A new 50V 25A Fully Automatic TRU, preferably installed inside an IP65 Enclosure and Pole Mounted.
  • A 2.5m deep Shallow Horizontal Anode Groundbed shall be 50m long and contain twenty-five (25) High-Chromium Centrifugally Cast (14 kg Min) Silicon Iron anodes. These shall be encapsulated in pitch-calcined carbonaceous backfill, centrally located at a 300mm diameter, and with 2m long hot-dip galvanised anode canisters.
  • The anode cable shall be a 10mm² PVC/XLPE cable. The cables must comply with IEC 60811-200 to 600-2012 series, as applicable.
  • Each anode cable will terminate via a T-cable jointing Kit (3M or technically approved equivalent) onto a 35mm² PVC/XLPE IEC 60811-200 to 600-2012 series certified ring main cable. All connections will be hydraulically crimped using a tinned copper t-ferrule and wrapped in self-vulcanising tape before being installed inside the cable jointing kit. The ring main cable will then terminate into the IP65 CP TRU Enclosure via suitable rated IP66 glands and onto a suitably rated tinned copper busbar.
  • All inline valves and manholes shall be cross and continuity bonded outside using two 16mm2 PVC/XLPE (black) IEC 60811-200 to 600-2012 series certified cables. The cables will be supported outside the chambers using 50mm plastic (uPVC) conduit and shall be cleated to the wall and/or buried outside (if construction permits). Each Manhole needs to be tested during construction to ensure that no reinforcing steel or extraneous earth is connected at the Manholes.
  • Eight (8) new CP Test Stations as per EN 13509 Annex G Type D “IR Free” Test Points shall be included in the redlined Plot Plan Drawing and terminate inside the CP Test Point IP68 Enclosure. Note these may not be located inside a hazardous area; otherwise, EXd certification is required. There will be a requirement to install two 16mm2 PVC/XLPE (black) IEC 60811-200 to 600-2012 series certified cables to connect the 8″ PADMA pipeline to the 6″ BAF and other hydrants for compliance testing to EN 50162. These “bonding facilities” will be completed inside CP-TP enclosures at approximately four of the eight (8) locations, and this will be finalised upon final construction routing.
  • The pipeline extremities and all off-takes need to be isolated using Monolithic Insulating Joints, and these need to be protected for transient surges as per API RP2003 using certified 100KA Surge Protection Devices (SPD), e.g. Dehn EX-FS L300.

10 Executive Summary

  1. The Water Resistivity Survey data based upon certificate 110120677/16-17/CE for the Canal and Pond water indicates the soil will be corrosive towards steel, for which Cathodic Protection is strongly recommended. A detailed Soil Survey as per ASTM G57 (Wenner Four Method) was conducted, indicating that less than 25% of the surveyed route conducted in February 2017 is corrosive. The data is issued in Appendix B and shown graphically below. Soil sampling to DIN 50929-3 is also recommended (during construction) so that the data may be used for future integrity assessments and to determine high-risk areas, corrosion rates and corrosion indexes. 
  2. It is understood that the pipeline coating will be applied following ISO 21809-1 Table 1 Class A (-20EC to +60EC) and Table 2 Class A3 (Thickness). The Field Joint Coatings will comply with EN 12068 Class C HT50EC DVGW certified coating systems or ISO 21809-3 Code 2A or 2B Clause 11. EN 12068 DVGW Certified materials are the preferred coating system due to traceability and mechanical certification.
  3. Boundary Element Methods (BEM) were used to model the proposed PADMA, BAF and Hydrant system. The proposed ICCP system shall comprise of the following, as a minimum:
    1. A new 50V 25A Fully Automatic TRU, preferably installed inside an IP65 Enclosure and Pole Mounted.
    2. A 2.5m deep Shallow Horizontal Anode Groundbed shall be 50m long and contain twenty-five (25) High-Chromium Centrifugally Cast (14 kg Min) Silicon Iron anodes. These shall be encapsulated in pitch-calcined carbonaceous backfill, centrally located at a 300mm diameter, and with 2m long hot-dip galvanised anode canisters. The anode cable shall be a 10mm² PVC/XLPE cable. Cables are to comply with the IEC 60811-200 to 600-2012 series, as applicable.
    3. Each anode cable will terminate via a T-cable jointing Kit (3M or technically approved equivalent) onto a 35mm² PVC/XLPE IEC 60811-200 to 600-2012 series certified ring main cable. All connections will be hydraulically crimped using a tinned copper t-ferrule and wrapped in self-vulcanising tape before being installed inside the cable jointing kit. The ring main cable will then terminate into the IP65 CP TRU Enclosure via suitable rated IP66 glands and onto a suitably rated tinned copper busbar.
    4. All inline valves and manholes shall be cross and continuity bonded outside using two 16mm2 PVC/XLPE (black) IEC 60811-200 to 600-2012 series certified cables. The cables will be supported outside the chambers using 50mm plastic (uPVC) conduit and shall be cleated to the wall and/or buried outside (if construction permits). Each Manhole needs to be tested during construction to ensure that no reinforcing steel or extraneous earth is connected at the Manholes.
    5. There shall be eight (8) new CP Test Stations as per EN 13509 Annex G Type D “IR Free” Test Points, which shall be included in the redlined Plot Plan Drawing and terminate inside the CP Test Point IP68 Enclosure. Note these may not be located inside a hazardous area; otherwise, EXd certification is required. There will be a requirement to install two 16mm2 PVC/XLPE (black) IEC 0811-200 to 600-2012 series certified cables to connect the 8″ PADMA pipeline to the 6″ BAF and other hydrants for compliance testing to EN 50162. These “bonding facilities” will be completed inside CP-TP enclosures at approximately four of the eight (8) locations, and this will be finalised upon final construction routing.
    6. The pipeline extremities and all off-takes need to be isolated using Monolithic Insulating Joints, and these need to be protected for transient surges as per API RP2003 using certified 100KA Surge Protection Devices (SPD), e.g. Dehn EX-FS L300.
  4. All buried metallic structures (rebar, puddle flanges, etc.), i.e. extraneous earth that is not intended to be incorporated into the CP system, shall be electrically isolated from the piping that is to be incorporated into PADMA 8″ and 6″ BAF and Hydrant system to obviate “electrical drains” that prevent effective CP. Electrical isolation shall be carried out following NACE RP0286 “Electrical isolation of Cathodically protected pipelines” These structures and items include all Man-Hole reinforcing steel and puddle flanges, hard-surfacing reinforcing steel at Aprons and all above-ground appurtenances. This will be validated by the CP contractor, who will conduct regular Current Drain Tests (CDT) as per NACE TM0102 during construction. The piping contractor will supply and install all required IF/IJ. Still, each of these is to be protected using a Surge Protection Device, such as the Dehn EX-FS LX100 system or equivalent and located inside an EXd enclosure, should these be located in hazardous areas.
To all knowledge