Cathodic Protection Case Study – Padma Bangladesh

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“

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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 to which the metal is exposed. Read more on EPCMs Cathodic Protection

Four conditions must be met for corrosion to occur. The elimination of any of the four conditions will halt the corrosion reaction.

1. An 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 have the capacity 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 apposed to ionic current in the electrolyte).In order 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

Probability of corrosion of metallic materials when subject to corrosion from the outside Buried and underwater pipelines and structural components.

2 Cathodic Protection Case Study: Forms of Corrosion

Corrosion exhibits itself in a number of ways. A brief description of certain forms of corrosion is provided below.

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 due to 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 type of 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 that occurs 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 of importance 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 based upon 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. Where two metals with different potentials are connected to each other in a common environment, the current will flow causing corrosion to occur. The latter form of corrosion will occur, where 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 the coupling of 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 grades fo steel 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, that is 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 serves to electrically insulate 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 a perfect coating. Damage to the coating as a result of handling, transportation, installation, thermal stresses, and soil stresses 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 to the metal surface from an external source. 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 the structure to be protected. It is used extensively in preventing corrosion to underground and submerged steel structures; such as pipelines, production well casings, and tanks.

Effective application of cathodic protection can provide complete protection to any exposed areas for the life of the structure. The combination of an external coating and cathodic protection provides the most economical and effective choice for protection of 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 permits 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 obviates the flow of CP currents, exacerbating the corrosion process.

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

4.1 Pipeline Coatings – Primary Protection System

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

Pipeline anti-corrosion applications represent what is probably the largest worldwide volume market for coatings products. This market potential naturally draws the focus of every coatings manufacturer, distributor and applicator and 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 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, making a decision to select a specific product difficult to reach.

The ISO 21809-1 system and mill needs to be qualified, as per Clause 9. The latter qualification takes into account the various coating systems available, the skill levels regarding the application, environmental and mill/site-specific conditions controlling its application, as well as 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 take place 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 prior to coating production commencing.

Subsequent to the approval of the documentation detailed above, a Procedure Qualification Trial (PQT) should take place and should be witnessed by the client or the duly appointed and authorised person appointed by the client to witness that 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 prior to 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 of which most would be applicable on 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 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 but has been commercialised since the 1920s. CP essentially means the reduction or elimination of 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 types of 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 with respect to the electrolyte, corrosion of the structure is eliminated. Cathodic Protection is by no means new or of doubtful effectiveness in controlling corrosion.

It is also generally required that the CP system operates 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 and so there will always be small areas of steel which are 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 the repair of individual defects.

The coating provides the initial barrier against the corrosive environment and cathodic Protection provides protection at the coating defects. This apparently ideally complementary behaviour occurs as a result of the low resistance path offered by the defects, as opposed to the high resistance path offered by the coating.

A coating will deteriorate both chemically and mechanically during its lifetime. This results in an increase in both the number of defects and the current required in order 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, providing that the is of sufficient magnitude. This naturally implies that the Cathodic Protection system must be designed such that it has sufficient reserve in order to provide the necessary additional current.

Cathodic Protection (CP) may be achieved by means of Impressed Current Cathodic Protection (ICCP) or Sacrificial Anode Cathodic Protection (SACP). The choice of which system to use is based on both technical and economic factors.

5.2 Cathodic Protection Definitions

A number of 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 the external electromotive force is supplied by a galvanic anode.

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

Anode Groundbed: One or more anodes installed below the earth’s surface for the purpose of supplying 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 distributed in close proximity to the structure requiring protection, in order 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 is not applicable to the MI-BAF-SAIAF PADMA Project.

6.2 Impressed Current Cathodic Protection System

An ICCP system is used to protect large bare and coated structures and structures in “high” resistivity electrolytes. The design of any ICCP system must take into consideration 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.

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 on 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 pertaining to the CP Design.

• Every effort must be made during the construction of the new underground piping in order to ensure that minimal damage occurs to the coating system during construction.
• 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.,
• In order 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 they come above ground using Insulating Flanges (IF) and if possible, Monolithic Insulating Joints (IJ).
• All IJ/ IFs must, in turn, be protected in order 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/IF 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 the new pipeline(s) can be protected by Cathodic Protection. The proposed pipeline route is detailed below.

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 be installed and the anode ground beds located suitably in a congested petrochemical environment. An incorrect system may result in poor or no protection, overprotection if the anodes are not correctly located, and this 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) which will consist of a shallow horizontal anode groundbed and automatic CP controller will be the most commercially viable system based upon 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 with regards to studies relating to the prevention of 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 is 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 defects surveys are intricate, elaborate and expensive and often do not yield all of the required data without substantial excavations, at great risk and expense.

In order to ensure a highly efficient and low-cost Cathodic Protection (CP) system for pipelines particularly in a congested petrochemical facility, it was necessary to optimize the design of the CP system(s). This essentially requires an understanding of both the behaviour of the electrical/electrochemical process 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), utilising powerful software to simulate the electrical/electrochemical processes taking place.

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 needs to be placed directly adjacent to the pipeline in order to reduce the IR- drop in the soil and across the coating to the coating defect. The value obtained in this situation is referred to as 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 and important 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, resulting in an overestimate of 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 being ostensibly cylindrical in nature are essentially considered as 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) has 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 complete level of protection afforded to the proposed BAF, SAIA and Hydrants are in the output models which are also detailed individually below and in Appendix A.

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

The BEM model indicates that all of the “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 highest closest to the Cp Station and 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, in order to polarise the pipeline and prevent corrosion.

However, the total current is a 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 groundbed.

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

The complete BEM Output Model Data is detailed in Appendix A and indicates that the location of the proposed groundbed 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 single 2.5m deep Shallow Horizontal Anode Groundbed which shall be shall be 50m in length and contain twenty-five (25) High Chromium Centrifugally Cast (14Kg Min) Silicon Iron anodes and shall these shall be encapsulated in pitch calcined Carbonaceous Backfill, centrally located in 300mm diameter and 2m long hot-dip galvanised anode canisters.
• The anode cable shall be a 10mm² PVC/XLPE cable. Cables to 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 to 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 Man-Hole needs to be tested during construction to ensure that no reinforcing steel or any extraneous earth is connected at the Man-Holes
• 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 these shall 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 and indicates that less 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 and corrosion rates and corrosion indexes
2. It is understood that the pipeline coating will be applied in accordance with 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) was 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 single 2.5m deep Shallow Horizontal Anode Groundbed which shall be shall be 50m in length and contain twenty-five (25) High Chromium Centrifugally Cast (14Kg Min) Silicon Iron anodes and shall these shall be encapsulated in pitch calcined Carbonaceous Backfill, centrally located in 300mm diameter and 2m long hot-dip galvanised anode canisters. The anode cable shall be a 10mm² PVC/XLPE cable. Cables to comply with 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 to 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 Man-Hole needs to be tested during construction to ensure that no reinforcing steel or any extraneous earth is connected at the Man-Holes
   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 these shall 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 are 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 in accordance with 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. All required IF/IJ will be supplied and installed by the piping contractor, but each of these is to be protected using a Surge Protection Device, such as Dehn EX-FS LX100 system or equivalent and located inside an EXd enclosure, should these be located in hazardous areas.