Cathodic Protection of Steel in Concrete

Cathodic Protection of Steel in Concrete

This article is for the design, materials, installation, and pre-commissioning testing of impressed current cathodic protection (ICCP) systems for existing and new reinforced concrete structures. All technical information and international codes and standards requirements are discussed. This article is useful for engineers, supervisors, managers and technicians who are working in petrochemical plants, refineries and big construction projects.

International Codes and References

Reference is made in this standard to the following documents. The latest issues, amendments, and supplements to these documents shall apply unless otherwise indicated.

Related Articles:

Cathodic Protection of Plant Facilities
Commissioning & Operation of CP Systems of Reinforced Concrete Structures

American Concrete Institute (ACI)

506R Guide to Shotcrete
506.2R Specifications for Shotcrete
546R Concrete Repair Guide

American Society for Quality Control (ASQC)

ANSI/ASQC Q9001 Quality Systems-Model for Quality Assurance in Design, Development, Production, Installation and Servicing.

American Society for Testing and Materials (ASTM)

C33 Specification for Concrete Aggregates
C39 Test Method for Compressive Strength of Cylindrical Concrete Specimens
C150 Specification for Portland Cement
C876 Test Method for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete
C1084 Test Method for Portland-Cement Content of Hardened Hydraulic-Cement Concrete
C1152 Test Method for Acid-Soluble Chloride in Mortar and Concrete
C1218 Test Method for Water-Soluble Chloride in Mortar and Concrete.

European Standards
EN 12696-1 Cathodic Protection of Steel in Concrete

National Association of Corrosion Engineers (NACE)
RP0290-90 Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete
Structures.
Occupational Safety and Health Administration (OSHA) of U.S.A.
29CFR 1910 OSHA Standards and Compliance Guidelines

3 Definitions

For the purpose of understanding this standard, the following definitions apply.

Anode. The electrode at which oxidation reactions, for example corrosion reactions, occur. For CP of reinforced concrete, the anode is an inert material, for example catalyzed titanium ribbon mesh, which is used to distribute protective current to the reinforcing steel.

Cathode. The electrode at which reduction reactions occur. In a CP system for reinforced concrete, the cathode is the reinforcing steel.
Current Distributor / Conductor. An uncoated strip of titanium which is used to feed current to the anode system and connect adjacent lengths of anode mesh together electrically. The current distributor is welded to the anode mesh or anode ribbon mesh in the field, with a portable resistance welder.
Current On’ Potential. The potential of the reinforcing steel measured by the reference electrode
when the CP system is in operation, that is, with CP current flowing. This potential includes the
polarization potential and other voltage drops resulting from the flow of current (IR drop).

Depolarization Test. An acceptance test used for the performance evaluation of CP systems for
reinforced concrete structures. Depolarisation is determined by interrupting the protective current and measuring the potential decay between the reinforcing steel and a reference electrode. The
depolarisation equals the final potential minus the instant off potential.

‘Instant Off’ Potential. To measure the true polarized potential, the potentials are measured with the current turned off instantaneously, thus eliminating the IR drop (see „Current On‟ Potential above).
Natural Potential. Corrosion of the reinforcing steel occurs when there is a net flow of electrical current between one part of the reinforcement cage and another. This tendency to corrode can be measured with a voltmeter and a reference electrode and is called the „natural potential‟ or „corrosion potential‟.
Polarisation. When the CP system is in operation, there is a net flow of electrical current between the anodes and the reinforcing steel. As a result of this current flow, steel/concrete potential is shifted towards more negative potentials. This potential shift from their open circuit corrosion potentials is called „polarisation‟. This polarization potential can be varied by varying the current flow in the CP system. Accordingly, a desired level of corrosion protection can be selected.
Rebar Clip. Plastic clip that is attached to the exposed reinforcing steel to support the anode ribbon mesh. The rebar clip is used to provide a stand off (separation) between the anode and reinforcing steel.
Reference Electrode. A half-cell of reproducible potential, for example silver-silver chloride (Ag/AgCl). A standard against which potentials of other electrodes can be measured or compared. Reference electrodes may be portable or permanently installed in the concrete structure.
System Negative Connections. Cables electrically connected to the steel reinforcement in the
concrete. These cables are connected to the negative terminals in the rectifier.
Transformer Rectifier or Power Supply. A device used to convert alternating current (ac) to direct current (dc). In a CP system, the transformer rectifier(TR) or power supply (PS) is used to control the voltage, current or potential to each anode zone.
Zone. An area of the CP system that can be independently powered and controlled. The anode cables, and the system negative cables, from each zone are connected to positive and negative terminals respectively, in the rectifier (commonly referred to as a rectifier or power „output‟).

4. General Requirements

4.1 Structures for Cathodic Protection

4.1.1 All parts/areas of the structures containing seawater, i.e. intake/discharge ponds and/or basins, cooling towers, pump sumps, canals, basins and sumps shall be cathodically protected.
4.1.2 SABIC shall determine other critical structures and foundations requiring a CP system, for example, process or fresh water containing ponds, basins & cooling towers, and slurry ponds & clarifier tanks, and reactor, compressor, turbine, & boiler foundations.

4.2 CP Design and Supervision

The CP of steel in concrete requires expertise in the field of electrochemistry, civil/structural
engineering, and CP engineering.
4.2.1 The CP design engineer shall be a NACE certified (USA) CP specialist and/or MICorr (UK) professional member. The CP specialist’s professional experience shall be minimum 8 years in CP of reinforced concrete structures.
4.2.2 The engineer responsible for routine daily inspection, testing, and ensuring QA/QC programme during the CP system installation shall either be a NACE (USA) certified CP tester or equivalent (CP Technician Level 2) from MICorr or Institute of Corrosion Training & Certification Scheme. However, the “Hold Points” shall be checked and signed off only by a CP supervising specialist, which shall either be NACE (USA) certified CP Technologist or MICorr (UK) professional member. The professional experience of CP tester/technician and CP supervising specialist shall be minimum 5 and 8 years respectively in CP of reinforced concrete structures.
4.2.3 A CP system may either become a structural component or significantly affect the serviceability and structural performance of a reinforced concrete structure; therefore, a structural engineer shall review the effect of the CP system.

4.3 Warranty

The contractor shall provide a written warranty of 5 years for the components of the CP system. In the event of malfunctioning or failure of any component of the CP system, the contractor shall rectify the fault or replace the faulty component at its own cost, to SABIC satisfaction.

4.4 Manufacturer’s Procedures

In addition to the standards referenced in section 2, the SABIC approved anode manufacturer‟s own recommended installation and materials standards and procedures shall be recognized as part of this standard. No deviations from manufacturer recommendations or quality standards shall be permitted without prior approval by SABIC.

4.5 Health and Safety

Work associated with CP of reinforcing steel in concrete structures shall comply with SABIC Health and Safety Procedures, SASO SSA 336 and OSHA 29CFR 1910. Work permits shall be obtained from respective authorities when necessary.

5 Pre-Design Survey, Testing and Considerations

5.1 Existing Structures

5.1.1 Prior to CP design and application, appropriately trained and experienced engineers shall perform a condition survey of the structure to:

a. Determine cause(s) of corrosion.
b. Establish its material condition and structural integrity.
c. Determine extent of deterioration and how to repair it.
d. Confirm suitability of CP.
e. Provide system design input information.

5.1.2 Records

a. Prior to the start of site survey, available design drawings (particularly structure‟s plans and
steel reinforcement layout drawings), specifications and records shall be reviewed, to assess the
location, quantity, type, for example normal, galvanized, epoxy-coated or pre-stressed, and
continuity of the reinforcement.
b. The embedded discontinuous steel in areas to be cathodically protected shall be identified, for
example anchor bolts and base plates.
c. Constituents and quality of the concrete shall be reviewed and assessed for suitability of CP.

5.1.3 Visual Inspection

a. All accessible parts/elements of the structure shall be visually inspected as closely as possible
to determine the type, causes and extent of defects, and to identify any features of the structure or its surrounding environment which could influence the application and performance of CP system.
b. Previously repaired areas shall be identified, together with their repair methods and materials.
c. All defects, for example cracks, honeycombing, or poor construction joints, which could permit
significant water penetration and subsequently affect the performance of CP system, shall be
recorded.
d. Areas of structure where deterioration of concrete is not due to corrosion of reinforcing steel
shall be identified, and the cause of deterioration determined. If any signs of structural distress are evident, an assessment of both the load bearing capacity of the structure and the need for
temporary or permanent strengthening shall be carried out.

5.1.4 Delamination Survey

a. The areas of the structure which require to be cathodically protected shall be checked for
delamination of the concrete cover, to identify the delaminated layers.
b. Hammer sounding or other techniques, for example impulse radar, thermography and
ultrasound, whichever is most economical and practical, may be used for identification of
delaminations in concrete.

5.1.5 Chloride and Cement Content

a. Chloride content profile relative to weight of cement in concrete shall be determined. Analysis
shall be in accordance with ASTM C1152 and C1218 or other as approved by SABIC.
b. Cement content shall be determined by chemical analysis of representative samples of
crushed hardened concrete, tested in accordance with ASTM C1084 or other as approved by
SABIC.
c. Maximum aggregate size shall be considered when selecting the core or drill diameter.
d. Sufficient samples shall be taken to determine the chloride profile in all parts of the structure.
5.1.6 Alkali Silica Reaction (ASR) Assessment
a. When the concrete to be cathodically protected contains aggregates which may be sensitive
to alkali, the risk of ASR shall be considered.
b. If the presence of ASR is identified, then CP shall not be recommended.

5.1.7 Concrete Cover

a. To confirm or determine the concrete cover depth, reinforcement type, size and position, the
reinforcing steel shall be exposed at a few locations by drilling cores or using other SABIC
approved tools.
b. High and low cover areas shall be identified, to assess comparative current flow through them,
and the risk of short circuit between the reinforcing steel and anode.
c. Areas with high steel densities shall be identified, to assess the local current requirement, and
to design the anode layout accordingly for uniform current distribution.
d. Areas where the reinforcement to be protected is surrounded, covered or shielded by
embedded metal meshes, metal fibers or plates or plastic sheets or non-conductive repair
materials shall be identified. Investigations shall be carried out to determine the effectiveness of the CP system in those areas, and to eliminate or reduce shielding of the protective current to the
reinforcing steel.

5.1.8 Carbonation Depth Measurements

a. Carbonation depth shall be measured on freshly fractured, not cut or drilled, concrete
surfaces, by spraying with aqueous phenolphthalein solution.
b. Tests shall be conducted particularly in areas with low cover to concrete, and where the
concrete appears to be porous or honeycombed.

5.1.9 Reinforcement Continuity

a. For successful operation of a CP system, the reinforcing and other partly or fully embedded
steel shall be electrically continuous, otherwise the discontinuous steel will be subject to stray
current corrosion. Therefore, reinforcement layout drawings shall be checked for theoretical
continuity. This shall then be proved on site by measuring the resistance or potential, or both,
between different rebars at the same and at mutually remote locations across the structure.
b. Continuity testing at this stage shall only be conducted for the purpose of confirming CP
feasibility and providing design information. Testing shall at least provide information on the
following items on a representative basis determined by the specialist:

i. Continuity between elements of the structure within each proposed zone of the CP system
ii. Continuity of reinforcement within elements of the structure
iii. Continuity of metallic items other than reinforcement to the reinforcement
iv. Parts of the structure where further continuity testing is required during the installation of CP system.
c. Testing shall be in accordance with 8.2.8 and 8.2.9.

5.1.10 Potential Mapping

a. Potential mapping shall be conducted in representative areas selected by the specialist, of
both damaged and undamaged concrete, in accordance with ASTM C876 or other SABIC
approved relevant standards.
b. Potential measurements shall be carried out using a portable reference electrode on a grid, at
a maximum spacing of 500 mm.
c. Portable reference electrode shall preferably be Ag/AgCl/0.5M KCl designed for use either
directly on the concrete surface or in conjunction with Luggin probes.
d. Portable reference electrodes shall be supplied with a calibration certificate. They shall be
stored, maintained and handled in accordance with the manufacturer‟s instructions, and checked
against a known laboratory standard reference electrode, or similar, at the beginning and end of
each site application.
e. Potential mapping data shall be used to determine anodic areas. Some may then be selected
for the placement of embeddable reference electrodes in the detailed CP design.

5.1.11 Concrete Resistivity

a. Resistivity of the concrete in areas to be cathodically protected shall be measured in
representative areas selected by the specialist, using an adapted Wenner four probe array. A
probe spacing of between 10 and 75 mm shall be selected, taking into account the concrete‟s
coarse aggregate size and cover to reinforcing steel or other spacing as approved by SABIC.
b. Measured concrete resistivity shall be used in the design of the CP system.
c. Resistivity and potential mapping on the area under investigation shall be conducted at the
same time, to give an accurate basis for interpretation of potential measurement.

5.2 New Structures

5.2.1 When including a CP system in the original construction, to prevent corrosion of the reinforcing steel, the specialist shall review the construction drawings to determine the feasibility and design requirements of the CP system, and its compatibility with the structure‟s design and construction.

5.2.2 Reinforcement drawings shall be reviewed for the:

a. Rebar type, size and layout, which shall show spacing between two adjacent rebars, and inner
and outer layers of steel reinforcement for appropriate anode design
b. Steel density in different parts of the structure, for appropriate configuration of anode zones or
anode materials grade or both
c. Provision and checking of reinforcement continuity
d. Location and connection of other partly or fully embedded metallic fixtures, fixings, or other
items, to check for their electrical continuity to the steel reinforcement and avoid undesirable
influences from the CP system
5.2.3 Layout of steel reinforcement cage shall be reviewed closely and in full detail, to ensure adequate securing and protection of monitoring sensors (embeddable reference electrodes) and cables and their connections, to avoid their damage or disturbance during concrete placement and vibration.
5.2.4 Concrete mix and its expected electrical resistivity shall be considered in the design of CP system.
5.2.5 Locations of expansion and construction joints, and concrete pouring sequence shall be taken into consideration, for appropriate handling of anode materials and configuration of anode zones.
5.2.6 For concrete surfaces exposed to corrosive liquid, corrosivity shall be considered, for appropriate selection of design current density and anode positioning, to meet the protective current requirement at the rebars nearest to the liquid.
5.2.7 Anchor bolt locations for handrails, ladders ….etc. shall be decided during design stage to avoid short circuit in the CP system during installation.

6 Design

6.1 General

6.1.1 Prior to starting the detailed CP design, the CP designer (consultant or contractor) shall develop a conceptual CP design which shall be submitted to SABIC (PMT/STC-J) for review and approval.
6.1.2 The CP system shall provide a cost effective design life commensurate with the required life of the structure to be protected. The specialist shall consider, as a minimum, lifetime requirements, service environment, weight, and installation sequence and constraints.
6.1.3 The specialist shall familiarize with operation of the unit attached to the structure to be protected, and shall ensure that CP system installation works will not obstruct these operations significantly.
6.1.4 The specialist shall ensure that location and size of CP system components shall not cause obstruction to operation of the existing instruments.
6.1.5 The specialist shall ensure that CP system components are specified, manufactured and installed in accordance with the hazardous area classification requirements of SABIC plant.

6.1.6 The detailed CP design shall include the following as a minimum, which shall be submitted for SABIC (PMT/STC-J) review and approval:

a. Design report
b. Detailed calculations
c. Detailed design (installation) drawings
d. Detailed material specifications.

6.2 Protection Criteria

6.2.1 Any representative monitoring point shall meet any one of the following three criteria:
a. An instant off potential (measured between 0.1 s and 1 s after switching the dc circuit off)
more negative than -720 mV with respect to Ag/AgCl/0.5M KCl.
b. A potential decay of at least 100 mV from instant off over a maximum period of 24 hours.
c. A potential decay over an extended period (typically 48 hour or longer up to maximum of 96
hour) of at least 150 mV from the instant off subject to continuing decay (using only
embeddable reference electrodes at representative locations)
6.2.2 In meeting any of the above criteria, instant off steel potential of the protected structure shall not be permitted to be more negative than -1100 mV with respect to Ag/AgCl/0.5M KCl for reinforcing steel or 900 mV Ag/AgCl/0.5M KCl for prestressing steel.

6.2.3 A fully depolarized steel potential of more positive than -150 mV Ag/AgCl/0.5M KCl obtained after a long-term current interruption (switching off) of the CP system (typically 7 days or longer) may be considered appropriate by the SABIC CP specialist.

6.3 Design Criteria

6.3.1 CP system shall be capable of delivering sufficient protective current to polarize the structure satisfactorily so that selected criterion for CP is attained efficiently.
6.3.2 CP system type shall only be impressed current cathodic protection (ICCP) for all different parts or sections of the structure.
6.3.3 Minimum design life of the CP system major components shall be 25 years.
6.3.4 The current distribution to different parts of the concrete structure shall be adequately uniform and under good control.
6.3.5 The design steel current density for all new structures and foundations shall not be less than 5 mA/m2 of steel surface area.
6.3.6 The design steel current density for all existing old and deteriorating structures and foundations shall not be less than 20 mA/m2 of steel surface area. For submerged areas only, design steel current density ranging between 10 to15 mA/m2 of steel surface area can be allowed provided the reinforcing steel is not experiencing extensive corrosion. The contractor shall obtain PMT/STC-J approval for applying design current density between 10 to15 mA/m2 of steel surface area.
6.3.7 Maximum allowable current density at the anode-concrete interface shall be 110 mA/m2 of anode surface.
6.3.8 In submerged areas of seawater and other liquid containing structures, there shall be a separate dedicated CP system (independently powered & controlled) for exposed metallic equipment and ancillary steel items, e.g. sluice gates, screens, pumps, anchors, ladders etc. in accordance with SES L02-E01.

6.4 Zones and Sub-Zones

6.4.1 A zone is a discrete section of structure powered by an independently controlled output from a dc power supply. A zone may be divided into smaller elements, called sub-zones, comprising different sections of the concrete structure.
6.4.2 The anode system shall be installed as a number of independent anode zones to provide uniform current distribution to the reinforcing steel and to have better control over current adjustment in different parts of the structure.
6.4.3 Following parts or sections of the structures that are exposed to different environments shall be protected under different anode zones:

i. Underground or below grade areas.
ii. Atmospherically exposed areas.
iii. Submerged areas.
iv. Tidal and/or splash areas.
v. Humid areas.

6.4.4 Sections of concrete structure that may be combined together into a single zone shall have similar environmental exposure regimes. These combinations of sub-zones shall also be restricted to those areas which experience similar conditions of rebar density and concrete quality.
6.4.5 Sections or parts of concrete structure to be protected by different anode systems or types shall not be combined together into a single common zone.
6.4.6 Exposed metallic equipment and ancillary steel items in submerged areas, e.g. sluice gates, screens, pumps, anchors, ladders etc. shall be protected in a separate anode zone.
6.4.7 Location and boundaries of each anode zone and sub-zone shall be clearly shown on design drawings. There shall be a separate and dedicated drawings showing layout of all zones in each structure.

6.4.8 Anode zone size may vary within a structure, typically between 200 and 700 m2 of concrete surface area or more for very large structures. Under similar exposure and conditions, anode zone size shall be designed taking into account the geometry of the structure and the maximum current requirement, to ensure uniform current distribution within the zone.
6.4.9 For new structures, anode zone size and zone design current shall not exceed the following limits, i.e. whichever is met first :

6.4.10 For existing structures, anode zone size and zone design current shall not exceed the following limits, i.e. whichever is met first :

6.4.11 Anode zones shall have at least two positive (feeder cable connection to anode system) and two negative (cable connection to reinforcing steel) connections, subject to the concrete elements in a given zone being continuous sections of concrete. Where different concrete sections (or sections where reinforcing steel is discontinued, for example, across the construction or expansion joints) are combined into a single zone, there shall be at least two positive and negative connections for each different or isolated section.
6.4.12 Performance of each anode zone and its sub-zones shall be monitored by a number of embeddable reference electrodes located at representative locations, see 6.7.2.

6.5 Anode Design

6.5.1 The anode system shall provide protection against corrosion for a minimum period of 25 years. Design and installation of all elements shall be such that no major maintenance or replacement shall be required during the design life period unless otherwise specified or required for particular applications.
6.5.2 The anode current density shall conform to the design and shall not exceed values that will result in reduction in performance of either:
(i) the concrete at the anode/concrete interface or
(ii) the anode during the design life of the anode. In undertaking this assessment the specialist(s) involved in the design and selection of the anode material shall take due account of likely variations in cathode current density requirements, steel distribution, concrete electrical resistivity and any other factors likely to result in uneven distribution of current demand or current discharge from the anode, and the possibility of these resulting in early failure of isolated parts of the anode system.
6.5.3 The selected anode material shall resist the effects of the electrochemical reactions that occur at the anode-concrete interface.
6.5.4 The design of the anode system shall be such that it contains sufficient redundancy, so that not more than 5 percent of anode within a given zone is made inoperative under one of the following conditions:
a. One random break in the power feed
b. Two random breaks in the anode panel
c. Specific constraints on anode design
d. No anode materials may cross an expansion joint or construction joint for new structure.

6.5.5 The anode quantity and distribution shall ensure sufficient and good current distribution to all reinforcing steel requiring protection. The current distribution, particularly to remote steel reinforcement requiring protection, shall be sufficient to polarize the steel satisfactorily in the negative direction.
6.5.6 It shall be possible to operate concrete elements within a section bounded by expansion or construction joints independently of all other sections, that is they shall be independent zones or sub-zones. Combinations of CP anode systems within such elements shall only be made in the junction boxes and not within the concrete.
6.5.7 Distribution of anode or anode grades/types within each zone shall be determined by calculations of current requirement of the steel reinforcement, subject to the current spread considerations. The minimum anode spacing determined shall be maintained. Calculations shall be provided to demonstrate compliance with this requirement.
6.5.8 For existing structures, maximum spacing between discrete anodes, for example platinized titanium rod anodes, or mixed metal oxide coated mesh ribbon strips, shall not be more than 300 mm.
6.5.9 For new structures, maximum spacing between discrete anodes, for example platinized titanium rod anodes, or mixed metal oxide coated mesh ribbon strips, shall not be more than 400 mm.
6.5.10 All rebar cages having more than 200mm separation shall have their own anode plane. For rebar cages that have a separation of less than 200mm they may both be protected from a single anode plane mounted on one cage.
6.5.11 Each high silicon iron anode (see 7.2.2-e) shall be connected to the power supply current output via a appropriate size shunt and variable resistor for anode current measurement and current balancing between anodes respectively.

6.6 Cathode Circuit

6.6.1 Reinforcement shall be electrically continuous within each concrete element. In addition, each zone or sub-zone shall be provided with separate steel connections (system negative) to the reinforcement.
6.6.2 Cathode current density shall be calculated for all sections of the structure. Typical section drawings shall be adopted in calculation of steel surface area. Localized increases in reinforcement density shall only be considered where the variation extends for a distance of greater than 400 mm across the surface. An example of this would be in the protection of reinforcement overlap areas, in which the overlap extends for 400 mm.
6.6.3 Steelwork other than reinforcement, which lies in, or is mounted on the concrete surface, shall also be included in calculations of cathode current requirement.

6.7 Monitoring

6.7.1 CP system shall have sufficient number of embeddable reference electrodes, located at typical representative locations, to monitor and assess the performance of the system.
6.7.2 Zones shall contain a minimum of three embeddable reference electrodes. The minimum number of reference electrodes in zones of different sizes shall be as follows:

6.7.3 Where a zone consists of two or more sub-zones, one reference electrode shall be provided in every sub-zone up to and including 100 m2 in size, and two reference electrodes in every sub-zone above 100 m2 in size.
6.7.4 Where a zone consists of beams and/or columns, minimum number of embeddable reference electrodes in each zone shall be according to the number of beams and/or columns as follows:

6.7.5 Reference electrodes shall be positioned in a way that they represent the most exacting geometric configuration for each zone or sub-zone, for example diametric opposites. The selected locations of reference electrodes shall include the following:
a. Particular sensitivity to corrosion or under-protection
b. Particular sensitivity to over protection
c. High corrosion risk or activity.

6.7.6 Where possible in existing structures, reference electrodes shall not be located in areas that require repair of the concrete, since they are not normally used for performance evaluation in existing structures.
6.7.7 Reference electrodes (RE) shall be positioned away from the anode feeder points, i.e. conductor bars. In each zone only one RE shall be located nearby the anode feeder and all other REs shall be evenly distributed and positioned at mid and furthest distances from the conductor bar.
6.7.8 Each RE cable shall be run from junction box to transformer rectifier (TR) and terminated at TR monitoring panel for system monitoring at TR.

6.8 Power Supplies and Remote Monitoring

6.8.1 DC power supply units are classified into two categories as follows:

a. d.c power supply unit with manual monitoring/adjustment facility

b. d.c. power supply unit with remote monitoring/adjustment facility

Zone Size (m2) (concrete surface area)	Minimum Number of Reference Electrodes
Up to 1000	7
Up to 1000	7

6.8.2 For outdoor environment installation, d.c. power supply (PS) or transformer rectifier (TR) units shall only be oil cooled type.

6.8.3 Air cooled d.c. PS or TR units shall be permitted only for installation and operation inside an air-conditioned room or container.
6.8.4 For large size structures, where CP system comprises of more than 30 zones or 150 monitoring reference electrodes (whichever condition is met first), d.c. power supply or TR units shall be supplied with remote monitoring/adjustment facility.
6.8.5 The voltage output of each independent zone d.c. PS or TR unit shall not exceed 30 V d.c. with a ripple content not exceeding 5% at maximum rated output and with a minimum frequency of 100 Hz.
6.8.6 The rated current output of each independent zone d.c. PS or TR unit shall not be less than the maximum anode current capacity.
6.8.7 For detailed design and specification of oil and air cooled PS or TR units, software & hardware for remote monitoring/ adjustment, see clause 7.7.

6.9 External Circuitry

6.9.1 Voltage drop between the power supply terminals (JB) and the furthest point in the circuit of any anode zone typically shall be less than 300 mV.
6.9.2 Voltage drop on cables running between junction boxes and DC power supply or TR units shall not exceed 50% of the rated voltage output of each zone.
6.9.3 Cables shall have a minimum of a single layer of insulation and a single layer of sheathing. The selection of insulation and sheath shall take into consideration the proposed installation and functional requirements. Cable to be installed in contact with anode material shall be suitable for long term exposure to acidic conditions, typically pH 2, and those for installation in concrete, for long term exposure to alkaline conditions, typically pH 13.
6.9.4 Calculations shall be provided to SABIC, to demonstrate compliance to 6.9.1 to 6.9.2.

6.10 Stray Current Interference

6.10.1 Stray current interference currents can cause corrosion on metallic structures embedded in the concrete. This form of corrosion differs from other causes of corrosion damage in that the dc current, which causes the corrosion, has a source foreign to the affected structure. Appropriate tests shall be conducted in areas where these interference currents are suspected.
6.10.2 It may be appropriate not to cathodically protect certain metal items mounted on, in or adjacent to the protected structure. Electrical isolation and avoidance of stray current corrosion of these items shall be ensured during the CP system design.
6.10.3 Metallic structures embedded in or mounted on the concrete surface will be affected by the passage of CP currents and shall therefore be part of the cathode system, to prevent stray current corrosion.
6.10.4 The proximity of anodes to other embedded metallic components, for example form ties, chairs, tie wire, embedded plates and electrical conduit shall be determined. Minimum depth of cover over the reinforcement and cracks in a structure are important considerations.

6.11 Extent of Cathodic Protection

6.11.1 The installation of the CP system and extent of cathodic protection of reinforcing steel in different types of structures shall be as follows:

Structures	Extent of Protection
Seawater Structures:   Intake & discharge ponds and/or basins, cooling towers, pump sumps, canals, basins and sumps etc.	The CP system shall be designed and installed to protect all reinforcing steel within the entire protected structure, i.e. from bottom slab to full height including all parts, sections or elements that are buried, submerged and atmospherically exposed internal and external concrete surfaces.
Critical process water or liquid containing structures:   Ponds, basins & cooling towers, and slurry ponds & clarifier tanks etc.	The CP system shall be designed and installed to protect all reinforcing steel in all:  Buried areas and up to 0.5m above grade level.  Submerged areas up to maximum water level.  Tidal or splash zone areas, i.e. up to 1m above the maximum water level.
Critical Equipment Foundations: Reactor, compressor, turbine, & boiler foundations etc.	The CP system shall be designed and installed to protect all reinforcing steel in all buried areas and up to 0.5m above grade level.

6.12 Documentation

6.12.1 Detailed design drawings shall be prepared, to clearly show the overall layout of the structure to be protected for SABIC (PMT/STC-J) review and approval. The drawings shall show and include but not limited to the following:

i. Zone layout drawing showing the zone boundaries with plan views and sections.
ii. Anode layout with details of anode feeder connections.
iii. Layout of steel (system negative) connections, embeddable reference electrodes and associated steel signal connections with typical details of each.
iv. A CP general arrangement drawing showing locations of junction boxes (JBs)
and PS or TR units and anode zones.
v. A complete line circuit drawing for all system positive, system negative and system monitoring connections between the structure and the PS or TR through JBs.
vi. Typical details for the installation of JBs and PS or TRs.
vii. Typical positions for steel continuity testing.
viii. Layout of cable conduits and/or trays including the cable schedule or details.
6.12.2 Design or shop drawings, details and schedules for each CP installation shall be prepared, to show quantities, detailed anode layout, relevant typical cross sections and the location of the components within the protected structure(s). Tolerances shall be stated in design drawings.
6.12.3 Detailed calculations to support the design shall be submitted to SABIC (PMT/STC-J) for review and approval. These shall include but not limited to:
i. Reinforcement steel density in different parts of the structure to be protected.
ii. Steel surface area to be protected
iii. Cathode current requirement.
iv. Concrete surface areas
v. Anode size (grade), quantity and positioning.
vi. Zone size and current requirements.
vii. Maximum anode current capacity
viii. Circuit resistance‟s of each component.

ix. Voltage drop calculations
x. Power supply rating.

6.12.4 Design calculations shall only be produced on computer Excel sheets and should be in zone format so that all above items given in 6.12.3 can be checked, verified and approved independently.
6.12.5 Prior to starting the detailed design calculations, a typical zone calculation shall be produced and submitted along with CP conceptual design for SABIC (PMT/STC-J) review and approval.
6.12.6 Construction method procedures shall be produced, and submitted for SABIC approval.
6.12.7 Full QA/QC document shall be produced, and submitted for SABIC approval. Document shall include details of:

a. Qualified project personnel, and their specific areas of responsibility
b. Materials specification, procurement and handling
c. Continuity inspection
d. Installation procedures
e. Inspection and test certificates
f. Inspection test plan with hold points
g. Reference electrode on-site test and calibration procedures, i.e. before and after encapsulation.
6.12.8 Commissioning procedure.
6.12.9 Operation and Maintenance manuals
6.12.10 As built drawings

7 Materials and Equipment

7.1 Materials for Concrete Repairs and Anode Overlays

7.1.1 Repair is a reinstatement of the damaged or deteriorated concrete substrate prior to installation of CP anode system, as well as reinstatement at locations where concrete has been removed to provide access to reinforcement, and to install cable connections and embeddable reference electrodes. All other repairs which may be required prior to the installation of CP system, for example strengthening, extensive patching or coating, as determined during the condition survey of the structure, shall be carried out in accordance with ACI 546R, except where stated otherwise in this standard or other applicable SES.

7.1.2 After the anode installation in existing structures, a cementitious overlay shall be applied, to enclose the anode material, and to provide physical protection and an ionic current path between the anode material and the rebar.
7.1.3 Materials for concrete repairs shall be of proven suitability for use with CP. Only cementitious materials shall be used for concrete repairs and anode overlays. Materials consisting principally of resins, for example, epoxy, polyester and acrylic resins, shall not be used.

7.1.4 For horizontal deck surfaces, the repair/overlay material shall consist of a poured concrete mix, which shall be free from polymeric additives. For vertical and overhead surfaces, the material shall consist of shotcrete or proprietary pre-packaged material, as specified. When employing proprietary material systems, they shall be used in accordance with the manufacturers instructions and recommendations, except where they conflict with this standard. In such cases, the materials manufacturer shall obtain SABIC approval for an alternative procedure in conformance with this standard.

7.1.5 The exact nature of the repair or overlay material shall be determined by the contractor and approved by SABIC, subject to compliance with the following:
a. The electrical resistivity and mechanical characteristics (for example Young’s modulus),
including low shrinkage, shall be similar to those of the existing concrete
b. The contractor shall submit the proposed design mix for SABIC approval
c. The recommended average bond strength between existing concrete and overlay shall be
1.5 N/mm2 but it shall not be less than 1.0 N/mm2, or if it is, the test failure shall be within the
existing concrete.
d. The specific components of the overlay shall conform to the following and SES B51-S01
where applicable:

Cement: ASTM C150 Type I. One brand of cement shall be used for the entire project.
Aggregate: For sprayed concrete, this shall be double washed Riyadh Wadi Zone 2 sand
conforming to the requirements of ASTM C33. It shall contain not less than 3 percent and not more than 5 percent moisture by weight. The maximum aggregate size shall not exceed one third of the required thickness.
Water: Mixing water shall be fresh, clean and potable quality. It shall be kept free from
oil, vegetable matter, alkalis and other contaminants which may be injurious to the concrete or
reinforcement.
Admixtures: These shall not be used without the prior approval of SABIC. Where approved
they shall conform to the relevant ACI standard.
Curing: For shotcrete and concrete as described, the curing shall be with potable water
for a minimum of 14 days
e. For concrete durability, the proposed material shall conform to SES B51-S01 and the following
standards wherever applicable:
Compressive Strength: ASTM C39, a mean value of 24 MPa at 7 days with no single value
less than 22 MPa.
Bond Strength: By direct pull-off testing a mean value of 1.25 MPa at 7 days with no
single value less than 1.0 MPa.
Chloride Content: Less than 0.15 percent by weight of cement.
Cement Content: Minimum 364 kg/m3

Water/Cement Ratio: Maximum 0.4
Alkali content Less than 3 kg/m3, or less than 0.6 percent by weight of cement, whichever is
less Water Soluble Sulphate Less than 4 percent SO3 by weight of cement

7.2 Anode Systems

7.2.1 General

a. The anode system shall conform to the CP design, see 6.3. Its calculated or anticipated life
shall be sufficient for the design life of the CP system.
b. Anode system materials shall be supplied only from SABIC approved vendors/manufacturers.

7.2.2 Materials for Existing Structures

The approved anode systems are as follows:

(a) Mixed Metal Oxide (MMO) Coated Expanded Titanium Mesh

(i) This anode system is suitable for installation on the concrete surface. The complete anode
system shall comprise MMO coated expanded titanium mesh and titanium conductors (current
distributors) contained within a cementitious overlay. They shall be fixed securely to the concrete
surface with plastic fasteners.

(ii) The titanium conductors shall be spot welded to the mesh, to distribute current to the
component parts of the anode and to facilitate electrical connections to the anode.
(iii) The anode type/grade and quantity shall meet the current requirement and conform to the
anode design and the maximum anode current density.

(iv) The contractor shall use materials (for the approved anode system) which have been in use
for a minimum of 10 years and have extensive and proven track records in the Gulf countries.
(v) The materials shall be NACE certified and tested by an independent laboratory using NACE
TM0294. Prior to procurement of these anodes, independent laboratory testing certification shall be submitted to SABIC (PMT/STC-J) for review and approval.

(b) Mixed Metal Oxide (MMO) Coated Expanded Titanium Ribbon

(i) This anode system shall either take the form of solid or mesh strips and is suitable for
recessing in to grooves cut in to the cover concrete. Current shall be fed in to the anode strips via
titanium conductors spot-welded to the anode strips within a zone.
(ii) After the anode placement, grooves or slots cut in the concrete shall be suitably repaired,
using appropriate cementitious repair materials.
(iii) Size, type/grade and distribution pattern of the ribbon strips shall be selected to meet the
current requirement locally, and to also conform to the anode design and the maximum anode
current density.
(iv) The contractor shall use materials (for the approved anode system) which have been in use
for a minimum of 10 years and have extensive and proven track records in the Gulf countries.
(v) The materials shall be NACE certified and tested by an independent laboratory using NACE
TM0294. Prior to procurement of these anodes, independent laboratory testing certification shall be submitted to SABIC (PMT/STC-J) for review and approval.

(c) Discrete Activated Titanium Anodes

These types of anodes are suitable for embedding within the structure. The anode type, form and
embedment within the structure shall be one of the following:

(i) Electro-catalytically coated titanium in the form of strip, mesh, or tubes shall be embedded into
a cementitious repair mortar in holes drilled in to the concrete.
(ii) Anodes of a similar form or platinum coated titanium rods shall be used in conjunction with a
conductive graphite based backfill.

(iii)The backfill, with its operating current density based upon the dimensions of the hole drilled in
the concrete, and the anode current density within the backfill, shall conform to the design. It shall
also be limited to values which can be demonstrated by trials or past projects, to enable the
requisite anode, backfill and anode/cable connection performance to be achieved. Where graphite backfill is utilized, the graphite shall be considered as the anode in calculating the minimum anode/reinforcement spacing of 15 mm.

(iv) The contractor shall use materials (for the approved anode system) which have been in use
for a minimum of 10 years and have proven track records in the Gulf countries.
(d) Anode Overlay. See 7.1.
(e) High Silicon Iron Chrome Dicrete Anodes
(i) These types of anodes are suitable and shall only be for buried parts of the structure. They are
embedded in soil and closely distributed around the protected structure. They are supplemented
with carbonaceous backfill in order to extend the life of the anode and also reduce the
anode/electrolyte (ground-bed) resistance.
(ii) The anodes shall be solid rod prepackaged in steel cannisters containing carbonaceous backfil.
(iii)The anode shall conform to the following specification:
Si 14.20 – 14.75%
Cr 3.25 – 5.0%
Mn 1.50%Max.
C 0.7 – 1.10%
Mo 0.2%Max.
Cu 0.5%Max.
Fe Balance
(iv)The consumption rate shall not be more than 100 mg/amp-yr (with coke backfill).

7.2.3 Materials for New Structures

a. At present, the only approved system for new structures is the mixed metal oxide coated
titanium expanded mesh ribbon. The complete system shall consist of catalyzed titanium mesh
ribbon, titanium conductors, insulated titanium anode connectors and plastic rebar clips or cement block spacers.
b. Anode mesh ribbon shall be installed on the rebar cage using plastic clips or cement block
spacers, ensuring there will be no short circuit between the anode and the reinforcing steel during
and after the concrete pour.
c. Titanium grade 1 anode mesh ribbon shall be used. Size, type/grade and distribution pattern
of the ribbon strips shall be selected to meet the current requirement locally, and to also conform to the anode design and the maximum anode current density. The width of the ribbon shall be
between 13 and 20 mm. The minimum thickness of ribbon shall be 0.5 mm.

d. The current distributor shall be a solid grade 1, uncoated titanium bar, 12.7 to 15 mm wide,
0.9 mm thick minimum.

e. The contractor shall use material types which have proven track record in use for a minimum
of 10 years. The materials shall be NACE certified and tested by an independent laboratory using
NACE TM0294. Prior to procurement of these anodes, independent laboratory testing certification shall be submitted to SABIC (PMT/STC-J) for review and approval.

7.3 Reference Electrodes

7.3.1 Performance and effectiveness of the CP system shall be monitored and recorded using permanently embedded reference electrodes. These electrodes shall be commercially available devices, with a proven track record of use in concrete, particularly in hot climate environments. Details of previous applications of the cells proposed by contractor shall be included as part of the technical submittal provided to SABIC prior to acceptance.
7.3.2 The reference electrodes shall be Ag/AgCl/0.5M KCl gel electrodes contained within a suitable robust case. Minimum silver content in the electrodes shall be 3.0 g.
7.3.3 Each reference electrode shall be supplied along with a test and calibration certificate, clearly indicating its calibration value as recorded in a 3 percent sodium chloride solution at 25
laboratory standard calomel reference electrode. For an electrode to be acceptable, the measured potential shall b mV of the anticipated value.
7.3.4 Reference electrodes shall have a life expectancy of 25 mV for the 25 mV over any 24 hour period.

7.3.5 Reference electrode shall be designed to operate in an environment between 0
manufacturer shall also provide the temperature coefficient and its temperature range.
7.3.6 Reference electrodes shall be fitted with a suitable length of cable, so that no splices are required between placement location and junction box. Lead cables shall conform to 7.4.3.
7.3.7 The connection between the cable and the electrode shall only be factory fitted (reference electrode manufacturer only) and completely sealed, and capable of total immersion without leakage with a water head of one meter.
7.3.8 The contractor shall use reference electrodes of those manufacturers which have proven track record in use for a minimum of 10 years. Prior to procurement, contractor shall submit the details of the proposed reference electrodes for SABIC (PMT/STC-J) review and approval.
7.3.9 Reference electodes shall be supplied only from SABIC approved manufacturers.

7.4 Cables

7.4.1 General

a) All cables shall be of 450/750V grade, and resistant to moisture and UV degradation.
b) All cables shall be stranded copper and shall have a minimum of seven strands.
c) All cables shall have a minimum of one layer of insulation and a single layer of sheathing which shall conform to IEC 502.
d) Single core cables shall be colour coded as follows, unless otherwise directed:

Colour System
Red System Positive Cables
Black System Negative Cables
Blue Reference Electrode
Yellow Steel Signal Cables

e) Color coding shall be same for all areas.
f) Multi-core cables shall be colour or number coded.
g) All cables shall be run in appropriate size conduits between the structure and the junction box and also between the junction box and the power supply or TR unit which shall conform to NEC.
h) All cables shall be clearly labelled at termination points with permanent labels.

7.4.2 DC Cables

a) d.c cables shall be single conductor, copper cored high molecular weight polyethylene (HMWPE) insulation. The minimum insulation thickness shall be 0.8 mm.
b) Minimum cross-section area shall be 10mm2.
c) Cables shall meet the following requirements:

i) carry the design current +25% within permissible temperature increases allowed under IEC 60502 as appropriate to the maximum environmental temperatures.
ii) limit the voltage drop at 125% of the designed maximum current in the CP system circuit to a value compatible with the power supply voltage output and the anode/cathode voltage requirements and provide uniform zone current distribution.

7.4.3 Reference Electrode Cables

a) The minimum cross-sectional area of single core cables shall be 2.5mm2.
b) The cable insulation shall be HMWPE with a minimum thickness of 0.8mm.
c) The cable length shall be sufficient to reach the nearest junction box without splicing.
d) All cables shall be factory fitted.

7.4.4 Steel Signal Cables

a) The minimum cross-sectional area of single core cables shall be 2.5mm2.
b) The cable insulation shall be HMWPE with a minimum thickness of 0.8mm.
c) The cable length shall be sufficient to reach the nearest junction box without
splicing.

7.4.5 Cabling between JB and TR or PS

a) d.c. cables shall be as specified above in 7.4.2. Multi-core cables shall be used if
required.
b) Monitoring cables shall be low noise and screened. The cable insulation shall be
HMWPE with a minimum thickness of 0.8mm. Minimum cross-sectional area of single
core cables shall be 2.5mm2. Multi-core cables may also be used but they shall be of
screened multi-core, multi-strand type of minimum cross-section of 1. mm2
per core.
c) Prior to procurement of multi-core cables, contractor shall submit the data sheets of the proposed cables for SABIC review and approval.

7.5 Cable Conduit

7.5.1 The cable conduit below grade level and/or where embedded in concrete shall be rigid PVC and above grade level rigid PVC coated galvanised steel. All fittings and accessories shall also be rigid PVC and rigid galvanised steel below and above grade level respectively.
7.5.2 All conduit shall be appropriately sized to carry the cabling. The diameter of the ring main conduit shall be 50mm minimum which shall conform to NEC.
7.5.3 The conduit shall be supplied in standard lengths of 3m (10ft), including coupling, one coupling to be furnished with each length. Each length shall be reamed and threaded on each end.

7.6 Junction Box

7.6.1 Junction boxes shall be non-metallic and constructed from glass fiber reinforced polyester or equivalent. They shall be rated in accordance with IEC 60529 to render appropriate environmental protection taking into account the type of connections made within the box and the worst case external environmental and mechanical exposure to which the box is to be subjected. Minimum levels shall be IP55 for indoor use, IP67 for outdoor locations subject to marine or coastal exposure and IP 65 for outdoor locations not subject to marine or coastal exposure.

7.6.2 Junction boxes for high silicon iron anodes (see 7.2.2-e) or MMO coated Ti rod or plate anodes (see 7.2.2-f)) shall be metallic and shall contain appropriate size shunts and variable resistors for individual anode current measurement and current balancing between different anodes.
7.6.3 Junction boxes for classified (hazardous) areas shall also be metallic and shall conform to all relevant and applicable NEC articles. The enclosure shall be explosion proof and shall meet NEMA type 8 standards. The enclosures shall carry the American or European certification and shall be marked with the class and/or group for which they have been certified.

7.6.4 All doors shall be hinged type, gasketed, lockable and stiffened. All locks shall be capable of being opened with the same key. Cable entry shall be by suitable compression gland or in sealed conduits. Appropriate precautions shall be taken to ensure that the cable entry system in no way compromises the junction box IP rating.
7.6.5 The terminals shall be clearly marked with the zone/sub-zone, component type and number as appropriate and shall also be marked with suitable identification corresponding to each particular unit. The typical control layout for the control panel shall be shown in the design drawings. All terminals shall be clearly labeled with their correct function, using white engraved background on black surface. Material shall be traffolyte or equivalent.

7.6.6 Cable connectors shall be by DIN rail mounted terminals. Only one conductor per terminal shall be permitted. Circuit expansion shall be achieved by standard bridging strips, barrels and screws. The spacing between the two adjacent and parallel DIN rails shall be minimum 200mm. Layout of terminals/panels within the junction boxes shall be shown in the detail drawings. Detail of the proposed layout shall be submitted to SABIC for approval prior to the commencement of any work.
7.6.7 Size and volume of the junction boxes shall be in accordance with all the relevant and applicable NEC articles (e.g 314.16,314.28 & others)

7.7 Power Supply, Control and Monitoring Equipment

7.7.1 General Requirements

a) The transformer rectifier or power supply (PS) unit shall be supplied only by SABIC approved and pre-qualified Manufacturers.
b) The units shall be similar to those PS units that are commonly used to provide d.c. power
supply to cathodic protection systems after converting a.c. power input.
c) Detail design of the PS unit shall be by the manufacturer. The manufacturer shall ensure the PS units are sized and oriented to allow clear access to the units.
d) The PS shall be designed and manufactured in accordance with the nominated standards and
with the requirements given in the Specification and shall require minimal maintenance for a
period of 25 years after installation.

e) When the PS units are supplied with a remote monitoring system (RMS), it shall be delivered as a complete system comprising hardware and software required to: energize, monitor and control (current & voltage adjustment) the cathodic protection system from a remote location through a control unit via telephone line or LAN. Each such PS unit shall also have overriding provision over RMS and have all the necessary controls, interrupters and terminations (sockets) where current, voltage and steel potentials (both current on & off) can be measured manually using hand held multi-meters and current adjustments can be made in the event of malfunctioning or temporary failure of RMS.

f) All necessary fixings for mounting the PS unit shall be provided. All fixings shall be corrosion
protected.
g) Prior to procurement of power supply (PS) units, and RMS, the contractor shall submit details of the proposed PS units, RMS including features and specifications of both hardware and software, dimensioned general arrangement, a component layout, a circuit diagram and a testing schedule, for SABIC review and approval.
h) For outdoor installation, the PS unit shall only be oil cooled. Air-cooled units shall only be
permitted for indoor installation in a air-conditioned room or container.

7.7.2 Service Conditions

The PS unit shall be continuously rated, self contained and suitable for operating in the
following conditions.

Indoor Condition: Temperature range 0°C to 40°C,
Relative Humidity 50%

Outdoor Condition: Ambient temperature 0°C to 50°C (with metallic surface temperature
reaching to 75°C due to solar radiation.
Relative Humidity: 20-100%
Atmosphere: Coastal

7.7.3 Control

The PS units shall be designed to be switchable and operate in any of the following three
modes of operations:

i) Constant Current
ii) Constant Voltage
iii) Constant Reference Potential.

7.7.4 Rated DC Outputs

a) The current and voltage outputs shall be rated as required by the design, including sufficient
allowance for anticipated changes in current and particularly voltage with time.
b) The current output rating of each independent zone shall not be less than the maximum allowable anode current capacity of that zone.

c) The rectifier output shall be smoothed to provide no more than 5% ripple between 30% and 100% of the full rated current output. Ripple frequency shall be greater than or equal to 100Hz.
Maximum allowable operating voltage of different anode systems shall also be considered in
designing the voltage output rating of the units.

7.7.5 Current Interrupter

a) A variable timer controlled d.c. relay system interrupting the current output to facilitate
“instantaneous off” reinforcing steel potential measurement shall be provided. The current
circuit breaker on the output shall be capable of interrupting the DC output in a period of
less than 0.1 seconds at any load. The interrupter shall be capable of switching the full load
current at maximum output on a variable time cycle of up to 10 seconds “on” and 10
seconds “off”.

b) Operation of the interrupter shall not affect electrical supply to any other circuits (monitoring,
metering etc.) and their accurate operation.

7.7.6 On Load Adjustment

a) The PS units shall be designed so that on load adjustment of the output may be carried out safely. Rectifiers shall be capable of operating continuously at rated output current at any output voltage from 0 to 100%, without damaging any rectifier components.

b) On load regulation shall be provided to facilitate step less constant voltage, constant
current or constant potential control from a maximum of 5% of rated output to full rated
output. Full rated DC output voltage shall be adjustable by not less than 25 equal steps
from approximately 5% of rated voltage to full rated output.

7.7.7 AC Supply

a) The PS unit input voltage, phase, and earth system shall be designed as per each SABIC affiliate local requirement. The incoming a.c. supply shall be terminated via an appropriately rated, double pole neutral linked switch fuse or circuit breaker and residual current device in accordance with the SABIC affiliate requirement and/or American or European standards.

b) The input voltage of the supply system may be subject to transients, comprising of voltage depressions of up to 20% of the nominal voltage. The frequency may occasionally dip to 95% of
the rated frequency. In addition the AC supply could on occasions be interrupted, by power cuts
and the PS shall be capable of resisting damage resulting from peak surges as the AC power
supply is instantaneously returned.

7.7.8 Transformers

a) The main transformers shall be an isolating transformer conforming to EN 60742 continuously
rated and suitable for connection to the low voltage a.c. supply.

b) Transformer temperature rise, as measured by thermocouples within the transformer, shall not
exceed 85C.

c) The transformer efficiency shall be not less than 95%.

7.7.9 Rectifying Elements

The rectifier shall conform to appropriate SABIC or American or European standards with
suitable a.c. surge protection. Fast acting fuses shall be used to protect the rectifiers on the
a.c. side and varistors to protect them on the d.c. side. Rectifiers shall be rated for
continuous operation at the specified outputs with peak inverse voltage of at least 600 V.
Varistors shall be compatible with the rectifier peak inverse voltage levels.

7.7.10 DC Output Monitoring Facility

a) Each individual PS unit (i.e. each d.c output) shall include two pairs of socket terminals to facilitate the following independent measurements using a hand held digital multi-meter:-

i) Output voltages
ii) Output currents(by voltage drop across a shunt resistor with an accuracy of ± 0.5%).
iii) Steel/concrete potentials with respect to the reference electrodes

b) For d.c outputs, the socket terminals shall be red for the d.c positive terminal connections and black for the d.c negative terminal connections. For monitoring unit, the socket terminals shall be
red for the embedded reference electrode terminal connections and black for the associated steel
signal terminal connections.

c) The function and rating of all sockets and the multiplying factor of all shunts shall be clearly
marked.

d) In addition to d.c output measuring sockets, analog voltmeter and ammeters for each d.c output shall be installed and shall be clearly visible through a window in the housing. They shall be of the continuous reading meter type. Meter accuracy shall be a minimum of ± 2% of full scale at 30C,
and shall be temperature compensated to vary no more than 1% per 10C temperature variation. Scale faces shall be metal.

e) The PS unit shall have LEDs (light emitting diodes) or other means of indicating a.c.
power supply “on” and d.c. output “operational”.

7.7.11 Remote Monitoring System

a) The power supply and remote monitoring system (PSRMS) shall enable the operator to fully
monitor and control the CP installation locally (as a standalone system) and/or from a remote
address.
b) The PSRMS shall be able to carry out the following functions as minimum but not limited to:
i. Energise and de-energise each PS unit independently.
ii. Read and set the operating parameters for each PS unit independently.
iii. Conduct depolarisation tests using embedded reference cells.
iv. Retrieve depolarisation test data and routine monitoring data stored in the Computer Unit.
Monitor individual units in real time.
v. Print data for reports.
vi. Alarm enabling and disabling function.
vii. Alarms shall be displayed when instant-off potential, current and voltage outputs set maximum
and minimum limits are exceeded.
viii. Read and store ‘natural potential’ data for reference electrodes before energising the system
Read and store ‘current-on potential’ and Instant-off potential’ data for reference electrodes after
energisation of the CP system
ix. Control in either constant current or constant voltage
x. Set minimum and maximum limits for output voltage (with resolution of 0.01 volts)
xi. Set minimum and maximum limits for output current (with resolution of 0.001 amps)
xii. Automatically switch on PS outputs after the completion of depolarisation tests. Shows current
and voltage for each channel on PS Unit
xiii. Show ‘Natural potential’ and ‘Instant-of potential’ for each reference electrode
xiv. Display data with zoom functions
xv. Print data & graph
xvi. Create spreadsheet filesOverview screen showing layout of plant and protected structures.
xvii. System overview screen showiong real time status on functionality of all power supplies.
xviii. System overview screen showing summary of criteria compliance of all reference electrodes in each zone.
xix. Auto commissioning or initial energizing of the multiple zones at output of 10%, 25%, 50% and 100% of the design current.
xx. Log in entry for three levels.
xxi. Export and import data files.

7.7.12 Enclosure

a) The electrical components comprising transformer, rectifier, instruments, monitoring and
control equipment shall be installed and/or housed within a weatherproof, vandal proof,
impact resistant and corrosion protected enclosure. The enclosure shall provide
protection against the worst case environment in accordance with IEC 60529 and/or
NEMA standards as follows:

Indoor Condition: NEMA 4 equivalent to IP55
Indoor Condition in classified area: NEMA 7
Outdoor Condition in unclassified area: NEMA 4X equivalent to IP65
Outdoor Condition in classified area: NEMA 8

b) For classified (hazardous) areas, the enclosures shall be suitable for safe operation in Class 1
Division 1 (equivalent to Zone 0 & 1) areas.

c) The enclosures shall be fabricated of minimum 3.0 mm thick mild steel sheet. All external
surfaces shall be protected against corrosion using zinc flame spray and 2 part
Epoxy/Polyurethane coating system, which shall comprise as follows:

7.7.13 Wiring

Shot blast to: SA2.5
Zinc flame spray: 100µm min DFT
Epoxy undercoat: 190µm min DFT
Polyurethane topcoat: 250µm min DFT

d) Monitoring, control and protection components shall be installed in such a manner as to permit
rapid and convenient changeover in the event of failure of a component or component group.

e) The PS unit and enclosures shall be certificated to American or European standards for use in a classified (hazardous) area. Original certificates produced by the certifying bodies shall be
produced specifically made for the subject PS unit and not for the batch of PSs made for the PS
manufacturer. These certificates shall be submitted to SABIC for review and approval.

f) Where multiple PSs or multiple channels for independent multiple anode zones are
housed in a common equipment/enclosure, each PS and channel shall be fully identified
and shall conform to the above clauses.
a) All internal wiring shall be neatly fixed and shall be covered with insulation appropriate for its use
and conforming with IEE Wiring Regulations.

b) Only one conductor per terminal shall be permitted. Circuit expansion shall be achieved by
standard bridging strips, barrels and screws.

c) All cables and wiring shall be appropriately identified at each end using labels intended for this.

7.7.14 Protection purpose. Where cable identifications have been given in the Drawings, they shall be used. Any cable not identified with a label shall be labeled using an appropriate identification system by the Contractor.
a) a.c. input and a.c terminals shall be shrouded in accordance with IEE Wiring Regulations to
prevent accidental contact.

b) A separate isolating unit shall be connected between the a.c. power input cable and the PS to
allow the safe removal of the PS if necessary.

c) Appropriately rated surge protection shall be provided in the d.c. output and a.c. input circuits.

7.7.15 Labels and Markings

a) The PS unit shall include a rating plate located behind the cabinet door showing as a minimum
requirement, name and address of manufacturer, date of manufacture, temperature rating, a.c.
input, maximum d.c. output current and voltage.

b) All fuses shall be labeled with circuit designation and fuse characteristics.
c) All major components and fittings within each unit shall be marked and labeled to indicate
technical data relevant to the components using permanent, mechanically secured, engraved
labels.

Markings shall include but not be limited to:
Output Circuit Rating
System Positive Terminals
System Negative Terminals

7.7.16 Packing

a.c. Input Terminals
Circuit Control Identification
Max. Operating Voltage
Max. Operating Current
Fuse Ratings
Meter Selector Switch
Meter Circuit Identification
All monitoring socket Terminals

The unit shall be adequately packed for transportation. Particular care shall be taken to prevent
damage due to mishandling or the ingress of dust or water whilst in transit.

7.7.17 Recommended Spares

A complete list of recommended spares and one complete set of spare fuses, lamps and other
consumables shall be delivered with the PS unit.

7.7.18 Operating Instructions & Maintenance Handbook

The unit shall be supplied complete with an operation manual/ maintenance handbook which shall include step by step operating instructions. The following data shall also be included with the manual:

i) A copy of the acceptance test data and certificate
ii) Drawings showing

8. Installation

– Cabinet manufacturer detail
– Internal layout with component names, size and supplier
– Schematic circuit with component name, rating and supplier
– Panel layout
– Module detail (other than proprietary information).

8.1 Repair of Existing Structures Prior to Cathodic Protection

8.1.1 Repairs shall be carried out on all areas where CP is to be installed. This shall be treated in a manner determined by the pre-existing concrete damage distribution.
8.1.2 Unsound concrete shall be removed and repaired. Unsound concrete includes spalled, delaminated, deteriorated and honeycombed concrete, and cracks of width greater than 0.5 mm.
8.1.3 Exterior surface of the designated concrete area shall only be removed to the depth of the reinforcing layer, either by chipping hammers or by use of high pressure water blasting. Care shall be taken to ensure that damage to the existing reinforcement does not occur during concrete removal.

8.1.4 The breakout shall continue in all directions until complete removal of the unsound material. It shall not be necessary to remove mechanically sound but chloride contaminated concrete. Breakout shall be terminated at a swan edge, which shall be at least 20 mm deep. Debris generated by this concrete removal shall be continuously stockpiled at a single point, and removed in accordance with the prevailing local regulations concerning debris removal.
8.1.5 To ensure a good bond between the repair material and the reinforcement steel (existing and replacement as required), the surface of the steel shall be cleaned, to remove all traces of loosely adherent corrosion product only. It shall not be necessary to clean to a bright metal finish.
8.1.6 Chipped surface of the base concrete shall be grit blasted to remove all dust, dirt, loose particles and other surface contaminants, leaving a visually clean surface, showing exposed aggregate particles and a peak to trough depth of at least 8 mm between aggregate particles.
8.1.7 After all cleaning, the reinforcement shall be inspected. If the rebar has lost more than 25 percent of its cross-section (20 percent if 2 or more consecutive parallel bars are affected), a structural engineer shall be consulted. The structural engineer shall recommend either replacement of rebars or addition of supplemental rebars. This may necessitate additional breakout and cleaning to facilitate the bond development length, in which case the provisions of the above sections shall apply.

8.1.8 Original and additional exposed reinforcement shall be coated within 60 minutes of achieving the surface condition specified above. This coating shall be to prevent flash rusting which may occur during pre-wetting, and shall not be intended as a long-term corrosion protection strategy. The only material which may be considered as coating for the reinforcement, shall be a cement wash. Polymer modified or based materials shall not be acceptable.

8.1.9 Prior to placement of repair materials, base concrete surface shall be scaled thoroughly with potable water for a 24 h period. Immediately prior to material replacement, concrete shall be allowed to surface dry, so that no free-standing water exists.
8.1.10 The following materials shall be used to re-profile the concrete breakout areas:
a. Shotcrete for vertical and overhead applications
b. Concrete for horizontal applications
c. Hand placed mortar for patches less than 100 cm2 (0.1 m2) in area.
8.1.11 The materials properties and installation products shall be in accordance with 7.1.
8.1.12 Prior to placement of repair materials, electrical continuity testing and installation of steel connections and reference electrodes in those areas shall be completed.

8.2 Reinforcement Electrical Continuity

8.2.1 The contractor shall ensure that the reinforcement in a new or existing structure is electrically continuous, prior to the application of CP. Rebars exposed during concrete repairs or other works shall be tested for electrical continuity by following the method described below.
8.2.2 For continuity testing locations in existing structures, contractor shall follow the design instructions and recommendations given either in the form of design drawings showing test locations, or described in the specifications, based on the condition survey test results. If such information is not made available the reinforcement drawings of the structure shall be inspected, to locate areas where continuity might not exist.

8.2.3 For new structures, continuity testing shall be carried out between reinforcement cage and all externally mounted steelwork, and between different sections of the reinforcement. The contractor shall be responsible for ensuring that the steel reinforcement layers including, for example, links and tie basaddles and any other embedded metallic fixtures within the structure, are electrically continuous.
8.2.4 The locations selected (both for new and existing structures) shall represent the most exactinggeometric configurations possible, for example change of section, change of plane of concrete, ordiametric opposite.

8.2.5 Resistance readings shall be recorded on a plan sheet designating each location needed.
8.2.6 If discontinuous steel is located, as defined previously, it shall be bonded to the continuous section of the main reinforcement, or connected into the cathode circuit using external cabling materials and procedures, which duplicate those for negative connections.
8.2.7 Following bonding at these locations, the new reinforcement resistance shall be recorded and submitted to SABIC.

8.2.8 Electrical continuity shall be tested by a dc reverse polarity resistance measurement technique, or a dc potential difference measurement technique.
8.2.9 The acceptance criteria for such testing shall be as follows:
a. Stability. For continuous steel, resistance readings shall not change more than 0.5 mVs in
15 seconds, or by 1  when the leads are reversed.
b. Resistance shall be less than 1  or the potential difference less than 1mV.

8.3 Steel Connections

8.3.1 Each zone of the CP system shall be provided with multiple connections to the reinforcement as required by the design, both for the CP current, and for measurement of steel/concrete potentials with respect to permanent embedded reference electrodes.
8.3.2 The exact locations of these connections shall be as approved by SABIC during the installation.

8.3.3 Prior to making the steel connections, contractor shall submit the method statement of the proposed method for connections and the details of materials for SABIC approval.
8.3.4 Reinforcement shall be cleaned to bright metal at each connection location a few minutes before making the connection.
8.3.5 Cable connections shall be made to the reinforcement by methods which provide a long-term cable/reinforcement resistance of less than 0.01.

8.3.6 Connections shall be protected from bimetallic corrosion by appropriate coating. Immediately aftermaking the connection, connection and adjacent reinforcement shall be coated with an approved nonconductive epoxy resin. Epoxy resin shall be allowed to harden before any further repair work is carried out in the vicinity. See Figures 1 and 2.
8.3.7 Connection cables shall be appropriately labelled and run to the nearest or appropriate junction box without any splicing.

8.3.8 After the installation of steel connections, contractor shall test the electrical continuity between the cable and the reinforcement in accordance with 8.2 and ask SABIC to inspect the connections for approval prior to overlay placement or concrete pour.
8.3.9 Continuity test results shall be recorded and submitted to SABIC.

8.4 Reference Electrodes

8.4.1 The contractor shall install embeddable reference electrodes at locations shown on the design drawings. The exact position of these electrodes shall be approved by SABIC on site.
8.4.2 Reference electrodes shall be marked clearly and discretely on the electrode case and at the cable termination points both at the junction box and transformer rectifier monitoring panel. The number shall be recorded on the QC test certificate and against its location on the „As-Built‟ drawings.
8.4.3 Prior to installation, electrodes shall be stored on site in accordance with the manufacturers recommendations. A copy of this procedure shall be submitted to SABIC for approval prior to shipment to site.
8.4.4 The reference electrodes shall be positioned close to the rebar, using plastic cable ties or plastic clips on holders, parallel with it but not touching it. They shall be positioned between 10 and 20 mm from the reinforcing steel, see Figure 3.

8.4.5 In existing structures, wherever possible, reference electrodes shall be positioned close to reinforcing steel that is not exposed and is still encased in original concrete (typically 10-20 mm cover).
8.4.6 The contractor shall ensure that concrete is adequately compacted around the reference electrodes, particularly at their measuring interface, and does not contain voids or air pockets.
8.4.7 Formation of air pockets or voids at the measuring interface of reference electrodes can be avoided by pre-potting the reference electrodes in concrete of similar constituents to the anode encapsulation material. Reference electrode shall be encapsulated to a depth of 20 mm all around. Encapsulation shall occur not more than 4 to 5 days prior to their placement in concrete pour. Surface of this encapsulation shall be roughened prior to placement, to prevent a shrinkage interface being formed. The contractor shall submit the procedure to be adopted for SABIC approval prior to pre-potting the cells. A typical installation is shown in Figure 4.

8.4.8 Reference electrode cables shall be protected from damage before and after their placement in concrete, and until they are terminated in the nearest or nominated junction box. Their cables shall not be spliced between the reference electrode location and the junction box.
8.4.9 Prior to encapsulation and installation each reference electrode shall be tested on site before and after encapsulation under SABIC representative supervision.
8.4.10 Reference electrodes shall not be encapsulated more than 3 to 4 days prior to their installation and concrete pouring. After installation, encapsuled reference electrodes shall be kept wet or moist until concrete pour.

8.5 Anode System Installation

8.5.1 The form and type of the anode system determines the installation methodology. The anode system shall be installed by methods and under controlled environmental conditions which have been proven by trials or past projects.
8.5.2 Anode system shall be installed in accordance with the anode material manufacturer‟s or the anode system developer‟s instructions. Typical layout and installation details of a mesh anode system for existing concrete structures are illustrated in Figure 5.

Figures 6 to 8 illustrate the typical installation of anode mesh ribbon in new concrete structures.
8.5.3 Particular attention shall be given to avoiding short circuits between the anode system and any reinforcement steel, ancillary metallic components, reinforcement tie wire, or scrap steel in the surface of the concrete.

8.5.4 Prior to application of any overlay or surface sealant over the anode systems, anode/cathode resistance and potential difference shall be measured, to ensure that short circuits have been avoided.
8.5.5 Multiple anode feeder cable connections shall be made to the anode material in each independent anode zone. Layout of connections shall be designed so that the failure of any one anode/cable connection shall not reduce the performance of the CP system in that zone.
8.5.6 The anode/cable connection system shall be of a type and be installed to standards that can be demonstrated by trials or past successful projects to give the required anode and anode/cable
connection performance. The contractor shall submit the proposed method for such connections to SABIC for approval prior to their installation.
8.5.7 Electrical continuity of anode/cable connections shall be tested and recorded. The contractor shall ensure that the anode system of each zone is electrically continuous, and shall also ensure the discontinuity of anode systems of two adjacent independent anode zones, prior to covering the anode material in overlay.
8.5.8 The anode feeder cables shall run, without splicing, to the nearest or nominated junction box as required by the design.

8.6 Overlay Installation

8.6.1 The contractor shall ensure that the application of overlay does not damage electrical components, for example anode and cables, either within the pouring panel or on adjacent panels. Items not designated for total encapsulation shall be adequately protected during installation.

8.6.2 Prior to anode and overlay application, entire concrete surface shall be prepared to the following level:
All traces of laitance shall be removed, to expose clean aggregate by scabbling, chipping or abrasive blasting. Whichever shall be the case, the prepared profile shall be a minimum of 50 percent maximum aggregate size or 8 mm peak to trough between aggregate particles, whichever shall be greater.

8.6.3 Surface preparation shall be carried out on surfaces to which anode is to be installed, irrespective of whether the substrate is original concrete or repair material. Care shall be taken to ensure that the surface preparation activities do not cause weakness of the interface due to fracture of aggregate or loosening of the bond. In the event that this occurs, further surface preparation by grit blasting or water blasting shall only occur until this situation is remedied.

8.6.4 Following preparation and anode installation, surfaces shall be pre-wetted with potable water for twenty four hours immediately prior to overlay application, to reduce absorption of curing water by the substrate concrete. Where considered necessary, additional precautions shall be taken, for example shading or polyethelene sheeting, to assist the saturation of the existing concrete before application.

8.6.5 Maximum time between mixing and application shall be 30 minutes
8.6.6 8.6.6 When pouring overlay onto the deck areas on top of the anodes, only external surface vibrators shall be used to compact the concrete. Concrete shall be poured in a checkerboard pattern on the deck.
8.6.7 Poured overlay shall be applied in a single layer of nominal thickness as shown on the design drawings. Attention shall be given to provision of designated slope to drains. If staged lifts are adopted, time between pours shall be carefully controlled, to avoid cold joints. Formwork shall be fixed securely to the base substrate and made rigid and watertight. It shall be of sufficient strength to prevent bulging and sagging during pouring. Approved releasing agent shall be used, to prevent surface blemish creation on form removal. If such blemishes arise, they shall be repaired by hand application of a similar mix to the pour, with due consideration for aggregate size.

8.6.8 Where sprayed concrete is applied, the application shall conform to ACI 506R and ACI 506.2R. Contractor shall be required to install a test panel of proposed mix and procedure, to ensure compliance with this standard. Only those nozzlemen who successfully complete this testing shall operate on this project. All tests shall be performed on site, witnessed by SABIC. When using proprietary materials, manufacturer’s instructions shall be followed. Only those materials and procedures which successfully complete this testing shall be installed on this project. All tests shall be performed on site, witnessed by SABIC. Concrete overlays shall be cured with potable water only, for 14 days minimum. Shading shall be provided for surfaces in direct sunlight. Curing agents shall not be used.

8.6.9 Normal concrete placement work and curing shall be carried out when ambient or sub-surface temperature during application and curing is between 10 temperature rises above 30
a) Cement and sand shall be stored in a shaded area until needed for application
b) Water used for mixing shall be maintained at less than 29 C, in insulated containers. If necessary,
ice shall be added to the water to maintain the temperature within the limits given.
c) Prior to application, temperature of the substrate and the freshly placed concrete shall not exceed 30 C.

8.6.10 Concrete operations shall be suspended under the following conditions:
a) High wind and dust conditions that affect either proper application or protection of fresh concrete.
b) Rain.

8.6.11 Overlay which lacks uniformity, exhibits segregation, honeycombing, lamination or which contains dry patches, voids or sand pockets shall be removed from the works and discarded. The contractor shall repair such areas after approval of the contractor method statement. Failure to repair to SABIC satisfaction shall require total removal and replacement of the entire section of work.

8.7 Cabling and Junction Boxes

8.7.1 Cables, including ac and dc and monitoring (reference electrode and steel signal), shall be laid in conduit/trunking. Cable connection’s/joints shall be made only at junction boxes.
8.7.2 Cable conductors shall be terminated by crimped connectors suitable for the terminals provided in the junction boxes.
8.7.3 Mains voltage cables shall be terminated in a separate junction box from low voltage dc cables.
8.7.4 Cables shall be uniquely identified with marker tags at the dc power supply, at any junction box, and their point of connection.

8.7.5 Cables shall be adequately supported and protected from environmental, and human damage.
8.7.6 The junction box installation shall conform to relevant NEC standards, taking into account the classification of that area where installed. They shall be securely and rigidly fastened in place, and grounded in accordance with relevant NEC standards.

8.8 Power Supplies

8.8.1 All power supplies with or without remote monitoring facilities shall be installed in accordance with the manufacturer’s instructions.
8.8.2 The contractor shall submit the proposed installation plan and layout of the equipment to SABIC for approval prior to commencing the installation.

9 Testing

9.1 General

9.1.1 The Contractor shall perform sufficient inspection of materials, processes and completed items to assure compliance with the Contract. Furthermore the Contractor shall carry out sufficient testing to ensure that all the materials and workmanship complies with the performance criteria and minimum requirements of the Specification.
9.1.2 The inspection and testing works detailed in this section shall be seen as complementing those detailed in the preceding sections.

9.1.3 SABIC representative or nominated inspectors may witness any or all testing whether carried out on site at the place of manufacture or at an Approved Laboratory.
9.1.4 Where inspection or testing indicates that materials and/or works fail to satisfy the requirements of the Specification, such materials and/or works which do not meet the required standard for approval shall be removed and reinstated in accordance with the Specification by the Contractor at the Contractor’s expense.
9.1.5 The criteria for acceptance shall be the fulfilment of the requirement of this specification.
9.1.6 All test equipment shall be calibrated and the calibration traceable to international Standards.

9.2 Anodes

9.2.1 Test Certificates shall be submitted to SABIC to demonstrate all requirements of the anodes as detailed in the Specification are met. Information shall also be supplied of previous installations of similar anodes in hot climate or middle east environments.

9.3 Reference electrodes (RE)

9.3.1 All REs shall be tested at least at 20oC and 40oC, and certified by the RE manufacturer or other approved body before transport to site.
9.3.2 All REs shall be tested on site following manufacturer‟s method and their potential readings shall be compared with those given on the calibration certificates. If the RE on the test does not have a stable potential, or the potential is more than 10mV different from calibrated values then it shall be rejected and not used.
9.3.3 After encapsulation, each RE potential shall be measured at both high and low impedance against a saturated calomel electrode in only moist (not submerged) concrete condition. If the measured potential varies by more than 2mV when measured at low impedance, then it shall be rejected and not used.

9.4 CP System

9.4.1 System Positive Continuity Testing.

Continuity tests of all anode connections and anode feed cables shall be carried out by the
Contractor immediately after laying the anode and cable. Should any check indicate discontinuity or system defect the Contractor shall report and repair or replace the anode and associated cable.
9.4.2 Negative Return Continuity Testing

The Contractor shall test the continuity of all negative return connections and cables at the
following stages:

i. immediately following the securing of the cable
ii. between the steel and the nearest junction box.
iii. at the completion of the system wiring.

Should any check indicate discontinuity or system defect the Contractor shall report and then
repair or replace the defective cable or connection.

9.4.3 System Testing

Before Concrete Pour:

At the completion of wiring of each anode zone the SABIC inspector will witness and may
independently repeat any part of the testing carried out by the Contractor as follows:

i. Continuity between mesh and current distributor bars after welding (before the
installation of CP overlay)
ii. Continuity between mesh and system positive cable at junction boxes (before the
installation of CP overlay)
iii. Continuity between the negative return cables within each zone.
iv. The stability and repeatability of all RE potential measurements.
v. The resistance between the anode feed and negative return cables.

Should any check indicate discontinuity, malfunction or a short circuit or any other defect the
Contractor shall submit a proposal and effect the necessary repair or replacement of the
defective cable or connection all to the satisfaction of the SABIC inspector.

After Concrete Pour:

The contractor shall undertake and record the following measurements at 1, 7, and 30 days after
the concrete pour and submit the results to SABIC inspector:

i. Resistance and potential difference between the anode and the steel (cathode) for
each zone.
ii. Steel potential at the location of all embedded reference electrodes in each zone.

9.5 Power Supply, Control, and Monitoring Equipment

9.5.1 General Requirement

a) The PS (transformer rectifier) manufacturer shall conduct tests at his premises to
demonstrate full functional conformity and fitness for purpose. The tests shall be arranged to
represent realistic on-site working conditions and the results shall be fully documented and
shall constitute part of the permanent records for the works.

b) Unless otherwise specified, all electrical tests shall be carried out in a manner prescribed by
the relevant and applicable NEMA/ANSI/IEEE specifications, codes and/or standards. The
PS unit(s) shall not be delivered to site until the successful completion of the testing
described below. Test results shall be recorded and a copy submitted to SABIC for review,
approval and records.

c) Prior to dispatching (shipping)PS units to site, the manufacturer (and/or the contractor) shall
inform and invite SABIC (PMT/STC-J) for factory acceptance testing (FAT) at manufacturer‟s
premises. The request for FAT shall be raised only when the manufacturer has fully
completed fabrication and the required testing of PS unit(s) and minimum 3-4 weeks in
advance of their shippment.

9.5.2 Temperature Rise Test

Temperature rise test shall be run for minimum 24 hours. The maximum acceptable temperature rise during that period from ambient temperature shall be less than 20°C. Temperature test points shall be placed on top, middle side, middle back and bottom of the enclosure. Temperature measurement shall be made by thermocouple or resistance change method.

9.5.3 Transformer Efficiency

Overall input/output efficiency testing at 25%, 50%,75%, 80% and 100% of full load for each
transformer rectifier. The efficiency shall be greater than 85%.

9.5.4 Power Factor:

The power factor of the rectifiers shall be greater than 75%.

9.5.5 Rated output Test

Rated output tests shall be conducted on each unit to insure the following:
 Transformer does not saturate at high line.
 Rectifier is capable of providing the rated output at low line.
 Regulation is less than 3% between 10% and 100% of the rated output current.
 Adjustment provides consistent output voltage increments.

9.5.6 Dielectric Test

The insulation characteristics of primary circuit to secondary circuit, primary circuit to dead metal
parts and secondary circuit to dead metal part shall be sufficient to withstand a 2000 volt, 60 Hz
signal applied for 1 minute. Leakage current shall be less than 5 mA, and no amount of arcing is
acceptable.

9.5.7 Output Ripple Voltage:

Output ripple voltage shall not exceed 5% at maximum rated output voltage and current.

9.5.8 DC Voltage and Current Output Control Test

Test shall be conducted to verify that the rectifier shall automatically maintain the set voltage and
current within ±2.5% under varying load condition, as long as the output voltage or current does not exceed the value established by the voltage or current control.

9.5.9 Automatic Potential Control Mode Testing

Tests shall be conducted to verify that at the automatic potential control mode, the desired set
potential can be maintained from +0.5 to 3.0 V (± 5mV) between the structure and reference
electrode.

9.5.10 Remote monitoring system

Testing shall include but not limited to the following:
a) The accuracy of PS voltage and current outputs shall be tested and synchronized between the
software and actual measured at the JB and PS Din rail. The test shall be conducted at 25%,
50%, 75% and 100% of rated output. The difference between the two reading shall not be more
than ± 1mV and ± 0.1mA.

b) Input signals of reference electrodes (structure potentials) shall be measured at the JB, PS Din rail and compared with those recorded in the software. The difference shall not be more than ± 3mV.
c) All PS units with RMS shall be tested as standalone system. The PS shall give stable current and voltage output and provide a cross check for any variations caused by RMS.
d) Software and Network testing shall be conducted to check and verify the following:

i) Accurate acquisition of reference electrode inputs, voltage & current outputs via the master
control unit.
ii) Accurate functioning of automatic data logging of current-on & instant-off steel potentials,
automatic and manual depolarization test data logging
iii) Data matching between the overview or summary screens and the logged data

10 Quality Assurance System

10.1.1 Each stage or element of the CP system, or both, for example design, installation, and testing, shall be documented and recorded in accordance with ANSI/ASQC Q9001 quality assurance plan. This quality assurance plan shall be used in design/development, installation and servicing.
10.1.2 Each stage of the design, design amplification or design verification shall be checked and documented.

10.1.3 Appropriate visual and mechanical or electrical testing, or both, shall be carried out for every stage of the installation work shall be documented.
10.1.4 Test instruments shall have valid calibration certificates traceable to international standards of calibration.
10.1.5 The quality documentation shall constitute part of the permanent record of the works.

11 Commissioning, Operation and Maintenance

For commissioning, operation and maintenance of CP system, see SES L02-M01.

Detail 1: Typical layout of mesh anode on a concrete wall

Detail 2: Anode feeder cable connection details

Detail 3: Anode mesh fastener Detail 4: Successive mesh strips connection

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