Commissioning and Operation of Cathodic Protection Systems of Reinforced Concrete Structures

1. SCOPE……………………………………………………………………………………
2. REFERENCE ……………………………………………………….
3. DEFINITIONS ……………………………………………………….
4. GENERAL REQUIREMENTS ……………………………………………………….
4.1. Supervision ……………………………………………………….
4.2. Quality Assurance System …………………………..
5. CRITERIA ……………………………………………………………………………………
5.1. Protection Criteria ……………………………………………………….
5.2. CP System Acceptance Criteria …………………………..
6. COMMISSIONING AND CP ADJUSTMENT …………………………..
6.1. Pre-Commissioning Testing and Inspection
6.2. Pre-Energizing Measurements …………………………..
6.3. Initial Energizing and Current Adjustment …………………………..
6.4. Initial Performance Assessment …………………………..
6.5. Adjustment of Current Output …………………………..
7. SYSTEM RECORDS AND DOCUMENTATION…………………………..
7.1. Quality and Test Records ……………………………………………………….
7.2. Installation & Commissioning Report …………………………..
7.3. Operation and Maintenance Manual…………………………..
7.4. Submittals and Completion Dates …………………………..
8. OPERATION AND MAINTENANCE …………………………..
8.1. System Operation ……………………………………………………….
8.2. System review report. ……………………………………………………….
8.3. Long Term Operation ……………………………………………………….
APPENDIX A ……………………………………………………………………………………
APPENDIX B ……………………………………………………………………………………
APPENDIX C ……………………………………………………………………………………

1. SCOPE

This specification establishes the minimum requirements for the commissioning, operation
and maintenance of impressed current cathodic protection (ICCP) systems for reinforced
concrete (RC) structures. This standard shall be read and applied in conjunction with SES
L02-E02.
2. REFERENCE

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

SABIC Engineering Standards (SES)

L02-E02
3. DEFINITIONS

Cathodic Protection of Steel in Concrete.

Saudi Arabian Standards Organization (SASO)

SSA 336 Industrial Safety and Health Regulation Part 8: Welding, Cutting and Brazing.

Occupational Safety and Health Administration (OSHA ) US

29 CFR 1910 & 1926 Occupational Safety and Health Standards

Other Standards

ANSI/ASQC Q9001 Quality Systems-Model for Quality Assurance in Design, Development, Production,
Installation and Servicing.
For the purpose of understanding this standard, the following definitions apply.
CONSTANT CURRENT CONTROL – Mode of operation of a transformer rectifier to provide
constant current output. In this operation mode, drive voltage automatically adjusts with
changes in the circuit resistance to provide constant current.
CONSTANT VOLTAGE CONTROL – Mode of operation of a transformer rectifier to provide
constant voltaget output. In this operation mode, current automatically adjusts with changes
in the circuit resistance to provide constant voltage.
CURRENT-ON POTENTIAL – The potential of the reinforcing steel measured by the
reference electrode when the cathodic protection system is in operation, i.e., with cathodic
protection current flowing. This potential includes the polarization potential and any other
voltage drops resulting from the flow of current (IR drop).
DEPOLARIZATION / POTENTIAL DECAY – The change in electrode potential with time
resulting from the interruption of the applied current.
DEPOLARIZATION TEST – An acceptance test used for the performance evaluation of
cathodic protection systems for reinforced concrete structures. Depolarization is determined
by interrupting the protective current and measuring the potential decay between the
reinforcing steel and a reference electrode. The depolarization equals the final (decayed)
potential minus the instant off potential.
ENERGIZING – The process of the initial application of power to the cathodic protection
system.

INSTANT-OFF POTENTIAL – in order 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).
INTERRUPTER – A timing device that permits a cyclic off/on interruption to the flow of
cathodic protection current.
NATURAL POTENTIAL – Corrosion of the structure occurs when there is a net flow of
electrical current between one part of the structure 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”.
POLARIZATION – When the cathodic protection system is in operation, there is a net flow of
electrical current between the anodes and the reinforcing steel. As a result of that current
flow steel/concrete potential is shifted towards more negative potentials. This potential shift
from their open circuit corrosion potentials is called “polarization”. This polarization potential
can be varied by varying the current flow in the cathodic protection system. Accordingly, a
desired level of corrosion protection can be selected.
TRANSFORMER RECTIFIER – A device used to convert alternating current to direct current.
In a cathodic protection system, the transformer rectifier is used to control the voltage, current
or potential to each CP system.
ZONE – An area of the cathodic protection system that can be independently powered and
controlled. All 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
In addition to the above standards, referenced in section 2, the anode manufacturer‟s own
recommended installation/materials standards and procedures shall be recognized as part of
this standard. No deviations from that recommended, and/or quality standards shall be
permitted without prior written agreement by SABIC.
4.1. Supervision
The cathodic protection of steel in concrete requires expertise in the field of electrochemistry, civil/
structural engineering and cathodic protection engineering.
4.1.1. The engineer responsible for CP system pre-commissioning checks and testing shall either
be a NACE (USA) certified CP tester or equivalent (CP Technician Level 2) from MICorr or
Institute of Corrosion Training & Certification Scheme. The professional experience of CP
tester/technician shall be minimum 5 years in CP of reinforced concrete structures.
4.1.2. The CP engineer responsible for CP system initial energizing, monitoring data analysis and
current adjustment, and long-term operation and maintenance, shall either be a NACE (USA)
certified CP technologist or MICorr (UK) professional member. The professional experience
of CP engineer shall be minimum 8 years in CP of reinforced concrete structures.
4.2. Quality Assurance System
4.2.1. Each stage of the CP system commissioning, initial energizing, and long-term operation &
assessment shall be fully documented and recorded in accordance with ANSI/ASQC Q9001
quality assurance plan.

4.2.2. Appropriate visual and mechanical or electrical testing, or both, shall be carried out for every
stage of the pre-commissioning checks (circuit verification), initial energizing, long-term
operation & assessment and maintenance. Testing shall be documented.
4.2.3. Test instruments shall have valid calibration certificates traceable to international standards
of calibration.
4.2.4. The quality documentation shall constitute part of the permanent record of the works.

5. CRITERIA
5.1. Protection Criteria
Any representative monitoring point shall meet any one of the following three criteria:
a) A potential decay of at least 100 mV from instant off steel potential over a maximum period of
24 hours.
b) 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)
c) An instant- off potential (measured between 0.1 s and 1 s after switching the dc circuit open)
more negative than -720 mV with respect to Ag/AgCl/0.5M KCl.
Note 1:
In meeting any of the above criteria (given in clause 5.1 above), instant off 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 pre-stressing steel.
Note 2:
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.

5.2. CP System Acceptance Criteria
The criteria for the acceptance of CP systems at different stages shall be as follows:
Stage 1: Commissioning & 30 Day Performance Verification Acceptance
30 days after initial energizing of the CP system, the system commissioning and performance shall
be considered satisfactory and verified if it meets the following criteria:
a) The specified criteria (as given above in 5.1) are met at 60% of the monitoring locations
(embedded reference electrodes) in each anode zone.
b) At 40% of monitoring locations within a zone that do not meet the criteria specified in 5.1
above, minimum 50mV decay from instant-off potential is achieved.

Note:
If the above criteria is met then the system shall be deemed commissioned and the 12 month
monitoring period shall commence. If the above criteria is not met then the current shall be
increased in the zones which did not meet the criteria and left for agreed period of time with SABIC
Engineer (typically 14 to 28 days). After agreed time period has elapsed a second performance
verification shall be conducted. If no further adjustments are required after this time, the
performance verification will be certified as acceptable and the date of submission of the
performance verification shall be considered as completion of the commissioning of the CP system.

Stage 2: 12-Month System Performance Assessment & Final Acceptance
The CP system shall be accepted only if its performance assessment meets the following criterion:
a) The specified protection criteria (as given above in 5.1) are met at all (100%) monitoring
locations.

6. COMMISSIONING AND CP ADJUSTMENT
6.1. Pre-Commissioning Testing and Inspection
Appendix A provides typical forms (Forms 1 to 5) for CP system circuit verification. These forms are
examples for testing and inspection data recording. These example forms can be modified for specific
requirements.

6.1.1. Prior to energizing, the following inspection and testing shall be conducted as a minimum:

a) Power supplies shall be inspected, to verify ac input and dc output connections. Mechanical
fasteners shall be inspected, tightened, or replaced if required.
b) Correct polarity shall be verified for all circuits. Test results shall be recorded on Form 5,
Appendix A.
c) Continuity of the anode circuits within each anode zone shall be tested and verified. Test results
shall be recorded on Form 1, Appendix A.
d) Discontinuity between positive and negative circuits and adjacent and isolated anode circuits
shall be tested and verified. Test results shall be recorded on Form 4, Appendix A.
e) Continuity of negative circuits shall be tested and verified. Test results shall be recorded on
Forms 2 and 3, Appendix A
f) CP system components shall be visually inspected for proper installation, labeled where
appropriate, and protected from environmental and human damage. Other testing shall be
undertaken as required, to ensure performance of the CP system.
6.2. Pre-Energizing Measurements

6.2.1. Prior to energizing of the CP system, the following measurements shall be made and
recorded in accordance with section 4.3:
a) „As Found‟ steel/concrete interface corrosion potentials shall be measured with respect to
permanently installed reference electrodes. The specialist shall measure the steel/concrete
potentials both at low (about 10 MΩ to 20 MΩ) and high (about 500 MΩ to 1000 MΩ) input
impedance to determine whether the contact resistance of the electrodes or cells to the soil or
concrete is excessive.
b) „As Found‟ steel/concrete interface corrosion potentials with respect to portable reference
electrodes at locations determined by the specialist
c) „As Found‟ steel/concrete interface corrosion potentials with respect to the anode system.

6.3. Initial Energizing and Current Adjustment
Appendix B provides typical form (Forms 6) for CP system initial energizing. Appendix C provides
typical form (Form 7) for CP system performance assessment and verification. These forms are

examples for testing and inspection data recording. These example forms can be modified for specific
requirements.

6.3.1. After a minimum curing period of 14 days for cementitious overlay or repair materials, CP
system shall be energized initially at low current (10 to 20 percent) capacity.
6.3.2. Within a few minutes after energizing, potential of the steel/concrete shall be measured with
respect to the permanently installed reference electrodes to confirm that steel/concrete
potential has shifted in a negative direction from the values measured in accordance with
6.2.1.a and 6.2.1.b. If any values shift in a positive direction, they shall be investigated by the
specialist who shall determine any requirements for additional testing or remedial works or
both.
6.3.3. After confirming steel/concrete potential polarization towards more negative potentials at all
monitoring locations, the specialist shall determine the value of current at each zone of the
CP system that shall be set for its initial operational period.
6.3.4. Current shall be increased incrementally until the „current-on‟ steel/concrete potentials
measured with respect to embedded reference electrodes have shifted towards more
negative potentials by 200 to 300 mV. Current shall be increased gradually and in small
increments. Slow polarization at relatively low current density may be beneficial. Individual
anode current output adjustment procedures shall be followed for each separate zone. Test
results shall be recorded on Form 6, Appendix B.
6.3.5. The specialist shall ensure that steel/concrete potential is not more negative than -1100 mV
(instant-off) Ag/AgCl at any reference electrode location for plain reinforcing steel or -900 mV
Ag/AgCl for pre-stressing steel.

6.3.6. The specialist shall determine the period of initial polarization during which these initial
settings of current shall be maintained for polarization prior to initial performance
assessment. Typically it shall be between 7 days and 28 days after initial energizing
depending upon the actual rate of polarization. If a slow polarization energizing policy (low
initial current) is adopted, full polarization may require longer than 28 days. Test results shall
be recorded on Form 6, Appendix B.
6.3.7. The specialist shall measure and record the output voltage and current values of dc power
supplies providing current to the CP systems at regular intervals (as and when required)
during the initial polarization period. Test results shall be recorded on Form 6, Appendix B.

6.4. Initial Performance Assessment

Appendix C provides typical form (Form 7) for CP system performance assessment and verification.
These forms are examples for monitoring data recording and can be modified for specific requirements.
6.4.1. Initial performance of the CP system shall be assessed after the initial polarization period has
elapsed. This assessment shall include the following measurements:
a) Voltage output and current supply to each anode zone and calculation there from of circuit
resistance

b) Instant off (IR free) potentials at permanently installed reference electrodes and at other locations
determined by the specialist, after interrupting the applied current for a very short period of time.
Results shall be recorded on Form 7, Appendix C.
c) Potential decay after switching off the applied current for a period of 24 hours, or longer if required.
Potential decay shall be recorded on Form 7, Appendix C. Potential decay at embedded reference
electrodes shall be measured at time intervals of 1, 4, and 24 hours after current interruption. In the
event of more than 24 hour decay period, the specialist shall determine the appropriate period of
potential decay and the intervals during which potential decay values are measured.
6.4.2. The time interval between the current interruption and the measurement of „instant off‟
steel/concrete potential shall be sufficient to avoid any transient voltage arising from
switching surges, capacitance or reactance effects, and sufficiently short to avoid significant
depolarization. Typical values are between 0.1 and 0.5 seconds but appropriate values will
vary from system to system and with the extent or period of polarization. The measurement
period (for digital „counting‟) should be sufficiently short to avoid significant depolarization
during the measurement period, but of sufficient length not to degrade the accuracy or noise
rejection capability of the measurement system. Typical values are between 0.1 and
0.5 seconds, but calibration and other instrumentation calculation steps may dictate a longer
period than this between subsequent measurements.
6.4.3. The off:on ratio of such switching regimes shall be minimum 1:4. Typical values for manual
data collection are 3 seconds off, 12 seconds on. For electronic data collection it is
advantageous to link the data logging system to the switching system so that measurement
wait periods and measurement periods are accurately related to the instant of switch off.
Longer switching periods would slow data collection and risk depolarization during the off
period.

6.4.4. The specialist shall analyze the data collected in accordance with 6.4.1 above to assess
compliance with protection criteria specified in 5.1 above.

6.5. Adjustment of Current Output

6.5.1. Based upon the interpretation made in accordance with 6.4.4, the specialist shall determine
whether the output current should be increased, decreased or maintained. The specialist
shall similarly determine whether this current should be maintained under constant current
control, allowed to vary with circuit resistance changed under constant voltage supply, or be
the subject of some form of closed loop monitoring and automatic control.
6.5.2. Following initial adjustment, the specialist shall demonstrate compliance with protection
criteria specified in 5.1 above to SABIC.
6.5.3. A copy of „CP system performance data‟, in compliance with 6.4.1, shall be submitted to
SABIC before it leaves the site.

7. System Records and Documentation
7.1. Quality and Test Records
The quality assurance system plan, the quality documents arising therefrom, and the inspection and test
results shall form the permanent records of the installation of the system.

7.2. Installation & Commissioning Report
Installation and commissioning report for the CP system shall be prepared, which shall have the following as
a minimum:
a) A general description of the works
b) SABIC, design engineer, supervising engineer, contractor, subcontractor(s) and the specialist(s) and
their responsibilities
c) A copy of the materials specifications, installation procedures, and design calculations
d) A detailed description of the installation, completion date, and commissioning date
e) As-built drawings, detailing the installation and its components to a sufficient detail to facilitate future
requirements for inspection, maintenance, and reconstruction of the system and its major components.
They shall also indicate deviations or variations from the original design drawings.
f) A list of the major components of the CP system with data sheets and the source(s) of spare parts and
maintenance for these components and for the overall system
g) Test results of pre-commissioning checks and inspection
h) Results of the measurements and data taken before energizing the system, while the system was
energized, and during the initial system performance
i) A record of the „as left‟ operating conditions of the system
j) A copy of the permanent records, in accordance with 7.1
k) Recommendations for any modifications to the CP system
l) Other documents required by SABIC

7.3. Operation and Maintenance Manual
Operation and maintenance manual shall be prepared for the CP system, which shall incorporate the
following as a minimum:
a) A detailed description of the system, describing what it does, how it works and when it was installed and
commissioned
b) A set of „as built‟ drawings and a list of components used in CP system along with names and
addresses of their manufacturers and suppliers
c) Details of the power source, its rating, fittings, protection system, earthing, power and control circuit
wiring diagram
d) Detailed (step by step) guide for system operation, that is, how and when to adjust, which controls
perform what function, operating limits, procedures for shutting down and re-energizing. For remote
monitoring systems see Note 1 below.
e) Detailed guide and procedures for system monitoring
f) Detailed recommended routine maintenance and inspection intervals and procedures in accordance
with 8.2 and 8.3.
g) Recommended procedures for future performance assessments and the interpretation of the data there
from

h) Forms or computer data for recommended routine maintenance, inspection and performance
assessment activities
i) Fault finding procedures for faults within the CP electrical power supply (ac and dc), short circuits and
open circuits in the CP system
j) Maintenance and repair procedures for the electrical power supply equipment, any data logging and
control equipment and the anode system with any overlay, sealant or decorative coating
k) Other documents required by SABIC

Note:
In case of a “Remote Monitoring System” the contractor shall provide a detailed step up step guide
for each (major & sub menu) screen window on system operation and adjustment. The contractor
shall also provide a comprehensive demonstration and training to SABIC CP Engineers and/or
Technicians on operation of both hardware and software. The training shall include both theoretical
and practical (hands on-operation) sessions.

7.4. Submittals and Completion Dates

a) Records of testing and commissioning shall be available, as specified in section 4.3, for review by
SABIC during all stages of execution of the works. In accordance with the quality assurance plan,
SABIC may certify or approve some of these records during the works.
b) Installation and commissioning report and the operation and maintenance manual shall be completed
and supplied to SABIC within 30 days after completion of the initial performance assessment, or within
a period agreed between SABIC and the contractor.
c) The installation and commissioning of the CP system shall be considered complete only when accepted
by SABIC, after successful demonstration of the satisfactory performance of the system by the
contractor in accordance with 5.1 & 5.2.
d) Prior to issuing the completion certificate, SABIC will check and ensure compliance with 6.1 to 6.5 and
7.2 and 7.3.
e) SABIC will ensure performance of CP system as demonstrated by the contractor in compliance with 5.1
and 5.2.
8. Operation and maintenance
Appendix C provide a typical form for logging the system monitoring data and performance assessment. These
forms are included here as guideline for customizing the forms for different systems.

8.1. System Operation

8.1.1. After commissioning, initial performance assessment and acceptance by SABIC, the system
shall be operated by the contractor for a period of 12 months (The final acceptance of the
system by SABIC shall be after 12 months subject to satisfactory operation of the system).
The system operation shall include the following:
a) Function check of the following (typically every 1 month by SABIC or every 3 months by the
contractor).
i. Confirmation that all sub-systems are functioning
ii. Measurement of output voltage to each zone of the cathodic protection system.

iii. Measurement of output current to each zone of the cathodic protection system.
b) Performance monitoring of the following (typically every 3 months by the Contractor.
i. Measurement of “current-on” potentials.
ii. Measurement of “instantaneous off” polarized potentials.
iii. Measurement of potential decay at 1, 4 , 24 and 48 (if required) hours after the current has
been switched off.
iv. Measurement of parameters from any other sensors installed as part of the performance
monitoring system.
v. A full close-up visual inspection of the cathodic protection system and structure.
vi. Assessment of data by the Specialist.
vii. Adjustment of current output
8.1.2. All measurement/testing/inspections shall be in accordance with section 6 above.

8.2. System review report.

8.2.1. The report shall cover following as minimum and shall be submitted to SABIC within 30 days
after completion of system review:

a) The work undertaken
b) The data collected
c) Recommendations for any changes to the operation and maintenance procedures
d) Recommendations for any changes to the cathodic protection system
e) Recommendations for frequency and scope of monitoring
8.3. Long Term Operation
8.3.1. The system shall continue to be monitored and maintained by SABIC in accordance with
8.1.1 and at time intervals given in 8.2.1e.
8.3.2. Each performance monitoring shall include and perform the measurements and adjustments
described in 8.1.1a and 8.1.1b.
8.3.3. The SABIC engineer who will conduct the routine monitoring shall review the previous data
and the recommendations made in the system review report for future monitoring and apply
them where necessary.
8.3.4. The SABIC engineer shall consider extending the intervals between routine inspection and
testing if no faults, damage or significant variation in system performance are indicated by
successive inspections/tests.

NOTE:
It is emphasized that long-term polarization arising from long term cathodic protection will result in a
reduction in the requirement for current and a reduction in the rate of potential decay occurring when
switching off the system.

Typical Form for CP System – Circuit Verification

Form 1
Continuity Checks Between System Positive Output and Anode Feeders

Structure: ______________________ Inspection Date & Time: __________________________
Contractor QA/QC Engr. Name & Signature: __ _______________________________________
CP Sub-Contractor, CP Tech./Engr. Name & Signature: ________________________________
CP Sub-Contractor, CP Specialist Name & Signature: _________________________________