Asset Protection Cathodic Protection Cathodic Protection System Maintenance and Testing. Procedure No.:

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1 Asset Protection Cathodic Protection 9019 Maintenance and Testing Approved by: National Technical Training Manager 1 PURPOSE This procedure specifies the maintenance and testing requirements of cathodic protection (CP) systems for steel gas transmission pipelines, distribution networks and associated structures. 2 SCOPE The procedure covers operation and maintenance checks on the following equipment:- Cathodic Protection Units (CPU s) Sacrificial Anodes Test Points Earth Connections Surge Protection Devices and Copper / Copper Sulphate Half Cells The objective of carrying out these checks is to:- Ensure compliance with all legislative and statutory requirements legislated by governing bodies across APT O&MS operational area is achieved. Comply with all APT O&MS safety policies and processes. Ensure that cathodic protection units and sacrificial anodes are working properly and operating with current and voltage outputs within the expected range. Obtain voltage and current output readings for analysis to determine cathodic protection unit faults, sacrificial anode ground beds deterioration or any other fault likely to effect cathodic protection performance. Check the soundness of electrical connections associated with cathodic protection units, test points, sacrificial anodes, surge diverters and earthing equipment. Check the operation of power supplies and batteries supporting cathodic protection units. This procedure also describes the surveys and testing to be done to measure and assess the effectiveness of the cathodic protection system and determine any adjustments and modifications required to adequately protect the buried steel assets from corrosion. These tests may include:- Full pipe to soil potential surveys. Cased crossing potential surveys. Corrosion probe resistance and polarisation readings and potentials. Interference drain testing and stray current surveys to measure the interference effects of stray currents from electric traction systems and other sources. 3 REFERENCES 6602 Thermit Welding. Work Instruction 6603 Soil Resistivity Measurement. Work Instruction 6604 Testing of Insulating Joints. Work Instruction 6605 Loop Resistance Measurement. Work Instruction 6606 Cathodic Protection Potential Survey. Work Instruction 6607 Foreign Structure Test Point Potential Testing. Work Instruction 6608 Recorded Instrument Potential Survey. Work Instruction 6609 Electromagnetic Coil Pipe Locating Equipment. Work Instruction 6610 Cathodic Protection Unit Inspection. Work Instruction 6611 Maintenance and Calibration of Reference Cells. Work Instruction 6612 Cathodic Protection Maintenance of Offshore Platforms (sacrificial anode). Work Instruction 6613 Cathodic Protection Maintenance of Offshore Platforms (impressed current). Work Instruction Issue 4 December 2009 Page 1 of 15

2 6614 Use of a Stray Current DATA Logger. (Straycorder) Work Instruction 6615 Impressed Current Instantaneous OFF Potential Measurement Survey. Work Instruction 6617 Earth Bed and Earthing Grid Checks. Work Instruction 6618 Surge Diverter Inspection and Testing. Work Instruction 6619 Use of a Stray Current DATA Logger. (Brymen) Work Instruction 6620 JR 1 Current Interrupter. Work Instruction 3.1 Standards References AS Gas and Liquid Pipelines Part 3 Operation and Maintenance. AS 1697 SAS Gas Pipeline Code. AS 2832 Guide to the Cathodic Protection of Metals, Parts 1 & 2. AS 2239 Galvanic (Sacrificial) Anodes for Cathodic Protection. AS 2374 Power Transformers. AS 4853 Electrical Hazards on Pipelines. AS 4799 Installation of Underground Utility Services Within Railway Boundaries. BS 7361 Cathodic Protection Part 1, Code of Practice for Land and Marine Application. Victorian Government Cathodic Protection Regulations GENERAL INFORMATION 4.1 Introduction Corrosion protection systems are designed, monitored and maintained as a cost effective means of preserving underground steel assets and controlling maintenance and replacement costs of gas transmission pipelines and distribution networks. Unprotected steel pipelines require rapidly increasing maintenance as they age. Effective corrosion protection systems are a major means of controlling maintenance costs, with accompanying safety and environmental benefits due to almost entire elimination of corrosion related gas escapes. Corrosion protection for the gas transmission and distribution networks is achieved by the use of protective coatings, cathodic protection, and stray traction current drainage. Electrical isolation and electrical surge protection are necessary adjuncts to these systems. 4.2 Safety Where required, ensure all Hazardous Task Permits are obtained and implemented before commencing work. Caution is required when working on CP (and other) equipment connected to pipelines due to the potential for large electric voltages to be induced in the pipeline structure. Large DC and AC voltages can be induced in the pipeline from nearby overhead electricity transmission lines, traction equipment such as electric trams and trains, and from lightning and electrical storms. Equipment connected to the pipeline shall not be worked on during storm activity when thunderstorms can be seen or heard in the vicinity. All safety/work instructions regarding isolation and tagging of equipment shall be adhered to. The use of cross bonding leads where required shall be adhered to. When driving between work locations, ensure that driving techniques and speeds are to the appropriate conditions. Experience and training in four-wheel drive vehicle handling may be required. Be aware of heat exhaustion and exposure to ultra violet light. When working in remote areas keep the relevant control centre or supervisor informed of your location and proposed scope of work, it is considered to be good practice to arrange for regular check ins when in remote areas. Where access is required to private property, consideration needs to be given to contacting the occupier of the land prior to carrying out work on their property. If deemed necessary, this process can be done by the worker doing the checks or the Issue 4 December 2009 Page 2 of 15

3 supervisor, or if required, through the company property liaison officer. Persons conducting the checks should be familiarised with the location of all the cathodic protection equipment to be checked. Ensure only suitably qualified and assessed competent persons conduct operations on cathodic protection equipment. 4.3 Environment Damage to native vegetation and re-growth should be kept to a minimum. Where practical, vehicle access shall be restricted to existing roads and tracks. Transfer of weeds from infested areas along the route should be prevented by taking steps to avoid picking up seeds, and if necessary, by washing down vehicles and equipment before leaving infested areas. For additional environmental requirements to be considered during surveys, refer to the Environmental Management Plan for the specific pipeline. 4.4 Definitions For the purpose of Cathodic Protection procedures the following definitions apply: Cathodic Protection (CP) Prevention of corrosion by application of direct electric current to the surface of a metal such that oxidation reactions are prevented from proceeding. Cathodic Protection Unit (CPU) A device providing cathodic protection current, powered from an external energy source. Such energy sources include mains power, solar, etc. Cathodic protection units require permits and registration in accordance with the Cathodic Protection Regulations 1988 in Victoria. No formal permits are required in SA, only courtesy advice to potentially affected parties. In Queensland permits are required for units exceeding 5 amps output. Copper/Copper Sulphate Half Cell The half-cell is a transparent tube filled with a saturated copper sulphate solution with a copper electrode immersed in the solution. The electrode passes through a seat at one end of the cell and is then connected to a suitable DC voltmeter by a flexible wire. The other end of the cell is closed off with a porous disc, which remains damp to provide electrical contact to the electrolyte surface. When placed in the ground a potential is developed across the half-cell. The digital voltmeter connected between the halfcell and a buried pipeline test point measures the pipe to soil potential. Corrosion Probe or Resistance Probe A strip of metal of similar metallic composition to the pipeline is electrically connected via a test point directly to the pipe. The exposed metal strip is then exposed to the same cathodic protection current available at the location of installation. If the cathodic protection is found inadequate the strip will corrode at a given rate. Prior to installation, the electrical resistance of the strip is measured with a device called a Corrosometer. The electrical resistance of the probe will increase as the metal strip corrodes and can be translated into metal loss per year by simple calculations. Electrical Isolation The electrical separation of structures to be protected from other structures and/or electrical systems. This is achieved by the installation of insulating flanges, monolithic insulating joints and insulating couplings. Galvanic (Sacrificial) Anode A block of metal that provides protection by itself corroding in preference to the steel structure corroding. Magnesium is commonly used for underground service, although sometimes zinc is preferred. (Refer to AS 2239 for further details.) Interference Drainage Bond An electrical connection via cable, from a point on the pipeline system to tram Issue 4 December 2009 Page 3 of 15

4 or train substations, or to other sources of interference currents, to prevent adverse effects from stray currents. These installations include equipment to control the direction and magnitude of current flowing. Pipe to Soil Potential A steel structure may be considered to be protected when the potential on all parts of its surface is equal to or more negative than -850mV relative to a saturated copper/copper sulphate reference electrode. This is known as the pipe to soil potential and is the key parameter measured to assess whether the buried pipeline is adequately protected from external corrosion. Spot Potential Reading A measurement of a pipe-to-soil potential, taken at a given location at a particular point in time. Such readings can be used to assess protection status where potentials do not vary with time. However, in circumstances where potentials fluctuate due to telluric or stray current influences, recordings of potential over a period of time (usually 20 hours) are necessary to identify when these influences are at their minimum during the day. Stray Current Electrolysis A form of corrosion, often severe, caused by stray electrical current entering the ground from electric tram and train systems, third party CP systems, or other electrical systems generating stray currents, which then affects buried metallic structures. Surge Protection. Is the term used to describe devices installed along a pipeline to protect both pipe and personnel working on, or inadvertently contacting, the pipeline from electrical shock that could result in serious injury. Sources of electrical hazards of this type include, lightning, low frequency load current induction, low frequency fault current induction and electrified railway lines. Telluric Effects. Pipelines are subject to the affects of telluric current fluctuations caused by changes in the earth s magnetic field due to sunspot or other solar activity. The effect of these currents needs to be measured and allowed for when assessing the effectiveness of the CP system on those pipelines. Test Point. A conveniently located termination point for electrical cables connected to a buried pipeline. This allows measurement of the pipeline potential, and is the principal method of assessing the effectiveness of corrosion protection. 4.5 Protection Methods and Equipment Involved. Cathodic Protection. Buried steel gas transmission pipelines and distribution networks are effectively protected from corrosion by the application of cathodic protection. Protection is provided by galvanic (sacrificial) anodes, impressed current cathodic protection units, or a combination of both. Stray/interference Currents. Steel pipelines affected by stray currents from sources of electric interference such as train and tram systems (Stray Current Electrolysis) have interference drainage facilities (drainage bonds) installed where required. In the states of Victoria, NSW and Queensland the State Electrolysis Committee takes a lead role in managing stray current systems. Their role is to coordinate regular area testing which confirms the need and optimum location for such installations. They also coordinate the installation, commissioning and testing of the required equipment. In some states (eg SA) the problem of stray currents is not as significant and is managed directly between representatives of the various utilities who make up the local Electrolysis Committee. Issue 4 December 2009 Page 4 of 15

5 Electric Isolation. All buried steel pipelines are electrically isolated from aboveground pipe work, other structures and all electrical systems. Sensing lines and SCADA monitoring facilities are electrically isolated from cathodically protected pipe work by various means. Electric Surges. Steel pipe work forming part of the gas transmission system is protected from the effects of electrical surges ("surge protection"). This protection shall be sufficient to prevent damage to the pipe work or injury to personnel who may be in contact with the pipe work, and shall meet the requirements of Australian Standard AS Electrical Hazards on Metal Pipelines. Electrical isolation points likely to be damaged by electrical surges have electrical surge protection devices fitted. Such devices include Polarisation Cells, Nicad Batteries, Varistor Spark Gap combinations, Earthing beds and Electronic Polarization Cell Replacements. Corrosion Monitoring Points. Test points are installed in accordance with AS at locations along the pipeline to effectively monitor and maintain the effectiveness of corrosion protection systems. Electrical Continuity. Bonding leads are installed to ensure the electrical continuity of steel pipe work where there are buried flanges or valves electrically isolating sections within a cathodic protection area. 5 REQUIREMENTS The frequency of checks and surveys are as shown in Appendix A unless more frequent routines have been instituted by the Corrosion Engineers to address specific problems on a particular pipeline system. 5.1 Operational Checks Operational checks are carried out on all installed CP equipment on a pipeline or distribution network system to check its overall condition and that it is operating within the set limits Cathodic Protection Units (CPU s) Minor and Major Maintenance Minor inspections of CPU s are usually conducted on a monthly basis to ensure the functionality and integrity of all equipment associated with Cathodic Protection Unit. The frequency of minor inspections shall be no greater than 2 monthly. Major maintenance of CPU s shall be carried out on a 12 monthly basis. For the details of minor inspections of CPU s and major maintenance of CPU s and Ground Beds refer to Work Instruction 6610 Cathodic Protection Unit Inspection SCADA Monitored Sites Where in-ground half cells are installed and connected back to a control centre via telemetry, and CPU outputs are similarly telemetered back, these routine operational checks may be performed remotely. In reacting to any changes however, the reliability of the telemetry will need to be confirmed. Also, the permanent reference cell will need to be checked against a calibrated portable cell to confirm its operation. In areas where stray traction currents or telluric currents may influence results, a chart of potential between the 2 cells needs to be taken over a 20 hr period once a year to determine times of high and low activity Earthing Beds The condition and connections for earthing beds shall be checked on a six monthly basis. Check the tightness of the earth bed to pipe work connections at stations and at test points where installed. Full earth bed resistance testing for CP system earthing and station earthing is carried out 12 monthly as a specialist exercise as part of electrical systems maintenance checks. The test procedure is described in Work Instruction 6617 Earth Grid and Earthing Bed Checks. Issue 4 December 2009 Page 5 of 15

6 5.1.3 Surge Protection Devices Varistor Spark Gap Devices and Solid State Polarisation Cell Replacements: The condition and connections for varistor spark gap devices and solid state polarisation cell replacements shall be checked on a six monthly basis. Check connections for tightness and retighten if necessary. Inspect body for burn marks or signs of unit having fired. Mark down on report form for replacement if found faulty. In addition to the above, varistor Spark Gaps need to be checked 5 yearly with a Surge Protection Tester to confirm their performance capability. Devices with a performance characteristic outside the manufacturer s tolerances must be replaced. For details on this test procedure refer to Work Instruction 6618 Surge Diverter Inspection and Testing Chemical Battery Polarisation Cells The condition and connections for chemical battery polarisation cells shall be checked on a six monthly basis. Check connections for tightness and retighten if necessary. Check electrolyte level in battery and top up with distilled water if required. Check electrolyte solution for sludge or contamination, and oil seal layer if provided. Mark down on report form for change out if solution or unit suspected of being faulty. Caution: These devices can conduct high AC and DC currents and contain potassium hydroxide, a caustic and highly toxic substance. Any maintenance work required on these devices must only be carried out by suitable qualified, trained and experienced electrical tradespersons. Every 5 years these polarisation cells need to be cleaned and overhauled, and the electrolyte changed. The Polarisation Cells are to be removed and replaced with refurbished units. The removed units are to be sent to an overhaul service provider qualified to carry out the overhaul safely. Caution Prior to disconnecting the polarisation cell and connecting a bonding link, the battery must be discharged. This can be achieved by connecting a purpose built fused resistance link across the battery terminals. When the battery is discharged, a bonding link must then be installed between the pipeline connection and the earthing grid connection prior to removing the polarisation cell. This is required to continue to drain to earth residual AC currents. This work must not be undertaken during periods of storm activity due to risk of electrocution from lightning strikes Solid State Polarisation Cell Replacements The condition and connections for solid state polarisation cells shall be checked on a six monthly basis. Check connections for tightness and retighten if necessary. Inspect body for burn marks or signs of unit having fired. Mark down on report form for replacement if found faulty. Solid state polarisation Cells shall also be removed and inspected to manufacturer s instructions every 5 years. Bonding links must be installed between the pipeline connection and earthing bed connection prior to removal, however, as these devices are not equipped with batteries discharging is not required. Issue 4 December 2009 Page 6 of 15

7 5.1.4 Copper/Copper Sulphate Half Cell 12 Monthly Maintenance The Copper/copper sulphate half cell consists of a cylinder filled with a saturated copper sulphate solution with a copper electrode immersed in the solution. At one end of the cylinder is a porous plug. A terminal is connected to the copper electrode at the other. The items to be maintained are:- Cleanliness of the porous plug. Cleanliness of the solution and. Cleanliness of the copper electrode. This is achieved by the following:- The porous plug should be wiped clean of dirt and sand build up after usage. The solution needs to be monitored for clarity and changed out if it becomes cloudy or creamy in appearance. On a 12 monthly basis, remove the copper electrode from the solution and using emery cloth or other nonmetallic abrasive paper, clean the surface of any oxide layer build up. Check terminals and connections for soundness. For further maintenance and calibration details refer to Work Instruction 6611 Maintenance and Calibration of Reference Cells. 5.2 Cathodic Protection Potential Surveys Pipe to Soil potential surveys of the whole pipeline and network system are carried out to measure the level of protection being provided by the CP system. The buried pipeline can be considered to be adequately protected if the potentials measured fall within the criteria listed in section 5.4 Protection Criteria For Sacrificial Anode Potential Surveys, Anode Test Point and Operational Checks and Anode Current reading details, refer to Work Instruction 6606 Cathodic Protection Potential Survey Impressed Current System ON-OFF Potential Survey Full line potential surveys on Transmission pipelines and distribution networks in remote and rural areas are to be conducted by this method every 12 months. Surveys on Transmission Pipelines and distribution networks in urban areas are to be conducted every 6 months. For details to conduct an On Off Potential Survey, refer to Work Instruction 6615 Impressed Current Potential Measurement Survey Cased Crossing Potentials Survey A serious corrosion risk is possible if a pipeline is in electrical contact with the steel casing of a cased crossing. During 6 or 12 monthly potential surveys, the potentials of casings to soil need to be taken to determine if there is contact. A casing not in contact with the cathodically protected pipe sits at its natural potential to soil of between 400mV and -750mV with reference to a copper/copper sulphate half cell for an unprotected steel casing. For casings with zinc sacrificial anodes fitted the natural potential to soil will be between -1000mV and -1100mV. A casing to soil potential of the same order as the pipe to soil potential suggests that contact is likely to be occurring and further investigation will be required Insulated Flange Potentials Survey Analysis of the readings taken at the test points at an insulated flange during the potential survey will indicate if there is a problem with the insulation. At above ground insulated flanges, if there is no test point installed then a pipe to soil potential needs to be taken on the flange surface. A spike will be required to make good contact. If the potentials measured indicate a problem with the insulated flange then further investigation will be required. Further details for testing Insulated Flanges are described in Work Instruction 6604 Testing of Insulating Joints. Issue 4 December 2009 Page 7 of 15

8 5.2.4 Corrosion Resistance Probe and Polarisation Probe Readings Where corrosion resistance probes are fitted to measure local corrosion rate and the effectiveness of CP against corrosion the frequency of taking readings is specified by the Corrosion Engineer. The following steps are required to gather data for analysis:- Using a Corrosometer, measure and record the corrosion probe readings. Record the polarised potential of the resistance probe strip with reference to a copper/copper sulphate reference electrode placed and watered as close as practical to the probe position. The potential is measured by briefly interrupting the flow of cathodic protection current to the strip by placing a magnet over the magnetically operated reed switch installed in the special test point facility. The potential measure on the strip should be recorded within two seconds of interruption. The general guidelines in AS Appendix D also provide an informative description of the test. Results should be recorded on the Corrosion Probe Resistance report form. The completed form should be forwarded to the pipeline system Operations Manager for discussion and review with Corrosion Engineering Specialists. Results shall be assessed against the relevant protection criterion and entered into a suitable Corrosion Asset Management System Stray Current Drain Current Measurement During the routine 6 monthly 20-hour potential survey the current flow through stray current drains also needs to be measured. This is done by installing a shunt resistor in each drainage circuit and measuring the potential drop across the resistor during the survey. The current is then calculated and compared to the previous readings. Any change found requires investigation. In Victoria the change is reported to the Electrolysis Committee and it is their responsibility to investigate and organise any corrective action required. 5.3 Stray Current Surveys Responsibilities and Frequency of Surveys In Victoria, where a large number of sources of stray current interference exist through the electric tram and rail networks, the State Electrolysis Committee coordinates a complete survey of the underground protected systems in the metropolitan area every 5 years. This is achieved by requesting equipment owners to carry out a full 20-hour potential survey in nominated areas each year. Owners are advised which sections are required to be done in a particular year and asked to perform a 20 hour survey on their system if it is due in that year. The results are forwarded on to the committee for their analysis to determine corrective measures required, if necessary. In other states testing is done on a more as needs basis, with surveys only being organised in a particular area when new CP installations are commissioned in that area, or if interference with existing systems is suspected. APT O&MS, as a maintainer of CP systems is required to carry out the 20-hour surveys on request and to forward the results to the committees in Victoria, NSW and Queensland. In the other states the results are analysed by the companies who organised the survey General Procedure for Stray Current Survey For information on how to conduct a 20 hour survey, refer to Work Instruction 6608 Recorded Instrument Potential Surveys. For the bulk of the survey time ON potentials only are taken. At nominated times during the survey the operators are requested to interrupt the CP to obtain ON - OFF readings. This is usually timed to be during the stray current quiescent period when traction systems are Issue 4 December 2009 Page 8 of 15

9 shut down or when other sources of interference are at a minimum 5.4 Protection Criteria For the purpose of assessment of the protection being afforded a buried pipeline by s, the following criteria as specified in AS may be considered applicable. Protection Potential A steel structure may be considered to be protected when the potential on all parts of its surface is equal to or more negative than -850 mv relative to a saturated copper/copper sulphate reference electrode. Measurement of this potential is only considered valid when not affected by any significant voltage drop between the reference electrode and the pipeline. Fluctuating Potentials Where structures are subject to fluctuating potentials (such as in stray current electrolysis), the structure may be considered protected provided the following criteria are met: - Note: These structures are usually found in major metropolitan areas that are heavily influenced by AC and DC stray currents from Train and Tram traction systems. For pipelines with short polarization times i.e. pipelines with sound coating and which have shown to polarize and de-polarize rapidly in response to stray currents, the average potential needs to be more negative than -850 mv and anodic excursions more positive than mv should not occur for more than 5% of the time in any 24 hour period. Further more: The potential shall be not less negative than the protection criterion plus 50 mv (i.e mv), for more than 2% of any test period. The potential shall be not less negative than the protection criterion plus 100 mv (i.e mv), for more than 1% of any test period. The potential shall be not less negative than the protection criterion plus 850 mv (i.e. zero mv), for more than 0.2% of any test period. For pipelines with poor coating, and which have shown long polarisation and depolarisation times in response to stray current, the potential shall not be less negative than -85OmV for more than 10% of the test period. Telluric Effects Magnetic field variation magnetometer recordings shall be obtained for the full testing period through the Australian Geological Survey Organization, who maintains magnetometer facilities for all Australian regions. Access to oneminute interval data is available on their Internet site. The magnetic disturbance K-indices which is a measure of activity compared to a quiet geomagnetic day with a magnitude of zero (0) being calm and nine (9) being severe should also be considered during logged potential and ON OFF survey evaluation. To evaluate the telluric stray current effects, it is necessary to record the potential over a nominal period of 20 hours. If a data Logger is used for the monitoring of potential, its frequency for sampling shall not be less than one sample per minute. The potential of the pipeline subject to telluric current effects shall not be less negative than the protection potential Criterion for more than 10% of the test period. When determining the extent of the potential variations, an assessment should be made of the degree of ionospheric disturbance at the time of the recording. 5.5 Overprotection Excessive levels of cathodic protection may result in accelerated disbonding of a coating or other deleterious effects. The pipeline potential should not be more negative with respect to a copper/copper sulphate reference electrode, with the cathodic protection system energised ( on potential), than the levels shown below for the respective coating types: Issue 4 December 2009 Page 9 of 15

10 -1.5V for tape coated pipelines and spray applied coatings -1.5V for coal tar enamel or most field applied liquid coatings -1.7 V for high quality coatings such as Extruded Polyethylene, Cintercoat, Fusion Bonded Epoxy and Trilaminate. 5.6 Documentation, Tools and Equipment The following documents are required: Maps of the pipeline showing location of stations, test points and CP facilities. Relevant work instructions for the respective checks being performed. Relevant CP System Operational Check Sheets and Potential Survey Report forms designed for the pipeline system. Operations and Maintenance Manual for the specific pipeline. Persons conducting the checks should be familiarised with the location of all the cathodic protection equipment to be checked. Tools and equipment required includes: - Copper/Copper sulphate half-cell. Silver/Silver Chloride reference cell. Digital multimeter or hand held scope meter. Hand tools for connecting and disconnecting test point connections, surge devices and anode connections. Bonding leads. AC Voltage Tester. Current Clamp. Earth Resistance Tester. Surge Protection Tester. Any other tools and equipment specifically referred to in the associated work instructions. Measuring and recording equipment shall have accuracy equivalent to or better than the characteristics as described in AS Special Requirements for Offshore Platforms Carryout platform induction training with the Platform Safety Officer if a period of more than six months has expired since your last visit to the platform. At each visit discuss any safety precautions required with the Platform Supervisor. Some hazards that may be encountered are: High noise levels. Hydrogen Sulphide. Hydrocarbons. Platform cranes operating from the main deck. Slip and trip hazards. Grating conditions. Access to the sea deck/cellar. General electrical safety at all locations. At all times only intrinsically safe instruments shall be used. Obtain the required general work permit from the Platform Supervisor. Notify the Platform Safety Officer when entering the sea deck to conduct any work. The following requirements shall be met when working from the sea deck: Buoyancy vests shall be worn at all time. A minimum of two people shall perform all works. Notify the Platform Safety Officer when you have exited the sea deck area. When all works have been completed arrange to have the general work permit signed off by the Platform Supervisor. 6 RECORDS Supervisor and Operations/Facility managers shall ensure that any maintenance or other work required is documented, placed with the pipeline records, and its completion followed up. Operational Check Reports, Potential Surveys and any records of maintenance work done on the CP systems shall be filed with the pipeline records and kept for the life of the pipeline. Issue 4 December 2009 Page 10 of 15

11 Maintenance and Testing Procedure No.: 9019 Appendix A Activity Description Transmission Pipelines Frequency Distribution Networks Frequency Comments Inspections and Maintenance Cathodic Protection Equipment, Routine Operational Checks. Underground tanks, bases of above ground storage vessels. Take voltage and current readings of transformer rectifier units along the pipeline. Cathodic Protection Units Minor Inspection Check condition and connections of test points, surge arrestors, Earthing beds and polarisation cells where fitted. Full Earth Bed Resistance Testing. Electrical test of surge arrestor varistors and spark gap. Overhaul and electrolyte change of polarisation cells. Tank to soil potentials, electrical isolation and earthing. Check condition and connections of test points, surge arrestors and polarisation cells where fitted. 2 Monthly 2 Monthly SCADA Monitoring would cover this requirement providing account is made for Telluric and Traction Current effects. 2 Monthly 2 Monthly Refer to W.I monthly 6 Monthly 12 monthly 12 Monthly Refer to W.I yearly 5 Yearly Refer to W.I monthly 6 Monthly Issue 4 December 2009 Page 11 of 15

12 Maintenance and Testing Procedure No.: 9019 Activity Description Transmission Pipelines Frequency Distribution Networks Frequency Comments Cathodic Protection Equipment, Major Inspections. Major inspection of TR units and polarisation cells at stations along the pipeline. Urban 6 monthly Remote 12 monthly Urban 6 monthly Remote 12 monthly Refer to W.I Pipeline CP Potential Survey. Stray Current Drainage Bonds. Stray Current Electrolysis Survey. (Electrolysis Area Testing. DCVG Coating Survey. Copper/Copper Sulphate Reference Cells. Silver/Silver Chloride Reference Cells. Full pipe to soil potential survey along complete pipeline. On off potential survey for impressed current cathodic protection areas. Measure current flow at sacrificial anodes. Check Current flow for correct polarity and against previous readings. Program co-ordinated by the Victoria Electrolysis Committee. Above ground survey to detect defects or holes in buried pipeline coatings. Urban 6 monthly Remote 12 monthly 6 monthly 6 Monthly 5 yearly 5 Yearly Prior to expiry of defect warranty period & 5 yearly. Urban 6 monthly Remote 12 monthly Refer to W.I & W.I Yearly surveys Victoria only. Other states done as required. Need not be done if an intelligent pig has been run within the 5 year period, or other methods of pipeline integrity assessment have been undertaken. Refer Proc DCVG Surveys Maintenance 12 monthly 12 Monthly Refer to W.I Maintenance 1 week prior to offshore work. Victoria Only Issue 4 December 2009 Page 12 of 15

13 Maintenance and Testing Procedure No.: 9019 Appendix B SAMPLE POTENTIAL SURVEY REPORT FORM CATHODIC PROTECTION SURVEY RESULTS TEST POINT KP SEPARATIO N DISTANCE ON POTENTIAL PIPELINE FOREIGN STRUCTURE CATHODIC PROTECTION UNIT OUTPUTS OFF POTENTIAL ON POTENTAL OFF POTENTAL VOLTAGE (Volts) CURRENT (Amps) CASING POTENTAL DATE RECORDED TIME RECORDED COMMENTS Issue 4 December 2009 Page 13 of 15

14 APPENDIX C ITEMS TO BE RECORDED AT CP SYSTEM OPERATIONAL CHECKS Depending on the equipment installed, report forms designed for specific pipeline CP checks need to include boxes to record the following information:- Cathodic Protection Unit - 12 monthly checks Pipeline system or section Date of Checks Performed By CPU Identification number or location CPU Output - Voltage - Current - Operating Mode Solar panel condition OK Needs Attention Batteries OK Needs Attention Electrolyte Level OK Any other comments Sacrificial Anodes 6 Monthly Checks Pipeline system or section Date of Checks Performed By Zone or Control Area Test point location or identification number Pipe to Soil Potential Anode Current Any other comments Surge Protection Devices 6 Monthly checks Pipeline system or section Date of Checks Performed By Surge Device location or identification number Connections OK General Condition OK Needs Replacement Issue 4 December 2009 Page 14 of 15

15 Appendix C (continued) Ni-Cad Battery Polarisation Cells Pipeline system or section Date of Checks Performed By Polarisation Cell location or identification number Connections OK General Condition OK Needs Replacement Battery Electrolyte Level OK Electrolyte Condition OK Needs replacement CPU and Ground Bed 12 Monthly Major Maintenance Pipeline system or section Date of Checks Performed By CPU Identification number or location CPU Condition External OK Needs Attention CPU Condition Internal OK Needs Attention Wiring condition/security OK Needs Attention Component Mountings OK Needs Attention Vents/cooling fan OK Needs Attention Ground Bed Cable OK Needs Attention Ground bed Loop resistance Any Other Comments Copper/Copper Sulphate Half Cell Half Cell Identification number Date of maintenance Performed By Issue 4 December 2009 Page 15 of 15