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Cathodic Protection

Rev1
IssuedOct 12, 2026
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1 Scope

NOTE This standard governs the cathodic protection system as a system: the survey that establishes the need, the party that designs it, the anodes, rectifiers, anode beds, test stations, reference electrodes, bond cables and their connections, isolation devices, and decoupling devices that make it up, the commissioning that proves it, the potential survey and the report that record it, and the surveys that keep it working. (1.1)
NOTE This standard is read with Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process, the umbrella for the process discipline, which carries the submittal register and procedures, the factory test witnessing policy, the manufacturer's field services, the equipment nameplates, the spare parts basis, the anchorage basis, the site and service conditions, and the warranty term for every process scope; nothing here restates them. (1.2)
NOTE A buried or submerged metal structure corrodes where current leaves it for the electrolyte. Cathodic protection makes the whole structure the cathode of a deliberate cell, so that current enters the structure everywhere and leaves only from an anode placed for the purpose. A galvanic system gets that current from the potential difference between the structure and a less noble metal, magnesium, zinc, or aluminum, which is consumed in its place. An impressed-current system gets it from a rectifier driving current through anodes that are chosen to be consumed slowly or not at all. A coating does most of the work on a coated structure, and cathodic protection takes care of the holidays the coating leaves; on a bare or encased structure the system carries the whole current demand and is sized accordingly. (1.3)
NOTE The piping standards and this standard divide the buried line in one way. Ductile Iron Process PipingDuctile Iron Process PipingResolves to the current adopted revision.sync/ductile-iron-process-piping and Steel And Stainless Process PipingSteel and Stainless Steel Process PipingResolves to the current adopted revision.sync/steel-and-stainless-process-piping furnish the pipe, its exterior coating or polyethylene encasement, and the holiday testing of a bonded coating, and the piping installer installs the joint bonds under those standards. This standard specifies the bond cable, the connection, the coating of the connection, and the continuity test that proves the bonds, and furnishes everything from the test station outward. A tracer wire laid with plastic pipe under Plastic Process PipingPlastic Process PipingResolves to the current adopted revision.sync/plastic-process-piping locates the pipe for an excavator and is never used as a test lead, because it is not connected to the structure the system protects. (1.4)
NOTE Water Storage TanksWater Storage TanksResolves to the current adopted revision.sync/water-storage-tanks furnishes the tank, its interior lining, and the hand holes, the reference electrode fittings, and the rectifier mounting pad and conduit sleeve that the interior system needs. This standard furnishes the interior system under AWWA D104, NACE SP0196, or NACE SP0388 and the bottom-exterior system under the tank, and the tank standard's provisions are sized and located to suit the system submitted under this standard. (1.5)
NOTE The following are governed elsewhere and are outside this standard: (1.6)
  • the pipe, the fittings, the exterior coating, the polyethylene encasement, the corrosivity scoring of the soil for the encasement determination, and the installation of the joint bonds, under Ductile Iron Process PipingDuctile Iron Process PipingResolves to the current adopted revision.sync/ductile-iron-process-piping and Steel And Stainless Process PipingSteel and Stainless Steel Process PipingResolves to the current adopted revision.sync/steel-and-stainless-process-piping
  • the dissimilar-metal insulating flange kit at a stainless-to-ferrous connection, under the piping standard for the pipe
  • the tracer wire and its test station on plastic piping, under Plastic Process PipingPlastic Process PipingResolves to the current adopted revision.sync/plastic-process-piping
  • the tank, its lining, and its fittings, under Water Storage TanksWater Storage TanksResolves to the current adopted revision.sync/water-storage-tanks; the well casing and screen, under Water WellsWater Supply WellsResolves to the current adopted revision.sync/water-wells
  • the factory sacrificial anodes, the dielectric nozzle bushings, and the STI R051 commissioning of a steel underground fuel tank, under Fuel Dispensing And Storage TanksFuel Storage TanksResolves to the current adopted revision.sync/fuel-dispensing-and-storage-tanks; where the drawings assign a cathodic protection system to buried fuel piping under Fuel Oil SystemsFacility Fuel-Oil SystemsResolves to the current adopted revision.sync/fuel-oil-systems, that system is specified under this standard
  • buried steel gas piping and its corrosion protection, under Natural Gas PipingNatural Gas PipingResolves to the current adopted revision.sync/natural-gas-piping and the serving utility
  • the anode inside a water heater, under Water HeatersCommercial Water HeatersResolves to the current adopted revision.sync/water-heaters
  • galvanic anodes embedded in a concrete repair, under Concrete Repair And RestorationConcrete Repair and RestorationResolves to the current adopted revision.sync/concrete-repair-and-restoration; cathodic protection of reinforcing steel in concrete under NACE SP0290, not yet owned by a SynC standard
  • electrically isolated post-tensioning tendons, under Post Tensioned ConcretePost-Tensioned ConcreteResolves to the current adopted revision.sync/post-tensioned-concrete
  • lightning protection, under Lightning ProtectionLightning Protection SystemsResolves to the current adopted revision.sync/lightning-protection
  • shop galvanizing, zinc-rich primers, and other sacrificial coatings, under Shop Painting And GalvanizingShop Painting and Galvanizing of SteelResolves to the current adopted revision.sync/shop-painting-and-galvanizing
  • the grounding electrode system, the equipment grounding of the rectifier, and the electrical safety bonding of metallic piping and tanks, under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding
  • the rectifier branch circuit and its disconnect, under Common Work Results ElectricalCommon Work Results for ElectricalResolves to the current adopted revision.sync/common-work-results-electrical; its conductors, under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables; its raceway, under Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit
  • trench excavation, dewatering, and backfill above the pipe zone, under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork
  • marine structures, and the water transmission mains and pipelines beyond the plant fence that a pipeline operator's corrosion program governs, not yet owned by a SynC standard
1.7 Cathodic protection under this standard shall be furnished for every structure the drawings assign to it, as shown on the corrosion protection drawings.
NOTE A structure the drawings do not assign to the system is protected by its coating, its encasement, or its material alone, which is the condition of most buried ductile iron in a plant yard and of every plastic line. The assignment is the design's, made from the corrosivity survey, and this standard begins where that assignment is made. (1.8)

2 Referenced Standards

2.1 Materials, equipment, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where the Contract Documents, the adopted codes, the manufacturer's published instructions, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE The corrosion standards once published by NACE International are now maintained by AMPP, the Association for Materials Protection and Performance, under the same designations, and the two names are used interchangeably in this standard and in the industry. (2.3)
Standard Title
NACE SP0169 Control of External Corrosion on Underground or Submerged Metallic Piping Systems
NACE SP0196 Galvanic Anode Cathodic Protection of Internal Submerged Surfaces of Steel Water Storage Tanks
NACE SP0388 Impressed Current Cathodic Protection of Internal Submerged Surfaces of Steel Water Storage Tanks
NACE SP0193 External Cathodic Protection of On-Grade Carbon Steel Storage Tank Bottoms
NACE SP0286 Electrical Isolation of Cathodically Protected Pipelines
NACE SP0572 Design, Installation, Operation, and Maintenance of Impressed Current Deep Anode Beds
NACE SP0177 Mitigation of Alternating Current and Lightning Effects on Metallic Structures and Corrosion Control Systems
NACE SP0207 Performing Close-Interval Potential Surveys and DC Surface Potential Gradient Surveys on Buried or Submerged Metallic Pipelines
NACE SP0104 The Use of Coupons for Cathodic Protection Monitoring Applications
NACE TM0497 Measurement Techniques Related to Criteria for Cathodic Protection on Underground or Submerged Metallic Piping Systems
NACE TM0101 Measurement Techniques Related to Criteria for Cathodic Protection of Underground Storage Tank Systems
NACE TM0109 Aboveground Survey Techniques for the Evaluation of Underground Pipeline Coating Condition
AWWA D104 Automatically Controlled, Impressed-Current Cathodic Protection for the Interior Submerged Surfaces of Steel Water Storage Tanks
AWWA C105/A21.5 Polyethylene Encasement for Ductile-Iron Pipe Systems (Appendix A, soil evaluation)
AWWA M27 External Corrosion Control for Infrastructure Sustainability
ASTM G57 Standard Test Method for Measurement of Soil Resistivity Using the Wenner Four-Electrode Method
ASTM G187 Standard Test Method for Measurement of Soil Resistivity Using the Two-Electrode Soil Box Method
ASTM B843 Standard Specification for Magnesium Alloy Anodes for Cathodic Protection
ASTM B418 Standard Specification for Cast and Wrought Galvanic Zinc Anodes
NFPA 70 National Electrical Code (Articles 110, 250, and 300)
NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum)
UL 1012 Power Units Other Than Class 2
NSF/ANSI/CAN 61 Drinking Water System Components, Health Effects
AMPP Cathodic Protection Program Certification levels CP1 Tester, CP2 Technician, CP3 Technologist, and CP4 Specialist

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before any material of the system is ordered:
  • the corrosivity survey report, where the survey is performed under this standard, with the resistivity readings, the soil analyses, the stray current and interference findings, and the survey locations plotted on the yard piping plan
  • the cathodic protection design, where design is delegated under this standard, comprising the current requirement calculation for each structure, the anode life calculation, the anode bed resistance calculation, the rectifier sizing, the attenuation check on each line, the interference assessment, and the drawings showing every anode, anode bed, rectifier, test station, bond, isolation device, and decoupling device, sealed as this standard requires
  • product data for galvanic anodes with their alloy certification and packaged backfill, impressed-current anodes with their lead attachment detail, carbonaceous backfill, rectifiers with their wiring diagram and output curves, anode junction boxes, test stations, permanent reference electrodes, coupons, bond and test lead cable, exothermic weld materials and weld caps, isolation devices, casing spacers and end seals, and decoupling devices
  • shop drawings showing the terminal arrangement and wiring of every test station and junction box, the rectifier connections, the deep anode bed construction where one is furnished, and the tank interior anode suspension where a tank system is furnished
  • the qualification record of the cathodic protection specialist, of each field technician who will perform the surveys and the commissioning, and of the installer, as this standard requires
  • the commissioning plan, listing each structure, the native survey locations, the energizing sequence, the interruption arrangement for each DC source, the polarization period, the final survey method, the interference tests with each foreign structure owner, and the instruments to be used
Action Submittalscheckbox
☑ Corrosivity survey report
☑ Delegated cathodic protection design, sealed
☑ Product data for anodes, backfill, rectifiers, test stations, electrodes, cable, isolation, and decoupling devices
☑ Test station, junction box, rectifier, anode bed, and tank anode shop drawings
☑ Specialist, technician, and installer qualification records
☑ Commissioning plan
3.1.2 No anode, rectifier, or anode bed material shall be ordered before the design covering it has been reviewed and returned, whether the design is the Engineer of Record's or a delegated design under this standard.

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following as the work proceeds:
  • the native potential survey record for each structure, before any anode is connected or any rectifier is energized
  • the bond continuity test record for every bonded joint and every run between test stations, before the pipe zone above the bond is backfilled and again after backfill
  • the isolation test record for every isolation device and every casing, before backfill and again at commissioning
  • the rectifier factory test report, before shipment
  • the deep anode bed driller's log and the resistance readings taken during installation, where a deep anode bed is furnished
  • the energizing record for each rectifier and each galvanic anode group, with the initial settings and the readings at energizing
  • the interference test record for each foreign structure, signed by the foreign structure owner's representative where that owner attended
Informational Submittalscheckbox
☑ Native potential survey record
☑ Bond continuity test records before and after backfill
☑ Isolation test records before backfill and at commissioning
☑ Rectifier factory test report
☑ Deep anode bed driller's log and installation readings
☑ Energizing record
☑ Interference test record

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before substantial completion:
  • the commissioning report described under Commissioning Report, reviewed and signed as this standard requires
  • record drawings showing the installed location of every anode and anode bed, rectifier, test station, bond, isolation device, decoupling device, and permanent reference electrode, with the test station and rectifier identification and the cable routing, and with each location given by coordinates
  • the operation and maintenance data under Operation And Maintenance DataOperation and Maintenance DataResolves to the current adopted revision.sync/operation-and-maintenance-data, including the rectifier manual, the rectifier reading log form, the annual survey procedure and record form, the as-left settings of every rectifier and controller, and the instructions for replacing a galvanic anode, an impressed-current anode, and a reference electrode
  • the twelve-month survey report, where that survey is performed under this standard, submitted when it is complete
Closeout Submittalscheckbox
☑ Commissioning report
☑ Record drawings with coordinates
☑ Operation and maintenance data with survey forms and as-left settings
☐ Twelve-month survey report
NOTE A cathodic protection system is invisible once the trench is closed, and the record drawing is the only way a future excavator finds the anode bed before cutting through it or the operator finds the test station after the yard is regraded. Coordinates survive a regrading; a dimension from a fence does not. (3.3.2)

4 Quality Assurance

4.1 Design Responsibility

4.1.1 The cathodic protection system shall be designed by the party indicated in the datasheet.
Cathodic Protection Design Responsibilityradio
○ The Engineer of Record
○ Delegated to a cathodic protection specialist retained by the Contractor
NOTE An Engineer of Record who designs the system has the corrosivity survey, the piping layout, and the foreign structures in one set of drawings before bid, and the bidders price a defined quantity of anodes, stations, and rectifiers; the design then rests on the survey made before the yard was regraded and on the piping as drawn rather than as built. A delegated design puts the work with a specialist who surveys the site as it is, designs to the as-built routing, and warrants the result, at the cost of a design that is not priced until after award and a review the Engineer of Record performs without having done the design. Plant yard piping systems are let both ways, and the choice follows whether the Owner retains a corrosion consultant on the design side and whether the piping routing is settled at bid. (4.1.2)
4.1.3 Where design is delegated, the design shall be performed by an AMPP CP4 Cathodic Protection Specialist or by a professional engineer licensed in the project jurisdiction whose practice includes cathodic protection, and the design submittal shall bear that engineer's seal.
4.1.4 Where design is delegated, the design shall meet the design life, the criteria of protection, the coating efficiency, and the interference requirements of this standard, and shall be reviewed and returned by the Engineer of Record before any material of the system is ordered.
4.1.5 Where design is delegated, a structure that fails to meet the criteria of protection at commissioning shall be brought to the criteria by the Contractor, including additional anodes, a larger rectifier, or a relocated anode bed, at no change in the Contract Sum.
4.1.6 Where the Engineer of Record designs the system and a structure fails to meet the criteria at commissioning with the system installed as designed, the Engineer of Record shall direct the correction, and its cost shall be settled under the Contract's provisions for a change in the work.

4.2 Personnel Qualifications

4.2.1 The native survey, the energizing, the final potential survey, the interference tests, and the twelve-month survey shall be performed by a technician holding a current AMPP cathodic protection certification at one of the levels indicated in the datasheet.
Survey and Commissioning Technician Certificationcheckbox
Any of:
☐ AMPP CP1 Cathodic Protection Tester
☑ AMPP CP2 Cathodic Protection Technician
☑ AMPP CP3 Cathodic Protection Technologist
☑ AMPP CP4 Cathodic Protection Specialist
NOTE A CP1 Tester takes readings under direction and is the level a crew member holds; a CP2 Technician takes and interprets readings, adjusts a rectifier, and runs an interference test, and is the level most projects require of the person who signs the field data; a CP3 Technologist and a CP4 Specialist design and evaluate systems, and a project that requires one of them in the field is paying for design judgment at the test station, which is wanted where the structure is large, the foreign structures are many, or the survey is a close-interval survey whose interpretation decides the acceptance. (4.2.2)
4.2.3 The commissioning report shall be reviewed and signed by an AMPP CP4 Cathodic Protection Specialist or by the licensed engineer who sealed the delegated design, whether or not that person took the readings.
4.2.4 Exothermic welds and pin-brazed connections shall be made by persons trained by the manufacturer of the weld or brazing materials in the process furnished, and the training record shall be included in the installer qualification record.
4.2.5 The installer of the system shall have installed cathodic protection systems of the type furnished on not fewer than three completed projects, and shall name them in the qualification record.

4.3 Instruments

4.3.1 Potentials shall be measured with a voltmeter having an input impedance of not less than 10 MΩ, with a resolution of 1 mV, calibrated within the twelve months preceding the survey.
4.3.2 Every portable reference electrode used to produce a recorded value shall be checked against a master electrode kept for that purpose and not used in the field, before each day's readings, and an electrode that differs from the master by more than 5 mV shall be replaced or refurbished before use.
4.3.3 Current interrupters used for instant-off measurements shall be synchronized by satellite timing where more than one DC source influences the structure under survey, and the on and off intervals used shall be recorded with every instant-off reading.
NOTE A copper-copper sulfate electrode drifts with contamination, sunlight, and temperature, and a reference that reads 30 mV off makes a protected structure look unprotected or an unprotected structure look protected. The master electrode check is the only thing standing between a potential that looks authoritative and one that is right, which is why the check is part of the record. (4.3.4)

4.4 Coordination

4.4.1 Before any buried piping that the system protects is lowered into its trench, the Contractor shall convene a coordination meeting attended by the cathodic protection installer, the piping installer, the electrical trade, the tank builder where a tank system is furnished, the cathodic protection specialist where design is delegated, and the Engineer of Record, to settle the bonding sequence, the test station and anode locations against the as-staked piping, the rectifier power supply, and the interference tests with foreign structure owners.
4.4.2 Minutes of the coordination meeting shall be distributed to every attendee and to the Engineer of Record within five working days.
4.4.3 The Contractor shall notify every owner of a foreign buried metallic structure within the influence of the system, in writing, not less than ten working days before the system is energized, and shall invite that owner to attend the interference test.

5 Corrosivity Survey

5.1 The corrosivity survey on which the design rests shall be on the basis indicated in the datasheet.
Corrosivity Survey Basisradio
○ Performed by the Contractor under this standard
○ Taken from the geotechnical report, with no survey by the Contractor
NOTE A survey the Contractor performs is made on the regraded site along the as-staked piping and is current when the design is made, which is the arrangement of a delegated design; a survey read from the geotechnical report was made at the boring locations before the site was graded, which the Engineer of Record's design has already used and which the Contractor does not repeat. The geotechnical report's resistivity and chemistry serve the polyethylene encasement determination of the piping standards whichever basis is selected here. (5.2)
5.3 Where the survey is performed under this standard, its scope shall include the elements indicated in the datasheet.
Corrosivity Survey Scopecheckbox
☑ Soil resistivity by the Wenner four-pin method along every buried line
☑ Soil samples analyzed for pH, redox potential, chloride, sulfate, sulfide, and moisture
☐ Soil box resistivity of samples from each soil type
☐ Stray direct current survey of the site
☐ AC interference survey where a transmission line shares the corridor
☑ Foreign structure survey identifying every buried metallic structure within the influence of the system
5.4 Soil resistivity shall be measured by the Wenner four-pin method of ASTM G57 at pin spacings that bracket the depth of the pipe invert, at intervals along every buried line not exceeding the interval indicated in the datasheet, and at every change in soil type, every crossing of a foreign structure, and every proposed anode bed location.
Resistivity Measurement Interval Along Buried Linesrange
ft
1002002503005001000
NOTE Resistivity is the single number that sizes a galvanic anode and places an anode bed, and it varies more across a plant yard than along a transmission main, because the yard is cut, filled, and drained unevenly. A reading every 100 or 200 ft finds the low-resistivity pocket at a drainage swale or an old fill; a reading every 500 or 1,000 ft is the spacing of a long main through uniform soil and is adopted where the yard is small and the soil is known. (5.5)
5.6 Soil samples shall be taken from the pipe zone at every resistivity location where a sample is required by the datasheet, and shall be analyzed by a laboratory for pH, redox potential, chloride, sulfate, sulfide, and moisture content, with the resistivity of each sample measured in a soil box under ASTM G187 where that element is selected.
5.7 Where a direct current transit system, a high-voltage direct current ground, a welding ground, or another cathodic protection system is within one mile of the site, or where the survey finds a fluctuating structure-to-soil potential on an existing structure, the survey shall include a stray current survey that records the potential of a test structure or an existing structure over not less than 24 hours at each location of suspected influence.
5.8 Where a high-voltage alternating current transmission line shares a corridor with any buried line the system protects for more than 1,000 ft, or crosses it, the survey shall include an AC interference assessment under NACE SP0177, reporting the induced voltage on the pipe and the AC current density expected at a coating holiday.
5.9 The survey report shall plot every measurement on the yard piping plan, shall classify each reach of each line by resistivity range, and shall state for each structure whether the soil is corrosive to it by the scoring of AWWA C105 Appendix A for ductile iron and by resistivity and chemistry for steel.

6 Protection System Type and Design Basis

6.1 Buried Structure Protection System Type

6.1.1 Buried piping, valves, fittings, casings, well casings, and buried steel structures assigned to the system shall be protected by the system type indicated in the datasheet.
Buried Structure Protection System Typeselect
Galvanic anode system
Impressed-current system
Galvanic anode system with the test stations, header cable, and rectifier pad provisions for conversion to impressed current
NOTE A galvanic system has no power supply, no rectifier to read, and nothing to fail but the anode, and it delivers only the current the potential difference between magnesium or zinc and iron can push through the soil, which is enough for a coated steel line, a short encased ductile iron line, or a valve cluster in soil of moderate resistivity, and is not enough for a long bare or encased line, a high-resistivity soil, or a structure with a large current demand. An impressed-current system delivers whatever current the rectifier is sized for, over any resistivity, from one anode bed, and brings a rectifier that needs power, a reading every two months, and a positive cable whose nick becomes an anode; it also interferes with foreign structures in a way a galvanic system rarely does. The conversion provision is bought where the current demand is expected to grow, as when a coating is expected to degrade or the yard will be extended, and it costs the test stations and the cable of the larger system without the rectifier. (6.1.2)
6.1.3 Where the drawings assign different system types to different structures, each structure shall be protected by the type the drawings assign to it, and the selection in this datasheet shall apply to every structure the drawings do not so assign.

6.2 Design Life

6.2.1 The system shall be designed to deliver the current required to meet the criteria of protection on every structure it serves for not less than the design life indicated in the datasheet, with galvanic anodes sized for that life at the design current and a utilization factor not exceeding 85%, and impressed-current anodes sized for that life at the rated rectifier output.
Cathodic Protection Design Liferange
years
10152025304050
Default: Not less than 20 years
NOTE Twenty years is the design life most water and wastewater owners specify for a galvanic system, because it matches the interval at which the anodes of such a system are expected to be replaced and the yard reopened for other reasons; a longer life is bought for an impressed-current anode bed, whose anodes are costly to replace and whose rectifier is replaceable without excavation, and for a structure under a tank, which cannot be reached at all. A shorter life is the position for a temporary facility or a structure the Owner plans to replace. (6.2.2)

6.3 Criteria of Protection

6.3.1 A structure shall be accepted as protected where every measurement on it meets one of the NACE SP0169 criteria admitted in the datasheet, measured in accordance with NACE TM0497 with the reference electrode placed as that method describes.
Criteria of Protection Admittedcheckbox
Any of:
☑ -850 mV polarized (instant-off) potential to a copper-copper sulfate electrode
☐ -850 mV on-potential to a copper-copper sulfate electrode with the IR drop considered and documented
☑ 100 mV cathodic polarization shift, measured by formation or decay
NOTE The polarized potential of -850 mV is the criterion that a coated structure with an interruptible source meets and proves in one reading, and it is the criterion nearly every new system is commissioned to. The 100 mV shift is the criterion for a bare or encased structure, an old structure, or a high-resistivity soil, where -850 mV cannot be reached without over-driving the system, and it needs a depolarization period, hours to days, during which the structure is unprotected and the technician waits. The on-potential with IR drop considered applies where no source can be interrupted and no coupon exists, and it rests on an IR drop assessment the reviewer has to accept, which is why some owners do not admit it. Admitting two criteria lets the technician prove each structure by the one it meets. (6.3.2)
6.3.3 Where the survey finds a sulfide-bearing or anaerobic soil with a redox potential indicating sulfate-reducing bacteria, the Engineer of Record shall set a more negative polarized potential criterion for the structures in that soil, and the commissioning plan shall identify them.
6.3.4 The polarized potential of a coated structure shall not be driven more negative than -1,200 mV to a copper-copper sulfate electrode, nor more negative than the limit the coating manufacturer publishes for the coating furnished where that limit is less negative.
NOTE Overprotection generates hydrogen at the steel surface and lifts a bonded coating from it, so that a system set to make every reading comfortably negative disbonds the coating it exists to back up; the limit exists so that the rectifier is set to the criterion rather than to the maximum. (6.3.5)

6.4 Coating Efficiency

6.4.1 The current requirement of each coated structure shall be calculated with the coating efficiency indicated in the datasheet, applied to the bare current density the design states for the soil, and the design shall record the value used.
Coating Efficiency Assumed in the Designrange
%
508090959799
NOTE A coating efficiency is the fraction of the surface the coating is assumed to keep from the soil over the design life, and it sizes the anodes more than any other number: a line assumed 99% coated needs a hundredth of the current of a bare line, and a line assumed 90% coated needs ten times what the 99% line needs. New fusion-bonded epoxy or polyurethane, holiday-tested, is assumed at 97 to 99% at installation; tape and coal tar lower; and a design that must carry the line for twenty years assumes the coating will degrade and uses the end-of-life value, which is why the number is the engineer's and is recorded rather than defaulted. Polyethylene-encased ductile iron and bare steel are designed at 0% because the encasement is not a bonded coating and admits current at every wrap. (6.4.2)
6.4.3 Where polyethylene encasement is furnished under Ductile Iron Process PipingDuctile Iron Process PipingResolves to the current adopted revision.sync/ductile-iron-process-piping on a structure this standard protects, the design shall treat the encased pipe as a bare pipe with the current demand AWWA M27 and AWWA C105 describe for encased pipe under cathodic protection, and shall not credit the encasement as a coating.

6.5 Quantities Set by the Design

6.5.1 The number, size, spacing, and location of anodes and anode beds and the rated output of each rectifier shall be as indicated in the datasheet.
Anode Quantity, Size, and Spacingtext
Enter value...
Per drawings — the corrosion protection drawings, or the delegated cathodic protection design where design is delegated (deferred by default)
Rectifier Rated Direct Current Output, Volts and Amperestext
Enter value...
Per drawings — the corrosion protection drawings, or the delegated cathodic protection design where design is delegated (deferred by default)
NOTE The quantities follow from the current requirement, the resistivity, and the design life, and no template can carry them; what the template carries is the life, the criteria, the efficiency, and the materials the quantities are computed from. A rectifier is rated with a margin above the calculated current and voltage so that the anode bed can age and the coating can degrade without a replacement, and that margin is the design's. (6.5.2)

7 Galvanic Anode Systems

7.1 Requirements in this article apply where a galvanic anode system is selected under Buried Structure Protection System Type or assigned by the drawings to a structure.
7.2 Galvanic anodes shall be of the alloy indicated in the datasheet, cast with a galvanized steel core, and furnished with a certified analysis of each heat.
Galvanic Anode Alloyselect
High-potential magnesium, ASTM B843 alloy M1C
Standard-potential magnesium, ASTM B843 alloy AZ63
Zinc, ASTM B418 Type II
Aluminum alloy, for seawater or brackish water
Derived — the soil resistivity from the corrosivity survey at the anode location (by default)
NOTE High-potential magnesium drives about -1.75 V to copper-copper sulfate and is the alloy for soil above roughly 2,000 Ω-cm, where nothing less will push a useful current; standard magnesium drives about -1.55 V and lasts longer per pound, and serves between roughly 500 and 2,000 Ω-cm; zinc drives only about -1.10 V, cannot overprotect a coated structure, and is the alloy for soil below roughly 1,500 Ω-cm and for a structure where a magnesium anode would deliver more current than the coating tolerates; aluminum alloy is an anode for seawater and brackish water and passivates in soil. The alloy follows from the resistivity, which is why the field starts derived from the survey. (7.3)
7.4 Galvanic anodes for burial shall be furnished prepackaged in a permeable cloth bag with a backfill of 75% ground gypsum, 20% powdered bentonite, and 5% anhydrous sodium sulfate by weight, filling the bag around the anode, with the anode centered in the bag.
NOTE The packaged backfill lowers the resistance between the anode and the soil, keeps the anode moist, and makes it corrode evenly rather than pitting, so that a packaged anode delivers more current and lasts longer than the same bare anode in the same hole. (7.5)
7.6 Each galvanic anode shall be furnished with a factory-attached lead wire, No. 12 AWG solid or stranded copper with high molecular weight polyethylene insulation, silver-soldered to the core and encapsulated in epoxy at the attachment, of a length that reaches the test station without a splice.
7.7 Galvanic anodes shall be connected to the structure through a test station, with the anode lead landed on a terminal through a shunt of 0.01 Ω so that the anode current can be measured, and shall not be connected directly to the structure unless the drawings designate a direct connection.
NOTE An anode landed in a test station can be disconnected for an instant-off reading, measured for current output, and replaced from grade; an anode welded directly to the pipe can be none of those things, and its output is known only by excavating it. Direct connection is the arrangement for a single anode on a valve or a fitting where no test station is close, and the drawings designate it where it is accepted. (7.8)
7.9 Galvanic anodes shall be installed with the top of the packaged anode below Frost DepthFrost DepthParameterEach project supplies its own value.frost-depth, at the depth and the horizontal distance from the structure the design shows, in a vertical augered hole or a horizontal trench as the design shows, in native soil or in fine backfill free of rock, and never in the pipe zone bedding stone.
NOTE Frozen soil has a resistivity many times that of the same soil thawed, so an anode in the frost zone stops delivering current for the winter; crushed stone bedding has almost no electrolyte at all, so an anode set in the pipe zone stone delivers nothing in any season. (7.10)
7.11 Each packaged anode shall be wetted with not less than five gallons of water after it is set and before the hole is backfilled, and the backfill shall be compacted around it without stretching or nicking the lead wire.

8 Impressed-Current Systems

8.1 Requirements in this article apply where an impressed-current system is selected under Buried Structure Protection System Type or assigned by the drawings to a structure, and to the rectifier and anodes of a tank system where the tank articles of this standard invoke it.

8.2 Rectifier Construction

8.2.1 Each rectifier shall be a listed cathodic protection rectifier under UL 1012, with a silicon diode stack, an AC input circuit breaker, a DC output circuit breaker or fuses, an output voltmeter and ammeter readable with the enclosure closed or on opening the door without exposing live parts, and a DC output shunt.
8.2.2 The rectifier shall be cooled as indicated in the datasheet.
Rectifier Coolingradio
● Air-cooled, convection, in a ventilated enclosure
○ Oil-immersed
NOTE An air-cooled rectifier is lighter, needs no oil to maintain or dispose of, and is the unit nearly every water and wastewater plant installs; an oil-immersed unit seals the stack from the atmosphere and is bought where the rectifier sits in a corrosive, dusty, or salt-laden atmosphere that a ventilated enclosure would admit, or where the output is large enough that convection cooling needs a cabinet the site has no room for. (8.2.3)
8.2.4 The rectifier output shall be controlled as indicated in the datasheet.
Rectifier Output Controlselect
Manual, by coarse and fine AC taps, constant voltage
Constant current, with the output current set and held automatically
Automatic potential control from a permanent reference electrode
NOTE A tap-controlled rectifier holds a voltage, delivers a current that rises as the soil wets and falls as it dries, and is read and reset by hand, which is the arrangement of most buried piping systems, where the seasonal swing is tolerated and the technician visits anyway. A constant-current unit holds the current the design set through the seasons and is bought where the anode bed resistance varies widely or the structure's demand is known and fixed. Automatic potential control reads a permanent reference electrode and holds the structure at a set potential, protecting without overprotecting as the demand changes, and it is what AWWA D104 requires inside a water tank, where the water level, temperature, and ice change the demand daily; on a buried structure it depends on one reference electrode in one place speaking for the whole structure. (8.2.5)
8.2.6 Where automatic potential control is selected, the rectifier shall include a manual mode selectable at the unit, a reference electrode failure alarm that reverts the output to a settable manual value, and a settable maximum output.
8.2.7 The rectifier enclosure shall be rated under NEMA 250 to the type indicated in the datasheet.
Rectifier Enclosure Typeselect
Type 1
Type 12
Type 3R
Type 4
Type 4X, stainless steel
Type 4X, non-metallic
8.2.8 A rectifier installed outdoors shall be in an enclosure rated Type 3R or higher.
8.2.9 A rectifier installed in a wet, washdown, or corrosive location, or in a chemical storage or feed area, shall be in an enclosure rated Type 4X.
8.2.10 A rectifier installed in a location classified under NFPA 70 Articles 500 through 504 shall be listed for that location.
NOTE A rectifier sits outdoors at the anode bed or at the tank far more often than it sits in a building, and a Type 3R ventilated cabinet is what the rectifier manufacturers build as standard for that, which is why Type 3R is the default; Type 1 and Type 12 serve a rectifier mounted inside an electrical room or a pump station; Type 4 and 4X are bought for the rectifier at a chemical building or a coastal site, in stainless steel where it will be struck and in a non-metallic material where chlorides would pit the steel, and an air-cooled unit in a Type 4 or 4X cabinet is derated or oil-immersed because the cabinet cannot be ventilated. (8.2.11)
8.2.12 The rectifier shall be furnished with the accessories indicated in the datasheet.
Rectifier Accessoriescheckbox
☑ Surge arresters on the AC input and the DC output
☐ Elapsed-time meter
☑ Terminals for an external current interrupter
☐ Built-in programmable current interrupter
☐ Remote monitoring unit reporting output, alarms, and reference potential
☑ Padlockable door with a dead-front panel
☐ Efficiency filter choke on the DC output
NOTE Surge arresters protect the stack from the lightning the anode bed and the pipe collect, and the interrupter terminals let the technician take instant-off readings without opening the output circuit by hand; both are defaulted because every survey needs the second and every storm season tests the first. An elapsed-time meter proves the rectifier ran between readings; a built-in interrupter is bought where the Owner surveys often; a remote monitoring unit sends the readings the regulations or the Owner's program would otherwise have a technician drive out for every two months, and it is what a plant with a supervisory system expects; the efficiency filter raises the DC output for the AC drawn and is bought on a large unit where the power cost is real. (8.2.13)
8.2.14 Where a remote monitoring unit is furnished, the rectifier output voltage, output current, structure potential where automatic control is furnished, and the loss-of-output and reference-electrode-failure alarms shall be exposed to the plant control system under Control Systems IntegrationControl Systems Integration and TestingResolves to the current adopted revision.sync/control-systems-integration.
8.2.15 The rectifier AC supply shall be as indicated in the datasheet.
Rectifier AC Supplytext
Enter value...
Per drawings — the electrical one-line diagram and the panel schedules (deferred by default)
8.2.16 The AC branch circuit, its overcurrent protection, and the disconnecting means within sight of the rectifier shall be furnished under Common Work Results ElectricalCommon Work Results for ElectricalResolves to the current adopted revision.sync/common-work-results-electrical, the conductors under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables, and the raceway under Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit, and the Contractor shall reconcile the rectifier's input current against the circuit shown before the rectifier is released for manufacture.
8.2.17 Each rectifier shall be factory tested at full rated output for not less than one hour, with the input and output voltages and currents, the efficiency, and the temperature rise recorded on the factory test report.
8.2.18 Each rectifier shall bear a nameplate stating the rated AC input and DC output, the serial number, the structure it protects, and the rectifier identification shown on the corrosion protection drawings, and the positive and negative output terminals shall be permanently marked.
8.2.19 Each rectifier shall be mounted on the pole, the pad, or the wall shown on the corrosion protection drawings, with the enclosure bottom not less than 36 in. above finished grade where pole- or pad-mounted.

8.3 Impressed-Current Anodes

8.3.1 Impressed-current anodes shall be of the type indicated in the datasheet, furnished with the anode manufacturer's certification of the rated current output and the consumption rate on which the design life rests.
Impressed-Current Anode Typeselect
Mixed-metal-oxide coated titanium, tubular or rod
Mixed-metal-oxide coated titanium wire or ribbon
High-silicon chromium cast iron, tubular
High-silicon chromium cast iron, solid rod
Graphite
Platinized titanium or niobium
NOTE Mixed-metal-oxide titanium carries the highest current per anode at a consumption rate measured in milligrams a year, so that a bed of a few small anodes replaces a bed of many heavy ones, and it is what a deep anode bed and a tank system are built with; the oxide coating cannot be scratched through in handling without creating a spot that passivates. High-silicon chromium cast iron is the anode of the surface bed, heavy, tolerant of handling, consumed at about a pound per ampere-year in coke breeze, and tubular where the lead connection must sit at the center so the anode consumes evenly rather than necking off at the end. Graphite is the oldest anode, cheap, brittle, and consumed faster than cast iron, and it is specified where a plant already runs graphite beds. Platinized metals carry the highest current density of all at the highest price and are chosen for seawater and for a confined installation where anode size is the constraint. (8.3.2)
8.3.3 Each impressed-current anode shall be furnished with a factory-attached lead of not less than No. 8 AWG stranded copper, connected to the anode by the anode manufacturer's method, pull-tested, and sealed against the electrolyte at the connection by an epoxy or elastomer encapsulation, with the connection resistance stated on the certification.
8.3.4 The positive header cable and the anode leads shall be insulated as indicated in the datasheet, and the negative cable and the structure leads shall be insulated with high molecular weight polyethylene.
Positive Cable Insulationradio
○ High molecular weight polyethylene, 600 V
○ Dual insulation, fluoropolymer primary with a high molecular weight polyethylene jacket, 600 V
NOTE Every point where the positive cable's copper touches the electrolyte is an anode, and a copper anode at a nick is consumed to an open circuit in months, taking the anode bed with it; high molecular weight polyethylene resists abrasion and is the insulation of a surface bed laid in sand, and the dual insulation adds a fluoropolymer layer that resists the chlorine and the acid generated at the anode, which is what a deep anode bed and a cable in coke breeze see. (8.3.5)
8.3.6 Impressed-current anodes in a surface or deep bed shall be surrounded by calcined petroleum coke breeze of the particle size and the resistivity the design specifies, placed to fill the hole around and beyond the anode by the dimensions the design shows, and tamped in a surface bed or placed as a pumped slurry or by tremie in a deep bed so that no void remains around the anode.
NOTE Coke breeze is the real anode of an impressed-current bed: the current leaves the metal anode into the breeze and leaves the breeze into the soil over a surface many times the anode's, so the anode is consumed slowly and the bed resistance is low; a void in the breeze concentrates the current at the metal and consumes it there. (8.3.7)

8.4 Anode Beds

8.4.1 Impressed-current anodes shall be arranged in the anode bed configuration indicated in the datasheet, at the location shown on the corrosion protection drawings.
Anode Bed Configurationradio
○ Distributed anodes along the structure
○ Remote surface bed, horizontal or vertical, in a single excavation
○ Deep anode bed in a drilled hole
NOTE Distributed anodes follow the structure, protect it with little interference to anything else, and are the arrangement for a congested plant yard where a remote bed would see every other buried metal before it saw the pipe, at the cost of many small anodes and many cable runs; a remote surface bed throws current from one place across the whole structure, costs least per ampere, and needs open ground and a structure that is electrically continuous and well isolated, because the current reaches everything between the bed and the pipe; a deep anode bed puts the anodes in a drilled hole 100 ft or more below grade, where the current reaches the structure from below rather than from the side, interferes least, and needs no surface land, at the cost of a drilling rig, a vent for the chlorine the bed generates, and the regulatory treatment of a well. (8.4.2)
8.4.3 A deep anode bed shall be designed, drilled, and constructed under NACE SP0572, with a driller's log, a casing or stabilizer where the formation requires one, a vent pipe from the active column to grade, a seal above the active column that prevents the migration of water between aquifers, and the permit or notification the state well program requires for a drilled hole of its depth.
8.4.4 The resistance to earth of a deep anode bed shall be measured as each anode is lowered and after the backfill is placed, recorded on the driller's log, and compared with the design value before the hole is sealed, and a bed whose measured resistance exceeds the design value shall be reported to the Engineer of Record before the rectifier is sized or energized.
8.4.5 Where distributed anodes are furnished, the anode leads shall be landed in an anode junction box through individual shunts of 0.01 Ω so that the current of each anode can be measured and an anode can be disconnected, and the junction box shall be in an enclosure of the same NEMA 250 type as the rectifier.
8.4.6 Every anode bed shall be separated from every foreign buried metallic structure by the distance the design states, and shall be set back from any property line so that no anode is placed on land the Owner does not control.

9 Test Stations, Reference Electrodes, and Coupons

9.1 Test stations shall be of the type indicated in the datasheet.
Test Station Typeselect
Flush-mounted at grade in a cast iron or polymer box with a lockable lid
Post-mounted above grade with a terminal head
Wall-mounted inside a structure, vault, or building
NOTE A flush station survives traffic, mowing, and snow removal and is the station for a paved yard and a roadway, at the cost of a lid that fills with soil and water and a reading taken on the knees; a post-mounted station is found from across the yard, is read standing, keeps its terminals dry, and is struck by every vehicle that leaves the pavement, which is why it is the station for a grassed area and a fence line; a wall-mounted station inside a vault or a building is read without going outside and serves the lead pairs at a wall pipe or an isolation flange, and it needs the cable to be routed through the wall in conduit under the raceway standard. (9.2)
9.3 Test stations shall be installed at every location shown on the corrosion protection drawings, and at not less than the following, whether or not shown: at each isolation device, at each end of each casing, at each crossing of or parallel run with a foreign buried metallic structure, at each galvanic anode group, at each connection between structures the system protects, at each tank, and at each end of each buried line the system protects.
9.4 Each test station shall have a terminal board of not fewer than five terminals, with two structure leads, the anode, foreign structure, casing, reference electrode, and coupon leads the location requires, each lead landed on its own terminal, with shunts where the design shows them, and with the terminals identified on the board by the lead designation shown on the test station wiring diagram.
NOTE Two structure leads at every station let the technician measure the potential on one lead while current flows in the other, so that the reading does not include the voltage drop in the lead carrying the current; a station with a single structure lead cannot take a clean reading or a current measurement. (9.5)
9.6 Test leads shall be No. 12 AWG stranded copper with high molecular weight polyethylene insulation, color-coded and labeled in accordance with the test station wiring diagrams on the corrosion protection drawings, and connected to the structure by the connection method of the Joint Bonding and Electrical Continuity article of this standard, with the connection coated as that article requires.
9.7 Each test station shall be marked with the station identification shown on the corrosion protection drawings, on a permanent tag inside the station and on the lid or the post, and a flush lid shall be marked with the words "CP TEST".
9.8 Where the drawings show a permanent reference electrode at a test station, under a tank bottom, or inside a tank, it shall be of the type indicated in the datasheet.
Permanent Reference Electrodeselect
Copper-copper sulfate, prepackaged, long-life
Zinc, high-purity, prepackaged
Silver-silver chloride, for seawater or brackish water
NOTE A copper-copper sulfate electrode reads in the same scale as every portable electrode and every criterion in NACE SP0169, which is why it is the permanent electrode of nearly every buried and fresh-water installation; a zinc electrode is a metal, not a half-cell, drifts less in a dry soil and lasts longer, reads about 1,100 mV from the copper-copper sulfate scale so that every reading is converted, and is chosen where the electrode cannot be replaced; a silver-silver chloride electrode is the electrode for chloride water and seawater, where a copper-copper sulfate electrode is contaminated within weeks. (9.9)
9.10 Permanent reference electrodes shall be rated by their manufacturer for a service life of not less than 15 years in the electrolyte of the installation, shall be furnished with a factory-attached lead of the insulation the Test Stations article requires, and shall be installed in native soil or in the manufacturer's prepackaged backfill in contact with the electrolyte, at the location the design shows, and not in bedding stone.
9.11 Each permanent reference electrode shall be checked against a calibrated portable electrode at commissioning and at the twelve-month survey where that survey is performed, and an electrode that differs from the portable electrode by more than 10 mV shall be replaced.
9.12 Coupons for instant-off measurement shall be furnished as indicated in the datasheet, under NACE SP0104.
Test Couponsradio
○ A coupon at every test station with a permanent reference electrode
○ No coupons
NOTE A coupon is a small bare steel sample buried beside the structure and connected to it through the test station, so that the coupon alone can be disconnected for an instant-off reading while the structure stays connected; it is the only way to take a polarized potential on a structure whose sources cannot all be interrupted, such as a line with directly connected galvanic anodes or a structure also bonded to a foreign system, and it also gives a measured current density on a known area. It costs a coupon and a reference at each station and a technician who knows how to read it. (9.13)

10 Joint Bonding and Electrical Continuity

10.1 Every joint in buried piping the system protects, other than a welded joint and a joint the drawings designate as an isolation joint, shall be bridged by a bond cable, including push-on, mechanical, restrained, and flanged joints, sleeve couplings, flexible connectors, dismantling joints, and the joints at each buried valve and fitting.
10.2 Joint bonds shall be furnished under this standard and installed by the piping installer under Ductile Iron Process PipingDuctile Iron Process PipingResolves to the current adopted revision.sync/ductile-iron-process-piping or Steel And Stainless Process PipingSteel and Stainless Steel Process PipingResolves to the current adopted revision.sync/steel-and-stainless-process-piping for the pipe the bond serves, to the cable, connection, coating, and test requirements of this article.
NOTE Cement-mortar coated and welded steel lines are electrically continuous; a rubber-gasketed joint, a coupling, and a bolted flange with a coated gasket and coated bolts are not, and a cathodic protection system drives current to every foot of pipe it can reach and leaves unprotected every foot beyond a break in continuity. The bond is what makes the line one conductor, and it is made by the crew that makes the joint, with the cable and the weld this standard specifies, because the joint is backfilled minutes later. (10.3)
10.4 Bond cables shall be stranded copper with high molecular weight polyethylene insulation of the size indicated in the datasheet, of a length that bridges the joint with slack for joint movement and no more.
Bond Cable Sizeselect
No. 8 AWG
No. 6 AWG
No. 4 AWG
No. 2 AWG
No. 1/0 AWG
No. 2/0 AWG
No. 4/0 AWG
NOTE The bond carries the protective current of every foot of pipe beyond it, and on a long bonded line the bonds near the drain point carry the whole line's current; No. 4 AWG carries the current of a galvanic or small impressed-current system on pipe through 24 in. with a resistance below that of the joint it bridges, and is the size most water utilities bond with; No. 2 and larger are specified for larger pipe, for a line near the drain point of a large impressed-current system, and where the bond also carries fault or stray current; No. 6 and No. 8 serve the short bonds across a valve or a small fitting on a small line. The size is the design's where the design states one, and the datasheet carries it where the design does not. (10.5)
10.6 Each bonded joint shall be bridged by not fewer than the number of bond cables indicated in the datasheet.
Bond Cables per Jointrange
123
Default: Not less than 1
NOTE One bond per joint is the installation of nearly every line; a second bond is specified on a large line, near a drain point, or where the Owner wants a bond that survives the failure of the other, and a third is a position for a line that will carry drainage or fault current, so that a single broken weld does not open the line. (10.7)
10.8 Bond cables and test leads shall be connected to the structure by the method indicated in the datasheet.
Bond and Test Lead Connection Methodselect
Exothermic weld
Pin brazing
Mechanical connection to a welded or drilled-and-tapped stud
NOTE An exothermic weld fuses the copper to the iron in a single charge, needs no power, and is the connection of nearly every bond and test lead in the industry; the charge heats a spot of the pipe wall, which is why its size is limited on thin walls and on ductile iron, whose graphite can be affected by the heat. Pin brazing drives a brazing pin through a flux with a low-heat electric arc, puts less heat into the wall, and is the method where exothermic welding is prohibited by the pipe manufacturer or by a permit, at the cost of a brazing unit and an operator trained on it. A mechanical connection to a stud welded or tapped into the pipe is the method on a structure that cannot be heated at all, and its contact resistance rises as it corrodes unless it is coated and sealed as carefully as a weld. (10.9)
10.10 Exothermic weld charges shall be of the size the weld material manufacturer publishes for the cable size and the pipe wall, and shall not exceed 15 grams on ductile iron pipe or on steel pipe with a wall thinner than 0.25 in.
10.11 Before a connection is made, the pipe surface shall be cleaned to bright metal over the connection area and the cable conductor shall be clean and dry, and after an exothermic weld is made, the slag shall be removed and the weld struck with a hammer, and a weld that moves or shows a void shall be removed and remade.
10.12 Every connection to the structure shall be covered with a prefabricated weld cap filled with elastomeric or mastic sealant, and the cap and the bared pipe around it shall be coated with a coating compatible with the pipe's exterior coating, or wrapped with tape and the polyethylene encasement repaired under AWWA C105 where the pipe is encased, before the joint is backfilled.
NOTE The coating of a connection is not cosmetic: a bare weld on a coated pipe is a holiday that draws current from the system for the life of the line, and on an encased pipe a tear left at the bond is where the soil reaches the iron. (10.13)
10.14 After each bond is made and before it is coated, the Contractor shall measure the resistance across the bonded joint with a four-terminal low-resistance ohmmeter, and a joint reading more than the resistance indicated in the datasheet shall be rebonded.
Resistance Across a Bonded Jointrange
mΩ
1251020
Default: Not more than 5 mΩ
NOTE A sound No. 4 AWG bond 2 ft long reads under 1 mΩ, and a bond with a cold weld reads tens of milliohms or open, so a 5 mΩ limit passes every sound bond and fails every bad one without failing a long bond on a large joint; a tighter limit is specified where the bonds are short and the line is near a drain point, and a looser one where the bonds are long or doubled. (10.15)
10.16 After backfill and before the final potential survey, the electrical continuity of every buried run between consecutive test stations shall be verified by passing a measured current through the run between the structure leads of the two stations and measuring the voltage drop, and a run whose resistance exceeds 120% of the value calculated from the pipe wall and the bonds shall be investigated, the defective bond located by potential survey, excavated, and remade at the Contractor's cost.
10.17 A tracer wire furnished under Plastic Process PipingPlastic Process PipingResolves to the current adopted revision.sync/plastic-process-piping or under a piping or utility standard shall not be used as a test lead, a bond, or a structure connection, and shall not be landed in a cathodic protection test station.

11 Electrical Isolation

11.1 Buried structures the system protects shall be electrically isolated from exposed piping at every wall pipe and building or vault entry, from foreign piping and structures at every connection, from steel casings at every crossing, and from the tank at every tank nozzle where the tank is not within the same system, at the locations shown on the corrosion protection drawings, by the isolation device indicated in the datasheet for the joint type.
Isolation Deviceselect
Insulating flange kit, full-face gasket with bolt sleeves and washers
Monolithic weld-in isolation joint
Insulating union, threaded, 2 in. and smaller
Insulating sleeve coupling with insulating gaskets and sleeves
NOTE An insulating flange kit isolates any flanged joint, is inspected and replaced from the outside, and fails where a bolt sleeve is omitted or a washer is cracked, which is invisible after assembly; a monolithic joint is a factory-made, pressure-tested, welded-in spool with the insulation built into it, cannot be assembled wrong in the field, is buried without a vault, and cannot be repaired in place; an insulating union serves a threaded line and nothing larger; an insulating sleeve coupling isolates a plain-end joint where no flange exists and is the device of a repair or a connection to an existing line. (11.2)
11.3 Where an insulating flange kit is selected, it shall comprise the gasket, the sleeve on every bolt, and the washers that Ductile Iron Process PipingDuctile Iron Process PipingResolves to the current adopted revision.sync/ductile-iron-process-piping or Steel And Stainless Process PipingSteel and Stainless Steel Process PipingResolves to the current adopted revision.sync/steel-and-stainless-process-piping requires of an insulating kit for the pipe material, rated for the design pressure and temperature of the line, and shall be installed where it remains accessible or, where buried, shall be fully encapsulated with a cold-applied or heat-shrink coating system over the flanges, bolts, and the adjacent pipe.
11.4 A monolithic isolation joint shall be factory hydrostatically tested at 1.5 times its rated pressure and dielectrically tested at not less than 5 kV, shall be furnished with the test certificates, shall be of the pressure class of the line, and shall be coated at the factory with a coating compatible with the line's exterior coating.
11.6 Where a buried line the system protects passes through a steel casing, the carrier pipe shall be centered in the casing on casing spacers with non-metallic or coated runners that isolate the carrier from the casing, the casing ends shall be closed with end seals, the casing shall not be bonded to the carrier, and a test station with two carrier leads and two casing leads shall be installed at one end of the casing.
NOTE A casing shorted to the carrier shields the carrier inside it from the system and drains current to the casing, so that the casing is protected and the carrier it was meant to protect is not; the spacers and the end seals are what keep the two apart, and the four-lead station is what proves it. (11.7)
11.8 Every isolation device and every casing shall be tested for electrical isolation after installation and before backfill, and again at commissioning after backfill, by a radio-frequency insulation tester or by the potential and current methods of NACE SP0286, and a device or a casing found shorted shall be corrected at the Contractor's cost and retested.
11.9 Where the fluid in an isolated line is conductive enough that the design requires the interior of the pipe to be coated on each side of the isolation device to limit the internal current path, that coating shall extend the length the design states on the corrosion protection drawings.
NOTE An isolation joint in a line full of conductive water is bridged inside by the water itself, and a short interior path carries enough current to consume the first few inches of the unprotected side; an interior coating for a few pipe diameters each side lengthens the path until the current it carries is harmless. (11.10)

12 Grounding System Interface

12.1 Metallic piping, tanks, and structures that NFPA 70 Article 250 requires to be bonded to the grounding electrode system shall be bonded under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding, and cathodic protection shall not be a reason to omit, remove, or interrupt an electrical safety bond.
NOTE A protected structure that is bonded to the grounding electrode system is bonded to every ground rod, every building steel column, and every foundation on that system, and the cathodic protection current drains to all of them: the structure is harder to protect and the copper ground rods are protected instead. The remedy is never to cut the safety bond, which is what keeps a fault on a motor from making the pipe a shock hazard; it is to put a device in the bond that passes AC fault current and lightning and blocks the DC the system uses, or to size the system to protect the grounding system too. (12.2)
12.3 The interface between each protected structure and the grounding electrode system shall be as indicated in the datasheet.
Grounding System Interfaceradio
○ Decoupling device in every bond between the protected structure and the grounding electrode system
○ Direct bond, with the grounding electrode system included in the protected structure and the system sized for it
NOTE A decoupling device keeps the DC on the protected structure, keeps the system small, and keeps the ground rods out of the cathodic circuit, and it is the arrangement of nearly every impressed-current system and of a galvanic system on a structure with more than a few bonds to ground; a direct bond with the grounding system inside the protected structure is simpler, has no device to fail, and is the arrangement of a small galvanic system on a short line in a pump station, where the current to protect a few ground rods is affordable and a decoupler would cost more than the anodes. (12.4)
12.5 Where a decoupling device is selected, it shall be of the type indicated in the datasheet.
Decoupling Device Typeradio
● Solid-state decoupler
○ Polarization cell, electrolytic
NOTE A solid-state decoupler blocks DC up to its threshold voltage, conducts AC fault current and lightning through a listed, sealed device with nothing to maintain, and fails shorted, which is the safe failure for a safety bond; it is the device nearly every new installation uses. A polarization cell does the same with nickel plates in potassium hydroxide, needs the electrolyte checked and topped up, and is specified where a plant already maintains them or where the fault current and duration exceed what a solid-state unit of the available size carries. (12.6)
12.7 Each decoupling device shall be rated for the available fault current and its clearing time at the point of connection, as determined under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, and for a lightning surge of not less than 100 kA at an 8/20 microsecond waveform, with a DC blocking threshold selected so that the device does not conduct at the most negative polarized potential the system is set to.
12.8 Each decoupling device shall be installed in an accessible enclosure rated for its location, with the structure side and the ground side of the device each landed on an identified terminal so that the device can be bypassed and tested, and the device shall be tested for DC blocking and AC conduction at commissioning and recorded in the commissioning report.
12.9 Where an isolation device separates a protected structure from a structure that is grounded, in an area subject to lightning or to AC fault current on either structure, an over-voltage protector or a decoupling device shall be installed across the isolation device under NACE SP0286 so that the isolation is not punctured by a surge.
12.10 The rectifier enclosure and the anode junction box enclosure shall be grounded as electrical equipment under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding, and the rectifier negative output shall be connected to the structure only, not to the equipment grounding conductor.

13 Water Storage Tank Interior Systems

13.1 Requirements in this article apply to each steel water storage tank the drawings assign to the system, whose tank, interior lining, hand holes, reference electrode fittings, and rectifier mounting pad and conduit sleeve are furnished under Water Storage TanksWater Storage TanksResolves to the current adopted revision.sync/water-storage-tanks.
13.2 The interior submerged surfaces of each tank shall be protected by the system type indicated in the datasheet.
Tank Interior System Typeradio
● Automatically controlled impressed-current system under AWWA D104
○ Manually controlled impressed-current system under NACE SP0388
○ Galvanic anode system under NACE SP0196
NOTE An automatically controlled impressed-current system reads a permanent reference electrode in the tank and holds the submerged surface at its set potential as the water level, the temperature, and the ice change the demand from hour to hour, which is why AWWA D104 was written around it and why it is the system installed in nearly every new elevated and ground tank; a manually controlled impressed-current system holds a voltage and is reset by hand, and is a position for a tank with a steady water level and an operator who reads it; a galvanic system has no rectifier, no controller, and no power at the tank, delivers a current that falls as the anodes are consumed, cannot be adjusted for a lining that degrades, and is the system of a small standpipe or a tank with a new lining and a small current demand. (13.3)
13.4 Tank interior anodes shall be of the material indicated in the datasheet.
Tank Interior Anode Materialselect
Mixed-metal-oxide coated titanium wire or rod
Platinized titanium or niobium wire
High-silicon chromium cast iron
Aluminum alloy galvanic anodes
Magnesium galvanic anodes
NOTE Mixed-metal-oxide titanium wire is light enough to hang from the roof in long strings, consumed at a rate that makes it last the life of the lining, and is the anode of nearly every impressed-current tank system; platinized wire carries more current per foot and costs more, and serves a tank with a large bare area; cast iron anodes are heavy, are hung in short rods, and serve where an Owner has standardized on them. Aluminum alloy galvanic anodes drive a modest current, do not overprotect a lined tank, and add aluminum to the water within the limits the certification allows; magnesium drives more current, is consumed faster, and is the galvanic anode for a tank with a larger demand. (13.5)
13.6 Anodes, hangers, cable, reference electrodes, and every other component submerged in a tank holding water intended for drinking shall carry the NSF/ANSI/CAN 61 certification required under Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process.
13.7 The anode suspension shall be designed for icing as indicated in the datasheet.
Tank Anode Suspension Design for Icingradio
○ Ice-resistant, with anode strings submerged below the ice zone on weighted or tensioned hangers that release or ride the ice
○ Standard suspension from the roof, for a tank that does not ice
Derived — Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum and the tank's winter turnover (by default)
NOTE Ice in a tank forms at the surface, thickens to a floating slab, and rises and falls with the water level, and an anode string hung through the ice zone is torn out or carried down with the slab; an ice-resistant suspension keeps the active anode below the ice and hangs it on a system that survives the slab passing over it. Whether a tank ices follows from the winter temperature at the site and from how much water turns over in winter, which is why the field starts derived from the site condition. (13.8)
13.9 Each impressed-current tank system shall be furnished with not fewer than two permanent reference electrodes in the tank, one in the lower third of the submerged surface and one in the upper third, of the type selected under the Test Stations, Reference Electrodes, and Coupons article, each landed on its own terminal at the controller.
13.10 The controller of an automatically controlled system shall be a rectifier of the Impressed-Current Systems article with automatic potential control, shall hold the potential at the controlling reference electrode within the criteria of this standard, shall limit the polarized potential at any point on the lining to the limit the Criteria of Protection article states and the lining manufacturer publishes, and shall alarm loss of output and reference electrode failure to the plant control system under Control Systems IntegrationControl Systems Integration and TestingResolves to the current adopted revision.sync/control-systems-integration.
13.11 Anodes, hangers, and cable shall be installed through the hand holes and fittings the tank standard provides, so that any anode string and any reference electrode can be withdrawn and replaced from outside the tank without draining it and without entering it.
13.12 The Contractor shall coordinate the number, size, and location of the hand holes, the reference electrode fittings, and the rectifier mounting pad and conduit sleeve with the tank builder under Water Storage TanksWater Storage TanksResolves to the current adopted revision.sync/water-storage-tanks before the tank shell plates are fabricated, and shall furnish the tank builder the loads the anode suspension delivers to the roof.
13.13 A tank interior system shall be energized after the tank is filled and the lining has cured as the lining manufacturer requires, adjusted until the criteria are met at both reference electrodes, and surveyed at commissioning with a portable reference electrode lowered through the roof hatch to not fewer than three depths at not fewer than two positions, with every reading recorded.

14 Tank Bottom Exterior Systems

14.1 Requirements in this article apply to each steel tank the drawings assign to a bottom-exterior system, whose bottom plate and foundation are furnished under Water Storage TanksWater Storage TanksResolves to the current adopted revision.sync/water-storage-tanks.
14.2 The exterior of the tank bottom shall be protected by the system indicated in the datasheet, under NACE SP0193.
Tank Bottom Exterior Systemselect
Impressed-current grid of mixed-metal-oxide ribbon or wire under the bottom
Galvanic anode ribbon under the bottom
Distributed galvanic anodes around the tank perimeter
None, the bottom relies on its foundation and coating
NOTE An impressed-current grid laid in the sand pad under the bottom plate delivers current evenly to the whole bottom, is adjustable for life, and is the system for a large tank or any tank on a containment liner, where no current can reach the bottom from outside the ring wall; a galvanic ribbon in the sand does the same without a rectifier and cannot be adjusted or replaced; perimeter anodes reach only the outer part of the bottom of a small tank and cannot reach the center of a large one or anything above a liner. A bottom on a clean, drained sand pad with a coated underside and no liner is left unprotected on many small tanks, and that is the position the last option records. (14.3)
14.4 Under-bottom anodes, the header cables, and the permanent reference electrodes shall be installed in the sand pad after the ring wall and the pad are complete and before the bottom plates are laid, at the locations and the depth below the plate the design shows on the corrosion protection drawings, and the tank builder shall protect them during plate laying and welding.
14.5 Where a secondary containment liner is furnished under the tank, every anode and every reference electrode shall be installed above the liner, and the sand between the liner and the bottom plate shall be clean washed sand with a chloride content not exceeding 200 ppm and no oil or asphalt admixture.
NOTE An oiled sand pad was once laid under tank bottoms to keep the steel dry, and it insulates the bottom from any cathodic protection system, so that the system reads protected at the perimeter and protects nothing under the plate; a liner does the same from below, which is why everything the system needs sits above it. (14.6)
14.7 Permanent reference electrodes under a tank bottom shall be of the type selected under the Test Stations, Reference Electrodes, and Coupons article, installed at not fewer than the number the design shows, with at least one near the center of the bottom, and perforated access tubes for a portable electrode shall be installed under the bottom where the design shows them, under NACE TM0101 as it applies to measuring under a plate.
14.8 Under-bottom cables shall exit the sand pad through the ring wall in sleeves or conduit, shall be landed in a test station or junction box at the tank perimeter, and shall be routed so that no cable is pinched between the bottom plate and the ring wall.

15 Interference and Stray Current Mitigation

15.1 Where the corrosivity survey or the interference test finds that the system shifts the potential of a foreign buried metallic structure, the Contractor shall mitigate the interference by resistance bond, by relocating or resizing the anode bed, or by the other measures NACE SP0169 describes, with the foreign structure owner's agreement, until the foreign structure's potential is restored to within 20 mV of its native value or to the value the foreign structure owner accepts in writing.
15.2 Where the corrosivity survey finds stray direct current or AC interference, the mitigation components indicated in the datasheet shall be furnished at the locations the design shows on the corrosion protection drawings.
Interference and Stray Current Mitigation Componentscheckbox
☐ Resistance bonds to foreign structures, with adjustable resistors in a test station
☐ Drainage bonds to a transit system or other stray current source
☐ Solid-state decouplers from the structure to gradient control or grounding
☐ Zinc ribbon gradient control laid along the pipe
☐ Gradient control mats at test stations and exposed appurtenances
NOTE A resistance bond ties the foreign structure to the protected one through a resistor sized so that the current the system put onto the foreign structure returns through the bond rather than through the soil, and it is the mitigation of nearly every interference with a neighbor's pipe; a drainage bond returns the stray current of a transit system to its source and is negotiated with that operator; decouplers to grounding and zinc ribbon along the pipe give induced AC a path to earth that blocks DC, which is the mitigation of a pipe sharing a transmission corridor; gradient control mats bring the earth at a test station or a valve box to the pipe's AC potential so that a technician touching the lead is not across the induced voltage. (15.3)
15.4 After mitigation, the steady-state AC voltage between any accessible test lead or appurtenance of the system and the earth at arm's length shall not exceed 15 V, and the AC current density at a coating holiday shall be reduced below the value at which NACE SP0177 and the design identify a risk of AC corrosion.

16 Commissioning

16.1 Native Survey and Pre-Energizing Checks

16.1.1 Before any galvanic anode is connected and before any rectifier is energized, the native structure-to-electrolyte potential of every structure the system protects shall be measured at every test station and at every permanent reference electrode, and the potential of every foreign structure identified by the survey shall be measured at every crossing and every test station on it, with every reading recorded with the date, the time, the electrode placement, and the instrument.
NOTE The native survey is the baseline that every criterion is judged against and every interference claim is settled by: the 100 mV shift is measured from it, and a foreign structure owner's complaint is answered with it. A system energized before the native survey is taken has no baseline, and the baseline cannot be recovered. (16.1.2)
16.1.3 Before any source is energized, every bond continuity test, every isolation test, every casing test, and the decoupling device test shall be complete and passing, and the Engineer of Record shall have the records.

16.2 Energizing and Adjustment

16.2.1 Each galvanic anode group shall be connected at its test station, and the current of each anode measured across its shunt and recorded, and each rectifier shall be energized at a tap setting the commissioning plan states, with its input and output voltages and currents and the structure potential at the nearest test station recorded at energizing.
16.2.2 After energizing, the system shall be left to polarize for not less than the period indicated in the datasheet before the final potential survey is begun, with the rectifier readings taken and recorded not less than weekly during that period.
Polarization Period Before the Final Surveyrange
days
13714306090
Default: Not less than 30 days
NOTE A structure polarizes over days to weeks as the cathodic reaction consumes the oxygen at its surface and the potential drifts negative at a given current, so a survey taken the day after energizing reads a structure that will be well past the criterion a month later, and a rectifier set that day is set too high. Thirty days is the period most specifications allow and the period an impressed-current system on a coated structure needs; a week serves a galvanic system on a small structure, and sixty to ninety days are allowed for a bare or encased structure with a large demand, whose polarization is slow. (16.2.3)
16.2.4 Where the readings during the polarization period show a structure past the criterion by a margin, or a structure approaching the overprotection limit, the rectifier shall be adjusted and the polarization period restarted for that structure.

16.3 Final Potential Survey

16.3.1 After the polarization period, the final potential survey of every structure the system protects shall be made by the method indicated in the datasheet, in accordance with NACE TM0497, with the reference electrode placed over the structure at every reading and the on and instant-off potentials, or the depolarized potential where the 100 mV criterion is applied, recorded at every location.
Final Potential Survey Methodradio
● On and instant-off potentials at every test station and permanent reference electrode
○ Close-interval survey over every buried line, with the test station and permanent reference electrode readings
NOTE Test station readings prove the potential at each station and assume the structure between stations is no worse, which is the survey of nearly every plant yard system, where the stations are close and the lines are short; a close-interval survey walks the reference electrode along the line at a few feet a reading, under NACE SP0207, and finds the low spot between stations, the shorted casing, the unbonded joint, and the coating damage that the stations cannot see, at the cost of a day per mile and an interrupter on every source. It is specified where the lines are long, the soil is variable, or the structure is one whose failure the Owner cannot tolerate. (16.3.2)
16.3.3 Where a close-interval survey is selected, readings shall be taken at intervals along the line not exceeding the interval indicated in the datasheet, with the electrode position referenced to the test stations and to the stationing of the yard piping plan.
Close-Interval Survey Reading Intervalrange
ft
2.5510
NOTE A reading every 2.5 ft resolves a single coating holiday on a small line; every 5 ft resolves the features a plant yard survey is after, an unbonded joint or a shorted casing, and is the interval most close-interval surveys walk; every 10 ft is the interval of a long main in uniform soil and misses the short feature. (16.3.4)
16.3.5 Where the instant-off potential is measured, every DC source influencing the structure shall be interrupted simultaneously by synchronized interrupters, and galvanic anodes shall be disconnected at their test stations or the instant-off reading taken on a coupon, and the interruption arrangement shall be recorded with the reading.
16.3.6 The final survey shall include the current output of every galvanic anode and every impressed-current anode measured across its shunt, the output of every rectifier, the potential of every foreign structure at every location measured in the native survey, and the AC voltage on every test lead where the survey identified AC interference.
16.3.7 A structure that does not meet the criteria of protection at every location at the final survey shall be corrected under the Design Responsibility article, and the polarization period and the final survey repeated for that structure, and a structure that meets the criteria at every location shall be recorded as protected with the rectifier settings and anode connections as left.
16.3.8 The final survey shall be witnessed by the Engineer of Record, on the notice the Field Test Rules of Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process require, and a foreign structure owner who has asked to attend the interference test shall be given the same notice.

16.4 Commissioning Report

16.4.1 The commissioning report shall include the native survey, the bond continuity, isolation, casing, and decoupling device test records, the energizing record, the polarization period readings, the final survey with every reading plotted against its test station or stationing, the anode and rectifier outputs as left, the interference test results and the foreign structure owner's acceptance, the instruments used with their calibration dates and the master electrode check, the record drawings, and the technician's and the reviewer's signatures.
16.4.2 The commissioning report shall be reviewed and signed as the Personnel Qualifications article requires, and shall be delivered within 30 days of the final survey and before substantial completion.
16.4.3 The report shall state for each structure whether it is protected under the criteria of this standard, and shall list every location that did not meet the criteria at any survey and the correction made.
NOTE The commissioning report is the baseline every annual survey is judged against for the life of the system and the proof the Owner holds that the yard was protected the day it was accepted. A report that records potentials without the current outputs and the settings cannot tell the technician five years later whether the anodes are consumed or the rectifier was turned down. (16.4.4)

16.5 Twelve-Month Survey

16.5.1 A twelve-month survey shall be performed as indicated in the datasheet.
Twelve-Month Surveyradio
○ Performed by the Contractor between eleven and twelve months after substantial completion, by the same method as the final survey
○ Not included, with the Owner's annual survey program beginning at twelve months
NOTE A survey at the end of the first year finds the bond that broke under settlement, the anode that was consumed faster than designed, the isolation device punctured by a surge, and the rectifier turned down by someone who did not know what it was, all while the Contractor is still responsible for them and before the warranty under Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process runs out. It costs a mobilization and a technician for a day or two, and it is left out where the Owner's own corrosion staff survey the plant every year anyway. (16.5.2)
16.5.3 Where the twelve-month survey is performed, a structure found below the criteria shall be corrected under the Warranty article and resurveyed, and the survey report shall be delivered within 30 days of the survey.
16.5.4 The operation and maintenance data shall state the rectifier reading interval, not longer than two months, the annual survey procedure and record form, and the criteria of this standard, so that the Owner's annual survey is made by the same method and judged against the same criteria as the commissioning survey.

17 Installation

17.1 Cables, Trenching, and Splices

17.1.1 Bond cables, test leads, anode leads, header cables, and reference electrode leads shall be buried at not less than the depth below finished grade indicated in the datasheet, with a detectable warning tape in the backfill above every cable run that is not in the pipe trench.
Cable Burial Depthrange
in
18243036
Default: Not less than 24 in
NOTE Twenty-four inches is the depth that puts a cathodic protection cable below a mower, a fence post, and the hand digging of a landscaper, and it is the depth most specifications bury at; a deeper cable survives a regrading and a plow, and is specified in a yard that will be regraded or in a farmed easement; 18 in. is the depth of a cable laid in the pipe trench beside the pipe, where the pipe's own cover protects it. (17.1.2)
17.1.3 Cables shall be laid in a trench free of rock, with slack and without tension, shall not be laid in the pipe zone bedding stone, and shall be backfilled with sand or screened earth to 6 in. above the cable before the trench is backfilled under EarthworkEarthworkResolves to the current adopted revision.sync/earthwork.
17.1.4 Cables shall be continuous from the structure or the anode to the test station, junction box, or rectifier, without a splice, except that a header cable may be spliced where the design shows a splice, by an exothermic weld or a crimped connector and encapsulated in a cast epoxy or heat-shrink splice kit rated for direct burial, with the splice location recorded on the record drawings.
17.1.5 Cables that rise above grade, pass through a wall, or run under pavement shall be installed in conduit furnished and installed under Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit, and the positive and negative cables of a rectifier shall be run in separate conduits or in one conduit without any other circuit.
NOTE A positive cable spliced in the ground is a positive cable with a second place to fail, and a positive cable in a conduit with a grounded circuit is a cable that arcs to that circuit's conductor if its insulation is nicked, which is why the splice is shown or not made and the conduit is dedicated. (17.1.6)
17.1.7 Every cable shall be tested for insulation integrity against ground after installation and before backfill, and a cable whose insulation is damaged shall be replaced, not repaired, except that a header cable may be repaired with an encapsulated splice kit where the design permits splices.

17.2 Test Station and Rectifier Setting

17.2.1 A flush test station shall be set in a concrete collar flush with the finished grade or pavement, with its lid oriented to open away from traffic, and a post-mounted station shall be set in a concrete footing with its terminal head not less than 30 in. above finished grade.
17.2.2 A test station shall be located within 2 ft of the structure it serves where it is at grade over the structure, and where it is offset, the offset shall be recorded on the record drawings.
17.2.3 Test stations and rectifiers shall be installed after the final grading of the area around them, or protected and reset to the final grade by the Contractor where they are installed before it.
NOTE A test station set to a grade that is later raised is lost under the fill, and one set to a grade that is later cut stands on a pedestal of soil with its cables exposed; both are found by the annual survey technician, who cannot read either. (17.2.4)

17.3 Protection and Coating Repair

17.3.1 Every excavation, backfill, and coating operation of other trades near an installed anode, cable, test station, or reference electrode shall be performed with the installed work located and protected, and work of this system damaged by another trade shall be repaired or replaced by the Contractor at no cost to the Owner and retested.
17.3.2 Coating or encasement of the structure damaged by the work of this system shall be repaired under the piping standard or the tank standard for the structure before backfill, and holidays in a bonded coating at every connection made under this standard shall be tested and repaired under that standard.

18 Delivery, Storage, and Handling

18.1 Prepackaged galvanic anodes shall be delivered in sealed plastic bags and stored dry and off the ground until the day they are installed, and an anode whose backfill has been wetted before installation shall be used within 24 hours or discarded.
18.2 Mixed-metal-oxide anodes shall be handled by their leads and bodies without scraping the oxide coating, shall be stored in their shipping containers, and an anode with a visibly damaged coating shall not be installed.
18.3 Permanent reference electrodes shall be stored in their sealed packaging within the temperature range their manufacturer publishes, shall not be allowed to freeze, and shall be installed within the shelf life the manufacturer states.
18.4 Cable reels shall be stored off the ground and out of sunlight, cable ends shall be sealed against moisture until terminated, and a reel that has been dragged, dropped, or run over shall have its cable insulation tested before use.
18.5 Isolation devices, decoupling devices, and rectifiers shall be delivered and stored as equipment under the Delivery, Storage, and Handling section of Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process, with insulating kits kept in their sealed packaging until the joint is assembled.

19 Warranty

19.1 The warranty term, the correction obligation, and the warranty administration for the system shall be as the Warranty section of Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process provides, and this article adds the performance obligations below.
19.2 Where any structure the system protects is found below the criteria of protection at the twelve-month survey or at any survey the Owner performs within the warranty period, the Contractor shall correct the system, including additional anodes, a replaced rectifier component, a remade bond, or a replaced isolation device, and shall resurvey the structure, at no cost to the Owner, within 30 days of written notice.
19.3 Where a galvanic anode is found at the twelve-month survey to be delivering a current that, continued, would consume it before the design life, the Contractor shall report the condition and its cause to the Engineer of Record, and where the cause is a bond, an isolation, or a design under this standard, shall correct it under the paragraph above.
19.4 The rectifier manufacturer's warranty on each rectifier, covering the stack, the controller, and the enclosure, shall be not less than the term indicated in the datasheet from the date of substantial completion.
Rectifier Manufacturer's Warranty Termrange
years
1235
NOTE A rectifier is the one component of the system with electronics in it, and the stack and the controller are what fail; a one-year term is what the makers carry as standard, and a longer term is bought, at a price, on an automatically controlled unit whose controller is the whole tank system. (19.5)

20 Spare Parts

20.1 The Contractor shall furnish the spare parts indicated in the datasheet, in addition to the spare parts basis of Common Work Results ProcessCommon Work Results for Process EquipmentResolves to the current adopted revision.sync/common-work-results-process, delivered to the Owner before substantial completion.
Cathodic Protection Spare Partscheckbox
☑ One set of rectifier fuses of each rating
☐ One rectifier diode stack or output module of each type furnished
☑ One portable copper-copper sulfate reference electrode and one high-impedance voltmeter
☐ One exothermic weld kit with molds, handle, and charges for the bond and lead sizes furnished
☐ One test station terminal board and lid of each type furnished
☐ One permanent reference electrode of each type furnished
☐ One decoupling device of each rating furnished
NOTE The fuses are what the operator replaces after the first lightning storm, and the portable electrode and voltmeter are what the Owner's annual survey is taken with; both are defaulted because a system without them is not read. A spare stack, a spare terminal board, and a spare decoupler are bought by an Owner without a corrosion contractor on call, and a spare permanent electrode is bought for a tank, where the installed one cannot be replaced without the fittings and the time. (20.2)
20.3 Spare galvanic anodes, prepackaged, shall be furnished in the quantity indicated in the datasheet.
Spare Packaged Galvanic Anodesrange
anodes
123510
NOTE A spare anode is installed when the annual survey finds an anode consumed or a structure below the criterion, and it is only useful if it is the alloy and weight of the installed ones; the count is set by how many anode groups the system has and how far the site is from a supplier, and a system with no galvanic anodes has none. (20.4)

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