USACE / NAVFAC / AFCESA / NASA UFGS-26 42 17.00 10 (November 2008)
-----------------------------------
Preparing Activity: USACE Superseding
UFGS-26 42 17.00 10 (April 2006)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 26 42 17.00 10
CATHODIC PROTECTION SYSTEM (IMPRESSED CURRENT)
11/08
NOTE: This guide specification covers the requirements for a cathodic protection
system using impressed current anodes.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
PART 1 GENERAL
1.1 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
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to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
The publications listed below form a part of this specification to the extent referenced. The publications are
referred to within the text by the basic designation only.
[ASTM INTERNATIONAL (ASTM)ASTM A 53/A 53M(2007) Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and SeamlessASTM B 418(2008) Standard Specification for Cast and Wrought Galvanic Zinc AnodesASTM B 843(2007) Standard Specification for Magnesium Alloy Anodes for Cathodic ProtectionASTM D 1248(2005) Standard Specification for Polyethylene Plastics Extrusion Materials for Wire and Cable][INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)IEEE C135.30(1988) Zinc-Coated Ferrous Ground Rods for Overhead or Underground Line ConstructionIEEE Std 81(1983) Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System (Part 1)Normal Measurements][NACE INTERNATIONAL (NACE)NACE RP0193(2001) External Cathodic Protection of On-Grade Carbon Steel Storage Tank BottomsNACE SP0169(2007) Control of External Corrosion on Underground or Submerged Metallic Piping SystemsNACE SP0188(2006) Discontinuity (Holiday) Testing of New Protective Coatings on Conductive SubstratesNACE SP0572(2007) Design, Installation, Operation and Maintenance of Impressed Current Deep Groundbeds][NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)NEMA C80.1(2005) Standard for Electrical Rigid Steel Conduit (ERSC)NEMA TC 2(2003) Standard for Electrical Polyvinyl Chloride (PVC) Tubing and Conduit][NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA 70(2007; AMD 1 2008) National Electrical Code - 2008 Edition][U.S. NATIONAL ARCHIVES AND RECORDS ADMINISTRATION (NARA)40 CFR 280Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST)49 CFR 192Transportation of Natural and Other Gas by Pipeline: Minimum Federal Safety Standards49 CFR 195Transportation of Hazardous Liquids by Pipeline][UNDERWRITERS LABORATORIES (UL)UL 467(2007) Standard for Grounding and Bonding EquipmentUL 506(2000; Rev thru May 2006) Standard for Specialty TransformersUL 510(2005; Rev thru Aug 2005) Polyvinyl Chloride, Polyethylene, and Rubber Insulating TapeUL 514A(2004; Rev thru Aug 2007) Standard for Metallic Outlet BoxesUL 6(2007) Standard for Electrical Rigid Metal Conduit-Steel]1.2 SYSTEM DESCRIPTION
1.2.1 General Requirements
a. Provide a complete, operating impressed current cathodic protection system in accordance with NFPA 70
, the applicable federal, state and local regulations, and the requirements of this contract. In addition
to the minimum requirements of these specifications, [construction of gas pipelines and associated cathodic
protection systems shall be in compliance with 49 CFR 192] [and] [construction of hazardous liquid pipelines,
and associated cathodic protection system shall be in compliance with 49 CFR 195] [and] [construction
and installation of underground fuel storage tanks and associated cathodic protection system shall be
in compliance with 40 CFR 280].
b. The system includes planning, inspecting the installation, adjusting and testing cathodic protection
and test system using rectifiers and impressed current anodes, supplemented with sacrificial anodes as
needed, for utilities and equipment shown. The cathodic protection system shall also include cables,
connectors, splices, corrosion protection test stations, ace power panels, and any other equipment required
for a complete operating system providing the specified protection. The cathodic protection system includes
(a) calculations for rectifier, anodes, and any recommendations for supplementing or changing the minimum
design criteria to provide the specified potentials and (b) equipment, wiring, and wiring devices necessary
to produce a continuous flow of direct current from anodes in the soil electrolyte to the pipe surfaces.
Submit Detail Drawings as specified in the Submittals paragraph. The installation shall meet the specified
protection criteria for a 25 year life.
1.2.2 Contractor's Modifications
The specified system is based on an impressed current system supplemented with magnesium anodes. The Contractor
may modify the cathodic protection system after review of the project, site verification and analysis if the
proposed modifications include the impressed current anodes and rectifiers and will provide better overall system
performance. The modifications shall be fully described, shall be approved by the Contracting Officer and shall
meet the following criteria. The proposed system shall achieve a minimum pipe-to-soil "Instant Off" potential
of minus 850 millivolts with reference to a saturated copper-copper sulfate reference cell on the underground
metallic components of the [piping] [tanks] [_____]. Take resistivity measurements of the soil in the vicinity
of the [pipes] [tanks] [_____] and ground bed sites; based upon the measurements taken, adjust current and voltage
of the rectifier as required to produce a minimum of minus 850 millivolts "Instant Off" potential between the
structure being tested and the reference cell. This potential shall be obtained over 95 percent of the metallic
area without the "Instant Off" potential exceeding 1200 millivolts.
1.3 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are for [Contractor Quality Control approval.] [information only. When used, a designation following the "G"
designation identifies the office that will review the submittal for the Government.] Submit the following in
accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-02 Shop Drawings
Detail Drawings[; G][; G, [_____]]
[Six] [_____] copies of detail drawings consisting of a complete list of equipment and material
including manufacturer's descriptive and technical literature, catalog cuts, results of system
design calculations including soil resistivity, installation instructions and certified test
data stating the maximum recommended anode current output density and the rate of gaseous production,
if any, at that current density. Detail drawings shall contain complete wiring and schematic
diagrams and any other details required to demonstrate that the system has been coordinated
and will function properly as a unit.
Contractor's Modifications[; G][; G, [_____]]
[Six] [_____] copies of detail drawings showing proposed changes in location, scope or performance
indicating any variations from, additions to, or clarifications of contract drawings. The drawings
shall show proposed changes in anode arrangement, anode size and number, anode materials and
layout details, conduit size, wire size, mounting details, wiring diagram, method for electrically
isolating each pipe, and any other pertinent information to the proper installation and performance
of the system.
SD-03 Product Data
Miscellaneous Materials[; G][; G, [_____]]
Within [30] [45] [_____] days after receipt of notice to proceed, an itemized list of equipment
and materials including item number, quantity, and manufacturer of each item. The list shall
be accompanied by a description of procedures for each type of testing and adjustment, including
testing of coating for thickness and holidays. Installation of materials and equipment shall
not commence until this submittal is approved.
Spare Parts
Spare parts data for each different item of material and equipment specified.
SD-06 Test Reports
Tests and Measurements
Test reports in booklet form tabulating field tests and measurements performed, upon completion
and testing of the installed system and including close interval potential survey, casing and
interference tests, final system test verifying protection, insulated joint and bond tests,
and holiday coating test. Each test report shall indicate the final position of controls.
Contractor's Modifications[; G][; G, [_____]]
Final report regarding supplemental magnesium anode installation. The report shall include
pipe-to-soil measurements throughout the affected area, indicating that the additions corrected
the conditions which made the additional anodes necessary, and current measurements for the
additional anodes. The following special materials and information are required: Calculations
on current and voltage for [100 V] [40 V] [_____] rectifier plus rectifier and meter specifications;
taping materials and conductors; zinc grounding cell, installation and testing procedures, and
equipment; coating material; system design calculations for rectifier, anode number, life, and
parameters to achieve protective potential; backfill shield material and installation details
showing waterproofing; bonding and waterproofing details; insulated resistance wire; exothermic
weld equipment and material.
SD-07 Certificates
Tests and Measurements
A certified test report showing that the connecting method has passed a 120-day laboratory
test without failure at the place of connection, wherein the anode is subjected to maximum recommended
current output while immersed in a 3 percent sodium chloride solution.
Cathodic Protection System
Proof that the materials and equipment furnished under this section conform to the specified
requirements contained in the referenced standards or publications. The label or listing by
the specified agency will be acceptable evidence of such compliance.
Services of "Corrosion Expert"[; G][; G, [_____]]
The "corrosion expert's" name and qualifications certified in writing to the Contracting Officer
prior to the start of construction, including the name of the firm, the number of years of experience,
and a list of not less than five of the firm's installations three or more years old that have
been tested and found satisfactory..
SD-10 Operation and Maintenance Data
Cathodic Protection System
[Six] [_____] copies of operating manual outlining the step-by-step procedures required for
system startup, operation, adjustment of current flow, and shutdown. The manuals shall include
the manufacturer's name, model number, service manual, parts list, and brief description of
all equipment and their basic operating features. [Six] [_____] copies of maintenance manual
listing routine maintenance procedures, recommendation for maintenance testing, possible breakdowns
and repairs, and troubleshooting guides. The manuals shall include single line diagrams for
the system as installed; instructions in making [pipe-] [tank-] to-reference cell potential
measurements and frequency of monitoring; instructions for dielectric connections, interference
and sacrificial anode bonds; instructions shall include precautions to ensure safe conditions
during repair of pipe system.
Training Course
The proposed Training Course Curriculum (including topics and dates of discussion) indicating
that all of the items contained in the operating and maintenance instructions, as well as demonstrations
of routine maintenance operations, including testing procedures included in the maintenance
instructions, are to be covered.
1.4 QUALITY ASSURANCE
1.4.1 Services of "Corrosion Expert"
Obtain the services of a "corrosion expert" to supervise, inspect, and test the installation and performance
of the cathodic protection system. "Corrosion expert" refers to a person, who, by reason of thorough knowledge
of the physical sciences and the principles of engineering and mathematics, acquired by professional education
and related practical experience, is qualified to engage in the practice of corrosion control of buried metallic
piping and tank systems. Such a person shall be accredited or certified by the National Association of Corrosion
Engineers (NACE) as a NACE Accredited Corrosion Specialist or a NACE certified Cathodic Protection (CP) Specialist
or be a registered professional engineer who has certification or licensing that includes education and experience
in corrosion control of buried or submerged metallic piping and tank systems, if such certification or licensing
includes 5 years experience in corrosion control on underground metallic surfaces of the type under this contract.
The "corrosion expert" shall make at least 3 visits to the project site. The first of these visits shall include
obtaining soil resistivity data, acknowledging the type of pipeline coatings to be used and reporting to the
Contractor the type of cathodic protection required. Once the submittals are approved and the materials delivered,
the "corrosion expert" shall revisit the site to ensure the Contractor understands installation practices and
laying out the components. The third visit shall involve testing the installed cathodic protection systems and
training applicable personnel on proper maintenance techniques. The "corrosion expert" shall supervise installation
and testing of all cathodic protection.
1.4.2 Isolators
Isolators are required to isolate the indicated pipes from any other structure. Isolators shall be provided
with lightning protection and a test station as shown.
1.4.3 Anodes and Bond Wires
Install anodes in sufficient number and of the required type, size and spacing to obtain a uniform current distribution
of 2.5 milliamperes per 0.09 square meters square foot minimum to underground metal surfaces. For each cathodic
protection system, the metallic components and structures to be protected shall be made electrically continuous.
This shall be accomplished by installing bond wires between the various structures. Bonding of existing buried
structures may also be required to preclude detrimental stray current effects and safety hazards. Provisions
shall be included to return stray current to its source without damaging structures intercepting the stray current.
The electrical isolation of underground facilities in accordance with acceptable industry practice shall be included
under this section.
1.4.4 Surge Protection
Install approved zinc grounding cells or sealed weatherproof lightning arrestor devices across insulated flanges
or fittings installed in underground piping as indicated on the drawings. The arrestor shall be gapless, self-healing,
solid state type. Zinc anode composition shall conform to ASTM B 418, Type II. Lead wires shall be number 6
AWG copper with high molecular weight polyethylene (HMWPE) insulation. The zinc grounding cells shall not be
prepackaged in backfill but shall be installed as detailed on the drawings. Lightning arrestors or zinc grounding
cells are not required for insulated flanges on metallic components used on nonmetallic piping systems.
1.4.5 Sacrificial Anodes
Locate sacrificial high potential magnesium anodes as required to provide localized cathodic protection or supplemental
cathodic protection for the impressed current system. Each sacrificial magnesium anode shall be routed through
a test station. The magnesium anode shall not be connected to the pipe.
1.4.6 Nonmetallic Pipe Systems
When nonmetallic pipe is approved, direct buried or submerged metallic components of the pipe system shall have
cathodic protection. Metallic components are connectors, tees, fire hydrants, valves, short pipes, elbows, tie
rods, or other metallic equipment. As a minimum, each metallic component shall be protected with a 4.1 kg 9
lb magnesium anode connected through a test station. The use of nonmetallic pipe does not change other requirements
of the specifications such as submittals, testing, or design calculations for each metallic component. Deviations
due to the use of nonmetallic pipe shall be approved by the Contracting Officer.
1.4.6.1 Coatings
Coatings for metallic components shall be as required for metallic fittings. Protective covering (coating and
taping) shall be completed and tested on each metallic component and shall be as required for underground metallic
pipe. Mechanical joints and fittings of either the electrically conductive or insulating type shall be coated
with an underground type dielectric coating system. Where external electrical continuity bonds are installed
across mechanical joints, bare or exposed metal, welds, bare wire and exposed coupling parts shall be coated
with a coating system.
a. Couplings and fittings which have a low profile exterior designed to permit tape coating shall be
primed and wrapped with an underground type pipe tape system or two-part epoxy system.
b. Couplings and fittings that cannot be properly taped shall be enclosed in a [spaced mold manufactured
for the purpose] [shroud of reinforced kraft paper] and filled with [cold applied dielectric compound]
[hot applied bituminous compound not exceeding 135 degrees C 275 degrees F in application temperature].
1.4.6.2 Tracer Wire
When a nonmetallic pipe line is used to extend or add to an existing metallic line, an insulated No. 8 AWG copper
wire shall be connected to a terminal in a test station located at each point of transition from metallic pipe
to nonmetallic pipe. At each of these test stations, the tracer wire terminal shall be strapped or bonded to
the terminal for the negative connection wire to the existing metallic line. The tracer wire shall be run the
length of the new nonmetallic line. This wire shall be used as a locator tracer wire and to maintain continuity
to any future extension of the pipe line.
1.5 DELIVERY, STORAGE, AND HANDLING
Storage for magnesium anodes will be designated by the Contracting Officer. If anodes are not stored in a building,
protect them from inclement weather. Packaged anodes damaged as result of improper handling or weather exposure
shall be resacked and the required backfill added.
1.6 EXTRA MATERIALS
Submit spare parts data for each different item of material and equipment specified, after approval of detail
drawings and not later than [_____] months prior to the date of beneficial occupancy. Include in the data a
complete list of parts, special tools, and supplies, with current unit prices and source of supply. Furnish
one spare anode of each type.
PART 2 PRODUCTS
2.1 IMPRESSED CURRENT ANODES
2.1.1 Bare High Silicon Cast-Iron Anodes
Cast-iron anodes shall be of the size indicated and shall conform to the following requirements:
2.1.1.1 Chemical Composition (Nominal)
Percent by Weight
Element Grade 2
Silicon 14.20-14.75
Manganese 1.50 Max.
Carbon 0.75-1.15
Chromium 3.25-5.00
Iron Balance
2.1.1.2 Electrical Resistivity
Seventy-two microhm-centimeter at minus 7 degrees C 20 degrees F.
2.1.1.3 Physical Properties (Nominal)
Tensile strength 103.4 MPa
Compressive strength 689.5 MPa
Brinell hardness 520
Density 7000 kilograms per cubic meter
Melting point 1260 degrees C
Coefficient of 132 nanometer per degree C
expansion from 0
to 100 degree C
Tensile strength 15,000 psi
Compressive strength 100,000 psi
Brinell hardness 520
Density 7.0 grams per cubic centimeter
Melting point 2300 degrees F
Coefficient of 0.00000733 centimeter
expansion from 32 per degree F
to 212 degrees F
2.1.2 Bare Graphite Anodes
Bare graphite anodes shall have a maximum electrical resistivity of 0.0011 ohm-centimeter.
2.1.3 Canister Contained Anodes
Canister contained anodes shall be packed at the factory in sheet metal canisters with calcined petroleum coke
breeze. The coke shall have a resistivity of 0.1 ohm-cm tested at 1034 kPa 150 psi. The coke shall be 11244
kg/cubic meter 70 lbs/cubic foot or greater. The maximum particle size shall be 1 mm 0.039 inch and the coke
shall be dust-free. The canisters shall be capped with tight fitting end caps secured to the body of the canister.
The canister shall provide a minimum annular space of 75 mm 3 inch all around the anode. The connecting cable
shall pass through a hole in an end cap designed to be tight fitting with the cable and protected from sharp
edges with a plastic or rubber grommet. The anodes shall be centered in the canisters and the annular space
filled with coke breeze compacted in place.
2.1.4 Anode Connecting Cables
Anodes shall have connecting cables installed at the factory. For deep ground beds, each anode located in the
borehole shall be accompanied by a reel of continuous cable having the length indicated. No spliced connections
will be permitted in deep well cables.
2.1.5 Mixed Metal Oxide Anodes
Mixed metal oxide anodes shall be of the size indicated and shall conform to the following requirements.
2.1.5.1 Conductive Material
The electrically conductive coating shall contain a mixture consisting primarily of iridium, tantalum, and titanium
oxides. The average composition is generally a 50/50 atomic percent mixture of iridium and titanium oxides,
with a small amount of tantalum. The resistivity, as tested by the manufacturer, shall be no more than 0.002
ohm-centimeter, and the bond strength shall be greater than 50 MPa 7.25 ksi to guarantee the current capacity
life and the quality of the conductive ceramic coating. The adhesion or bond strength shall be determined by
epoxy bonding a 2.54 mm 0.1 inch diameter stud to the ceramic coating and measuring the load to failure (about
70 MPa 10.15 ksi) of either the epoxy or the interface between the coating and the substrate. The anode must
be inert and the electrically conductive ceramic coating dimensionally stable. The ceramic coated anode shall
be capable of sustaining a current density of 100 ampere per square meter 10.764 square feet in an oxygen generating
electrolyte at 66 degrees C 150 degrees F for 20 years, to ensure the current capacity life. An accelerated
current capacity life test shall be performed by the manufacturer on every lot of anode wire used to construct
the anode as described. The mixed metal oxide coating shall be applied to the wire anode by a firm that is regularly
engaged in and has a minimum 5 years experience in manufacturing and applying mixed metal oxide coatings to titanium
anode substrates. The mixed metal oxide must be sintered to the titanium surface as to remain tightly bound
to the surface when bent 180 degrees onto itself.
2.1.5.2 Anode Life Test
The anode wire material shall sustain current densities of 100 ampere per square meter 10.764 square feet in
an oxygen generating electrolyte for 20 years. The manufacturer shall certify that a representative sample taken
from the same lot used to construct the anode, has been tested and meets the following criteria. The test cell
sustains a current density of 10,000 ampere per square meter 10.764 square feet in a 15 weight percent sulfuric
acid electrolyte at 66 degrees C 150 degrees F without an increase in anode to cathode potential of more than
1 volt. The cell containing the anode shall be powered with a constant current power supply for the 30 day test
period. The representative sample shall be 125 mm 5 inch in length taken from the lot of wire that is to be used
for the anode.
2.1.5.3 Canister Contained Mixed Metal Oxide Anodes
Canister contained mixed metal oxide anodes shall be packed at the factory in light weight, light gauge steel
uni-body TIG welded canisters with calcinated petroleum coke breeze. The canisters shall be capped with TIG
welded steel and caps providing a totally encapsulated construction. The connecting cable shall pass through
a hole in an end cap designed to be tight fitting with a heavy duty strain relief allowing for handling of the
canister by the cable. The anode shall be centered in the canister by centralizers to maintain rod position.
2.1.5.4 Anode Connecting Cables
Anodes shall have connecting cables installed at the factory. The connection between the anode rod or ribbon
and the lead wire shall be made with a solid crimp couple with solder. The connection shall be sealed in cast
epoxy.
2.1.5.5 Canister Connection Cables
Canister connecting cables shall consist of an ultra low resistance solder connection which is a minimum of three
times stronger than the cable. For ceramic coated canister anodes, the cable connection shall consist of two
molded dielectric layers (pressure seals), a flexible backfill resin encapsulant stabilizer, a schedule 40 PVC
pipe Type 1 seal, and Type 1 PVC pipe end plugs. The seals and end plugs shall resist chlorine gas and acid.
2.1.5.6 Deep Anode Connection Cables
For deep anode beds, each anode located in the borehole shall be accompanied by a reel of continuous cable having
the length indicated. For deep ceramic coated anode beds, anode connecting cables shall have molded multiseal
solder connections; splices will not be permitted. Chlorine gas resistant cable and shield shall be used for
chlorine environments.
2.2 RECTIFIERS AND ASSOCIATED EQUIPMENT
2.2.1 Rectifier Unit
NOTE: Air-cooled rectifiers will be used for most applications. Where highly
corrosive atmospheres exist, the equipment will be oil-immersed in a tank-type
housing. For hazardous area applications, oil-immersed equipment will be provided
with an explosion-proof or dust-ignition-proof housing, as appropriate. Transformer
tap adjusters will be provided in cases where an automatic system is not provided.
Rectifier unit shall consist of a transformer, rectifying elements, transformer tap adjuster, terminal block,
[one dc output voltmeter, one dc output ammeter,] [one combination volt-ammeter,] one toggle switch for each
meter, fuse holders with fuses for each dc circuit, variable resistors, an ac power-supply circuit breaker, lightning
arresters for both input and output, all wired and assembled in a weatherproof cabinet. The overall efficiency
of the rectifier shall be not less than 65 percent when operated at nameplate rating and shall be capable of
supplying continuous full rated output at an ambient temperature of 44 degrees C 112 degrees F in full sunlight
with expected life in excess of 10 years.
2.2.1.1 Transformer
Transformer shall conform to UL 506.
2.2.1.2 Rectifiers
NOTE: Below about 500 volt-amperes of dc rating output, single phase selenium
rectifiers cost less to acquire and operate than silicon rectifiers. Above
1000 volt-amperes silicon rectifiers are more economical for both single phase
and three phase. Silicon rectifiers are more economical to repair.
Rectifying elements shall be [silicon diodes] [selenium cells] connected to provide full-wave rectification.
Silicon diodes shall be protected by selenium surge cells or varistors against over-voltage surges and by current-limiting
devices against over-current surges.
2.2.1.3 Meters
Meters shall be accurate to within plus or minus 2 percent of full scale at 27 degrees C 80 degrees F, and shall
possess temperature stability above and below 27 degrees C 80 degrees F and shall possess temperature stability
above and below 27 degrees C 80 degrees F of at least 1 percent per 5 degrees C 10 degrees F. Separate meters
shall be 63.5 mm 2-1/2 inch nominal size or larger.
2.2.1.4 Circuit Breaker
A [single] [double] [three]-pole, flush-mounted, fully magnetic, properly rated non-terminal type circuit breaker
shall be installed in the primary circuit of the rectifier supply transformer.
2.2.1.5 Fuses
Cartridge-type fuses with suitable fuse holders shall be provided in each leg of the dc circuit.
2.2.2 Cabinet Construction
Cabinet shall be constructed of [not lighter than 1.56 mm 16 gauge [steel] [hot dipped galvanized steel] [stainless
steel] [aluminum]] [molded fiberglass reinforced polyester], and shall be provided with a full door. The enclosure
shall have oil-resistant gasket. The door shall be hinged and have a hasp that will permit the use of a padlock.
The cabinet shall be fitted with screened openings of the proper size to provide for adequate cooling. Holes,
conduit knockouts, or threaded hubs of sufficient size and number shall be conveniently located.
2.2.2.1 Wiring Diagram
A complete wiring diagram of the power unit showing both the ac supply and the dc connections to anodes shall
be on the inside of the cabinet door. All components shall be shown and labeled.
2.2.2.2 Grounding Provisions
Grounding provisions shall [be as specified in Section 26 20 00 INTERIOR DISTRIBUTION SYSTEM.] [comply with NFPA 70
and UL 467 including a ground terminal in the cabinet.] The grounding conductor from the terminal to the earth
grounding system shall be solid or stranded copper not smaller than No. 6 AWG. The earth grounding system shall
consist of one or more ground rods. Ground rods shall be of [copper-clad steel conforming to UL 467] [zinc-coated
steel conforming to IEEE C135.30] [solid stainless steel] not less than [16] [19] mm [5/8] [3/4] inch in diameter
by [2.4] [3.1] m [8] [10] feet in length. Rods shall be driven full length into the earth. Sectional type rods
may be used.
2.2.2.3 Resistance to Ground
NOTE: Remove this paragraph if not required in the project.
The resistance to ground shall be measured using the fall-of-potential method described in IEEE Std 81. The
maximum resistance of driven ground shall not exceed 25 ohms under normally dry conditions. If this resistance
cannot be obtained with a single rod, [_____] additional rods not less than 1.8 m 6 feet on centers, or if sectional
type rods are used, [_____] additional sections may be coupled and driven with the first rod. In high-ground-resistance,
UL listed chemically charged ground rods may be used. If the resultant resistance exceeds 25 ohms measured not
less than 48 hours after rainfall, the Contracting Officer shall be notified immediately. Connections below
grade shall be fusion welded. Connections above grade shall be fusion welded or shall use UL 467 approved connectors.
2.2.2.4 Cabinet Paint System
[The cabinet and mounting support shall be [painted] [hot dipped galvanized] [aluminum] [stainless steel] with
the manufacturer's standard painting system.] [The mounting support for the fiberglass cabinet shall be [painted]
[hot dipped galvanized] [aluminum] [stainless steel] with the manufacturer's standard painting system.]
2.2.3 Wiring
Wiring shall be installed in accordance with NFPA 70 utilizing type TW or RHW or polyethylene insulation. Fittings
for conduit and cable work shall conform to UL 514A. Outlets shall be of the threaded hub type with gasketed
covers. Conduit shall be hub type with gasketed covers. Conduit shall be securely fastened at 2.4 m 8 foot
intervals or less. Splices shall be made in outlet fittings only. Conductors shall be color coded for identification.
Cable for anode header and distribution shall be No. [2] [_____] AWG stranded copper wire with type [cathodic
protection high molecular weight polyethylene] [Dular/Halar] insulation.
2.2.4 Oil Immersed Enclosures
NOTE: The enclosure should not be used in areas prone to flooding unless required
for hazardous locations. Provisions should be made for flooding.
Enclosures shall be of 3.1 mm 11 gauge steel or heavier, with an accessible drain plug. The oil level shall
be clearly marked. The lid shall be hinged and have quick release clamps to secure it in closed position. A
stop shall limit the swing of the lid when opened. A compressible, oil resistant, positive sealing gasket shall
be provided. The gasket shall return to its original shape upon release of lid pressure. The gasket shall be
attached to the tank or lid and joints shall be free of gaps. Base mounting using 102 mm 4 inch high channels
shall be provided. Conduits entering the enclosure shall be internally sealed and shall enter or exit above
the oil fill line.
2.3 COKE BREEZE
2.3.1 Calcined Petroleum Coke Breeze (Dry)
Breeze shall conform to the following requirements:
2.3.1.1 Electrical Resistivity
Resistivity shall not exceed 1 milliohm-meter (0.1 ohm-cm) Great Lake Carbon C 12 A Test Method.
2.3.1.2 General Backfill Specifications
Bulk Density - 1044 to 1204 kg/cubic meter 65 to 75 lbs/cubic foot
Fixed Carbon - 99.0 percent or greater
Volatiles - 0.2 percent or less
Sizing - 100 percent less than 13 mm 1/2 inch
2.3.2 Metallurgical Coke Breeze (Processed)
Breeze shall conform to the following requirements:
2.3.2.1 Electrical Resistivity (Nominal)
Nominal electrical resistivity shall be:
a. 100 milliohm-meter (10 ohm-centimeter) Max., tightly compacted.
b. 100 milliohm-meter to 150 milliohm-meter, (10 to 15 ohm-centimeter,) lightly compacted.
c. 150 to 200 milliohm-meter, (15 to 20 ohm-centimeter,) loose.
2.3.2.2 General Backfill Specifications
Bulk density - 608 to 672 kg per cubic meter 38 to 42 pounds per cubic foot
Fixed Carbon - 80 percent or greater
Sizing - 100 percent less than 10 mm 3/8 inch
2.4 MISCELLANEOUS MATERIALS
2.4.1 Electrical Wire
2.4.1.1 Anode Connecting Wire
NOTE: Any pinhole, cut, scratch or other damage to the anode cable exposing
bare copper to the electrolyte will result in early failure of the cathodic
protection system. For this reason, special, extra heavy insulation is used
on anode cable. While it is often expedient to use the same type wire for the
cathodic (negative) cable in order to avoid a mix-up in the field, the cathode
cable is not subject to anodic failure and lesser insulation can be used.
Anode connecting wire shall be No. [8] [_____] AWG stranded copper wire with type CP high molecular weight polyethylene
insulation, 2.8 mm 7/64 inch thick, 600 volt rating. Cable-to-anode contact resistance shall be 0.003 ohms maximum.
Deep anode ground bed connecting wire shall be No. 8 AWG, stranded copper wire with an inner jacket of 1 mm 40
mils of Halar insulation covered by an outer jacket of 1.6 mm 65 mils CP high molecular weight polyethylene insulation,
600 volt rating. Cable-to-anode contact resistance shall be 0.02 ohms maximum.
2.4.1.2 Anode Header Cable
NOTE: The double insulated fluorocopolymer cable is intended for use in very
harsh environments such as deep anode bed installations where clorine and hydrogen
gases are generated. This cable can be installed directly in soil or submerged
in fresh, brackish, or salt waters. The CP high molecular weight polyethylene
cable is also a direct buried and submergible type cable suitable for harsh
environments, but not as quiet as durable as the double insulated cable would
be in the toughest of environments.
Cable for anode header and distribution shall be No. [_____] AWG stranded copper wire with type [CP high molecular
weight polyethylene, 2.8 mm 7/64 inch thick insulation] [HMWPE protective jacketed cable with a fluorocopolymer
inner or primary insulation], 600-volt rating.
2.4.1.3 Test Wires
Test wires shall be No. 12 AWG stranded copper wire with NFPA 70 Type TW or RHW or polyethylene insulation.
2.4.1.4 Resistance Wire
Resistance wire shall be AWG No. [16 or No. 22] [_____] nickel-chromium wire.
2.4.2 Deep Anode Ground Bed Casing
NOTE: A metal casing should not be used except for a maximum of 1.5 meter (5
feet) at the top for a well cap which also serves as a support for the suspension
ropes. The drilling mud on the sides of the hole will usually keep the hole
open until the anodes and coke breeze are installed. If a casing must be used,
it should be fiberglass reinforced plastic (nonmetallic) and should be located
above the anode string.
Casing shall be [_____] mm inch outside diameter, 3 mm 1/8 inch minimum wall thickness black steel pipe, conforming
to ASTM A 53/A 53M, Type E or S, Grade B. The top casing shall be [_____] mm inch outside diameter, 3 mm 1/8
inch minimum wall thickness black steel pipe, conforming to ASTM A 53/A 53M, Type E or S, Grade B. The metal
casing shall extend no more than [1.5] [_____] m [5] [_____] feet below the top of a well cap.
2.4.3 Anode Centering Device for Deep Anode Ground Beds
Anode centering device shall be nonmetallic and capable of maintaining centering in the hole without interfering
with other anode lead wiring, until coke breeze is packed in place.
2.4.4 Conduit
Nonmetallic conduit shall conform to NEMA TC 2.
2.4.5 Test Boxes and Junction Boxes
Boxes shall be outdoor type conforming to UL 514A.
2.4.6 Vent Pipes
All deep wells shall be vented in anode zones. Openings in the vent shall not be larger than 0.1524 mm 0.006
inch.
2.4.7 Polyethylene Insulation
Polyethylene insulation shall comply with the requirements of ASTM D 1248 and of the following types, classes,
and grades:
2.4.7.1 High Molecular Weight Polyethylene
High molecular weight polyethylene shall be Type I, Class C, Grade E5.
2.4.7.2 High Density Polyethylene
High density polyethylene shall be Type III, Class C, Grade E3.
2.4.8 Test Stations
Provide test stations complete with an insulated terminal block having the indicated number of terminals; provided
with a lockable cover and have a cast-in legend, "C.P. Test" and complete with an insulated terminal block having
the required number of terminals. (One terminal required for each conductor). Provide sufficient test stations
to monitor underground isolation points. Test-bond stations (potential measurement and stray current control)
shall be provided to monitor pipe to soil potential of proposed underground pipes or existing underground metallic
structures which may conduct stray current from the new cathodic protection system. The location of the test-bond
stations shall ensure that the pipe to soil potential of metallic pipe not designated to be protected is not
made less negative by the energization of the cathodic protection system. Test station terminal connections
and the terminal conductor shall be permanently tagged to identify each termination of the conductors (e.g. identify
the conductors connected to the protected structures). Conductors shall be permanently identified in the station
by means of plastic or metal tags, or plastic sleeves to indicate termination. Each conductor shall be color
coded in accordance with the drawings. The station test facility, including permanent Cu-Cu S04 reference cells
and test returns shall be installed as indicated. Pavement inserts shall be nonmetallic and shall allow Cu-Cu
S04 reference electrode to contact the electrolyte beneath the pavement surface. Abbreviations shall not be
used. Welding of electrical connections shall be as follows: Exothermic welds shall be "CADweld", "Thermo-weld",
or approved equal. Use and selection of these materials and welding equipment shall be in accordance with the
manufacturer's recommendations.
2.4.9 Calibrated Shunts
Install shunts calibrated in current per potential (e.g. mA/V) between the lead or header wire connected to the
anode and the current collector lead connected to the structure. The calibration of the shunt shall be clearly
marked and installed to be visible.
2.4.10 Sealing and Dielectric Compound
Sealing and dielectric compound shall be a black, rubber based compound that is soft, permanently pliable, tacky,
moldable, and unbacked. Apply compound as recommended by the manufacturer, but not less than 3 mm 1/8 inch thick.
2.4.11 Protective Covering
Except as otherwise specified, protective covering for underground metallic components including pipe and fittings
shall be applied mechanically in a factory or field plant specially equipped for the purpose. Valves and fittings
that cannot be coated and wrapped mechanically shall have the protective covering applied by hand, preferably
at the plant applying the covering to the pipe. Joints shall be coated and wrapped by hand. Hand coating and
wrapping shall produce a covering equal in thickness to the covering applied mechanically. Piping and components
installed in valve boxes or manholes shall also receive the specified protective coating.
2.4.11.1 Pipeline Metallic Components
Underground metallic pipelines and structures shall have a good quality factory applied coating. This includes
carbon steel, cast iron and ductile iron pipelines or vessels. If nonmetallic pipelines are installed, metallic
fittings or pipe sections shall be coated as follows.
a. The nominal thickness of the metallic pipe joint or other component coating shall be [0.2] [0.4]
[0.6] [1.0] [1.5] [_____] mm [8] [16] [24] [40] [60] [_____] mils, plus or minus 5 percent.
b. Pipe and joint coating for factory applied or field repair material shall be applied as recommended
by the manufacturer and shall be one of the following:
(1) Continuously extruded polyethylene and adhesive coating system.
(2) Polyvinyl chloride pressure-sensitive adhesive tape.
(3) High density polyethylene/bituminous rubber compound tape.
(4) Butyl rubber tape.
(5) Coal tar epoxy.
2.4.11.2 Field Joints
Coat field joints with material compatible with the pipeline coating compound. Apply the joint coating material
to an equal thickness as the pipeline coating. Unbonded coatings shall not be used on buried metallic piping.
This prohibition includes unbonded polymer wraps or tubes.
2.4.11.3 Inspection of Pipe Coatings
Once the pipeline or vessel is set in the trench, conduct an inspection of the coating including electrical holiday
detection as described in paragraph TESTS AND MEASUREMENTS.
2.4.11.4 Above Ground Piping System
Above ground piping shall be given two coats of exterior oil paint. Surface preparation shall be as recommended
by paint manufacturer, except as follows: ferrous, shop primed surfaces shall be touched up with ferrous metal
primer; surfaces that have not been shop primed shall be solvent cleaned; surfaces that contain loose rust, mil
scale, or other foreign substances shall be mechanically cleaned by power wire brushing and primed with ferrous
metal primer; and primed surfaces shall be finished with two coats of exterior oil paint or vinyl paint.
2.4.12 Preformed Sheaths
Preformed sheaths for encapsulating electrical wire splices to be buried underground shall fit the insulated
wires entering the spliced joint.
2.4.13 Epoxy Potting Compound
Epoxy potting compound for encapsulating electrical wire splices to be buried underground shall be a two package
system made for the purpose.
2.4.14 Backfill Shields
Backfill shields shall consist of approved pipeline wrapping or fiberglass reinforced, coal-tar impregnated tape,
or plastic weld caps, specifically made for the purpose.
2.4.15 Electrical Tape
Pressure-sensitive vinyl plastic electrical tape shall conform to UL 510.
2.4.16 Cable Marker Tape
Traceable marker tape shall be manufactured for the purpose and clearly labeled "Cathodic Protection Cable Buried
Below".
2.4.17 Electrically Isolating Pipe Joints
NOTE: The cathodic protection system will fail unless full consideration is
given to specifications for electrically isolating pipe joints, electrically
conductive pipe joints, and casing cradles and seals. Mechanical and electrical
specifications should reference this paragraph and paragraph "Electrically Conductive
Couplings."
Electrically isolating pipe joints for above or below ground use shall be [flexible, mechanical pipe couplings
of an electrically isolating type consisting of bolted or compression design provided with electrically isolating
joint harness if required to provide pull-out strength] [flexible, integral electrically isolating pipe couplings
designed for field installation by means of a swaging system and providing pull-out strength with a factor of
safety] [nonflexible flanged type electrically isolating pipe joints to be field assembled] [nonflexible factory
assembled electrically isolating pipe joints designed with stub ends for installation by welding and providing
pull-out strength with a factor of safety].
2.4.17.1 Threaded Fittings
Threaded type electrically isolating pipe joints shall have molded plastic screw threads and be used above ground
only. Machined plastic screw threads shall not be used.
2.4.17.2 Electrically Isolating Pipe Joints
Electrically isolating pipe joints shall be of a type that is in regular factory production.
2.4.18 Electrically Conductive Couplings
Electrically conductive couplings shall be of a type that has a published maximum electrical resistance rating
given in the manufacturer's literature. Cradles and seals shall be of a type that is in regular factory production
made for the purpose of electrically isolating the carrier pipe from the casing and preventing the incursion
of water into the annular space.
2.4.19 Joint and Continuity Bonds
Provide bonds across joints or any electrically discontinuous connections in the piping, and other pipes and
structures with other than welded or threaded joints included in this cathodic protection system. Unless otherwise
specified, bonds between structures and across joints in pipe with other than welded or threaded joints shall
be with No. 4 AWG stranded copper cable with polyethylene insulation. Bonds between structures shall contain
sufficient slack for any anticipated movement between structures. Bonds across pipe joints shall contain a minimum
of 100 mm 4 inch of slack to allow for pipe movement and soil stress. Bonds shall be attached by exothermic
welding. Exothermic weld areas shall be insulated with coating compound and approved by the Contracting Officer.
Continuity bonds shall be installed as necessary to reduce stray current interference. Additional joint bonding
shall be done where determined during construction or testing or as directed. Joint bonding shall include excavation
and backfilling. There shall be a minimum of 2 continuity bonds between each structure and other than welded
or threaded joints. Electrical continuity shall be tested across joints with other than welded or threaded joints
and across metallic portions of sewage lift stations and water booster stations.
2.4.19.1 Resistance Bonds
Resistance bonds shall be adjusted for minimum interference while achieving the criteria of protection. Alternate
methods may be used when approved.
2.4.19.2 Stray Current Measurements
Perform stray current measurements as indicated. Alternate methods may be used when approved. The stray current
test report shall indicate location of test, type of pipes tested, method of testing, [_____].
2.4.20 Electrical Isolation of Structures
Isolating fittings, including isolating flanges and couplings, shall be installed above ground or in a concrete
hand hole. As a minimum, isolating flanges or unions shall be provided at the following locations:
a. Connection of new piping to existing pipes.
b. Pressure piping under floor slab to a building.
Additionally, isolation shall be provided between new pipe lines and foreign pipes that cross the new lines within
3 m 10 feet.
2.5 MAGNESIUM ANODES
Weights and dimensions of magnesium anodes shall be approximately as follows:
TYPICAL MAGNESIUM ANODE SIZES
(Cross sections may be round, square, or D shaped)
NOMINAL GROSS
NOMINAL APPROX. WT kg PACKAGED NOMINAL PACKAGE
WT. kg. SIZE (mm) IN BACKFILL DIMENSIONS (mm)
1.4 76 X 76 X 127 3.6 133 X 133 X 203
2.3 76 X 76 X 203 5.9 133 X 133 X 286
4.1 76 X 76 X 356 12.3 133 X 508
5.5 102 X 102 X 305 14.5 191 X 457
7.7 102 X 102 X 432 20.5 191 X 610
14.5 127 X 127 X 521 30.9 216 X 711
22.7 178 X 178 X 406 45.5 254 X 610
TYPICAL MAGNESIUM ANODE SIZES
(Cross sections may be round, square, or D shaped)
NOMINAL GROSS
NOMINAL APPROX. WT LBS PACKAGED NOMINAL PACKAGE
WT. LBS. SIZE (IN) IN BACKFILL DIMENSIONS (IN)
3 3 X 3 X 5 8 5 1/4 X 5 1/4 X 8
5 3 X 3 X 8 13 5 1/4 X 5 1/4 X 11 1/4
9 3 X 3 X 14 27 5 1/4 X 20
12 4 X 4 X 12 32 7 1/2 X 18
17 4 X 4 X 17 45 7 1/2 X 24
32 5 X 5 X 20 1/2 68 8 1/2 X 28
50 7 X 7 X 16 100 10 X 24
2.5.1 Composition
Anode shall be of high potential magnesium alloy, made of primary magnesium obtained from sea water or brine,
and not from scrap metal. Magnesium anodes shall conform to ASTM B 843 and to the following analysis unless
otherwise indicated:
Element Percent by Weight
Aluminum 0.02 maximum
Manganese 1.50 maximum
Zinc 0.05
Silicon 0.10 maximum
Copper 0.02 maximum
Nickel 0.002 maximum
Iron 0.03 maximum
Impurities 0.30 maximum
Magnesium Remainder
Furnish spectrographic analyses on samples from each heat or batch of anodes used on this project.
2.5.2 Packaged Anodes
Provide anodes in packaged form with the anode surrounded by specially prepared quick-wetting backfill and contained
in a cloth or paper sack. Anodes shall be centered in the backfill material. The backfill material shall have
the following composition, unless otherwise indicated.
Material Percent by Weight
Gypsum 75
Bentonite 20
Sodium Sulfate 5
2.5.3 Lead Wires
Anode lead wires shall consist of No. 10 solid copper wire, with TW insulation. Lead wires shall be not less
than 3 m 10 feet in length, without splices.
2.5.4 Connection Wires
Wires shall consist of No. 10 solid copper wire with RHW-USE or polyethylene insulation.
2.5.5 Insulation
Type RHW-USE insulation shall comply with NFPA 70. Polyethylene insulation shall comply with ASTM D 1248; high
molecular weight polyethylene shall be Type I, Class C, Grade E5; high density polyethylene shall be Type III,
Class C, Grade E3.
2.5.6 Conduit Steel
Conduit steel shall conform to UL 6 and NEMA C80.1.
2.5.7 Tape
Pressure-sensitive vinyl plastic electrical tape shall conform to UL 510.
2.5.8 Backfill Shields
Provide shields consisting of approved wrapping of reinforced fiberglass coal-tar impregnated tape, or plastic
weld caps specifically made for the purpose and installed in accordance with the manufacturer's recommendations.
When joint bonds are required, due to the use of mechanical joints, the entire joint shall be protected with
kraft paper joint cover. The joint cover shall be filled with poured hot coal-tar enamel.
2.5.9 Electrical Connections
Electrical connections shall be done as follows:
a. Exothermic welds shall be "Cadweld" or Burndy "Thermo-Weld" or approved equal. Use of these materials
shall be in accordance with the manufacturer's recommendations.
b. Electrical shielded arc welds on steel pipe shall be approved via shop drawing action.
c. Other methods of welding shall be specifically approved for use by the pipe manufacturer.
2.5.10 Anode Installation
Anode configuration and size shall be as indicated. A minimum of [one] [two] [three] [ten] [15] [_____] anodes
are required to achieve minus 850 millivolts "instant off" potential and shall be required on the [_____] components
or structure. Details shown are indicative of the general type of material required and are not intended to
restrict selection of materials or of any particular manufacturer. The anode system shall be designed for a
life of 25 years of continuous operation.
2.6 LEAD WIRE CONNECTIONS
Lead wire to structure connections shall be by exothermic welding process. Weld charges made specifically for
use on cast iron shall be used on cast iron pipe. A backfill shield filled with a pipeline mastic sealant or
material compatible with the coating shall be placed over the weld connection and shall cover the exposed metal
adequately.
PART 3 EXECUTION
3.1 CRITERIA OF PROTECTION
Acceptance criteria for determining the adequacy of protection on a buried [pipe] [tank] shall be in accordance
with [NACE SP0169,] [and] [NACE RP0193,] and as specified below.
3.1.1 Iron and Steel
NOTE: If the second method is used, the requirement for obtaining measurements
over 95 percent of the entire metallic area is required as in the first method.
Verification of the 100 millivolts decay of polarization should be achieved
at points over 95 percent of the entire metallic area.
Use the following method a. for testing cathodic protection voltages. If more than one method is required, use
method b.
a. A negative voltage of at least minus 850 millivolts as measured between the [pipe] [tank] [specified
underground component] and a saturated copper-copper sulphate reference electrode contacting the (electrolyte)
earth directly over the [pipe] [tank] [specified underground component]. Determination of this voltage
shall be made with the cathodic protection system in operation. Voltage drops shall be considered for
valid interpretation of this voltage measurement. A minimum of minus 850 millivolts "instant off" potential
between the [structure] [pipe] [tank] [specified underground component] being tested and the reference
cell shall be achieved over 95 percent of the area of the structure. Obtain adequate number of measurements
over the entire structure, pipe, tank, or other metallic component to verify and record achievement of
minus 850 millivolts "instant off". This potential shall be obtained over 95 percent of the total metallic
area without the "instant off" potential exceeding 1200 millivolts.
b. A minimum polarization voltage shift of 100 millivolts as measured between the [pipe] [tank] and
a saturated copper-copper sulphate reference electrode contacting the earth directly over the [pipe]
[tank]. This polarization voltage shift shall be determined by interrupting the protective current and
measuring the polarization decay. When the protective current is interrupted, an immediate voltage shift
will occur. The voltage reading, after the immediate shift, shall be used as the base reading from which
to measure polarization decay. Measurements achieving 100 millivolts shall be made over 95 percent of
the metallic surface.
3.1.2 Aluminum
Aluminum [pipes] [tanks] shall not be protected to a potential more negative than minus 1200 millivolts, measured
between the [pipe] [tank] and a saturated copper-copper sulphate reference electrode contacting the earth, directly
over the [pipe] [tank] [metallic component]. Resistance, if required, shall be inserted in the anode circuit
within the test station to reduce the potential of the aluminum [pipe] [tank] to a value which will not exceed
a potential more negative than minus 1200 millivolts. Voltage shift criterion shall be a minimum negative polarization
shift of 100 millivolts measured between the [pipe] [tank] [metallic component] and a saturated copper-copper
sulphate reference electrode contacting the earth, directly over the [pipe] [tank]. The polarization voltage
shift shall be determined as outlined for iron and steel.
3.1.3 Copper Piping
For copper piping the following criteria shall apply. A minimum of 100 millivolts of cathodic polarization between
the structure surface and a stable reference electrode contacting the electrolyte. The polarization voltage
shift shall be determined as outlined for iron and steel.
3.2 GROUND BED INSTALLATION
3.2.1 Shallow Ground Beds
Shallow ground beds shall contain size and quantity of anodes designed to meet performance criteria of the cathodic
protection system at an initial operating current output density not exceeding [40] [50] [70] percent of maximum
recommended current output density.
3.2.1.1 Horizontally Buried Bare Anodes
Horizontally buried bare anodes shall be bedded on and covered with metallurgical coke breeze in a trench excavated
for the purpose at depths, spacing and locations as shown. Anodes shall be completely surrounded by the backfill
at bottom, sides, and top for a distance of not less than 100 mm 4 inch. Backfill shall be compacted.
3.2.1.2 Vertically Buried Bare Anodes
Vertically buried bare anodes shall be installed in vertical holes in the ground having a depth, spacing, and
location shown. The holes in the ground shall be sufficiently large to provide an annular space around the anode
not less than 100 mm 4 inch. The anodes shall be centered in the hole and backfilled with calcined petroleum
coke breeze or metallurgical coke breeze. Backfill shall be compacted.
3.2.1.3 Horizontally Buried Canister-Contained Anodes
Horizontally buried canister-contained anodes shall be buried in a trench excavated for the purpose at depths,
spacing, and locations shown.
3.2.1.4 Vertically Buried Canister-Contained Anodes
Vertically buried canister-contained anodes shall be installed in vertical holes in the ground having depth,
spacing, and locations shown. The holes in the ground shall be sufficiently larger in diameter than the canisters
to facilitate easy lowering into the hole and backfilling. The space between the canister and the wall of the
hole shall be completely backfilled with a wet slurry of earth free of stones.
3.2.1.5 Cable Protection
Positive cable to the ground bed and negative cable to the [pipe] [tank] to be protected shall be buried a minimum
depth of 750 mm 30 inch except where above ground construction utilizing conduit is used.
3.2.1.6 Multiple Anode Systems
Multiple anode systems shall consist of groups of anodes connected in parallel to a header cable, buried in the
ground at depths, spacing, and locations shown. The anodes shall be buried [horizontally] [vertically].
3.2.1.7 Distributed Anode Systems
Distributed anode systems shall consist of a line or row of anodes connected in parallel to a header cable and
buried in the ground parallel to the pipeline. The anodes shall be at the pipeline at depths, spacing, and locations
shown. The anodes shall be buried [horizontally] [vertically].
3.2.2 Deep Anode Ground Beds
Deep anode ground beds shall consist of an installation of anodes supported one above the other and supported
in place by a method that does not suspend the anodes from the connecting cable. Deep anode ground beds shall
be installed in accordance with NACE SP0572 and as specified in these specifications.
3.2.2.1 Anode Centering
Anodes shall be centered in the well by means of centering devices.
3.2.2.2 Casing
The casing shall be to a depth and elevation of not more than [_____] m feet.
3.2.2.3 Casing Insulation
The portion of casing above the top anode shall be coated with an electrically insulating underground type coating.
3.2.2.4 Anode Requirements
Anode sizes, spacing, number of anodes, depth of well, and other details shall be as shown.
3.2.2.5 Anode Lead Wire
Each anode shall have a separate, continuous wire extending from the anode to the junction box at the well head.
3.2.2.6 Anode Cables
Anode cables shall terminate in a nearby junction box, equipped with individual anode current shunts. Where
full length casing is used, two wire connections from casing shall terminate in the junction box.
3.2.2.7 Anode and Cable Installation
If the method of installation utilizes backfill support for anodes and cable, provide slack in the cable near
each anode and increase the cable insulation in thickness from 2.8 to 4.0 mm 7/64 to 5/32 inch utilizing an approved
composite of plastic and elastomeric materials.
3.2.2.8 Backfill
Backfill the well with calcined petroleum coke breeze or metallurgical coke breeze surrounding the anodes by
a method that does not leave voids or bridging. The recommended method is to pump the backfill from the bottom
upward. The well shall be over-filled with coke breeze allowing for settlement so that the settled level after
a number of days is as high as the level shown. The number of days allowed for settling of the coke breeze will
be determined by the Contracting Officer. If the top level of coke breeze is below the level shown after settlement,
put additional coke breeze in the well. The backfill used shall not require tamping. The top portion of the
well shall be sealed for 8 m 25 feet to prevent surface water run-off. All vents shall be vented above the high
water mark and at a safe height.
3.2.2.9 Cable Marker Tape
Locate traceable marker tape in the same trench above cathodic protection cables including structure leads, anode
leads, anode header cables, test station leads, bonding cables, and rectifier electrical power cables.
3.2.2.10 Pavement Inserts
Install pavement inserts at a minimum of 30 m 100 foot intervals for pipelines. The pavement inserts shall be
installed directly over the structure being protected and tested.
3.3 MAGNESIUM ANODE INSTALLATION
Installation shall not proceed without the presence of the Contracting Officer, unless otherwise authorized.
Anode locations may be changed to clear obstructions when approved. Install anodes in sufficient number and
of the required type, size, and spacing to obtain a uniform current distribution surface on the structure. Prepackaged
anodes shall be installed as shown on the drawings.
3.3.1 Installation of Packaged Anodes
Install packaged anodes completely dry, lower them into holes by rope sling or by grasping the cloth gather.
The anode lead wire shall not be used in lowering the anodes. Backfill the hole with fine soil in 150 mm 6 inch
layers and each layer shall be hand-tamped around the anode. The tamper shall not strike the anode or lead
wire. If immediate testing is to be performed, add water only after backfilling and tamping has been completed
to a point 150 mm 6 inch above the anode. Approximately 8 L 2 gallons of water shall be poured into the hole;
after the water is absorbed by the soil, backfilling and tamping shall be completed to the top of the hole.
Anodes shall be installed as shown. When rock is found prior to achieving specified depth, anode may be installed
horizontally to a depth at least as deep as the bottom of the pipe, with the approval of the Contracting Officer.
3.3.2 Underground Metal Pipe Line
Install anodes 610 mm 2 feet below the line to be protected unless otherwise noted on the drawings. To facilitate
periodic electrical measurements during the life of the sacrificial anode system and to reduce the output current
of the anodes if required, anode lead wires in a single group of anodes shall be buried a minimum of 610 mm 2
feet and each anode lead wire shall be connected to an individual terminal in a test station. The anode lead
cable shall make contact with the structure only through a test station. Resistance wire shall be installed
between the anode lead cable and the pipe cable in the test station to reduce the current output, if required.
3.3.3 Lead and Resistance Wire Splices
Lead wire splicing, when necessary, shall be made with copper split bolt connectors of proper size. The joint
shall be carefully wrapped with at least 3 layers of electrical tape. Resistance wire connections shall be done
with silver solder and the solder joints wrapped with a minimum of 3 layers of pressure-sensitive tape.
3.3.4 Magnesium Anodes for Metallic Components
As a minimum, each metallic component shall be protected with [2] [_____] [4.1] [7.7] [_____] kg [9] [17] [_____]
lb magnesium anodes located on each side of the metallic component and routed through a test station. Fire hydrant
pipe component shall have a minimum of [2] [3] [_____] [4.1] [7.7] [_____] kg [9] [17] [_____] lb magnesium anodes
routed through a test station for each hydrant. Pipe under concrete slab shall have a minimum of [5] [_____]
[7.7] [_____] kg [17] [_____] lb anodes for each location where metal pipe enters the building under the slab.
A permanent reference cell shall be provided adjacent to the pipe entrance to the slab. Conductors shall be
routed to a test station. Each valve shall have a minimum of [2] [_____] [4.1] [_____] kg [9] [_____] lb magnesium
anodes routed through a test station. Sections of metallic pipe 6.1 m 20 foot long, when used where force mains
are within 3 m 10 feet of the water pipe, shall have a minimum of [4] [_____] 7.7 kg 17 lb anodes.
3.4 MISCELLANEOUS INSTALLATION
NOTE: The cathodic protection system will fail unless full engineering considerations
are applied to selection, location and installation of electrically conductive
joints and electrically isolating joints including the use of underground type
dielectric coatings (not paint).
Adequate electrical conductivity of a pipe joint made by means other than welding
should be determined by the "corrosion expert". Allowable electrical resistance
depends on the cross sectional area of the pipe metal, the resistivity of the
pipe metal, and the effectiveness of the coating on the pipe. Effectively coated
pipe underground requires only a fraction of the electrical conductivity at
joints needed for bare pipe. Shop painted pipe is considered to be the same
as bare pipe and is not to be confused with pipe coated with an underground
type dielectric coating.
The type of electrical isolating pipe joint to be used requires engineering
design consideration. In general, the dielectric parts of an isolating joint
will not withstand structural or environmental stresses as well as an all-metal
type of joint. If the pipe on the cathodic protected side of the underground
electrically isolating pipe joint, including the joint, is not effectively coated,
interference type corrosion may occur unless other measures are taken. Factors
to be considered include:
a. Deflection stresses
b. Pull-out stresses
c. Expansion-contraction due to temperature changes
d. Is function as a union necessary?
e. Is field assembly of critical parts practical?
f. Hazardous locations to be avoided
g. Accessibility if above ground
h. Location of test box if below ground
i. Importance of coating the adjacent pipe if below ground
j. Vulnerability to short circuiting
Factor of safety on pull-out strength required has to be engineered for the
specific conditions involved since no blanket provisions are fully applicable
to all cases. The requirement for isolating flanges or couplings should be
based on a study of the conditions. If the new piping is a short extension
to an existing old piping system not under cathodic protection, an isolating
fitting should be installed at the point of connection, since the new piping
will be anodic to the older system. If the older system is under cathodic protection,
no isolating fitting should be used.
3.4.1 Rectifier Installation
Mounting shall be as shown. [Pole or wall mounting shall be equipped with a channel bracket, lifting eyes, and
a keyhole at the top.] [Cross-arm brackets shall accommodate a 102 by 102 mm 4 by 4 inch cross-arm.]
3.4.2 Wire Connections
3.4.2.1 Wire Splicing
NOTE: In water tanks, split bolts are used (above the water line only) because
working space is limited and the hydraulic or mechanical compression tools may
be cumbersome and hazardous to use; since a single split-bolt will work loose
when the wires it connects are moved, a minimum of two split bolts should be
used. At ground level or in trenches, compression tools can be used conveniently,
and the swaged sleeve connection produced by such tools is more reliable than
split bolts.
Connecting wire splicing shall be made with copper compression connectors or exothermic welds, following instructions
of the manufacturer. Split-bolt type connectors shall not be used.
3.4.2.2 Steel Surfaces
Connections to [ferrous pipe] [metal tanks] shall be made by exothermic weld methods as manufactured by an approved
manufacturer for the type of [pipe] [tank]. Electric arc welded connections and other types of welded connections
to ferrous pipe and structures shall be approved before use.
3.4.3 Pipe Joints
NOTE: This paragraph will be coordinated with and referenced in mechanical
and electrical specifications.
3.4.3.1 Electrical Continuity
Underground pipe shall be electrically continuous except at places where electrically isolating joints are specified.
Pipe joined by means other than welding shall meet the following electrical continuity requirements:
a. Mechanical joints that are not factory designed to provide electrical continuity shall be bonded
by installing a metallic bond across the joint. The bonding connections shall be made by the exothermic
welding process.
b. Mechanical joints designed to provide electrical continuity may be used.
3.4.3.2 Electrical Isolation of Structures
Perform electrical isolation of structures as follows:
a. Isolating Fittings: Isolating flanges and couplings shall be installed aboveground, or within manholes,
wherever possible, but an isolating device that electrically separates a pipeline shall not be installed
in a confined area where a combustible atmosphere may collect unless precautions are taken to prevent
arcing such as by means of externally located surge arresters, grounding cells, or other means. Isolating
flanges and couplings in lines entering buildings shall be located at least 300 mm 12 inch above grade
or floor level. Pipelines entering buildings either below or above ground shall be electrically isolated
from the structure wall with an electrically isolating [gas tight wall sleeve.] [wall sleeve.]
b. Gas Distribution Piping: Electrical isolation shall be provided at each building riser pipe to the
pressure regulator, at all points where a short circuit to another structure or to a foreign structure
may occur, and at other locations as indicated.
c. [Steam] [High Temperature] [Chilled] [Water] [Line Supply and Return Piping] [Line Conduit]: Electrical
isolation shall be provided at each building entrance, and at other locations as indicated.
d. [Fuel] [Gasoline] [Storage Tanks] [Fire Suppression] [_____]: Electrical isolation shall be provided
in each pipe [at the building] [at the tank] as shown.
e. Copper Piping: Copper piping shall be [electrically isolated at both ends of the pipe run] [wrapped
with pipeline tape and electrically isolated at both ends].
f. Underground Storage Tanks (UST): Tanks shall be electrically isolated from other metallic structures.
Components protected with the tank such as pipes, vents, anchors, and fill pipes shall be bonded to the
tank.
3.4.4 Dissimilar Metals
NOTE: This paragraph will be coordinated with and referenced in mechanical
and electrical specifications.
Buried piping of dissimilar metals including new and old steel piping, excepting valves, shall be electrically
separated by means of electrically insulating joints at every place of connection. The insulating joint, including
the pipes, shall be coated with an underground type dielectric coating for a minimum distance of 10 diameters
on each side of the joint.
3.4.5 Ferrous Valves
Dissimilar ferrous valves in a buried ferrous pipeline, including the pipe, shall be coated with an underground
type dielectric coating for a minimum distance of 10 diameters on each side of the valve.
3.4.6 Brass or Bronze Valves
Brass or bronze valves shall not be used in a buried ferrous pipeline.
3.4.7 Metal Pipe Junction
If the dissimilar metal pipe junction, including valves, is not buried and is exposed to atmosphere only, the
connection or valve, including the pipe, shall be coated with an underground type dielectric coating for a minimum
distance of 3 diameters on each side of the junction.
3.4.8 Casing
NOTE: This paragraph will be deleted if mechanical and electrical specifications
include these requirements.
Where a pipeline is installed in a casing under a roadway or railway, the pipeline shall be electrically isolated
from the casing, and the annular space sealed against incursion of water.
3.4.9 Test Stations
Test stations shall be of the type and location shown and shall be [curb box] [post] mounted. Buried electrically
isolating joints shall be provided with test wire connections brought to a test station. Changes in designated
location shall have prior approval. Unless otherwise shown, other test stations shall be located as follows:
a. At 300 m 1,000 foot intervals or less.
b. Where the pipe or conduit crosses any other metal pipe.
c. At both ends of casings under roadways and railways.
d. Where both ends of an insulating joint are not accessible above ground for testing purposes.
3.5 TRAINING COURSE
Conduct a training course for the operating staff as designated by the Contracting Officer. The training period
shall consist of a total of [16] [_____] hours of normal working time and shall start after the system is functionally
completed but prior to final acceptance tests. The field instructions shall cover all of the items contained
in the operating and maintenance instructions, as well as demonstrations of routine maintenance operations, including
testing procedures included in the maintenance instructions. At least 14 days prior to date of proposed conduction
of the training course, submit the training course curriculum for approval, along with the proposed training
date. Training shall consist of demonstration of test equipment, providing forms for test data and the tolerances
which indicate that the system works satisfactorily.
3.6 TESTS AND MEASUREMENTS
3.6.1 Baseline Potentials
Each test and measurement will be witnessed by the Contracting Officer. Notify the Contracting Officer a minimum
of 5 working days prior to each test. After backfill of the [pipe] [tank] [_____] and anodes is completed, but
before the anodes are connected to the [pipe] [tank] [_____], the static potential-to-soil of the [pipe] [tank]
[_____] shall be measured. The locations of these measurements shall be identical to the locations specified
for [pipe-] [tank-] [_____] to-reference electrode potential measurements.
3.6.2 Isolation Testing
Before the anode system is connected to the [pipe] [tank] [_____], an isolation test shall be made at each isolating
joint or fitting. This test shall demonstrate that no metallic contact, or short circuit exists between the
two isolated sections of the [pipe] [tank]. Any isolating fittings installed and found to be defective shall
be reported to the Contracting Officer.
3.6.2.1 Insulation Checker
Use a Model 601 insulation checker, as manufactured by ["Gas Electronics"] [_____] [or] [an approved equal],
for isolating joint (flange) electrical testing in accordance with anufacturer's operating instructions. An
isolating joint that is good will read full scale on the meter; if an isolating joint is shorted, the meter pointer
will be deflected at near zero on the meter scale. Location of the fault shall be determined from the instructions
and the joint shall be repaired. If an isolating joint is located inside a vault, the pipe shall be sleeved
with insulator when entering and leaving the vault.
3.6.2.2 Cathodic Protection Meter
Use a Model B3A2 cathodic protection meter, as manufactured by ["M. C. Miller"] [_____] [or] [an approved equal]
using the continuity check circuit for isolating joint (flange) electrical testing. Perform this test in addition
to the Model 601 insulation checker. Continuity is checked across the isolated joint after the test lead wire
is shorted together and the meter adjusted to scale. A full scale deflection indicates the system is shorted
at some location. The Model 601 verifies that the particular insulation under test is good and the Model B3A2
verifies that the system is isolated. If the system is shorted, further testing shall be performed to isolate
the location of the short.
3.6.3 Anode Output
After the rectifier is energized, the current output of the individual anode leads shall be measured by using
an approved method. This may be done with a shunt and MV meter, a low-resistance ammeter, or a clamp-on milliammeter.
The total current shall be measured and compared to the sum of all anode currents and to the rectifier output
current. If an individual anode output current meets or exceeds the recommended output for that anode, the system
shall be turned down or balancing resistors installed. Calculation of the wattage of the resistors shall be
sufficient to handle the maximum load which will be encountered on the anode lead. All measurements obtained,
the date, time, and locations of all measurements shall be recorded.
3.6.4 Electrode Potential Measurements
Upon completion of the installation and with the entire cathodic protection system in operation, electrode potential
measurements shall be made using a copper-copper sulphate reference electrode and a potentiometer-voltmeter,
or a direct current voltmeter having an internal resistance (sensitivity) of not less than 10 megohms per volt
and a full scale of 10 volts. The locations of these measurements shall be identical to the locations used for
baseline potentials. The values obtained and the date, time, and locations of measurements shall be recorded.
No less than 8 measurements shall be made over any length of line or component. Additional measurements shall
be made at each distribution service riser, with the reference electrode placed directly over the service line.
3.6.5 Location of Measurements
3.6.5.1 Coated Piping or Conduit
For coated piping or conduit, take measurements from the reference electrode located in contact with the earth,
directly over the pipe. Connection to the pipe shall be made at service risers, valves, test leads, or by other
means suitable for test purposes. Pipe to soil potential measurements shall be made at intervals not exceeding
[0.75] [1.5] [122] [_____] m [2.5] [5] [400] [_____] feet. The Contractor may use a continuous pipe to soil
potential profile in lieu of 0.75 m 2.5 ft interval pipe to soil potential measurements. Additional measurements
shall be made at each distribution service riser, with the reference electrode placed directly over the service
line adjacent to the riser. Potentials shall be plotted versus distance to an approved scale. Locations where
potentials do not meet or exceed the criteria shall be identified and reported to the Contracting Officer.
3.6.5.2 Underground Tanks
For underground tanks, make a minimum of three measurements taken from the reference electrode located:
a. Directly over the center of the tank.
b. At a point directly over the tank and midway between each pair of anodes.
c. At each end of the tank.
3.6.6 Casing Tests
Before final acceptance of the installation, the electrical separation of carrier pipe from casings shall be
tested and any short circuits corrected.
3.6.7 Interference Testing
NOTE: Adverse effects may be caused by the foreign pipeline.
Before final acceptance of the installation, interference tests shall be made with respect to any foreign [pipes]
[tanks] in cooperation with the owner of the foreign [pipes] [tanks]. A full report of the tests giving all
details shall be made.
3.6.8 Holiday Test
Repair any damage to the protective covering, during transit and handling, before installation. After field
coating and wrapping has been applied, inspect the entire pipe by an electric holiday detector with impressed
current in accordance with NACE SP0188 using a full ring, spring type coil electrode. The holiday detector shall
be equipped with a bell, buzzer, or other type of audible signal which sounds when a holiday is detected. Holidays
in the protective covering shall be repaired upon detection. Occasional checks of holiday detector potential
will be made by the Contracting Officer to determine suitability of the detector. Furnish labor, materials,
and equipment necessary for conducting the inspection. Inspect the coating system for holes, voids, cracks,
and other damage during installation.
3.6.9 Recording Measurements
Record all [pipe-] [tank-] to-soil potential measurements including initial potentials where required. Locate,
correct and report to Contracting Officer any short circuits to foreign [pipes] [tanks] [_____] encountered during
checkout of the installed cathodic protection system. [Pipe-] [Tank-] [_____] to-soil potential measurements
are required on as many [pipes] [tanks] [_____] as necessary to determine the extent of protection or to locate
short-circuits.