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Company •

• Corrosion and Cathodic Protection Phenomena

·-

• KAR PIRA KAVIR COMPANY

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Corrosion and Cathodic Protection Phenomena

1.1. Corrosion

Corrosion is the gradual destruction of materials (usually metals) by chemical reaction with its

environment.

In the most common use of the word, this means electrochemical oxidation of metals in reaction

with an oxidant such as oxyg;en. Rusting, the formation of iron oxides is a well-known example

of electrochemical corrosion. This type of damage typically produces oxide(s) or salt(s) of the

original metal. Corrosion can also occur in materials other tlhan .metals, such as ceramics or

polymers, althtough in this context,

the term degradation is more common.

Corr-osion degrades

the useful properties of materia Is and

structures inc luding strength,

appearance and permeability

Many structural alloys corrode merely from exposure to mo~sture in air, but the process ·can b·e

strongly affecte·d by exposure to certain substances. Corrosion can be concentrated locally to

form a pit or crack, or it can extend ~cross a wide area more or less uniformly corroding th.e

surface. Because corrosion is a diffusion-controlled process, it occurs on e·xposed surfaces.

As a resutt, methods to reduce the activity of the exposed surface, such as passivation and

chromate conversion, can increase a material's corrosion resistance. However, some

corrosion mechanisms are less visible and less predictable

1.2. Cathodic protection

Cathodic protection (CP) is a technique to control the corrosion of a metal surface by

making that surface the cathode of an el-ectrochemical cell. Cathodic protection systems

are most commonly used to protect steel, water, and fuel pipelines and tanks: steel pier

piles, ships. and offshore oil platforms.

1.2.1. Sacrificial anode protection

For effective C P, the potential of the steel surface is polarized (pushed) more negati ve

until the metal surface has a uniform potential. With a uniform potential, the. dr]ving force

for the conosion reaction is halted.

For galvanic CP systems, the anode

material corrodes under the influence

of the steel, and eventually it must be

replaced. The polarization is caused

by the current flow from the anode to

the cathode, driven by the difference

in electrochemical potential between

the anode and the cathode.

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KAR PIRA KAVIR COMPANY

1.2.2. 1mpressed current cathodic protection

For larger structures, galvanic anodes cannot economically deliver enough current to provide

complete protection. Impressed current cathodic protection (ICCP) systems use anodes

connected to a DC power source (such as a cathodic protection rectifier). Anodes for ICCP

sys~ems are tubular and solid rod shapes of various specialized materials. These include high

silicon cast iron, graphite, mixed metal oxide or platinum coated titanium or niobium coated

rod and wires.

Impressed Current Cathodic Protection

Karplra Kavir Company ·~·········· · .-············~·················· · ·'"


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2.1.Transformer Rectifier

Specification:

The transformer-rectifier will be composed of:

• An input unit.

• A regulating unit of the output voltage.

• Intelligent adjustment with reference electrod.e.

• Output option in constant Voltage, constant current and reference electrode.

• Step-down transformer.

• The measuring instruments.

• Full bridge- full control.

• The electric protection devices.

• Accessories.

All these equipment will be mounted inside a metallic cubicle, suitable for indoor/outdoor

installation.

Working Conditions:

• The oilimmersed transformer-rectifiers will be designed to meet the cathodic p rotection

requirements.

• A.C Supply: 380+10% V three phase 50 Hz, single phase 50 Hz 220 V DC Output: adapted to

requirement

Cooling:

The regulation unit, the step-down transformer and the bridge diodes will be oil-immersed in a

special tank formingthe interior part of the T/Rectifier.

Location: The transformer-rectifiers will be suitable for indoor and outdoor installation, in nonHazardou:s areas.

Cubicle :The transformer-rectifier equipment will contain two parts in a c.ubicle composed of:

• An oil tank where the step-down transformer, the regulating. unit and the bridge rectifier wil l

be located.

• A control unit fixed on the oil tank with all commands, Electrical circuits, measuring instruments, protective devices, fuses and terminals.

The cubicle will be:

• Waterproof and dustproof.

• Designed for mounting on a concrete plinth.

• Fitted with a hinged lockable door.

• Externally painted with two layers of ant irust undercoat and one final layer of pairit suitable

with the specified environment.

Input Unit:

• The trarnsformer-rectifiers will be connected through ON/OFF fuses -switch lockable either in ON or OFF position.

• The power outage and the insulation wil l be conforming to the IEC standard.

Output Regulation Device:

• Output regulation device sha II be provided to allow for a load variation of the output. The variation can be done incontinues method by manual volumes. Manual regulation control shall be easily accessible on control panel.

Bridge Rectifier:

• The bridge rectifier will be of SCR which reverse tension must be of 1200 V as mirnimum.

Measuring Instruments:

• The measuring instruments will be having built- in type, different dimensions.

• The range of measuring instruments will be such that the maximum working value is indicated at 70% of fu ll scale deflection.

• The ammeter will mounted in parallel to a calibrated to a suitable shunt.

• The voltmeter will be protected withsuitable fuses.

• A red line will indicate the maximum output value. The measuring instruments will be located inside thecontrol part of T/R cubicle in front face.

Electrical Protection Devices:

• Against Over Voltages

Resistance capacitor circuit will be connected in parallel to the bridge rectifier. An arrester will be connected between thie plus and minus poles of the TJRectifier.

• Against Over intensities

Ultra-fast fuses suitably dimensioned in 12.t will protect the A.C. and D.C. circuits.

• Personnel Safety

PVC caps will avoid direct contact with the different poles and instruments.

• Earthing

All metallic parts will be electrically continuous and one earthing terminal will allow their cGnnection to an externalcircuit.

• Accessories:

The transformer- rectifiers wi ll be supplied complete with all necessary accessories for installation, control and operation.

• Oil control

The oil tank part will be fitted with a dial thermometer calibrated. in degree centigrade and located in a pocket at thenormal oil level. The oil level inside the tank will be controlled tanks to a sight glass gauge externally locateq in thefront of the cubicle whic.h will be protected against the shocks py a hinged flipper marked "LEVEL"

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Fittings

For handling, two lifting rings will be foreseen at the top of the cubicle.To maintain a dry

atmosphere in the T/Rectifier, an external and removable silicagel cartridgewill be mounted on the

tank inside the control part. For incoming and outgoing cables, weatherproofpacking glands wil! be

foreseen j ust in front of the terminals on the control part.

Time Switch:

This equipment is intended to measure interferences between two pi:pelines catholically protected

or not and coatingresistance value of the pipeline.The time switch Will be composed of:

Two adjustable time relays. a selector switch connected to the mains supply. The time switch will

enable a continuouscycle of 2 minutes ON and 3 minutes OFF. It wiU be dimensioned according to

the T/R characteristics.

Factory Tests:

The transformer - rectifiers will be tested according to the IEC standards tests method. The

following routine testisshall be carried out on each unit.

Measurement of inherent regulation.

Insulation test.

Power loss measurement.

Power faction measurement.

Temperat1,1re rise test.

Load test at different steps.

Ratio and polarity test.

For type tests, factory test report may be

acceptable.

Ultra-fast fuses suitably dimensioned in

12.t will protect the A.C.and D.C. circuits.

High silicon Iron Anode

Silicon iron anodes are designed for the effective protection of steel structures and pipelines

from corrosion by the impressed current method. They are manufactured from lhigh si licon

cast Iron alloy, one of the most important anode materials used by the corrosion engnneer to

protect steel in a variety of situations. Three types of this anode are available, according to

standard ASTM A518 M.

Chemical Composition

Chemical Composit ion (WI%) Grade

c Si Cr Mo Cu Mn Fe

1 0.65-1.1 14.20-14.75 0.5 Max 0.5 Max 10.5 Ma.x 1.5 Max. Reminder

2 0.75-1.15 14.20-14.75 3.25-5.0 0.4·0.6 0.5 Max 1.5 Max. Remin der

3 0.7-1.1 14.20-14.75 3.25-5.0 0.2 Max 0.5 Max 1.5 Max. Reminder

Consumption Rate

EnvironmentCurre nt DensityAIM2 Consumption Rate Kg/A. Year

Fres.h Water 10 IU1

Sea Water 15 0.31

Sea Water 200 F 10 G.41

Buried Sea Water/Sand 8 0.68

Carbonaceo us Backfill 15 ().1 ww w . kapfk aco . co m

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• Physical Property of Silicon Iron

Properties Unit Re quire ment Test Method (ASTM)

Density glcm3 7-7.05 Approved Method

Hardness (Min) HB 500 E 10

Compressive Sirength (Min) Mpa 650 A256

Electrical Resistivity (Max) ..,rl.cm 72 B 193

Impact Resistance (Min) J 0.1 A 327 (Charpy Type)

Silicon Iron anodes are cast in several shapes and size to meet a variety of requirements.

The following table shows details of the lfange available.

• Size of Anode:

Rod Type

Diameter (mm) Head Diameter(mm) Lengh (mmJ Net Weight (kg)

51 76 915 14.5

51 76 1220 19

51 76 1525 22.5

76 102 915 29

76 102 1220 38

76 102 1525 49

• Tubular Type

Inside Oiameter(mm) Outside Diameter(mm) Thickness Lengtlil Net Weight (mm) (mm) (kg)

67 47 10 1067 14

56 ~6 10 2134 21

67 47 10 2134 29

95 75 10 2134 39

121 100 10 2134 50

121 86 17 2134 79

• Anode Cap

Anode caiPS may be factory fitted to cabled anodes. They are designed to counteract, and

effect, when single end anode connections are specified. The caps have protective

polymeric lining capable of withstanding corrosive environmental conditions including

chlorine and Sulphate attack.

They are manufactured from cross-linked polyethylerne and shrink fitted over the anode. The dielectric strength of the end caps is 10 kV per mm.

2.1 Mixed Metal Oxide (MMO)Anode

Mixed Metal Oxide Ribbon Anodes (Protection For Above Ground Tank Bottoms)

Cathodic protection is an economical method for controlling corrosion on aboveground stora·ge tank bottoms. While sacrificial systems can be used, impressed current designs have proven to be more cost effective and easier to install. The anodes are composed of a titanium ribbon substrate coated with a mixed metal oxide catalyst. Because the titanium Sl.!lbstrate. is naturally passivized by :an oxidizing film, the ribbon anode remains dimensionally stable over time. Direct current transfer is accomplished through the mixed metal oxide catalyst which is highly conductive, and fully oxidized so that higher current outputs are possible.

This two part composition allows for a

maximum current density of S.OmA/ft to

achireve a 50- 100 year design life. Spacing

between the metal anode strips can be

adjusted to achieve var'ious design life

requirements. The anodes can also be easily

cut so that placement may be made under all

areas of the tank. Because the strips are

electrically continuous, multiple paths ar.e

avairlable for current flow. This in turn lowers

the driving voltage required for protection, and

provides the anode with redundant electrical

connections for increaseq reliability. Greater

dependability is also achieved throug,h the

elim ination of fie ld splices.

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Mixed metal oxide rilbbon anodes are designed for use on both newly constructed aboveground storage tanks with

secondary containment liners, and existing tanks utilizing

double bottom construction. Unlike other umpressed current tank bottom anodes, ribbon anodes do not require

coke breeze. Tlhey can be used in sand with various levels

of moisture and salt content, and can be designed to provide effective protection for 50 years or more.

Chemical Composition

Substrate

AST.M B-265 Grade 1 Titanium

Catalyst

Nominal Dir:llensi6ris

Component Width Thickness

Inch mm Inch

Anode Ribbon 0.25 6.4 0.025

Anode Ribbon J.5 12.7 0.025

Conductor Bar 0.5 12.7 0.40

Mixed Meta I Oxide Tubular Anodes (Dimensionally Stable in All Environments)

mm

0.6

0.6

1.0

To obtain the highest level of protection from an impressed currentcatlilodic protection system, you need

an anode with a ve.ry low consumption rate and high current capacity. With tUbular mixed metal oxide line

of anodes, you get powerful protection.and unsurpassed stability. The anodes are made using tubular titanium substrates which are coated with a mixed metal oxide catalyst.

The catalyst is thermally applied to the titanium to form an extremely chemical resistant bond. This

special composition brings together the stability of titanium with the consuctive properties of the mixed

metal oxide catalyst to achieve supe_rior performance. In soil and fresh water applicattions, the anodes

have a recommended c;urrent density approximately 100Amp/m:!, and can be operated over 500Amp/

m2in sea water environments. Even at these relatively high drscharge levels, the anodes will be

consumed at less than 1.0 mg/A.year.

The tubular design of these anodes also

allows for numerousperformance benefits.

The tubular configuration provides a larger

surface area which in turn permits greater

current output and lower anodetoearthe

resistance.

The tubular style also means lead wire

connections can be made in the center of

the anode . With tupular anodes, th is

connection consists of a brass wedge

connector which grips firmly to the internal

circumference ofthe anode.

This connectio·n is protected from moisture

intrusion by a waterproofing sealant which

fills the entire anode tube. One end of the

anode is then covered with shrink tubing

for a comp letely sealed electrical

connection. Anodes are then tested for

quality assura111ce.

Standard Dimension and Shipping Weughts

Nominal Dimension Nominal Weight

Anode Type Diameter Length Bare Packaged

Inch mm Inch mm oz/ft g/m lbs kg

KPKG1 0.75 10.1 2.0 610 3.4 314 23 2.6

KPK02 0.75 19.1 4.0 1219 3.4 317 25 18 .. f

KPK 03 1.0 25.4 3.3 1000 3.8 351 25 11.4

KPK04 1.25 31 .8 4.0 1219 3.8 538 27 12.3

Based on 20 year design life in calcined petroleum grade <coke

Current Rating*

Am per

10.5

16.9

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Coke Breeze.2.1

Coke breeze is used for backfill in vertical, horizontal and well ground bed.

Advantages of backfill are:

Preventing from direct contact anode with soil (a

Increase anode dimen sion to decrease anode resistance (b

Decreasing resistively around anode (c

Providing uniform envirohmenl around anode {d

Physical Property of Silicon Iron

Properties of coke Type 1

Carbon Content (%Min.) 80

Moisture Content (%Max.) 5

Ash Content (%Max.) 15

Sulphur Content (%Max.} 1

Volatiles Content (%Max.) 5

Type 2

90

5

5

5

5

TypeS.

95

1

3

1

1

Density (l(g/m') 65<J.a00 700-1100 1050-1200

Type1 Less than 10mm 100%

Greater than 1 mm 90%

Typo 2 Loss thon 3 mm 100%

Greater lhar'i 0.5 mm 90%

Type 3 Less than 1.0 mm 100%

Less than 0.6 mm 80%

Greater than 0.4 mm 90%

Greater than 0. ' 5 99%

mm

Sacrificial Anode Cathodic Protection

Karp ira Kavir Company .................. , ...•....•........•.


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Magnesium anodes are used seldom in cathod rc protection with more than 10 years life design.

These anodes are not used in soils with high resistivity because drain of necessary current density

needs large amount of magnesium and it is not economic.

These are used wher:~ necessary current is low, soil

has low resistivity, and or when input current source

for transformer rectifier is not available.

Magnesium anodes have an advantage and it is

better and simpler current distribution than

impressed current system due to current drain in

small field .

There is over protection near drain point that is

causes current lose. Consequently, Current lose

can be minimized by proper control

Cflemk:al <:omposftlof\ (Aec~Jf&ng to ASTM 8 MS)

ELEMENT

AI

zn Cu

Sl

Fe

Mra

Pb

Mg

Other impurities, each

Total other impurities

Capacity = 1230 Ahr/kg

WEIGHT PERCENT

5.326.75

2.5·3.5

0.08 Max

0·.3 Max

0.005 Max

0.25 Max

0,03 Max

Reminder

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Anodes used in land shall be backfilled to reduce resistance a111d moisture absorption.

Specifications of anode backfill are as fol low:

Powdered Gypsum: 75%

Granular Bentonite: 20%

Sodium Sulphate: 5%

Also cables for anode connection shall be made from copper and XLPE or PVC insulation coat.

.,. 2 s -:rfflel r k.; i • '"' AO.d ..

Aluminum anodes are one type of sacrificial anodes in cathodic protection systems tlhat are

used generally in offshore industries for metals corrosion protection.

CHlHU:t.. CO PC. ITION

The chemical composition of anodes. is as follow according to DNV RP 8401 standard:

Element Weight Percent

FEt 0.09 max

Sl 0.12 max

Cu 0.003max

2n 2.5-5.0

hi 0.015~.040

Others 0.02 max

AI Remainder

.. LECT-.Oi'HE lr"L JEHAVIOR

According to DNV RP 8 401 standard, the electrochemical properties of aluminum anode

shall be as follow:

Minimum Electrochemical Efficiency: 2500 Ahr/kg. ·

Minimum Open circuit potential: -1.05 V respect to Ag/AgCI Reference Electrode.·

Minimum closed circuit potential: -0.8 V respect to Ag/AgCI Reference Electrode. ·

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Natural potential deference between zinc and steel produces an electrochemical cell and naturally

corrosion protection consequently. Zinc metal in this process is as an anode. Zinc anodes are used

generally in offshore industries due to protection voltage that is produced between zinc and steel.

These anodes are used in tank-ersand floaters generally.

Zinc anodes are produced in Karpira Kavir Company in deferent sizes and shapes.

I mlca4 Compo!Jtti~n (Accordtng f4 J l I P 401)

Element Weight Parcenl

Aluminum [).1-0.5

Cadmium 0.07 Max

Iron 0.005 Max

Lead 0.006 Max

Copper 0.005 Max

Zinc Remtnder

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RecomiTlilnded design electrochemical capacity and design dosed en-cult

potential for anode ma!erials at seawater ambient temperatures

Anode Material Environment Electrochemical Capacity Closed Cirou it Potential Ty!Pe (Ah/kg} (V)

·seawa!er 780 ·1.00 Zn·based

sediments 700 -0.95

Cathodic Protection Equipment

Karplra K avir Company


4.1. Pos[tive and Negative Bond Boxes

The standard bond box is designed for basic cable connections that do not require shunts or resistors,

and contains ol!lly terminallugs. They are provided in various sizes to accommodate numer.ous types

of wires. The non-conductive panels are resistant towarpage and weathering. Positive and negative

bond boxesshall be as per standard and meet the requirements of climatic conditions. The boxshall be

made of 3 mm thickness sheet steels and tine degree of protection shall beiP-55.After assembly of test

box to mounting pipe & prior to installation, all steel partsshall be painted with! following procedure:

a) Surface preparation to sa21/2.

b) One red lead primer(70microns).

c) One intermediate coat ofalk.yd paint (1 00 microns at least)

d) One finishing coat of alkyd glossy yellow color paint (1 00 microns)

(Total thickness of painting 270 microns at least)

4.2. Cathodic Protection Cables

CONDUCTOR

The conductors shall be plain annealed stranded copper. St randing shall be circular{noncompacted).

The material shall be copper of such quality and purity that the finished product shall have the

properties and characteristics prescribed in IEC Publication 228 Class 2, or ASTM specification 88

Class B. Conductor sizes, as wi ll be specified by the Purchaser, shall be in accordance with one of the

designations listed in Table 1 to achieve the resistance value required:

TABLE 1 - Phys ical Properties ofXLPEJPVC Cables

Nominal Cross Nominal Insulation Nominal Sheath Approx. Overall Approx. Weight Maximum Rasistance Of

Section Thickness Thickness Diameter (mm) Cond uctorat 2o•c

4mm• 0.7 mm 1.4 mm 6.8mm 77 kg/km 4.52 Q/Km

6mm' 0.7 mm 1.4mm 7.4 mm 100 kg/km 3.020/Km

1·0 mm• 0.7 mm 1.4 mm 8.3mm 144 kg/km 1.79 0 /Km

16 mm• 0.7mm 1.4 mm 9.3mm 207 kglkm 1.13 0/Km

25mm• 0.9 mm 1.4 mm 11.0mm 305 kg/km 0.712 0/Km

3smm• Q.9mm 1.4mm 12.2 mm 406 kg/krn 0,514 0/Km

50' mm• 1.0 mm 1.5mm 14 mm 560 kglkm 0.379 0 /Km

70mm• 1.1 mm 1.6mm 16 mm 770 kglkm 0.262 0 /Km

95mm• 1.1 mm 1.6 mm 18 mm 101 5 kglkm 0.19 0/Km

The size, cross-sectional areas, and direct

current resistance of the conductor in the

completed cable is conformed the minimum and

max imum val ues allowed by the above

referenced standards.

Single Core Plain annealed copper conductor,

XLPIE insulated I PVC extruded bedded I steel

wire armoured I PVC sheathed. 600 I "1 000 volts

grade to BS5467.

TABLE 2 - Physical Properties of XLPE I PVC I SWA I PVC Cables

Nominal Cross-Sectional Number of Strands Approximate

Area Overall Diameter

16 7 13.5

25 7 15.3

35 7 17.4

50 7 19.1

70 19 21 .1

95 19 23.4

120 19 26.3

INSULATION

Approximate Weight (Kg/1'\m)

435

575

805

1010

1210

1620

2100

Cable insulation shall be mad·e from ma~erials chemically and physically resistant to the environmental effects to be anticipate.d in buried or submerged service. It shall provide

continuous coverage, adequate dielectric properties, and have a high resistance to abrasion, stress cracking and notch propagation. The insulation shall be one of the types

listed asbelow. The insulation shall be applied t ightly to the conductor without adhering to it

and shall form a compact and homogeneous body.

The sheath Gacketing) shall be an extruded layer of the types listed as bel.ow. The sheath

shall be continuous having a thickness as uniform as possible and not less tharn the values

specified . It shall be possible to re-move the sheath of the cable without damaging the

insulation of the conductor. Cable insulation (primary insulation and sheath) shall be completely free of cracks, nicks, scratches, or other discontinuities. Cable insulation shall

have a voltage rating of 60011000 Volts in accordance with National Electrical Code.

The types of insulation ahd sheath compo1und c-overed by this Part of Standard SIPecification

are listed below.

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Polyvinytchloride (PVC)

Insulation and ~heafih compound based on polyvinylchloride or copolymer of vinyl chloride and vinyl

acetate conforming toASTM specifications 0 2219 (as Insulation) and 0 1'047 (as Jacketing).

High mol~cular weight polyethylene (HMWPE}

Insulation and sheat!h compound based on thermoplastic polyethylene conforming to ASTM

specifications D 1351 (as Insulation) and D 2308 (as Jacketing).The polyethylene before application

to the conductor (or cable) shall comply with the requirements of ASTM specification D 1248 for

type I, Class A. 8 , or C; category 5; grade E5 otr J3.

Cross-Linked polyethylene (XLPE)

Insulation compound based on chemically cross-linked polyethylene conforming to ASTM

specification 0 2655. The base polymer of this insulation consists substantially of polyethylene or a

polyethylene copolymer.

PolyvinyUdene fluoride (PVDF)

Insulation compound based on especially chemical-resistant modified polyvinylidene fluoride

conforming to ASTM specification 0 3144.

Thermit Welding

The complete Thermit welding (Cadweld) kit includes cadweld powder and other accessories like

cadweld mould,ignition gun and ...

Cadweld Powder

This part specification covers the minimum requirements for the supplyof Thermit weld(cadweld)

powder for connection of cathodic protection leads to new or in-servicesteel pipes by Thermit welding

process. The Thermit weld powder for all welds of coppercable to steel pipe irrespective of c.able size us

variable due to the cable s9ze. Each cartridgepowder charge shall be enclosed in a separate

polyethylene tube with ignition powder atthe bottom or separate. The ignition powder has special

degree for ignition.The materiaJshall be of such quality and purity that when applied , produces strong

and permanent higihconductivity connection. The material shall meet the initial properties after storage

forat least 3 years from the date of delivery at normal storage conditions.

Cadweld mould

Cadweld mould is in two types of horizontal and vertical connections of cable to the pipe. The

size of mould depends on the size of cable which wil l be connected.

Ignition Gun

To ignition the powder for beginning of the welding process the operator uses an ignition g:un.

The packing material ofthe welding cartridge will prevent the ingress of moisture. The size of

welding cartridge fits into the holder to be used.

Overall: 4" X 4''

0 P-lastic sheet: 2.75" x 4" {serrated) ~r (b :J II> c;·

Sheet lllfckness: 10 mHs

iil Plastic dome: 1.625" dia, 0.8" height

Adhesive lllickness: 165 mils

Weight 2.1 oz

Application temperature -20 to +120°F

Service temperature -40 to + 1as·F

Shelf life Rollate imn uany

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Portable Copper/Copper Sulfate Reference Electrodes

Reference electrodes provide accurate and reliable potential measurements on buried metallic

structures. Theirplacement in close proximity to protected structures permits readings which are more

exact andlless affected byfluctuating soil conditions than those obtained by portable cells. Long-fife

performance is achieved through a ruggeddesign, which includes impact resistant PVC tubing. The

tubing houses .a 99.99% pure copper element .and a supersaturatedsolution of copper su lfate. The

copper sulfate mixture ensures that the copper element remains electricallystable, so that the cell's

potential value will not fluctuate. From this special composition, the cell achieves a minimumdesign life

of fifteen years, and maintains an accuracy level of±5 mill ivolts.

PermanentCo pper!Copper Sulfate Refe renee Electrodes

The cell is pre-packaged in a cfo.th bag containing a low-resistance backfill material, an·d is completely

assembled and ready for immediate installation.

Plastic positioning pins on the cell assure that a sufficient amount of the backfill will exist around the

cell's electrical contact point. Because of this, a low-resistance ground bed can be created simply by

watering the area surrounding the cell. Lead wire connections to the cell are made, wire containing any

designed cable insulation (mostly 1 Osqmm PVC insulated). The length of the wire is depending o·f the

location of cell installation.

Reference electrodes are normally used for measuring structure/electrolyte potentials, or as sensing

electrodes for control system.

Zinc Grounding cells

Pre-package zinc ground ing cells

provide positive, long-life protection

wherevervoltages must be limited nn

underground meta llic systems to

reduce danger of shocker arcing &

burning of insulated joints.Typical

grounding installations include oil, gas

&water pipelines, power stations, oil

stor.age tanks & transmission line

towers & cables.

Usage

-Unprotected pipe

-Insulated flange

-Catholically protected pipe

-Insulated copper wires connecting zinc anodes & pipeline

-Two 60" zinc anodes separated by isolation spacers

-Low resistance backfill smrounding zinc anodes

Feat ures

-Two anode units available

-Pre-packaged for easy installation in study cardboard tubes with wood ends

-Zinc anode composition confo1rms to ASTM B-418-01 , Type I & II.

-Low resistivity backfill, 75% gypsum, 20% bentonite, 5% sodium sulfate

Zinc earthing cell dimension.

Type Dimension of each >electrode (inm)

EacA electrode Approx-gross

length wide height weight(kg) weight (kg)

I 1500 40 40 17 60

II 950 50 50 17 6•0

Ill 600 20 20 27.3 100

IV 300 50 50 5.5 2•0

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