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Cathodic Protection Calculation

This document provides calculations for cathodic protection of a gas pipeline with three sections running from an entrance to a block in Greisik, Indonesia. It outlines parameters for current density, coating breakdown factor, design life, anode capacity and consumption rate. Based on the pipe diameters, lengths, resistivity and other factors, it calculates the required current, weight of magnesium anodes, number of anodes and proposed number of anodes for each pipe section and the total project.

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Ahmad Dzulfiqar Rahman
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1K views1 page

Cathodic Protection Calculation

This document provides calculations for cathodic protection of a gas pipeline with three sections running from an entrance to a block in Greisik, Indonesia. It outlines parameters for current density, coating breakdown factor, design life, anode capacity and consumption rate. Based on the pipe diameters, lengths, resistivity and other factors, it calculates the required current, weight of magnesium anodes, number of anodes and proposed number of anodes for each pipe section and the total project.

Uploaded by

Ahmad Dzulfiqar Rahman
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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PAKET PEKERJAAN RANCANG BANGUN JARINGAN PIPA GAS DARI

ENTRANCE KE BLOK E KAWASAN JIIPE MANYAR GRESIK

CALCULATION FOR CATHODIC PROTECTION


DOCUMENT No. REV. A
NK
DATE DESCRIPTION Page 1 of 1
BY CHK'D APP'D
AH DW BA TAG No.

DATA: OUTPUT CURRENT METHOD


CURRENT DENSITY OF BARE PIPE (CD) : 20 mA/mm2 Formula:
COATING BREAKDOWN FACTOR (CB) : 0.01 = 1
DESIGN LIFE TIME (Y) : 20 years
CAPACITY OF MAGNESIUM (CAP) : 1138 Ah/kg Lmg : Length of prepackaged magnesium anode 18.5 lbs 0.83
CONSUMPTION RATE OF MAGNESIUM (CR) : 7.7 kg/Ayr Dmg : Diameter of prepackaged magnesium anode 18.5 lbs 0.15
UTILIZATION FACTOR (U) : 0.8 : Layer soil resistivity data (Ohm.cm) 1000
PROPOSED ANODE WIEGHT (W) : 7.7 kg (Assumed)
I : Magnesium anode current output (Amp)=(Ec-Ea) : Rmg
NOTES AND FORMULA Ip : Required current
OD : Outer diameter of pipe (In) Ec : Protective Potential (Volt) 0.85
DIA : Diameter of pipe (m) Ea : Close Potential (Volt) 1.75
L : Length of pipeline (m) N : Number of 18.5 lbs anode = Ip / I
Ap : Surface area to be protected = DIA x x Lp (m)
Ip : Protection current = Ap x CD
Wt : Weight of magnesium anode required = (Ip x Y x CR ) / U
Nos : Number of anode required = Wt / N
Nosf : Final number of anodes required
NosI : Number of anodes proposed to get better distribution

No. Section OD DIA L Ap Ip Wt Nos Nosf Rmg I Nos Nosf Nprpos'd


(in) (mm) (m) (m2) Amp (kg) pcs pcs ,cm Amp pcs pcs pcs

1 Section 1 16 0.406 2100 2681.2 0.536 103.22 13.4 14 1000 5.35 0.168 3.1878 4 14
2 Section 2 6.25 0.159 1100 548.6 0.11 23.233 3.02 4 1000 5.35 0.168 0.6523 1 4
3 Casing 1 10.25 0.260 60 49.075 0.01 2.0783 0.27 1 1000 5.35 0.168 0.0583 1 1
Total : 19

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