This document provides the design and calculation of an impressed current cathodic protection system for the Gunung Megang - Singa gas compression and pipeline facility in Indonesia. It outlines the pipeline details and location data, design concepts, calculation methods, and considerations for interference mitigation. The cathodic protection system will utilize mixed metal oxide anodes in a deep well groundbed configuration to protect the coated pipelines and achieve a protective potential between -900mV and -1,050mV. Calculations will be performed to determine surface area, current requirements, anode quantities, groundbed and cable resistances, transformer-rectifier output capacity, and potential attenuation. Mitigation of interference on neighboring pipelines will also be addressed.
know more about cathodic protection in such manner like some our basis of regular life and where we used parts of machine which is affected by water,air or some other things.
know more about cathodic protection in such manner like some our basis of regular life and where we used parts of machine which is affected by water,air or some other things.
This presentation will cover pipe support design, 3D modeling, Finite Element Analysis, special stress and thermal cases, along with the unique cases that brought on new pipe support designs. Increase your understanding of the value-added services that are offered by PT&P.
Quality aspects in Cross Country Pipeline constructionSuresh Zanwar
Quality aspects in Cross Country Pipeline construction
Alignment of Pipeline & precautions
Soil erosion in hilly areas & precaution in ROU grading
How pipelines get laid at lower cover & precautions in trenching
Where line pipe string is important and control needed
How to control failure of welding joints
What affects in field coating joint
Pipeline lowering & stress on pipeline – Best laid Pipeline experience
How backfilling makes difference in Pipeline corrosion
How pipeline get exposed on river banks & precaution in river crossing
Safety aspects in Pipeline construction
Why casing & carrier pipe gets shorted
How to make river bank protection
Where cathodic protection fails
This presentation will cover pipe support design, 3D modeling, Finite Element Analysis, special stress and thermal cases, along with the unique cases that brought on new pipe support designs. Increase your understanding of the value-added services that are offered by PT&P.
Quality aspects in Cross Country Pipeline constructionSuresh Zanwar
Quality aspects in Cross Country Pipeline construction
Alignment of Pipeline & precautions
Soil erosion in hilly areas & precaution in ROU grading
How pipelines get laid at lower cover & precautions in trenching
Where line pipe string is important and control needed
How to control failure of welding joints
What affects in field coating joint
Pipeline lowering & stress on pipeline – Best laid Pipeline experience
How backfilling makes difference in Pipeline corrosion
How pipeline get exposed on river banks & precaution in river crossing
Safety aspects in Pipeline construction
Why casing & carrier pipe gets shorted
How to make river bank protection
Where cathodic protection fails
Cathodic prevention of steel rebars in concrete the international outlookSimone Tremolada
The fundamental application of " cathodic prevention " of steel reinforcement in concrete was ideated and developed by Professor Pietro Pedeferri. It was successfully applied since 1989 in Italy on Viaduct St. Nicholas I of the highway Rome - Aquila - Teramo and in 1996 in the western underbroadwalk of the Sydney Opera House. Over the past 20 years it has spread throughout the world and particularly in Northern Europe, Middle East and Australia being recognized as the most reliable technique to combat corrosion for new buildings and infrastructure where reinforced concrete is exposed to possible contamination from chlorides. This memory is a review of some of the most significant industrial cases reported in the international literature.
Durrat Al Bahrain and the NAKILAT shipyard in Qatar are two recent projects developed in the Middle East. Cathodic Prevention of West Swanson Dock in Melbourne was the largest project completed in Australia in the last decade.
Other significant experiences in China and North Africa are a sign of the vitality of this technique in the developing countries.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
1. GUNUNG MEGANG - SINGA
GAS COMPRESSION & PIPELINE FACILITY
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC PROTECTION
0 13/07/09 PIM Issued For Approval SAT DGD
A 18/05/09 PIM Issued For Review SAT DGD
CHECK APVD CHECK APVD CHECK APVD
REV DATE BY DESCRIPTION
CPM MEB MEPI
STATUS: A = Issued for Review; B = Issued for Approval; C = Approved for Construction
TOTAL OR PARTIAL REPRODUCTION AND/OR UTILIZATION OF THIS DOCUMENT ARE FORBIDDEN WITHOUT PRIOR
WRITTEN AUTHORIZATON OF THE OWNER
DOC. NO
GMS-40-CS-014
REVISION STATUS
0 0
2. Doc No. : GMS-40-CS-014
Page : Page 2 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
TABLE OF CONTENT
1. INTRODUCTION ............................................................................................................ 2
2. REFERENCE.................................................................................................................. 3
3. DEFINITIONS................................................................................................................. 3
4. LOCATION DATA........................................................................................................... 4
5. DESIGN CONCEPT ....................................................................................................... 4
6. DESIGN METHOD IMPRESSED CURRENT CATHODIC PROTECTION .................... 5
7. CALCULATION FORMULA............................................................................................ 6
8. INTERFERENCE............................................................................................................ 9
8.1. Stray Current on Metallic Structures..................................................................... 9
8.1.1. At Area of Current Pick-Up ..................................................................... 10
8.1.2. Along the Structure Parallel Line (Parallel Line) ..................................... 10
8.1.3. At the Stray Current Discharge Location ................................................ 10
8.2. List of Instrument and Equipment......................................................................... 10
8.3. Criteria.................................................................................................................. 11
8.4. Interference Testing.............................................................................................. 11
8.5. Mitigation .............................................................................................................. 12
8.5.1. Install Interference Bond......................................................................... 12
8.5.2. Installation of Galvanic Anodes............................................................... 12
8.5.3. Using Coating to Mitigate Interference Effects........................................ 12
8.5.4. Install/burying a metallic shield next to the affected structure................. 13
1. INTRODUCTION
This document is to define the requirement of onshore pipeline cathodic protection system
for Gunung Megang – Singa pipeline and underground plant piping at Gunung Megang
Booster Station.
3. Doc No. : GMS-40-CS-014
Page : Page 3 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
The pipeline is coated with 1 layer epoxy primer and 2 layers PE wrapping tape. And also
protected by impressed current cathodic protection system with deep well groundbed type
installation.
2. REFERENCE
NACE RP-0169-2002 : Control of External Corrosion on Underground of
Submerged Metallic Piping System.
NACE RP-0177-95 : Mitigation of Alternating Current & Lightning Effect on
Metallic Structures & Corrosion Control System.
NACE RP-0572-2002 : Design, Installation, Operation and Maintenance of
Impressed Current Deep Ground beds.
NACE RP-0286-97 : Electrical Isolation of Cathodically Protected Pipelines.
DNV RP B401 : Cathodic Protection Design.
ASTM G57 : Standard Method for Field Measurement of Soil Resistivity
Using the Wenner Four- Electrode Method.
ISO 15589-1 : Petroleum and Natural Gas Industries Cathodic Protection
of Pipeline Transportation Systems Part 1 - On-land
Pipeline.
BS-7361-Part1-1991 : Cathodic Protection of Buried or Immersed Metallic
Structures. General Principles and Application for Pipelines.
AW PEABODY : Control of Pipeline Corrosion (Second Edition)
GMC-L-RE-001 Rev.A : Design Basis for 10” Gunung Megang – Singa Pipeline
3. DEFINITIONS
The following terms shall have the meaning stated:
Employer : PT. Mitra Energi Gas Sumatera
4. Doc No. : GMS-40-CS-014
Page : Page 4 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
Contactor : PT. Citra Panji Manunggal
Subcontractor : PT. Pelinkar Iso Mandiri
4. LOCATION DATA
The pipeline and in-plant pipeline is outline in the following table
SECTION PIPELINE DATA
Pipe Diameter Wall Thickness
AREA KP Start KP End
(Inch) (mm)
Pipe
Length
(m) (Inch) (mm)
Coating
System
Pipe
Status
MUARA
ENIM
KP.
0+000
(G.
Megang
Station)
Pig
Receiver
MEP
Metering
G.
Megang
KP.
17+500
(Singa
Station)
Slug
catcher
G.
Megang
Pig
Receiver
G.
Megang
10.75
10.75
6.625
10.75
273.0
273.0
168.23
273.0
17500
175.0
205
Equal to
123
0,365
0.365/
0.592
0.432
9,271
9.271/
15.04
10.973
1 Layer
Primer
Coating +
2 Layer
Wrapping
Tape
Buried
Pipeline material: 10” API 5L X56 and API 5L X65
In Plant piping material: 10” API 5L X56 and 6” API 5L Grade B
5. DESIGN CONCEPT
The external surface of pipeline shall be protected with combination an anti corrosion
coating and Cathodic Protection; where Impressed Current Cathodic Protection will be
used.
Design of the Impressed Current Cathodic Protection shall be 20 years life time.
5. Doc No. : GMS-40-CS-014
Page : Page 5 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
Protective Potential Requirement shall be in accordance with GMC – L – RE – 001 Section
6.8 of Design Basis to maintain at least -900 mV and not more than -1.050 mV measured
relatively to Ag/AgCl. This value is equal to -950 mV and not more than -1.100 mV
measured relative to a Cu/CuS04 reference electrode (CSE).
The other criteria and requirement of Clause 6.2 of NACE RP-0169 may be applied to
determine whether cathodic protection has been successfully achieved. These other
criteria shall be utilized only when it is not possible to achieve a polarized potential of -900
mV (CSE)
With specific regard to pipeline sections in high – resistivity aerated sandy soil condition,
less negative values may be acceptable – refer to Clause 6.2.2.3 of NACE PR-0169.
Acceptable lesser negative values may clearly laid out in ISO 15589-1 and reproduced
below for convenience.
Polarized Protection Potential
(Cu/CuSO4)
Soil Resistivity
(ohm meters)
-750 mV
-650 mV
100< ρ < 1000
1000 < p
Soil Resistivity Measurement required for Cathodic Protection design shall be obtained by
Contractor.
Construction drawings shall be prepared by Contractor showing details of Impressed
Current Cathodic Protection Proposed.
At any pipeline crossing or where pipeline running in parallel; where interference may
occured, the existing pipelines at crossing or parallel to be protected shall be either
insulated or shall be taken into account in the Cathodic Protection design.
6. DESIGN METHOD IMPRESSED CURRENT CATHODIC PROTECTION
The Impressed Current Cathodic Protection will include the following main material:
• Transformer Rectifier
• Mixed Metal Oxide Anode
• Cables
• Test Station
6. Doc No. : GMS-40-CS-014
Page : Page 6 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
• Current Measurement Test Station
• All accessories required for the system installation
• Junction box.
The methodology used for the Impressed Current Anode design is in accordance with the
recommendation stipulated in NACE RP-0169. Based on this methodology a calculation
sheet will be made to estimate the Cathodic Protection requirements.
The design of Impressed Current Cathodic Protection System for Gunung Megang – Singa
pipeline will be based on document no: GMG-L-RE-001.
• Pipeline Diameter 0.273 M
• Length of Pipeline 17,500 M + In Plant piping 300 M
• Maximum Design Temperature 200o
F = 93.33o
C
• Current Density at Maximum Temperature 88.33 mA
• Design Life 20 years
• Safety Factor 25%
• Positive Limit Protection Level w.r.t. Cu/CU SO4 -0.950 mV
• Negative Limit Protection Level w.r.t. Cu/CU SO4 -1.100 mV
Based on the above mentioned data, a calculation will be made to obtain the following:
• Surface Area
• Current requirement
• Quantity of anodes
• Resistance of groundbed
• Resistance of cable
• Total Resistance
• Transformer Rectifier DC Output Capacity Requirement
• Attenuation calculation
7. CALCULATION FORMULA
a. Surface Area to be protected (m2)
The protected area for pipeline is calculated according to the following formula:
SA = π x OD x Lp
7. Doc No. : GMS-40-CS-014
Page : Page 7 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
Where:
SA = Surface Area to be protected (m2)
OD = Outside diameter of pipe (m)
Lp = Length of pipe (m)
π = 3.1415
b. Cathodic Protection Current Requirement
The total protective current required is calculated according to the following formula:
Im = (Cr x SA x I )
Where:
Im = Current requirement (A)
Cr = Mean coating breakdown factors ( 3%)
SA = Surface area to be protected (sqm)
I = Current density in milliampere per square meter (A/sqm)
c. Total Minimum Anode by current requirement method (Method for MMO
Requirements)
Quantity of anode by current requirement is calculated by following equation:
Q = Ip / la
Where:
Q = Quantity of anode required (pcs)
Ip = Current requirement (A)
Ia = Current output of each anode
d. Resistance of Anode Groundbed
Resistance of Anode Groundbed is calculated by the following formula:
Rg = Ra + Rb x Inf
Where:
Rg = Total Resistance of Groundbed
Ra = Resistance of anode to the calcined petroleum backfill and is calculated by the
following formula:
Ra=
Where:
Ra = Resistance anode to backfill (ohm-m)
P = Calcined Petroleum coke breeze backfill Resistivity (ohm-cm)
NA = Number of Anode
8. Doc No. : GMS-40-CS-014
Page : Page 8 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
L = Length of anode in feet
d = Diameter of anode in feet
Rb = Resistance of Calcined Petroleum Coke Breeze backfill to Soil and is
calculated by the following formula:
Rb =
Where:
Rb = Resistance backfill to soil (ohm-m)
Ps = Soil resistivity (ohm-cm)
L = Length of column Calcined Petroleum coke breeze backfill in feet
d = Diameter of Column Calcined Petroleum coke breeze backfill in feet
Inf = Interferrence factors is safety factors + 1.
e. Resistance of Cable
The resistance of cable is calculated as follows:
Rc = 0.0172 x (Lc : Csq)
Where:
Rc = Resistance of Cable (ohm-m)
Lc = Length of Cable (m)
Csq = Cable Cross Section (mm2)
f. Total Resistance
The total resistance is calculated by the following equation:
R Total = Rg + Rc
R Total = Total Circuit Resistance (ohm-m)
g. Transformer Rectifier DC Output Capacity Requirement
Total DC voltage rating of the power supplies to achieve the desire DC current
output is calculated by the following equation:
T/R Volt = I x R total x (1+ SF) + back emf
I = Current Requirement in amperes
R total = Rg + Rc (ohm-m)
h. Attenuation Calculation
9. Doc No. : GMS-40-CS-014
Page : Page 9 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
The potential attenuation of a pipeline is calculated using the following formula:
Lp =
∆P
∆P0
α
. IdA. Cosh
A = л x E x (OD –E) [cross section area of pipe]
∆P = Positive Limit Protection Level
∆Po = Negative Limit Protection Level
Id = Current Density of Steel Coated at 25ºC (Normal Temperature)
α = Attenuation Factor, will calculated by the following formula:
α =
r
L = Longitudinal Resistance of pipeline. This will Calculated by following formula:
r
L = ra / a
ra = r25 x [1 + δ (T – To)]
r25 = Average steel resistivity for grade API 5L – X56 steel at 25o
C (ohm-m)
d = Temperature coefficient of resistance = 0.00306
T = 93.33o
C
To = 25
o
C
a = Surface area of pipe per meter length = OD x π x 1
E = Wall thickness of pipe
r
T = Transversal resistance of pipe ( ). This calculated by following formula:
r
T = rs / a
rs = Coating resistance after installation and 20 years life (Ω/m2)
8. INTERFERENCE
8.1. Stray Current on Metallic Structures
Stray currents are currents through electrical paths other than the intended circuit.
Stray current is not galvanic corrosion current between anodes on the same
structure. Stray current or interference current can refer to either alternating current
(AC) or direct current (DC). AC stray current is more of a safety hazard than a
corrosion problem. DC stray current causes significant corrosion of most metals.
10. Doc No. : GMS-40-CS-014
Page : Page 10 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
Specifically, the subject matter dealt within this document relates to stray current
caused by operation of Impressed Current Cathodic Protection System for Gunung
Megang – Singa pipeline to foreign crossing and/or parallel pipelines in the area.
Stray currents will occur if foreign pipeline crosses a groundbed voltage gradient and
it will promote current pick-up on the foreign pipeline within the area of influence.
Because current is picked up on the foreign pipeline, then current must discharge
outside the area of influence.
The effects of stray current on metallic structures can be harmful, beneficial or
innocuous depending on the magnitude of the current density, type o structure and
location of current pick-up and discharge areas.
8.1.1. At Area of Current Pick-Up
At the area of current pick-up, a negative shift will result in cathodic
polarization, and if the foreign structure is mild steel then there is a beneficial
effect as the structure is receiving some measure of cathodic protection. If
the structure is coated and has its own cathodic protection system, the
additional polarization from the stray current pick-up may result in cathodic
blistering of the coating.
8.1.2. Along the Structure Parallel Line (Parallel Line)
Stray current in metallic structure does not usually cause damage between
the stray current pick-up and discharge location unless the current is very
large (close to anode groundbed)
8.1.3. At the Stray Current Discharge Location
Considerable attention is given to identifying the site of current discharge in
stray current investigations because this is where corrosion damage is most
like to occur on all metallic structures. When a current transfers from a
metallic structure to earth, it must do so via an oxidation reaction which
converts electronic current to ionic current.
8.2. List of Instrument and Equipment
The Interference testing will be carried out using the following the
instrument/equipment:
1) GPS Synchronised Current Interrupters
2) Portable copper/copper sulphate reference electrodes
3) Reel of test wired
11. Doc No. : GMS-40-CS-014
Page : Page 11 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
4) Clamp ammeter
5) Electrician hand tools
All equipments will be calibrated and should have valid calibration certificates where
required.
8.3. Criteria
Three (3) criteria are commonly used in determining the adequacy of the mitigation:
1) The “NO SWING” criterion may be applied. This requires that the potential of the
effected pipeline does not shift in the positive direction when the foreign rectifier
cycles from off to on. This criterion is reasonably applicable to well coated
pipelines but maybe unnecessarily severe.
A “NATURAL POTENTIAL” criterion maybe applied. The affected pipe is to be
returned to the potential existing before the interference began by the installation by
mitigation measures such as an interference bond. In many cases the natural
potential may be very difficult to determine.
A “NO CORROSION” criterion may be applied. If it can be shown that the affected
pipeline is cathodically protected and meets the applicable potential criterion (criteria
for protection as defined ISO 15589-1:2003) for full cathodic protection then no
additional measures need by taken.
8.4. Interference Testing
Essentially where interference is suspected or there may be a possibility the rectifiers
on one line are cycled ON and OFF, measurements are made on both pipes at the
pipeline crossing and/or parallel to see if the potential on the foreign crossing and/or
parallel pipeline are being adversely affected. A positive shift on a foreign crossing
and/on parallel pipelines indicates interference.
1) Cycling the rectifiers ON and OFF will require the installation of GPS current the
interrupters on all cathodic protection current sources likely to influence the area
of the affected pipe crossing.
2) The pipe-to-soil potential measurements will require the installation a high
impedance DC voltmeter, portable copper/copper sulphate reference electrode
and a set of test lead wires.
3) A copper/copper sulphate reference electrode will be placed in the soil directly
over the pipeline. Make sure that there is good low resistant contact between the
soil & reference electrode. In dry soil it may be necessary to use some water to
wet a small area of soil.
4) Connect the lead wire of the reference electrode to the negative terminal of the
voltmeter. Connect the positive terminal of the voltmeter to the Pipelines via the
test station terminal (this will result a negative polarity on the DC display of digital
voltmeter).
12. Doc No. : GMS-40-CS-014
Page : Page 12 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
5) Adjust the voltmeter to the 2-Volt DC meter range and turn the meter on.
6) Observe and record the potential value at each test station location.
7) Records “ON” and “OFF” readings.
8.5. Mitigation
If the shift is more than allowed by BS-7361-Part 1: 1991 – 9.3.3.2, i.e. 20 mV, then a
number of methods can be used to lessen the harmful effects of stray currents as
listed below:
8.5.1. Install Interference Bond
An interference bond with an adjustable resistor allows the interference
current to be return from the foreign crossing pipeline via the bond cable and
the resistor. The resistor is adjusted so that just enough current flows to
remove the positive shift but not allow the foreign crossing to take too much
Cathodic Protection current. Not all crossing will require a bond. An
interference bond is a cable from one pipe to the other through a variable
resistor normally mounted in a junction box. The installation of variable
resistor is relatively simple. The variable resistor shall be slotted in the
junction box.
Condition on every crossing/parallel is different and the current drained and
the value of resistance is different. Generally speaking a small resistor say 0
to 1 ohm and 2 amperes is sufficient.
Upon installation of the interference bond, measurements as per section 8.4
shall be repeated.
8.5.2. Installation of Galvanic Anodes
When the area of stray current discharge is very localized, such as at
crossing with the interfering structure, the installation of galvanic anodes to
the foreign pipeline has considerable benefit. If the foreign pipeline is coated,
the path resistance through the galvanic anodes will be substantially less
than the coated pipeline.
8.5.3. Using Coating to Mitigate Interference Effects
13. Doc No. : GMS-40-CS-014
Page : Page 13 of 13
Date : 13 Juli 2009
Rev. : 0
DESIGN AND CALCULATION OF
IMPRESSED CURRENT CATHODIC
PROTECTION
Applying a coating is an attempt to increase the resistance of the stray
current path, thus decreasing the stray current magnitude. As a stand alone
method, coating should only be applied at current pick-up locations. If the
discharge area of a structure is coated, there is a risk of corrosion failure due
to high discharge current density at a holiday in the coating.
8.5.4. Install/burying a metallic shield next to the affected structure
The intent of a buried metallic conductor is to intercept the stray current and
thus provide an alternative low resistance path for the stray current compared
to the metallic structure path. Connecting the metallic shield, which could be
a bare cable or pipe, directly to the negative terminal of the transformer
rectifier would more effective. This is applied to anodic Interference. i.e.
foreign pipeline crosses a groundbed voltage gradient.