Ng22 180 Cat Zbj 000017 Pcp Design Nt

OML 58 Upgrade Phase 1/OUR Gas Pipeline

Document number:

PERMANENT CATHODIC PROTECTION DESIGN

NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 1 of 9


Rev.

Status

Rev. Date

Revision Memo

Issued by

Checked by

Approved by

C0

IFR

01-Nov-2011

Issued for Review

K. Okanigbe

C. Harburn

G. Okeke

D0

IFA

02-Dec-2011

Issued for Approval

K. Okanigbe

C. Harburn

G. Okeke

00

IFC

30-Jan-2012

Issued for Construction

K. Okanigbe

C. Harburn

E. Okoronkwo

01

IFC

30-Sept-2012

Issued for Construction

M. Nnadi

D. Nnanna

E. Okoronkwo

This document has been generated by an Electronic Document System. When printed it is considered as for information only copy. The controlled copy is the screen version and it is the holders responsibility that he/she holds the latest version.

This document is the property of TEPNG. It must not be reproduced or transmitted to others without written authorization from the company

NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 2 of 9

TABLE OF CONTENTS

1.0 INTRODUCTION3

1.1 PROJECT OVERVIEW3

1.2 PURPOSE3

2.0 REFERENCE DOCUMENTS4

2.1 TOTAL GENERAL SPECIFICATIONS4

2.2 NLNG SPECIFICATIONS4

2.3 INTERNATIONAL CODES AND STANDARDS.5

3.0 ABBREVIATIONS & DEFINITIONS5

4.0 CORROSION PROTECTION PHILOSOPHY OVERVIEW7

5.0 CURRENT DENSITIES REQUIREMENTS7

6.0 CURRENT CALCULATIONS8

7.0 CURRENT DEMAND9


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 3 of 9

INTRODUCTION

TEPNG intends to increase gas transportation capacity from OBITE TC to BONNY in line with the development of the gas production facility to meet gas requirement for existing and planned future NLNG trains. There is presently a project underway which shall increase the gas export capacity. This project entails the construction of a 42 by 45 Km pipeline to transport this gas from Obite TC to Rumuji.

Project Overview

The OUR Gas Pipeline Project will export increased gas to NLNG. The second phase (RumujiBonny pipeline segment) will be developed in accordance with future NLNG Plant extension program.

During this first phase, the new 42 Obite TCUbetaRumuji gas pipeline will be connected to the NAOC GTS4 36 gas pipeline manifold at the Rumuji Node. At the Rumuji Node, a 20 SPDC pipeline branch connection shall be provided on the 36 NLNG GTS1 pipeline manifold and blinded-off. This connection shall enable SPDC connect to the GTS1 pipeline in future. At Ubeta a 24 x 28 hot tap tie-in to GTS1 shall be provided, including another 42 connection for future tie-in to GTS6.

The new TEPNG 42 OUR gas pipeline shall be installed parallel to the existing gas pipelines from Obite-Rumuji (GTS1) in a new ROW adjacent to the existing ROW.

The scope of work for the O.U.R. Gas Pipeline project includes but it is not limited to the provision of Pig Launcher at Obite TC, Pig Receiver at Rumuji and related piping, valves and fitting connections to GTS1 and GTS4 at the various Nodes. The work also includes associated instrumentation, electrical, telecommunications, cathodic and corrosion protection facilities, associated civil/structural work, LSDS, FOC

Purpose

The purpose of this document is to calculate the current demand required for the permanent cathodic protection of the 42 OUR Pipeline.


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 4 of 9

REFERENCE DOCUMENTS

The design of the Cathodic Protection System for the OML 58 O.U.R. pipeline shall complywith the prevailing legislation application with the planning, design, construction, testing, commissioning and operation of CP system in the Federal Republic of Nigeria.

In all cases the latest edition of the relevant Regulations, codes, Guidelines, Standards

and Specifications shall be used unless specifically indicated within this document. Refer to NLNG and TOTAL Gap Analysis Report, NG-22-84-SOF-COR-REP-002001

TOTAL General Specifications

GS EP COR 111

External cathodic protection of onshore facilities

GS EP COR 110

External cathodic protection of buried pipelines

GS EP COR 210

Monolithic insulating joints

GS EP COR 220

Three layer polyethylene external coating for pipelines

GS EP COR 420

External field joint coatings of pipelines

2.2NLNG Specifications

DEP 30.10.73.31

Design of cathodic protection systems for onshore buried pipelines

DEP 30.10.73.10

Manual Cathodic Protection


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 5 of 9

2.3 International Codes and Standards.

ISO 15589 1

Petroleum and Natural Gas Industries - Cathodic Protection of

Pipeline Transportation Systems Part 1 On Land Pipelines

BS EN 12954

Cathodic Protection of Buried or Immersed Metallic Structures

General Principles and Applications for Pipelines

NACE RP 0169

Corrosion on Underground or Submerged Metallic Piping Systems

NACE RP 0286

Electrical Isolation of Cathodically Protected Pipelines

ASTM G 57-95

Standard Method for Field Measurements of Soil Resistivity using

the Wenner Four-Electrode Method

3.0ABBREVIATIONS& DEFINITIONS

3LPE3 Layer Polyethylene

AAmpere

ACAlternating Current

Ag / AgCl Silver / Silver Chloride

CPCathodic Protection

CPYTotal Exploration & Production Company Nigeria Limited (TEPNG)

CRACorrosion Resistant Alloys

Cu/CuSO4Copper / Copper Sulphate

DCDirect Current

DEPDesign and Engineering Practices (Version 18, owned by Shell)

DFTDry Film Thickness

Eoa (V)Design Protective Potential

FBEFusion Bonded Epoxy

fcCoating Breakdown factor

GSGeneral Specifications (Version 2005)

HMWPEHigh Molecular Weight Polyethylene

ICCPImpressed Current Cathodic Protection

IDInternal Diameter

KmKilometer

mAMilli-ampere

MLPPMulti-Layer Polypropylene

mVMilli-volt(s)

NAOCNigerian Agip Company

NLNGNigerian Liquefied Natural Gas Company


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 6 of 9

NNPCNigerian National Petroleum Corporation

OMLOil Mining Lease

OURObiteUbetaRumuji

PVCPoly Vinyl Chloride

RefReference

ROWRight of Way

SACPSacrificial Anode Cathodic Protection

SPDCShell Petroleum Development Company

SRBSulphate Reducing Bacteria

SWASteel Wire Armoured

ZBJZB Joint Venture Limited

VVolt(s)

Ohm(s)

(ohm.m) Soil Resistivity

XLPECross Linked Polyethylene

WORKS: Review and endorsement of the FEED documents, detailed engineering design and preparation of all documents necessary for procurement, including as-built after installation.

PIPELINE: Refers to the OUR Pipeline.

OUR: Obite Ubeta Rumuji.


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 7 of 9

CORROSION PROTECTION PHILOSOPHY OVERVIEW

As the primary (passive) protection against external corrosion, the buried steel pipe line in the O.U.R. Gas pipeline project will be coated with a high quality coating before installation. The coating will be 3 layer polyethylene in accordance with Project specifications GS COR 200 and GS COR 420 and epoxy on field joint coatings.

CURRENT DENSITIES REQUIREMENTS

The current densities listed in the table below are used for the calculations (as per GS EP COR 110).

Current density (mA/m)

Final (design life / year)

Coating system

Initial

10

20

30

years

years

years

Coal-tar, bitumen enamel, cold applied

0.2

0.4

0.6

0.8

tape

Fusion bonded epoxy

0.05

0.2

0.5

0.7

Three-layer PE or PP

0.02

0.05

0.1

0.3

The design life for permanent cathodic protection is 25 years for Permanent Cathodic Protection system.

The current densities used for calculations are:

0.2 mA/m for 3LPE coating;

0.6mA/m for epoxy coating.


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 8 of 9

6.0

CURRENT CALCULATIONS

Current calculations are presented in the table below:

Input Data :

Diameter of Pipeline (m) :

1.067

Length of Pipeline (km) :

45.500

Design Life (year) :

25

Coating :

3LPE

Final Current Density (as per GS EP COR 110 - mA/m) :

0.2

Field Joint Coating :

EPOXY

Final Current Density (as per GS EP COR 110 - mA/m) :

0.6

Approximate length of pipe (m) :

12

Approximate number of welds (m) :

3792

Approximate length of Field Joint Coating (m) :

0.80

TR Location (KP) / UBETA

12.500

TR Location (KP) / RUMUJI

45.500

Safety Margin for TR Sizing (%) :

25

Calculations :

Total Pipeline Surface (m) :

152520

Pipeline Surface with 3LPE coating :

142352

Pipeline Surface with EPOXY coating (Field Joint Coating) :

10168

Protection Current Demand (A) :

34,57

Protection Current Demand for Section 1 (KP 0,000 to KP 29) / (A) :

22,03

Protection Current Demand for Section 1 (KP 29 to KP 45,5) / (A) :

12,54

TR Sizing with safety margin / UBETA / (A) :

27.54

TR Sizing with safety margin / RUMUJI / (A) :

15.67


NG22-180-CAT-ZBJ-000017


Document number:


NG22-180-CAT-ZBJ-000017

Revision: 01

Status:

IFC

Approval Class: 2

Document Type :

REP

System / subsystem:

Discipline :CAT

Date :

25-Sept-2012

Page 9 of 9

The surface of the pipeline is calculated using the formula below:

S = P x d x L

Where:

d = diameter of the pipeline (m);

L = length of the pipeline (m) - length with 3LPE or epoxy coating.

The total current (I) requirement is calculated using the formula below:

I = I3LPE + IEPOXY

Where:

I3LPE = current density (for 3LPE) x surface (coated with 3LPE);

IEPOXY = current density (for EPOXY) x surface (coated with EPOXY).

Note: a safety margin of 25 % is used for the sizing of the TR.

7.0CURRENT DEMAND

The total current demand to protect the 42 OUR Pipeline against corrosion is 34.57 amperes.

The first Transformer Rectifier (located at UBETA Node) has to be designed to provide 22.03 amperes. The Transformer Rectifier rating is : 50 V / 30 A.

The second Transformer Rectifier (located at RUMUJI Node) has to be designed to provide 12.54 amperes. The Transformer Rectifier rating is : 50 V / 20 A.

End of Document


NG22-180-CAT-ZBJ-000017

Ng22 180 Cat Zbj 000017 Pcp Design Nt

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