EN ISO 15589-2:2024

Oil and gas industries including lower carbon energy - Cathodic protection of pipeline transportation systems - Part 2: Offshore pipelines (ISO 15589-2:2024)

This document specifies requirements and gives recommendations for the pre-installation surveys, design, materials, equipment, fabrication, installation, commissioning, operation, inspection and maintenance of cathodic protection (CP) systems for offshore pipelines for the petroleum, petrochemical and natural gas industries as defined in ISO 13623. Flexible pipelines, in-field flowlines, spools and risers are included in this document. Subsea production and injection equipment and structures are not included in this document.
This document is applicable to carbon steel, stainless steel and flexible metallic pipelines in offshore service.
This document is applicable to retrofits, modifications and repairs made to existing pipeline systems.
This document is applicable to all types of seawater and seabed environments encountered in submerged conditions and on risers up to mean water level.

Öl- und Gasindustrie einschließlich kohlenstoffarmer Energieträger - Kathodischer Schutz für Transportleitungssysteme - Teil 2: Offshore-Pipelines (ISO 15589-2:2024)

Dieses Dokument legt Anforderungen fest und gibt Empfehlungen hinsichtlich Untersuchungen vor der Installation, Auslegung, Werkstoffen, Ausrüstung, Fertigung, Installation, Inbetriebnahme, Betrieb, Inspektion und Wartung von kathodischen Korrosionsschutzsystemen (CP, en: cathodic protection) für Offshore-Rohr¬leitungen für die Erdöl- und Erdgasindustrie, wie in ISO 13623 festgelegt. Flexible Rohleitungen, Förderleitungen im Feld, Spulen und Steigleitungen sind in diesem Dokument enthalten. Unterwasser-Förder- und Injektionsausrüstungen und  anlagen sind nicht in diesem Dokument enthalten.
Dieses Dokument ist anwendbar für Rohrleitungen aus Kohlenstoffstahl, nichtrostendem Stahl sowie flexible Rohr¬leitungen aus Metall im Offshore-Betrieb.
Dieses Dokument ist anwendbar für Nachrüstungen, Änderungen und Reparaturen von bestehenden Rohrleitungs¬systemen.
Dieses Dokument ist anwendbar für alle Arten von Meerwasser- und Meeresbodenumgebungen, die unter Wasser und an Steigleitungen bis zum mittleren Wasserstand vorzufinden sind.

Industries du pétrole et du gaz y compris les énergies à faible teneur en carbone - Protection cathodique des systèmes de transport par conduites - Partie 2: Conduites en mer (ISO 15589-2:2024)

Le présent document spécifie les exigences et donne des recommandations pour les visites d'inspection avant installation, pour la conception, pour les matériaux, pour les équipements, pour la fabrication, pour l'installation, pour la mise en service, pour l'exploitation, pour l'inspection et pour la maintenance des systèmes de protection cathodique destinés aux conduites en mer pour les industries du pétrole, de la pétrochimie et du gaz naturel telles que définies dans l'ISO 13623. Les conduites souples, les lignes de production, les manchettes et les colonnes montantes sont incluses dans le présent document. Les équipements et structures de production et d'injection sous-marines ne sont pas inclus dans ce document.
Le présent document est applicable aux conduites en acier au carbone et en acier inoxydable ainsi qu'aux conduites métalliques souples utilisées en mer.
Le présent document est applicable aux rénovations, modifications ou réparations effectuées sur les systèmes de conduites existants.
Le présent document s'applique à tous les types d'environnements eau de mer ou fond marin rencontrés en configuration submergée et sur les colonnes montantes jusqu'au niveau d'eau moyen.

Naftna in plinska industrija, vključno z nizkoogljično energijo - Katodna zaščita cevovodov - 2. del: Cevovodi na morju (ISO 15589-2:2024)

Ta dokument določa zahteve in podaja priporočila za prednamestitvene preglede, projektiranje, materiale, opremo, izdelavo, namestitev, začetek uporabe, delovanje, preglede in vzdrževanje sistemov katodne zaščite za cevovode na morju za petrokemično industrijo ter industrijo za predelavo nafte in zemeljskega plina, kakor so določeni v standardu ISO 13623. V ta dokument so vključeni prožni cevovodi, vodi, navitja in dvižne cevi. Podmorski proizvodni sistemi in oprema za injiciranje in konstrukcije niso vključeni v ta dokument.
Ta dokument se uporablja za cevovode iz ogljikovega in nerjavnega jekla in prožne kovinske cevovode na morju.
Ta dokument se uporablja za rekonstrukcijo, spremembe in popravila na obstoječih cevovodnih sistemih.
Ta dokument se uporablja za vse vrste okolij morske vode in morskega dna v potopljenih pogojih in na dvižnih vodih do povprečnega nivoja vode.

General Information

• Status: Published
• Publication Date: 13-Feb-2024
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• Technical Committee: CEN/TC 219 - Cathodic protection (provisional)
• Drafting Committee: CEN/TC 219 - Cathodic protection (provisional)
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 14-Feb-2024
• Completion Date: 14-Feb-2024
• Ref Project: SIST EN ISO 15589-2:2024 - Oil and gas industries including lower carbon energy - Cathodic protection of pipeline transportation systems - Part 2: Offshore pipelines (ISO 15589-2:2024)

Relations

• Replaces: EN ISO 15589-2:2014 - Petroleum, petrochemical and natural gas industries - Cathodic protection of pipeline transportation systems - Part 2: Offshore pipelines (ISO 15589-2:2012)
• Effective Date: 28-Jan-2023

Overview

EN ISO 15589-2:2024 - titled Oil and gas industries including lower carbon energy - Cathodic protection of pipeline transportation systems - Part 2: Offshore pipelines (ISO 15589-2:2024) - specifies requirements and recommendations for cathodic protection (CP) of offshore pipelines. The standard covers the full lifecycle of CP systems for offshore carbon steel, stainless steel and flexible metallic pipelines: pre‑installation surveys, design, materials, fabrication, installation, commissioning, operation, inspection, maintenance and retrofits. It applies to seabed and seawater environments and to risers up to mean water level, and excludes subsea production and injection equipment and structures.

Key Topics and Requirements

The document addresses practical and technical aspects central to corrosion control of offshore pipelines:

• System selection - guidance on choosing sacrificial (galvanic) or impressed current CP systems suited to offshore conditions.
• Design parameters - protection potentials, CP system design life, coating breakdown factors, and design current densities (including specifics for splash zones, buried sections, high temperature areas and current drains).
• Anodes and materials - selection, electrochemical properties, shapes, utilization factors, and quality requirements for galvanic anodes (aluminium, zinc, etc.).
• Manufacturing and quality control - pre‑production testing, chemical analysis, mass and dimensional checks, defect inspection and electrochemical testing of anodes.
• Installation & commissioning - procedures for safe placement, electrical continuity, isolating joints and commissioning checks.
• Operation, inspection & maintenance - monitoring strategies, inspection intervals, performance criteria and requirements for retrofits, modifications and repairs.
• Special topics - HISC (hydrogen induced stress cracking) evaluation and thermally sprayed aluminium coatings are explicitly included.

Keywords: cathodic protection, offshore pipelines, ISO 15589‑2:2024, galvanic anodes, protection potentials, CP design, corrosion control.

Applications

EN ISO 15589-2:2024 is intended for practical application across the offshore oil, petroleum, petrochemical and natural gas sectors, and for lower‑carbon pipeline projects. Typical uses include:

• Designing CP for new offshore pipeline projects and flexible flowlines, spools and risers.
• Specifying materials and acceptance criteria for anode suppliers and fabricators.
• Developing inspection and maintenance plans for pipeline operators.
• Assessing and implementing retrofits, repairs and modifications to existing CP systems.

Who should use this standard

• Corrosion engineers and pipeline design engineers
• Offshore project managers and integrity teams
• Fabrication and anode manufacturers
• Inspection and commissioning contractors
• Regulators and owners/operators seeking compliance and best practice for offshore pipeline corrosion protection

Related standards

• ISO 13623 (defines pipeline systems scope)
• EN/ISO 15589‑1 (onshore pipelines - complementary guidance)
• Other CP and corrosion standards referenced within the document for testing and material specifications

EN ISO 15589‑2:2024 is the authoritative reference for implementing robust cathodic protection solutions that reduce corrosion risk and extend offshore pipeline service life.

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-2024
Naftna in plinska industrija, vključno z nizkoogljično energijo - Katodna zaščita
cevovodov - 2. del: Cevovodi na morju (ISO 15589-2:2024)
Oil and gas industries including lower carbon energy - Cathodic protection of pipeline
transportation systems - Part 2: Offshore pipelines (ISO 15589-2:2024)
Öl- und Gasindustrie einschließlich kohlenstoffarmer Energieträger - Kathodischer
Schutz für Transportleitungssysteme - Teil 2: Offshore-Pipelines (ISO 15589-2:2024)
Industries du pétrole et du gaz y compris les énergies à faible teneur en carbone -
Protection cathodique des systèmes de transport par conduites - Partie 2: Conduites en
mer (ISO 15589-2:2024)
Ta slovenski standard je istoveten z: EN ISO 15589-2:2024
ICS:
75.200 Oprema za skladiščenje Petroleum products and
nafte, naftnih proizvodov in natural gas handling
zemeljskega plina equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 15589-2
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2024
EUROPÄISCHE NORM
ICS 75.200 Supersedes EN ISO 15589-2:2014
English Version
Oil and gas industries including lower carbon energy -
Cathodic protection of pipeline transportation systems -
Part 2: Offshore pipelines (ISO 15589-2:2024)
Industries du pétrole et du gaz y compris les énergies à Öl- und Gasindustrie einschließlich kohlenstoffarmer
faible teneur en carbone - Protection cathodique des Energieträger - Kathodischer Schutz für
systèmes de transport par conduites - Partie 2: Transportleitungssysteme - Teil 2: Offshore-Pipelines
Conduites en mer (ISO 15589-2:2024) (ISO 15589-2:2024)
This European Standard was approved by CEN on 15 January 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15589-2:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 15589-2:2024) has been prepared by Technical Committee ISO/TC 67 "Oil and
gas industries including lower carbon energy" in collaboration with Technical Committee CEN/TC 219
“Cathodic protection” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2024, and conflicting national standards shall
be withdrawn at the latest by August 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 15589-2:2014.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 15589-2:2024 has been approved by CEN as EN ISO 15589-2:2024 without any
modification.
International
Standard
ISO 15589-2
Third edition
Oil and gas industries including
2024-02
lower carbon energy —
Cathodic protection of pipeline
transportation systems —
Part 2:
Offshore pipelines
Industries du pétrole et du gaz y compris les énergies à faible
teneur en carbone — Protection cathodique des systèmes de
transport par conduites —
Partie 2: Conduites en mer
Reference number
ISO 15589-2:2024(en) © ISO 2024

ISO 15589-2:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 15589-2:2024(en)
Contents Page
Foreword .v
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms. 4
4.1 Symbols .4
4.2 Abbreviated terms .5
5 General . 6
5.1 Competence assurance .6
5.2 Conformity .6
6 Cathodic protection system requirements . 6
6.1 General .6
6.2 Selection of CP systems.7
6.2.1 General .7
6.2.2 System selection considerations .7
6.3 Isolating joints .8
7 Design parameters . 9
7.1 General .9
7.2 Protection potentials .10
7.2.1 Potential criteria .10
7.2.2 HISC evaluation .11
7.2.3 Thermally sprayed aluminium . 12
7.3 CP system design life. 12
7.4 Design current densities for bare steel . 12
7.4.1 General . 12
7.4.2 Splash zone .14
7.4.3 Buried pipelines .14
7.4.4 Thermally sprayed aluminium coated pipelines .14
7.4.5 Elevated temperatures .14
7.4.6 Current drains .14
7.5 Coating breakdown factors . 15
8 Galvanic anodes . 17
8.1 Design of system .17
8.2 Selection of anode material .18
8.3 Electrochemical properties . .18
8.4 Anode shape and utilization factor .19
8.5 Electrical considerations . 20
9 Galvanic anode manufacturing .20
9.1 Pre-production test . 20
9.2 Coating . 20
9.3 Anode core materials . 20
9.4 Aluminium anode materials .21
9.5 Zinc anode materials . 22
10 Galvanic anode quality control.22
10.1 General . 22
10.2 Steel anode cores . 22
10.3 Chemical analysis of anode alloy . 22
10.4 Anode mass . 23
10.5 Anode dimensions and straightness . 23
10.5.1 Slender anodes . 23

iii
ISO 15589-2:2024(en)
10.5.2 Bracelet anodes . 23
10.6 Anode core dimensions and position .24
10.7 Anode surface irregularities .24
10.7.1 Slender anodes .24
10.7.2 Bracelet anodes .24
10.8 Cracks .24
10.8.1 General .24
10.8.2 Aluminium slender anodes. 25
10.8.3 Aluminium bracelet anodes . 25
10.9 Internal defects, destructive testing. 25
10.10 Electrochemical quality control testing . 26
11 Galvanic anode installation .27
12 Impressed-current CP systems .28
12.1 Current sources and control . 28
12.2 Impressed-current anode materials . 28
12.3 System design . 28
12.4 Manufacturing and installation considerations . 29
12.5 Mechanical and electrical considerations . 30
13 Documentation .30
13.1 Design, manufacturing and installation documentation . 30
13.2 Commissioning procedures .31
13.3 Operating and maintenance manual .31
14 Operation, monitoring and maintenance of CP systems .32
14.1 General .32
14.2 Monitoring plans . .32
14.3 Repair.32
Annex A (normative) Galvanic anode CP design procedures .33
Annex B (normative) Attenuation of protection .39
Annex C (informative) Performance qualification testing of galvanic anode materials .43
Annex D (normative) CP monitoring and surveys.44
Annex E (informative) Interference .50
Annex F (informative) Pipeline design for CP .52
Bibliography .58

iv
ISO 15589-2:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 67, Oil and gas industries including lower carbon
energy, Subcommittee SC 2, Pipeline transportation systems, in collaboration with the European Committee
for Standardization (CEN) Technical Committee CEN/TC 219, Cathodic protection, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 15589-2:2012), which has been technically
revised.
The main changes are as follows:
— in Clause 6, recommendations for isolating joints have been expanded;
— in Clause 7, NOTEs to Table 1 and text in 7.4 have been updated to avoid discrepancies with Figure 2;
coating breakdown factors have been revised for errors left in the previous edition and less conservative
values for some coating systems have been selected based on feedback from the industry;
— in Clause 8, NOTEs and guidance on the design of the system have been updated including recommendations
for buried pipelines; anode utilization factors have been expanded to cover additional anodes types;
— in Clause 9, Table 6 has been updated to reflect anode compositions in line with current industry practices
and other standards;
— in Clause 10, additional references have been provided for guidance on core dimensions and position as
well as testing for quality control of anode electrochemical properties;
— in Annex A, additional anode resistance formulae have been provided to cover different anode types.
— Annex B has been modified to present the NORSOK method as a requirement, with an alternative method
given for information.
— Annex C has been updated as informative and the test method replaced with references to current test
methods in line with current industry practice.

v
ISO 15589-2:2024(en)
— The previous Annex E has been removed and replaced by additional guidance on quality control testing
of anodes in 10.10.
— In the updated Annex E (Interference), additional references for alternating current interference have
been added.
A list of all parts in the ISO 15589 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

vi
ISO 15589-2:2024(en)
Introduction
Pipeline cathodic protection is achieved by the supply of sufficient direct current to the external pipe surface,
so that the steel-to-electrolyte potential is lowered on all the surface to values at which external corrosion is
reduced to an insignificant rate.
Cathodic protection is normally used in combination with a suitable protective coating system to protect
the external surfaces of steel pipelines from corrosion.
This document can also be used for offshore pipelines outside the petroleum, petrochemical and natural gas
industries.
vii
International Standard ISO 15589-2:2024(en)
Oil and gas industries including lower carbon energy —
Cathodic protection of pipeline transportation systems —
Part 2:
Offshore pipelines
1 Scope
This document specifies requirements and gives recommendations for the pre-installation surveys, design,
materials, equipment, fabrication, installation, commissioning, operation, inspection and maintenance of
cathodic protection (CP) systems for offshore pipelines for the petroleum, petrochemical and natural gas
industries as defined in ISO 13623. Flexible pipelines, in-field flowlines, spools and risers are included in this
document. Subsea production and injection equipment and structures are not included in this document.
This document is applicable to carbon steel, stainless steel and flexible metallic pipelines in offshore service.
This document is applicable to retrofits, modifications and repairs made to existing pipeline systems.
This document is applicable to all types of seawater and seabed environments encountered in submerged
conditions and on risers up to mean water level.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 630, Structural steels
ISO 1461, Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods
ISO 8044, Corrosion of metals and alloys — Vocabulary
ISO 8501-1, Preparation of steel substrates before application of paints and related products — Visual
assessment of surface cleanliness — Part 1: Rust grades and preparation grades of uncoated steel substrates and
of steel substrates after overall removal of previous coatings
ISO 9606-1, Qualification testing of welders — Fusion welding — Part 1: Steels
ISO 15589-1, Petroleum, petrochemical and natural gas industries — Cathodic protection of pipeline systems —
Part 1: On-land pipelines
ISO 15607, Specification and qualification of welding procedures for metallic materials — General rules
AWS D1.1/D1.1M, Structural Welding Code — Steel
EN 10025 (all parts), Hot rolled products of structural steels
EN 10204:2004, Metallic products — Types of inspection documents
ASTM D1141, Standard Practice for Preparation of Substitute Ocean Water
DNV-RP-B401, Cathodic Protection Design

ISO 15589-2:2024(en)
NACE TM0190, Standard Test Method — Impressed Current Test Method for Laboratory Testing of Aluminium
Anodes
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8044 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
anode sled
anodes installed on a structure and connected to the pipeline by a cable
3.2
closed-circuit potential
anode potential while electrically linked to the pipeline to be protected
3.3
coating breakdown factor
f
c
time-dependent factor to address increasing current requirements due to coating breakdown based on the
ratio of current density required to polarize a coated steel surface as compared to a bare steel surface
3.4
cold shut
horizontal surface discontinuity caused by solidification of the meniscus of the partially cast anodes as a
result of interrupted flow of the casting stream
3.5
driving voltage
difference between the pipeline/electrolyte potential and the anode/electrolyte potential when the cathodic
protection is operating
3.6
electric field gradient
change in electrical potential per unit distance through a conductive medium, arising from the flow of
electric current
3.7
electrochemical capacity
ε
total amount of electric charge that is produced when a fixed mass (usually 1 kg) of anode material is
consumed electrochemically
Note 1 to entry: Electrochemical capacity is expressed in ampere hours.
3.8
final current density
current density required to repolarise pipeline at the end of the CP design life
Note 1 to entry: Final current density is expressed in amperes per square metre.
3.9
hydrogen-induced stress cracking
HISC
cracking due to a combination of load and hydrogen embrittlement caused by the ingress of hydrogen formed
at the steel surface due to the cathodic polarization

ISO 15589-2:2024(en)
3.10
IR drop
voltage due to any current, measured between two points of the metal of the pipe or two points of the
electrolyte, such as seawater or seabed, in accordance with Ohm’s law
Note 1 to entry: IR drop and electric field gradient (3.6) are related terms.
3.11
master reference electrode
reference electrode, calibrated with the primary calibration reference electrode (3.15), used for verification
of reference electrodes that are used for field or laboratory measurements
3.12
mean current density
estimated average cathodic current density for the entire lifetime of the pipeline
Note 1 to entry: Mean current density is expressed in amperes per square metre.
3.13
protection potential
structure-to-electrolyte potential for which the metal corrosion rate is considered as insignificant
3.14
pitting resistance equivalent number
PREN
number, developed to reflect and predict the pitting resistance of a stainless steel, based on the proportions
of Cr, Mo, W and N in the chemical composition of the alloy
3.15
primary calibration reference electrode
reference electrode used for calibration of master reference electrodes (3.11)
3.16
remotely-operated vehicle
ROV
underwater vehicle operated remotely from a surface vessel or installation
[SOURCE: ISO 14723:2009, 4.32]
3.17
riser
part of an offshore pipeline, including any subsea spool pieces, that extends from the seabed to the pipeline
termination point on an offshore installation
[SOURCE: ISO 13623:2017, 3.1.20, modified — "including any subsea spool pieces" has been added.]
3.18
utilization factor
µ
fraction of the anodic material weight of a galvanic anode that can be consumed before the anode ceases to
provide the minimum required current output
3.19
pipeline lifetime
period that includes pipeline service life, and any prior or subsequent period planned by the operator

ISO 15589-2:2024(en)
4 Symbols and abbreviated terms
4.1 Symbols
∆E electrolytic potential drop
A
∆E metallic potential drop
Me
µ utilization factor
A anode exposed surface area
A total surface area
c
A cross-sectional area of the pipe wall
w
C anode cross-sectional perimeter
D pipeline outer diameter
d pipeline wall thickness
ΔΕ driving voltage
D pipeline internal diameter
i
E pipe-to-electrolyte potential shift at anode
E design closed-circuit potential of the anode
a
E design protection potential
c
E pipe-to-electrolyte potential shift at a distance x
x
f coating breakdown factor
c
f final coating breakdown factor
cf
I current flowing onto the pipe at anode
I individual current output at the end-of-life
af
I current demand
c
i current density
c
I current demand at the end of life
cf
I mean current demand
cm
I end-of-life individual anode current output
f
I current flowing onto the pipe at a distance x
x
L anode length
L distance between anodes
d
L half the distance between drain points
m
m net anode mass
ISO 15589-2:2024(en)
m individual net anode mass
a
n number of anodes
r anode radius
R pipe-to-electrolyte insulation resistance
R anode resistance /total circuit resistance
a
R anode resistance at end of life
af
R linear electrical resistance of the section of the pipeline
L
R transverse resistance
t
S arithmetic mean of anode length and width
t design life, expressed in years.
dl
α attenuation constant for the pipeline
ε electrochemical capacity
ρ environmental resistivity
ρ pipe material resistivity
Me
4.2 Abbreviated terms
AC alternate current
CAT cold-applied tape
CE carbon equivalent
CP cathodic protection
CRA corrosion-resistant alloy
CSE saturated copper electrode (Cu/CuSO )
DC direct current
EPDM ethylene propylene diene monomer
FBE fusion-bonded epoxy
HSS heat-shrinkable sleeve
ICCP impressed current cathodic protection
MIC microbially induced corrosion
PE polyethylene
PP polypropylene
PREN pitting resistance equivalent number
PU polyurethane
ISO 15589-2:2024(en)
ROV remotely-operated vehicle
SCE saturated calomel electrode (KCl)
SMYS specified minimum yield strength
SRB sulphate reducing bacteria
TSA thermally sprayed aluminium
3LPE three-layer polyethylene
3LPP three-layer polypropylene
5 General
5.1 Competence assurance
Personnel who undertake the design, supervision of installation, construction, installation supervision,
commissioning, supervision of operation, measurements, monitoring and supervision of maintenance of
cathodic protection systems shall have the appropriate level of competence for the tasks undertaken.
Competence of cathodic protection personnel to the level appropriate for tasks undertaken should be
demonstrated by certification in accordance with prequalification procedures such as ISO 15257, or by any
other equivalent scheme.
5.2 Conformity
A quality system and an environmental management system should be applied to assist conformity with the
requirements of this document.
NOTE ISO 29001 gives sector-specific guidance on quality management systems and ISO 14001 gives guidance on
the selection and use of an environmental management system.
6 Cathodic protection system requirements
6.1 General
The CP system shall be designed to prevent external corrosion over the pipeline lifetime and to:
— provide sufficient current to the pipeline to be protected and distribute this current so that the selected
criteria for CP are effectively attained on the entire surface;
— provide a design life of the CP system commensurate with the required life of the protected pipeline, or
to provide for periodic rehabilitation of the anode system;
— provide adequate allowance for anticipated changes in current requirements with time;
— ensure that anodes are installed where the possibility of disturbance or damage is minimal;
— provide adequate monitoring facilities to test and evaluate the system's performance.
The CP system shall be designed with due regard to environmental conditions and neighbouring structures.
Electrical isolation of offshore pipelines protected by galvanic anodes from other pipelines, structures,
subsea facility or floaters that are protected by impressed-current systems shall be evaluated for adverse
interaction between the two systems. An assessment shall be performed to identify the cathodic protection
system of these facilities and review the electrical connectivity with the proposed pipeline to ensure no
detrimental effects on each side related to inadequate or excessive polarization. Offshore pipelines shall be

ISO 15589-2:2024(en)
isolated from other unprotected or less protected structures, which can drain current from the pipeline's CP
system. If stray current problems are anticipated due to interaction between offshore pipelines and other
structures, providing electrical continuity of the pipelines to the other structures can be considered.
CP systems of adjacent pipelines or structures shall be verified to be compatible such that current drain
from one system into an adjacent system does not adversely affect the performance of either CP system.
The pipeline CP design shall take into account the pipeline installation method, the types of pipeline and
riser, and the burial and stabilization methods proposed. Guidance is given in Annex F.
The CP system based on galvanic anodes shall be designed for the lifetime of the pipeline system using the
calculation procedure given in Annex A.
The design of the CP system shall document what allowances have been made for the effects of water velocity
and erosion effects (e.g. from entrained sand silt or ice particles).
Installation of permanent test facilities should be considered, taking into account specific parameters such
as pipeline length, water depth and underwater access related to the burial conditions.
ISO 15589-1 should be used for the cathodic protection of short lengths of offshore pipelines and their
branches that are directly connected to cathodically protected onshore pipelines.
6.2 Selection of CP systems
6.2.1 General
CP shall be achieved using either galvanic anodes or an impressed-current system. Galvanic anodes shall be
connected to the pipe, either individually or in groups
Galvanic anodes are limited in current output by the anode-to-pipe driving voltage and the electrolyte
resistivity. Generally, anodes are attached directly to the pipe as bracelets. Sleds or mattresses of anodes
can also be placed at regular intervals along the pipeline. For these cases, an attenuation check in accordance
with Annex B shall be conducted to ensure the full length of pipeline is protected.
Some pipelines can be protected by anodes located at each end. Typically, this type of installation is used on
inter-platform pipelines. Anodes for the pipeline can be attached to the platform if the pipeline is electrically
connected to the platform. For this case, an attenuation check in accordance with Annex B shall be conducted
to ensure the full length of pipeline is protected.
Items that shall be considered in selecting the system to be used are covered in 6.2.2.
6.2.2 System selection considerations
Selection of the CP system shall be based on the following considerations:
— magnitude of the protective current required;
— resistivity of the seawater;
— availability and location of suitable power sources for impressed-current systems;
— existence of any stray currents causing significant potential fluctuations between pipeline and earth
that can preclude the use of galvanic anodes;
— effects of any CP interference currents on adjacent structures that can limit the use of impressed-current
CP systems;
— limitations on the space available, due to the proximity of foreign structures, and related construction
and maintenance concerns;
— future development of the area and any anticipated future extensions to the pipeline system;

ISO 15589-2:2024(en)
— cost of installation, operation and maintenance;
— reliability of the overall system;
— integrity of other pipelines and/or structures ex
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