ISO 15589-2:2004

Petroleum and natural gas industries — Cathodic protection of pipeline transportation systems — Part 2: Offshore pipelines

ISO 15589-2:2004 specifies requirements and gives recommendations for the pre-installation surveys, design, materials, equipment, fabrication, installation, commissioning, operation, inspection and maintenance of cathodic protection systems for offshore pipelines for the petroleum and natural gas industries as defined in ISO 13623. ISO 15589-2:2004 is applicable to carbon and stainless steel pipelines in offshore service. ISO 15589-2:2004 is applicable to retrofits, modifications and repairs made to existing pipeline systems. ISO 15589-2:2004 is applicable to all types of seawater and seabed environments encountered in submerged conditions and on risers up to mean water level. Note that special conditions sometimes exist where cathodic protection is ineffective or only partially effective. Such conditions can include elevated temperatures, disbonded coatings, thermal insulating coatings, shielding, bacterial attack, and unusual contaminants in the electrolyte.

Industries du pétrole et du gaz naturel — Protection cathodique des systèmes de transport par conduites — Partie 2: Conduites en mer

General Information

• Status: Withdrawn
• Publication Date: 04-May-2004
• Withdrawal Date: 04-May-2004
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• Technical Committee: ISO/TC 67/SC 2 - Pipeline transportation systems
• Drafting Committee: ISO/TC 67/SC 2 - Pipeline transportation systems
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 04-Dec-2012

Relations

• Consolidates: ISO/R 981:1969 - Title missing - Legacy paper document
• Effective Date: 28-Feb-2023
• Revised: ISO 15589-2:2012 - Petroleum, petrochemical and natural gas industries — Cathodic protection of pipeline transportation systems — Part 2: Offshore pipelines
• Effective Date: 20-Jun-2008

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15589-2
First edition
2004-05-01


Petroleum and natural gas industries —
Cathodic protection of pipeline
transportation systems —
Part 2:
Offshore pipelines
Industries du pétrole et du gaz naturel — Protection cathodique des
systèmes de transport par conduites —
Partie 2: Conduites en mer





Reference number
ISO 15589-2:2004(E)
©
ISO 2004

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ISO 15589-2:2004(E)
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ii © ISO 2004 – All rights reserved

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ISO 15589-2:2004(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols and abbreviated terms. 3
5 CP system requirements. 3
5.1 General. 3
5.2 Selection of CP systems . 4
6 Design parameters. 6
6.1 General. 6
6.2 Protection potentials . 7
6.3 Design life . 9
6.4 Design current densities . 9
6.5 Coating breakdown factors. 11
7 Galvanic anodes. 12
7.1 Design of system . 12
7.2 Selection of anode material . 13
7.3 Electrochemical properties. 13
7.4 Anode shape and utilization factor . 13
7.5 Special mechanical and electrical considerations . 13
8 Anode manufacturing . 14
8.1 Pre-production test . 14
8.2 Coating. 15
8.3 Anode core materials. 15
8.4 Aluminium anode materials . 15
8.5 Zinc anode materials . 16
9 Galvanic anode quality control. 16
9.1 General. 16
9.2 Steel anode cores . 16
9.3 Chemical analysis of anode alloy. 17
9.4 Anode mass. 17
9.5 Anode dimensions and straightness . 17
9.6 Anode core dimensions and position. 18
9.7 Anode surface irregularities . 18
9.8 Cracks . 18
9.9 Internal defects, destructive testing . 19
9.10 Electrochemical quality control testing. 20
10 Galvanic anode installation. 21
11 Impressed-current CP systems . 22
11.1 Current sources and control. 22
11.2 Impressed-current anode materials . 22
11.3 System design. 22
11.4 Manufacturing and installation considerations . 23
11.5 Mechanical and electrical considerations.23

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ISO 15589-2:2004(E)
12 Documentation .24
12.1 Design, manufacturing and installation documentation.24
12.2 Commissioning procedures.25
12.3 Operating and maintenance manual .25
13 Operation, monitoring and maintenance of CP systems .26
13.1 General .26
13.2 Monitoring plans.26
13.3 Repair .26
Annex A (normative) Galvanic anode CP design procedures .27
Annex B (normative) Performance testing of galvanic anode materials .35
Annex C (normative) Monitoring of CP systems for offshore pipelines .37
Annex D (informative) Laboratory testing of galvanic anodes for quality control.43
Annex E (informative) Interference .45
Annex F (informative) Pipeline design for CP.48
Bibliography.54

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ISO 15589-2:2004(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15589-2 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures
for petroleum, petrochemical and natural gas industries, Subcommittee SC 2, Pipeline transportation systems.
ISO 15589 consists of the following parts, under the general title Petroleum and natural gas industries —
Cathodic protection of pipeline transportation systems:
— Part 1: On-land pipelines
— Part 2: Offshore pipelines
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ISO 15589-2:2004(E)
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 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.
External corrosion control in general is covered by ISO 13623.
Users of this part of ISO 15589 should be aware that further or differing requirements may be needed for
individual applications. This part of ISO 15589 is not intended to inhibit alternative equipment or engineering
solutions to be used for the individual application. This may be particularly applicable where there is innovative
or developing technology. Where an alternative is offered, any variations from this part of ISO 15589 should
be identified.
Deviations from this part of ISO 15589 may be warranted in specific situations, provided it is demonstrated
that the objectives expressed in this part of ISO 15589 have been achieved.

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INTERNATIONAL STANDARD ISO 15589-2:2004(E)

Petroleum and natural gas industries — Cathodic protection of
pipeline transportation systems —
Part 2:
Offshore pipelines
1 Scope
This part of ISO 15589 specifies requirements and gives recommendations for the pre-installation surveys,
design, materials, equipment, fabrication, installation, commissioning, operation, inspection and maintenance
of cathodic protection systems for offshore pipelines for the petroleum and natural gas industries as defined in
ISO 13623.
This part of ISO 15589 is applicable to carbon and stainless steel pipelines in offshore service.
This part of ISO 15589 is applicable to retrofits, modifications and repairs made to existing pipeline systems.
This part of ISO 15589 is applicable to all types of seawater and seabed environments encountered in
submerged conditions and on risers up to mean water level.
NOTE Special conditions sometimes exist where cathodic protection is ineffective or only partially effective. Such
conditions can include elevated temperatures, disbonded coatings, thermal insulating coatings, shielding, bacterial attack,
and unusual contaminants in the electrolyte.
2 Normative references
The following referenced documents are indispensable for the application 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 1461, Hot dip galvanized coatings on fabricated iron and steel articles — Specifications and test methods
ISO 8044, Corrosion of metals and alloys — Basic terms and definitions
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 10474:1991, Steel and steel products — Inspection documents
ISO 13623, Petroleum and natural gas industries — Pipeline transportation systems
ISO 15589-1, Petroleum and natural gas industries — Cathodic protection of pipeline transportation systems —
Part 1: On-land pipelines
1)
ASTM D 1141 , Standard practice for the preparation of substitute ocean water

1) American Society for Testing and Materials, 100 Barr Harbour Drive, West Conshohocken, PA 19428-2959, USA.
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ISO 15589-2:2004(E)
2)
AWS D1.1/D1.1M , Structural Welding Code — Steel
3)
EN 287-1 , Approval testing of welders — Fusion welding — Part 1: Steels
EN 288-1, Specification and qualification of welding procedures for metallic materials — Part 1: General rules
for fusion welding
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8044 and the following apply.
3.1
anode potential
anode-to-electrolyte potential
3.2
closed-circuit anode potential
anode potential while electrically linked to the pipeline to be protected
3.3
coating breakdown factor
f
c
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
electric field gradient
change in electrical potential per unit distance through a conductive medium, arising from the flow of electric
current
3.6
electrochemical capacity
ε
total amount of electricity that is produced when a fixed mass (usually 1 kg) of anode material is consumed
electrochemically
NOTE It is expressed in ampere hours.
3.7
final current density
estimated current density at the end of the lifetime of the pipeline
3.8
IR drop
voltage, due to any current, developed between two points in the metallic path or in the lateral gradient in an
electrolyte such as seawater or seabed, measured between a reference electrode and the metal of the pipe, in
accordance with Ohm’s Law
cf. electric field gradient (3.5)

2) The American Welding Society, 550 NW Le Jeune Road, Miami, FL 33126, USA.
3) The European Committee for Standardization, Management Centre, Rue de Stassart, B-1050, Brussels, Belgium.
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ISO 15589-2:2004(E)
3.9
mean current density
estimated average cathodic current density for the entire lifetime of the pipeline
NOTE It is expressed in amperes per square metre.
3.10
protection potential
structure-to-electrolyte potential for which the metal corrosion rate is insignificant
3.11
remotely operated vehicle
ROV
underwater vehicle operated remotely from a surface vessel or installation
[ISO 14723]
3.12
riser
that part of an offshore pipeline, including any subsea spool pieces, which extends from the seabed to the
pipeline termination point on an offshore installation
[ISO 13623]
3.13
utilization factor
u
fraction of the anodic material that can be used in the cathodic protection process
4 Symbols and abbreviated terms
CE carbon equivalent
CP cathodic protection
N pitting resistance equivalent number
PRE
ROV remotely operated vehicle
SCE calomel reference electrode
σ specified minimum yield strength
SMY
5 CP system requirements
5.1 General
The main objectives and requirements of CP systems are to
 prevent external corrosion over the design life of the pipeline,
 provide sufficient current to the pipeline to be protected and distribute this current so that the selected
criteria for CP are effectively attained,
 provide a design life of the anode 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,
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ISO 15589-2:2004(E)
 install anodes where the possibility of disturbance or damage is minimal,
 provide adequate monitoring facilities to test and evaluate the system performance.
Design, fabrication, installation, operation and maintenance of CP systems for offshore pipelines shall be
carried out by experienced and qualified personnel.
The CP system shall be designed with due regard to environmental conditions, neighbouring structures and
other activities.
Offshore pipelines that are protected by galvanic anode systems should be electrically isolated from other
pipelines and structures that are protected by impressed-current systems. Offshore pipelines shall be isolated
from other unprotected or less protected structures, which could drain current from the pipeline's CP system. If
isolation is not practical or stray current problems are suspected, electrical continuity should be ensured.
Care shall be taken to ensure that different CP systems of adjacent pipelines or structures are compatible and
that no excessive current drains from one system into an adjacent 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 (see Annex F).
The CP system shall be designed for the lifetime of the installation using the calculation procedure given in
Annex A. In the design calculation, data given in Clause 6 of this part of ISO 15589 shall be used.
For areas with high water velocities and areas with erosion effects from entrained sand, silt, ice particles, etc.,
the design of the CP system needs special attention and additional design criteria shall be considered.
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.
For the cathodic protection of short lengths of submarine pipelines and their branches that are directly
connected to cathodically protected onshore pipelines, ISO 15589-1 shall be used.
5.2 Selection of CP systems
5.2.1 General
CP can be achieved using either galvanic anodes or an impressed-current system. Clause 6 covers the
design parameters to be used for both systems. An overview of these systems and items to be considered in
selecting the system to be used are covered in 5.2.2 to 5.2.5.
5.2.2 Distributed galvanic anode systems
Galvanic anodes are connected to the pipe, either individually or in groups. They 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 of anodes can also be placed at regular intervals along the pipeline.
5.2.3 Galvanic anode systems installed at ends of pipeline
Shorter 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.
5.2.4 Impressed-current anode systems
Impressed-current anodes can be of materials such as graphite, high-silicon cast iron, lead-silver alloy,
precious metals or steel. They are connected with an insulated cable, either individually or in groups, to the
positive terminal of a direct-current source, such as a rectifier or generator. The pipeline is connected to the
negative terminal of the direct-current source.
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ISO 15589-2:2004(E)
5.2.5 System selection considerations
Selection of the CP system shall be based on the following considerations:
 impressed-current system can protect a length of pipeline, depending on
 practical limitations on the locations for impressed-current anode and rectifier installations, e.g. at
either one or both ends of the pipeline, such as at landfalls and platforms,
 insulation resistance of the coated pipeline to the surrounding electrolyte at end of design life,
 longitudinal resistance of the pipeline;
 impressed-current systems can be more practical in high resistivity waters (e.g. large estuaries and
brackish water bays);
 lack of a source of external power can preclude the use of impressed-current systems;
 galvanic anode systems require minimal control and maintenance during the service life of the pipeline,
whereas impressed-current systems require regular control and maintenance;
 galvanic anode systems seldom cause serious interference problems on foreign neighbouring structures,
whereas impressed-current systems can have a significant effect;
 magnitude of the protective current required;
 existence of any stray currents causing significant potential fluctuations between pipeline and earth that
can preclude use of galvanic anodes;
 effects of any CP interference currents on adjacent structures that might 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;
 cost of installation, operation and maintenance;
 reliability of the overall system;
 galvanic anode systems have shown reliable performance for long-term protection;
 impressed-current systems located offshore are capable of providing long-term protection but are less
tolerant to design, installation and maintenance shortcomings than galvanic anode systems. Good service
can be expected if proper attention is paid to mechanical strength, connections, cable protection
(particularly in the wave or splash zone), choice of anode type and integrity of power source. Adequate
system monitoring should be provided;
 impressed-current systems may be preferred on short pipelines which terminate at platforms that have
impressed-current systems installed;
 impressed-current systems may be preferred as a retrofit system on pipelines with galvanic anode
failures, excessive anode consumption, operation beyond original design life or excessive coating
deterioration;
 impressed-current systems may be preferred on short pipelines where an impressed-current system is
operated from shore;
 impressed-current systems can cause detrimental effects on the integrity of other pipelines and/or
structures existing in the same area unless proper measures are taken to prevent these effects.
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ISO 15589-2:2004(E)
6 Design parameters
6.1 General
The design of a pipeline CP system shall be based on
 detailed information on the pipeline to be protected, including material, length, wall thickness, outside
diameter, pipe-laying procedures, route, laying conditions on the sea bottom, temperature profile
(operating and shut in) along its whole length, type and thickness of corrosion-protective coating(s) for
pipes and fittings, presence, type and thickness of thermal insulation, mechanical protection and/or
weight coating,
 environmental conditions, such as seawater composition, temperature and resistivity, at the seabed along
the whole length of the pipeline,
 burial status (extent of backfilling after trenching or natural burial) and soil resistivity,
 the design life of the system,
 information on existing pipelines in close proximity to or crossing the new pipeline, including location,
ownership and corrosion-control practices,
 information on existing CP systems (platforms, landfalls, etc.) and electrical pipeline isolation,
 availability of electrical power, electrical isolating devices, electrical bonds,
 applicable local legislation,
 construction dates, start-up date (required for hot lines),
 pipe, fittings, J-tubes, risers, clamps and other appurtenances, and
 performance data on CP systems in the same environment.
At water depths greater than 500 m and sometimes at shallower depths, seawater characteristics (dissolved
oxygen, salinity, pH, sea currents, and fouling) can vary significantly from shallower depths and affect cathodic
polarization and calcareous deposit formation. For these situations, the required information shall be obtained
from field surveys, corrosion test data or a review of operating experience, including the following:
 protective current requirements to meet applicable criteria;
 electrical resistivity of the electrolyte, including seasonal changes if relevant;
 pipe burial depth (if buried) and identification of exposed span lengths and locations;
 water temperature at the seabed;
 oxygen concentration at the seabed;
 water flowrate at the seabed, including seasonal changes if relevant;
 seabed topography.
When reviewing operating experience, the following additional data should be considered:
 electrical continuity;
 electrical isolation;
 external coating integrity;
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ISO 15589-2:2004(E)
 deviation from specifications;
 maintenance and operating data.
Design procedures for the CP systems shall be in accordance with Annex A.
6.2 Protection potentials
6.2.1 Introduction
The potential criteria and other measurements and observations that indicate whether adequate CP of a
pipeline is being achieved are listed in 6.2.2. The effectiveness of CP or other external corrosion control
measures can be confirmed by direct measu
...