prEN ISO 24656
(Main)Cathodic protection of offshore wind structures (ISO/DIS 24656:2020)
Cathodic protection of offshore wind structures (ISO/DIS 24656:2020)
This European Standard will address the external and internal cathodic protection for offshore wind farm structures. It will be applicable for structures and appurtenances in contact with seawater or seabed environments. This Standard addresses:
• Design and implementation of cathodic protection systems for new structures,
• Assessment of residual lifetime of existing cathodic protection systems,
• Design and implementation of retrofit cathodic protection systems for improvement of the protection level or for life extension of the protection,
• Inspection and performance monitoring of cathodic protection systems installed on existing structures,
• Guidance on cathodic protection of reinforced concrete structures
Kathodischer Korrosionsschutz von Offshore-Windparkstrukturen (ISO/DIS 24656:2020)
Diese Europäische Norm behandelt den äußeren und inneren kathodischen Korrosionsschutz für Offshore-Windparkstrukturen. Sie ist für Strukturen und Zubehörteile anwendbar, die mit Meerwasser oder Umgebungen am Meeresboden in Berührung kommen. Diese Norm behandelt:
- die Konstruktion und Umsetzung von kathodischen Korrosionsschutzsystemen für neue Stahlkonstruktionen;
- die Bewertung der Restlebensdauer von bereits vorhandenen kathodischen Korrosionsschutzsystemen;
- die Konstruktion und Umsetzung von nachgerüsteten kathodischen Korrosionsschutzsystemen zur Verbesserung des Schutzgrades oder zur Verlängerung der Lebensdauer des Schutzes;
- die Überprüfung und Leistungsüberwachung von kathodischen Korrosionsschutzsystemen, die bei vorhandenen Strukturen eingebaut sind;
- einen Leitfaden bezüglich des kathodischen Korrosionsschutzes von Stahlbetonkonstruktionen.
Protection cathodique des structures éoliennes offshore (ISO/DIS 24656:2020)
Katodna zaščita vetrnih konstrukcij na morju (ISO/DIS 24656:2020)
General Information
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN ISO 24656:2020
01-december-2020
Katodna zaščita vetrnih konstrukcij na morju (ISO/DIS 24656:2020)
Cathodic protection of offshore wind structures (ISO/DIS 24656:2020)
Kathodischer Korrosionsschutz von Offshore-Windparkstrukturen (ISO/DIS 24656:2020)
Protection cathodique des structures éoliennes offshore (ISO/DIS 24656:2020)Ta slovenski standard je istoveten z: prEN ISO 24656
ICS:
47.020.99 Drugi standardi v zvezi z Other standards related to
ladjedelništvom in shipbuilding and marine
konstrukcijami na morju structures
77.060 Korozija kovin Corrosion of metals
oSIST prEN ISO 24656:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 24656:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 24656
ISO/TC 156 Secretariat: SAC
Voting begins on: Voting terminates on:
2020-10-19 2021-01-11
Cathodic protection of offshore wind structures
ICS: 77.060; 47.020.99
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
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STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
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WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 24656:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
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oSIST prEN ISO 24656:2020
ISO/DIS 24656:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2020 – All rights reserved
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oSIST prEN ISO 24656:2020
ISO/DIS 24656:2020(E)
Contents Page
Foreword ........................................................................................................................................................................................................................................vi
Introduction ..............................................................................................................................................................................................................................vii
1 Scope ................................................................................................................................................................................................................................. 1
2 Normative references ...................................................................................................................................................................................... 1
3 Symbols and abbreviations ....................................................................................................................................................................... 2
3.1 Symbols ......................................................................................................................................................................................................... 2
3.2 Abbreviations ........................................................................................................................................................................................... 3
4 Terms and definitions ..................................................................................................................................................................................... 4
5 Competence of personnel ............................................................................................................................................................................ 8
6 Structural considerations ........................................................................................................................................................................... 8
6.1 Structures to be protected ............................................................................................................................................................ 8
6.2 Materials ....................................................................................................................................................................................................10
6.3 Corrosion protection strategy .................................................................................................................................................10
7 Cathodic protection criteria ..................................................................................................................................................................15
7.1 Temporary protection ....................................................................................................................................................................15
7.2 Steel structures ....................................................................................................................................................................................15
7.3 Reinforced concrete structures .............................................................................................................................................16
8 Cathodic protection design .....................................................................................................................................................................16
8.1 Objectives..................................................................................................................................................................................................16
8.2 Design considerations....................................................................................................................................................................16
8.2.1 General...................................................................................................................................................................................16
8.2.2 External cathodic protection ..............................................................................................................................17
8.2.3 Internal cathodic protection ...............................................................................................................................17
8.3 Design Life................................................................................................................................................................................................18
8.4 Surface area considerations......................................................................................................................................................18
8.4.1 General...................................................................................................................................................................................18
8.4.2 Structure sub-division ........................................................................................................................................... ...19
8.5 Environmental factors ...................................................................................................................................................................19
8.5.1 General...................................................................................................................................................................................19
8.5.2 Seawater flow velocity .............................................................................................................................................20
8.5.3 Electrolyte resistivity ................................................................................................................................................20
8.5.4 Seawater temperature..............................................................................................................................................20
8.5.5 Calcareous deposits ....................................................................................................................................................21
8.6 Protection current demand .......................................................................................................................................................21
8.6.1 General...................................................................................................................................................................................21
8.6.2 Calculation of current demand, external surfaces ...........................................................................21
8.6.3 Calculation of current demand, internal surfaces ............................................................................23
8.7 Electrical continuity and Continuity Bonds ................................................................................................................24
8.8 Current drains and interactions ............................................................................................................................................24
8.9 Installation considerations during design ...................................................................................................................25
9 Galvanic anode systems ..............................................................................................................................................................................26
9.1 General ........................................................................................................................................................................................................26
9.2 Anode current availability ..........................................................................................................................................................26
9.3 Galvanic anode alloys .....................................................................................................................................................................26
9.4 Anode selection ...................................................................................................................................................................................27
9.5 Anode requirements .......................................................................................................................................................................28
9.6 Anode distribution ............................................................................................................................................................................29
10 Impressed current systems ....................................................................................................................................................................30
10.1 General ........................................................................................................................................................................................................30
10.2 Design considerations....................................................................................................................................................................31
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10.2.1 Resilience of impressed current CP system by design .................................................................31
10.2.2 Current Requirement of impressed current CP system ..............................................................32
10.2.3 Impressed current CP system components ...........................................................................................32
10.2.4 DC power source ...........................................................................................................................................................32
10.2.5 Impressed current anodes .................. ..................................................................................................................33
10.2.6 Reference electrodes .................................................................................................................................................34
10.2.7 Dielectric shields .................. .................................................... .....................................................................................35
10.3 Installation of impressed current CP systems ..........................................................................................................35
10.4 Hybrid systems and temporary power for impressed current systems .............................................36
10.5 Continuity Bonds ................................................................................................................................................................................36
11 Cable systems ........................................................................................................................................................................................................36
11.1 General ........................................................................................................................................................................................................36
11.2 Cathodic protection DC cables ................................................................................................................................................37
11.3 Inter-array and export AC cables .........................................................................................................................................38
12 Commissioning and surveys ..................................................................................................................................................................41
12.1 Objectives..................................................................................................................................................................................................41
12.2 Galvanic anode systems ................................................................................................................................................................41
12.2.1 Detailed External Surveys .....................................................................................................................................42
12.2.2 Detailed Internal Surveys ......................................................................................................................................42
12.3 Permanent CP monitoring Systems ....................................................................................................................................42
12.4 Impressed current systems .......................................................................................................................................................43
13 CP surveying and monitoring ...............................................................................................................................................................44
13.1 Objectives..................................................................................................................................................................................................44
13.2 General considerations .................................................................................................................................................................44
13.3 Reference electrodes .......................................................................................................................................................................46
13.4 Frequency of Survey and Monitoring ...............................................................................................................................46
14 Retrofit cathodic protection systems ...........................................................................................................................................47
14.1 General considerations .................................................................................................................................................................47
14.2 Survey before retrofit .....................................................................................................................................................................47
14.3 Retrofit for inadequate protection ......................................................................................................................................48
14.4 Retrofit for life extension ............................................................................................................................................................48
14.5 All retrofits...............................................................................................................................................................................................48
14.6 Equipment considerations .........................................................................................................................................................50
15 Documentation ....................................................................................................................................................................................................50
15.1 Design report .........................................................................................................................................................................................51
15.1.1 General...................................................................................................................................................................................51
15.2 Material Specification requirements .................................................................................................................................53
15.2.1 General...................................................................................................................................................................................53
15.2.2 Galvanic anodes .............................................................................................................................................................53
15.2.3 Impressed current CP materials ......................................................................................................................54
15.3 Installation Drawings and Specifications ......................................................................................................................57
15.4 As-built installation and commissioning report requirements .................................................................57
15.5 Operation and Maintenance requirements .................................................................................................................57
16 Safety and cathodic protection ...........................................................................................................................................................58
16.1 Objectives..................................................................................................................................................................................................58
16.2 Physical obstructions .....................................................................................................................................................................58
16.3 Electric shock ........................................................................................................................................................................................58
16.4 Gas evolution .........................................................................................................................................................................................59
16.4.1 Hydrogen evolution ....................................................................................................................................................59
16.4.2 Chlorine evolution .......................................................................................................................................................59
Annex A (informative) Environmental checklist ...................................................................................................................................60
Annex B (informative) Method of using metocean data to calculate marked-up seawater
flow velocity ............................................................................................................................................................................................................61
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Annex C (informative) Guidance on Cathodic Protection current density requirement for
cathodic protection of wind offshore structures .............................................................................................................73
Annex D (informative) Coatings and coating breakdown for CP design .......................................................................81
Annex E (informative) Anode resistance and Life calculation ................................................................................................85
Annex F (informative) Calculation of voltage drop down connection cables ..........................................................93
Annex G (informative) Typical electrochemical characteristics for commonly usedimpressed current anodes ......................................................................................................................................................................95
Annex H (informative) Permanent monitoring system design process ........................................................................97
Annex I (informative) Cathodic Protection Modelling ................................................................................................................101
Bibliography .........................................................................................................................................................................................................................104
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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 documents 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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).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 156, Corrosion of metals and alloys.
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 2020 – All rights reserved
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Introduction
Cathodic protection (CP), possibly together with protective coating, is applied to protect the immersed
external surfaces of offshore wind farm structures and appurtenances from corrosion due to seawater
or seabed environments.CP, possibly together with protective coating, can be applied to protect the internal flooded and seabed
and sediment exposed surfaces from corrosion.The general principles of CP in seawater are detailed in ISO 12473, see chapter 2.
CP involves the supply of sufficient direct current to the surfaces of the structure in order to reduce the
steel to electrolyte potential to values where corrosion is considered insignificant or acceptably low.
CP is designed to protect the submerged and buried areas of the structure from corrosion. The parts
that are not permanently immersed will not be permanently protected by the CP system.
This standard introduces guidance for the use of available metocean data to• assess the CP demand of immersed and frequently wetted areas
• determine seawater flow velocities to assess the CP design parameters
This is in addition to the primary use of the metocean data in structural design.
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oSIST prEN ISO 24656:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 24656:2020(E)
Cathodic protection of offshore wind structures
1 Scope
This European Standard will address the external and internal cathodic protection for offshore wind
farm structures. It will be applicable for structures and appurtenances in contact with seawater or
seabed environments. This Standard address:• Design and implementation of cathodic protection systems for new steel structures,
• Assessment of residual lifetime of existing cathodic protection systems,• Design and implementation of retrofit cathodic protection systems for improvement of the protection
level or for life extension of the protection,• Inspection and performance monitoring of cathodic protection systems installed on existing
structures,• Guidance on cathodic protection of reinforced concrete structures
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 206, Concrete — Specification, performance, production and conformityEN 1992-1-1, Eurocode 2: Design of concrete structures — Part 1-1: General rules and rules for buildings
ISO 8044, Corrosion of metals and alloys — VocabularyISO 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 coatingsISO 12473, General principles of cathodic protection in seawater
ISO 12696, Cathodic protection of steel in concrete
ISO 12944-2, Paints and varnishes — Corrosion protection of steel structures by protective paint systems —
Part 2: Classification of environmentsISO 12944-9, Paints and varnishes — Corrosion protection of steel structures by protective paint
systems — Part 9: Protective paint systems and laboratory performance test methods for offshore and
related structuresEN 13670, Execution of concrete structures
EN 17243, Cathodic protection of internal surfaces of steel tanks, equipment, structures and pipi
...
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