ISO 23226:2020

INTERNATIONAL ISO
STANDARD 23226
First edition
2020-11
Corrosion of metals and alloys —
Guidelines for the corrosion testing
of metals and alloys exposed in deep-
sea water
Corrosion des métaux et alliages — Lignes directrices pour les essais
de corrosion des métaux et alliages exposés en eau profonde
Reference number
ISO 23226:2020(E)
©
ISO 2020

---------------------- Page: 1 ----------------------
ISO 23226:2020(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
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 23226:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Selection of test site . 2
5 Assembly and components . 2
5.1 Assembly . 2
5.2 Test rack . 4
5.3 Other parts and equipment . 4
5.3.1 Equipment for environmental monitoring . 4
5.3.2 Release system . 4
5.3.3 Surface water location unit . 4
5.3.4 Under water location unit . 4
5.3.5 Buoys . 4
5.3.6 Connecting accessories . 5
5.3.7 Tension rope . 5
5.3.8 Batteries . 5
5.3.9 Anchor system . 5
6 Specimens . 5
6.1 Preparation of specimens . 5
6.2 Mount of specimens . 6
6.3 Packaging and transportation of specimens . 7
7 Testing procedure . 8
8 Evaluation of specimens . 8
9 Test report . 9
Bibliography .11
© ISO 2020 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 23226:2020(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.
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.
iv © ISO 2020 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 23226:2020(E)

Introduction
With the developments of the offshore oil and gas industry, the activities of exploration and production
of oil and gas have been extended into deep sea. Many subsea equipment and systems for oil/gas
production have been deployed in deep-sea water. There are also some instruments placed in the
subsea for environmental observation and scientific exploration. Corrosion is a crucial problem for
these valuable installations because it seriously affects the performance, reliability and safety of these
equipment and systems.
This document gives guidance on the corrosion testing of metals and alloys exposed in deep-sea water.
The testing can be conducted based on the specified conditions and procedures, and meaningful
comparisons may be made for different tests.
© ISO 2020 – All rights reserved v

---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 23226:2020(E)
Corrosion of metals and alloys — Guidelines for the
corrosion testing of metals and alloys exposed in deep-
sea water
1 Scope
This document gives guidelines for the corrosion testing of metals and alloys exposed in deep-sea
water, including the selection of the test site, components and assembly of the test system, specimen
preparation, testing procedure, evaluation after the retrieval from exposure sites and test report.
This document is applicable to the general corrosion exposure testing of metals and alloys as well as
localized corrosion tests such as stress corrosion cracking (SCC) testing, galvanic corrosion testing and
crevice corrosion testing of specimens exposed in deep-sea water.
Testing with exposure in deep sea of other materials such as composites and elastomers can also be
carried out with reference to these guidelines, but the evaluation of these materials after the retrieval
is different from that of metals and alloys.
This document does not include the performance testing of sacrificial anodes for cathodic protection in
the field of deep sea, which can be conducted using specified testing cells and equipment in the deep-
sea exposure. However, this guidance can also provide useful information as reference for conducting
performance testing of sacrificial anodes in deep-sea water.
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 8044, Corrosion of metals and alloys — Vocabulary
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 terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
deep-sea water
sea water zone with a depth generally ranging from 200 meters to thousands of meters
Note 1 to entry: Deep-sea water has a corrosive environment with parameters such as temperature, salinity,
dissolved oxygen content, microorganism and biofouling that are quite different from those in surface sea water.
3.2
test site
location where corrosion tests exposed in deep sea are performed
© ISO 2020 – All rights reserved 1

---------------------- Page: 6 ----------------------
ISO 23226:2020(E)

3.3
service environment
environment for which the corrosion data is required
3.4
test rack
structure within which the specimens or modules of specimens are housed
4 Selection of test site
The selection of test site is very important for corrosion tests exposed in deep-sea water because the
environment can vary considerably at different test sites.
The selected test site should be suitable for conducting the testing. Generally, the test site should be
selected with consideration of the following requirements.
a) The environmental parameters of the test site should be representative of the service environment.
b) The seabed at the test site should be generally flat without protruding rocks or deep traps, and the
slope should be smaller than 3 %. The sediment at the seabed should be stable.
c) The test site should be in an open area, where sea water can flow freely without being blocked in a
valley or a basin.
d) The test site should be in a place where the assembly will not be damaged by shipping, trawling or
other foreseeable activities. Also, the as-set assembly at the test site should not affect the safety of
foreseeable activities such as shipping and trawling.
e) The test site should be selected in consideration of relevant rules and regulations. The risks of
environmental impact and safety should be assessed prior to any activity is undertaken.
5 Assembly and components
5.1 Assembly
5.1.1 The assembly should have at least the following functions:
a) carrying the specimens reliably during the test in deep sea;
b) gathering the key environmental parameters related to corrosion at the test site;
c) locating the assembly in deep sea;
d) retrieving the assembly at the end of testing.
5.1.2 The assembly is mainly composed of the following parts:
a) buoy(s);
b) tension rope;
c) test rack(s);
d) release system;
e) environmental parameter collection and storage unit;
f) surface water location unit and under water location unit;
g) anchor system.
2 © ISO 2020 – All rights reserved

---------------------- Page: 7 ----------------------
ISO 23226:2020(E)

5.1.3 The typical assembly of test system is shown in Figure 1. There may be a single test rack in the
assembly. Alternatively, there may be several test racks deployed at different elevations on the assembly.
This assembly with multiple test racks is longer and more complicated than the assembly with only one
test rack.
Key
1 top-of-string buoy A upper test rack
2 tension rope B middle test rack
3 environmental parameter collection and storage unit C lower test rack
4 tension rope
5 buoy
6 bottom-of-string buoy
7 release system
8 coupling between release system and anchor system
9 & 10 anchor system
Figure 1 — Diagram of a typical assembly of test system applied in deep-sea water
5.1.4 The assembly should be designed carefully to have high reliability and safety, and to be easy for
the operation of deployment and retrieval. It should be fixed at the test site with an anchor system. The
location of the test racks in the assembly should be determined according to the depth of sea water at
which the specimens are expected to be exposed. The dimensions of the test racks should be able to
contain all the specimens for the testing without interference. The buoys should be designed based on
© ISO 2020 – All rights reserved 3

---------------------- Page: 8 ----------------------
ISO 23226:2020(E)

the mass of the whole assembly to provide enough buoyancy to bring the assembly back to the surface
when released from the anchor system. The design of the assembly should be carried out by a suitably
qualified person.
5.1.5 The end user (and qualified personnel) is responsible for the test assembly installation,
implementation and retrieval. Checks of the set up should be carried out once installed.
5.2 Test rack
5.2.1 Test rack may be made of corrosion resistant materials with proven performance in deep water
environments. Alternatively, the test rack may be made of carbon steel provided it is protected from
corrosion using coating and sacrificial anode cathodic protection, which should be carefully designed to
avoid interference on specimens.
5.2.2 The test rack should have mechanical stability for the long-time service in deep-sea water.
It should be suitable for the particular types of specimen to be deployed. Refer to 6.1 for guidance
appropriate to different types of specimen.
5.3 Other parts and equipment
5.3.1 Equipment for environmental monitoring
Equipment for measuring environmental parameters should be located in or close to the test rack,
so that environmental data collected is representative of the conditions to which the specimens are
exposed.
Equipment is commercially available for the measurement of environmental parameters, such as oxygen
concentration, temperature, conductivity of sea water, hydrostatic pressure, sea current velocity, pH
value, etc., to characterize the local environment during the whole deployment period. Sensors to
measure other parameters, such as SO and H S concentration, may also be installed depending on the
2 2
requirements of testing.
The equipment should be pressure-proof and have low electrical energy consumption. The data
gathered will be stored automatically, so that they can be read out after the retrieval.
5.3.2 Release system
The controllable retrieval system is based on the release installed in the assembly, which can receive
the signal from the surface vessel. When receiving the command for releasing, the system can
automatically separate the test racks and buoys from the anchor system on the seabed. The buoys will
bring the test rack and the equipment back to the surface. It is recommended that two release units in
parallel configuration should be fixed in the assembly to enhance reliability for the retrieval.
5.3.3 Surface water location unit
Surface water location equipment (e.g. radio beacons) may be incorporated in the assembly to allow it
to be located after returning to the surface with release from the anchor system.
5.3.4 Under water location unit
Under water location equipment (e.g. SONAR) should be incorporated in the assembly to allow it to be
located in situ. The release system generally contains SONAR.
5.3.5 Buoys
Buoys should be suitable for the service environment. Note that glass floating spheres or syntactic
foams comprising microspheres embedded in a plastic matrix
...