ISO 23208:2005

INTERNATIONAL ISO
STANDARD 23208
First edition
2005-02-15

Cryogenic vessels — Cleanliness for
cryogenic service
Récipients cryogéniques — Propreté en service cryogénique




Reference number
ISO 23208:2005(E)
©
ISO 2005

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ISO 23208:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 23208:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Requirements . 2
4.1 General requirements. 2
4.2 Additional requirements for oxygen and oxidizing fluids . 2
5 Cleaning procedure . 2
6 Cleanliness evaluation . 2
7 Post-cleaning protection. 2
8 Identification. 3
Annex A (informative) Inspection methods . 4
Bibliography . 7

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ISO 23208:2005(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 23208 was prepared by Technical Committee ISO/TC 220, Cryogenic vessels.
ISO 23208 is based on the European Standard EN 12300.
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INTERNATIONAL STANDARD ISO 23208:2005(E)

Cryogenic vessels — Cleanliness for cryogenic service
1 Scope
This International Standard specifies the minimum requirements for the cleanliness of all surfaces of cryogenic
vessels and associated accessories that are in contact with the cryogenic fluid at any expected operating
conditions.
This International Standard defines the acceptable level of surface and particle contamination to minimize the
risk of malfunction of equipment and ensure safety against ignition when in contact with oxygen or oxidizing
fluids (see ISO 10156-2).
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 10156-2, Gas cylinders — Gases and gas mixtures — Part 2: Determination of oxidizing ability of toxic
1)
and corrosive gases and gas mixtures
ISO 21010, Cryogenic vessels — Gas/materials compatibility
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
cryogenic fluid
gas which is partially liquid because of its low temperature
NOTE 1 Includes totally evaporated liquids and supercritical fluids.
NOTE 2 In the context of this International Standard, refrigerated but non-toxic gases and mixtures of them are referred
to as cryogenic fluids.
NOTE 3 See also ISO 21029-1, ISO 20421-1 and/or ISO 21009-1.
3.2
oxidizing fluid
cryogenic fluid with oxidizing properties (in accordance with ISO 10156-2)


1) To be published.
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ISO 23208:2005(E)
4 Requirements
4.1 General requirements
Chips, foreign matter, and major potentially loose particles such as oxide scale and weld spatter are not
acceptable.
Particles visible under daylight or white light without magnification are not acceptable. Depending upon the
design of the system, more stringent requirements for particle size may be required to avoid malfunction of
equipment.
Free water shall not be detectable by visual examination.
4.2 Additional requirements for oxygen and oxidizing fluids
For oxygen and oxidizing fluids, hydrocarbon contamination, paint, adhesives, sealants and protective coating
shall not be detectable by visual examination using white light unless they are oxygen compatible in
accordance with ISO 21010.
2
The maximum acceptable hydrocarbon contamination (oil, grease, etc.) is 500 mg/m .
5 Cleaning procedure
Any cleaning procedure may be used, providing the requirements of 4.1 and 4.2, if relevant, are met. If solvent
or cleaning agents are used, they shall be compatible with all materials to be cleaned in particular plastics.
Special care shall be taken to remove any non-oxygen-compatible agents (see ISO 21010) from equipment
cleaned for oxygen or oxidizing fluid service.
6 Cleanliness evaluation
An inspection and sampling method shall be selected to ensure that the requirements of 4.1 and 4.2, if
relevant, are met. It shall take into account the cleaning procedure to be used, the equipment to be cleaned
and its level of contamination. Cleanliness evaluation methods may include those listed in Annex A.
The method of inspection shall not itself result in contamination levels greater than those specified in 4.1 and 4.2.
The cleanliness evaluation method shall be documented and the results obtained shall be recorded.
7 Post-cleaning protection
After cleaning, items shall be protected to maintain their clean condition until used. To reduce the risk of
condensing any atmospheric moisture during storage, consideration shall be given to purging and sealing the
equipment.
Any packaging, plugs, etc. that can contact the clean surfaces shall be clean and removable without leaving
any residue. Any packaging material shall be strong enough to resist the expected handling and storage
conditions and be able to be sealed and waterproof.
Any protective gas used shall be d
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