ISO 21012:2006

INTERNATIONAL ISO
STANDARD 21012
First edition
2006-11-15


Cryogenic vessels — Hoses
Récipients cryogéniques — Tuyaux





Reference number
ISO 21012:2006(E)
©
ISO 2006

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ISO 21012:2006(E)
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ii © ISO 2006 – All rights reserved

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ISO 21012:2006(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 General requirements. 2
4.1 Design and construction. 2
4.2 Materials. 3
4.3 Cleanliness. 3
4.4 Mechanical properties. 3
5 Hose sample tests . 4
5.1 General. 4
5.2 Non-destructive tests and inspection. 5
5.3 Destructive tests. 6
6 Production testing . 7
6.1 General. 7
6.2 Pressure test. 7
6.3 Leak test. 7
7 Marking. 7
8 Cleaning. 8
9 Test certificate. 8
Annex A (informative) Typical hose assembly. 9
Annex B (normative) Rolling bend cycling test for metallic hose assemblies and hose assemblies
made of materials with a record of satisfactory use in cryogenic service. 10
Annex C (normative) Rolling bend cycling test for hose assemblies constructed from materials or
composites not commonly used in cryogenic service. 12
Bibliography . 14

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ISO 21012:2006(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 21012 was prepared by Technical Committee ISO/TC 220, Cryogenic vessels.
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INTERNATIONAL STANDARD ISO 21012:2006(E)

Cryogenic vessels — Hoses
1 Scope
This International Standard gives design, construction, type and production testing, and marking requirements
for non-insulated cryogenic flexible hoses used for the transfer of cryogenic fluids within the following range of
operating conditions:
⎯ working temperature: from − 270 °C to − 65 °C;
⎯ nominal size (DN): from 10 to 100.
End fittings for mounting of any couplings are within the scope of this International Standard, but the couplings
are subject to other standards.
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 7369, Pipework — Metal hoses and hose assemblies — Vocabulary
ISO 10806:2003, Pipework — Fittings for corrugated metal hoses
ISO 21010, Cryogenic vessels — Gas/materials compatibility
ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1:
Temperatures below − 80 °C
ISO 23208, Cryogenic vessels — Cleanliness for cryogenic service
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7369 and the following apply.
3.1
hose
flexible leak-tight inner tube of either corrugated metal, elastomer or plastic
3.2
braid
layer, or layers, of cylindrically woven wires covering the hose and permanently attached to the flexible hose
assembly end fittings, serving the function of restraining the flexible hose against elongation
3.3
protection coil or cover
outer coil or cover fitted to protect the main hose and braid against damage and abrasion
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ISO 21012:2006(E)
3.4
end fitting
fitting (of material compatible with material and product transferred) attached to each end of the hose and
braid (when fitted)
3.5
hose assembly
hose with end fittings attached, complete with braid and/or other covering, ready for service
3.6
DN (nominal size)
alphanumeric designation of size for components of a pipework system, is used for reference purposes
NOTE It comprises the letters DN followed by a dimensionless whole number that is indirectly related to the physical
size, in millimetres, of the bore or outside diameter of the end connections.
[ISO 6708:1995, definition 2.1]
3.7
rated pressure
PR
〈of a hose〉 lowest Maximum Allowable Working Pressure (MAWP) of any component of the hose at 20 °C
3.8
rated minimum temperature
lowest temperature to which the hose assembly is rated by the manufacturer
3.9
cyclic life
minimum number of complete cycles which, at the test conditions, the hose assembly is designed to withstand
without failure
4 General requirements
4.1 Design and construction
A hose is typically made from corrugated metal, from strip steel. The corrugation may be parallel or helical.
If elastomers or composites are used, additional requirements shall be applied in accordance with 5.3.2.2.
A braid is commonly fitted over the hose. This generally consists of woven wire in one or two layers in
stainless steel, or a high strength copper alloy. It may have a cover that shall be compatible with the
surroundings and with the conveyed fluid.
End fittings shall be designed as a rigid seal to the ends of a hose to ensure:
⎯ a tight fit to the hose;
⎯ a strong joint between the braid, hose and end fitting to stabilize the hose against elongation at rated
pressure.
Fittings for corrugated metal hose assemblies shall conform to ISO 10806.
An area for marking shall be provided on one of the end fittings.
All joining methods used in corrugated hose assemblies shall be qualified. Manual welds shall be in
accordance with applicable standards.
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ISO 21012:2006(E)
A typical cryogenic hose assembly is shown in Annex A.
4.2 Materials
All materials shall be compatible with the fluid conveyed and shall be controlled by the manufacturer of the
hose assembly by a specification ensuring control of chemical content and physical properties, and quality at
least equivalent to an internationally recognized standard. Materials for the manufacture of corrugated metal
hose assemblies shall be selected on the basis of their suitability for fabrication, e.g. cold forming and welding,
etc. and for the conditions under which they shall be used. In addition the following requirements shall meet:
⎯ end connections and couplings shall be made of materials compatible with the other materials of the hose
assembly;
⎯ a test certificate providing the chemical content and physical property test results shall be provided with
the hose assembly.
The materials used in a cryogenic hose assembly shall:
⎯ maintain sufficient ductility at the rated minimum temperature (as specified in ISO 21028-1);
⎯ be oxygen compatible, if specified for oxygen or nitrous oxide service (as specified ISO 21010);
⎯ contain less than 70 % copper, in the alloy as well as the soldering materials, if it is specified for mixtures
containing acetylene.
4.3 Cleanliness
Hose assemblies specified for all cryogenic fluids shall be cleaned in accordance with ISO 23208.
4.4 Mechanical properties
4.4.1 Burst pressure
The burst pressure shall be at least three times the rated pressure. Failure shall occur only in the body of the
hose and braid and not in their connections.
4.4.2 Pressure cycles
Hose assemblies shall have a minimum cyclic life 10 000 cycles when repeatedly pressurized from < 1 bar to
their rated pressure in accordance with 5.3.1.
4.4.3 Bending
Hose assemblies shall have a minimum cyclic life of 50 000 cycles when repeatedly flexed at their rated
pressure in accordance with 5.3.2.
4.4.4 Resistance to abuse
Hose assemblies should have sufficient resistance to deterioration of the braid when they are dragged on the
ground. For additional protection of the braid a coil, can be used.
Hose assemblies shall withstand a crushing test, simulating a person stepping on the hose assembly,
...