ISO 21011:2008
(Main)Cryogenic vessels — Valves for cryogenic service
Cryogenic vessels — Valves for cryogenic service
ISO 21011:2008 specifies the requirements for the design, manufacture and testing of valves for a rated temperature of -40 °C and below (cryogenic service), i.e. for operation with cryogenic fluids in addition to operation at temperatures from ambient to cryogenic. ISO 21011:2008 applies to all types of cryogenic valves, including vacuum jacketed cryogenic valves up to size DN 150. ISO 21011:2008 is not applicable to pressure relief valves covered by ISO 21013-1.
Récipients cryogéniques — Robinets pour usage cryogénique
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 21011
First edition
2008-02-01
Cryogenic vessels — Valves for
cryogenic service
Récipients cryogéniques — Robinets pour usage cryogénique
Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved
Contents Page
Foreword. iv
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Requirements.4
4.1 Materials .4
4.2 Design .5
5 Testing .7
5.1 Type approval.7
5.2 Production tests.8
5.3 Test report .9
6 Cleanliness .9
7 Marking .9
7.1 Marking on the body of the valve.9
7.2 Marking on an identification plate.9
Annex A (informative) Recommended methods for leak tightness testing of cryogenic valves.10
Bibliography .12
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 21011 was prepared by Technical Committee ISO/TC 220, Cryogenic vessels.
iv © ISO 2008 – All rights reserved
INTERNATIONAL STANDARD ISO 21011:2008(E)
Cryogenic vessels — Valves for cryogenic service
1 Scope
This International Standard specifies the requirements for the design, manufacture and testing of valves for a
rated temperature of −40 °C and below (cryogenic service), i.e. for operation with cryogenic fluids in addition
to operation at temperatures from ambient to cryogenic.
It applies to all types of cryogenic valves, including vacuum jacketed cryogenic valves up to size DN 150.
This International Standard is not applicable to pressure relief valves covered by ISO 21013-1.
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 5208, Industrial valves — Pressure testing of valves
ISO 10434, Bolted bonnet steel gate valves for the petroleum, petrochemical and allied industries
ISO 11114-1, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents — Part 1: Metallic materials
ISO 11114-2, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas
contents — Part 2: Non-metallic materials
ISO 15761, Steel gate, globe and check valves for sizes DN 100 and smaller, for the petroleum and natural
gas industries
ISO 17292, Metal ball valves for petroleum, petrochemical and allied industries
ISO 21010, Cryogenic vessels — Gas/materials compatibility
ISO 21028-1, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 1:
Temperatures below −80 degrees C
ISO 21028-2, Cryogenic vessels — Toughness requirements for materials at cryogenic temperature — Part 2:
Temperatures between −80 degrees C and −20 degrees C
ISO 23208, Cryogenic vessels — Cleanliness for cryogenic service
ASME B16.34, Valves — Flanged, threaded, and welding end
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
nominal size
DN
alphanumeric designation of size for components of a pipe work system, which is used for reference
purposes.
NOTE 1 It comprises the letters “DN” followed by a dimensionless whole number which is indirectly related to the
physical size, in millimetres, of the bore or outside diameter of the end connections.
NOTE 2 Adapted from ISO 6708:1995.
3.2
rated pressure
PR
maximum pressure difference between the inside and outside of any pressure retaining boundary for which
the boundary is designed to be operated at 20 °C
NOTE The PR of the valve is the lowest PR of any component of the valve.
3.3
rated minimum temperature
lowest temperature for which the valve is rated by the manufacturer
3.4
valve category A
valve type which passed the operation simulation test for 2 000 cycles during type approval testing
NOTE See 5.1.3.3.
3.5
valve category B
valve type which passed the operation simulation test for 100 cycles during type approval testing
NOTE See 5.1.3.3.
3.6
flow coefficient
basic coefficient used to state the flow capacity of a valve under specified conditions
NOTE 1 Flow coefficients in current use are K and C depending upon the system of units.
v v
NOTE 2 Even though the dimensions and units used with flow coefficient K differ from those used with flow coefficient
v
K
v
C , it is possible to relate the two flow coefficients numerically by means of the relationship = 0,865 .
v
C
v
NOTE 3 The flow coefficient definitions given in 3.6.1 (for K ) and in 3.6.2 (for C ) include certain units, nomenclature
v v
and temperature values which are not consistent with the parts of IEC 60534 other than IEC 60534-1. These
inconsistencies are limited to 3.6.1 and 3.6.2 of this International Standard, and their sole purpose is to illustrate the
unique relationships traditionally used in the valve industry. These inconsistencies do not concern any parts of IEC 60534
other than IEC 60534-1.
2 © ISO 2008 – All rights reserved
3.6.1
flow coefficient K
v
K
v
special volumetric flow rate calculated in cubic metres per hour (capacity) through a valve, where the static
1)
pressure loss across the valve is 0,1 MPa (1 bar) , and the fluid is water within a temperature range 5 °C to
40 °C (278 K to 313 K)
NOTE The value of K can be obtained from test results by means of the following equation:
v
∆p
⎛⎞
⎛⎞ρ
K
v
KQ=
⎜⎟
v ⎜⎟
⎜⎟
∆p ρ
⎝⎠⎝⎠w
where
Q is the measured volumetric flow rate, in m /h;
∆p is the static pressure loss of 0,1 MPa (1 bar);
K
v
∆p is the measured static pressure loss across the valve, in MPa (bar);
ρ is the density of the fluid, in kg/m ;
3 3
ρ is the density of water, in kg/m (1 000 kg/m ).
w
This equation is valid when the flow is turbulent and no cavitation or flashing occurs.
3.6.2
flow coefficient C
v
C
v
non-SI valve coefficient which is in widespread use worldwide
NOTE Numerically, C is represented as the number of US gallons of water, within a temperature range of 40 °F to
v
2)
100 °F, that will flow through a valve in 1 min when a pressure drop of 6 894,76 Pa (1 psi) occurs. For conditions other
than these, C can be obtained using the following equation:
v
∆p
⎛⎞⎛⎞
C ρ
v
CQ=
⎜⎟⎜⎟
v
⎜⎟
∆p ρ
⎝⎠w
⎝⎠
where
3)
Q is the measured volumetric flow rate, in US gallons per minute ;
4)
ρ is the density of the fluid, in pounds per cubic foot ;
ρ is the density of water within a temperature range of 4 °C to 38 °C (40 °F to 100 °F), in pounds per cubic foot;
w
∆p is the measurement state pressure loss across the valve, in psi;
∆ p = 1psi .
C
v
This equation is valid when the flow is turbulent and no cavitation or flashing occurs.
1) 1 bar = 0,1 MPa.
2) 1 psi = 0,068 948 bar = 6 894,76 Pa.
-5 3
3) 1 gal (US)/min = 309 x 10 m /s.
3 3
4) 1 lb/ft = 16,018 kg/m .
3.7
bonnet
cylindrical part connecting the valve body to the seal packing chamber
4 Requirements
4.1 Materials
4.1.1 General
Materials shall be in conformance with an internationally recognized standard and compatible with the fluid.
Galling, frictional heating and galvanic corrosion shall be considered in the selection of materials. Materials
shall also be oxygen compatible, if relevant (see 4.1.5.1).
Materials not listed in an internationally recognized standard shall be controlled by the manufacturer of the
valve by a specification ensuring control of chemical content and physical properties, and ensuring quality at
least equivalent to an internally recognized standard. A test certificate providing the chemical content and
physical property test results shall be provided with the valve.
4.1.2 Metallic materials
Metallic materials to be used in the construction of cryogenic valves shall meet the requirements of
ISO 21028-1 or ISO 21028-2 as appropriate for the rated minimum temperature.
These requirements apply only to the valve parts exposed to low temperatures in normal service. Metallic
materials which do not exhibit ductile/brittle transition and non ferrous materials which can be shown to have
no ductile/brittle transition do not require additional impact tests.
Forged, rolled, wrought and fabricated valve components from raw materials from these processes need not
be impact tested if the rated minimum temperature is higher than the ductile/brittle transition range
temperatures of the material. Castings meeting the requirements of one of the applicable mandatory
Appendices I and IV or II and III of ASME B16.34 for forgings and rolled or wrought material, or conforming to
equivalent standards, need not be impact tested if the rated minimum temperature is higher than the
ductile/brittle transition range temperatures of the material. When impact testing is required, at least one
randomly selected valve body (including bonnet, if applicable) material from each production lot castings shall
be impact tested at the rated minimum temperature.
4.1.3 Non-metallic materials
Non-metallic materials are well established only for use in packing and glands and for use for inserts within
the plug/stem assembly to provide leak tightness across the seat when the valve is closed. If such materials
are to be used for structural parts, they shall have the properties appropriate to the application and conform to
ISO 21028-1 or ISO 21028-2, as appropriate to the rated minimum temperature.
Non-metallic materials shall also:
⎯ have mechanical properties that will allow the valve to pass the type approval test for ca
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