ISO 21159:2018

INTERNATIONAL ISO
STANDARD 21159
First edition
2018-11
Ships and marine technology —
Butterfly valves for use in low
temperature applications — Design
and testing requirements
Navires et technologie maritime — Robinets à papillon destinés aux
applications à basse température — Exigences de conception et d'essai
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Pressure-temperature rating . 3
5 Structure . 3
5.1 General . 3
5.1.1 Structure . 3
5.1.2 Materials . 4
5.2 Design and materials of the body. 4
5.2.1 Design . 4
5.2.2 Materials . 4
5.2.3 Manufacturing . 4
5.3 Design and materials of the extended bonnet . 5
5.3.1 Design . 5
5.3.2 Materials . 5
5.4 Design and materials of the disc . 5
5.4.1 Design . 5
5.4.2 Materials . 5
5.5 Design and materials of the stem . 5
5.5.1 Design . 5
5.5.2 Materials . 6
5.6 Stem sealing . 6
5.7 Design and materials of the seat . 6
5.7.1 Design . 6
5.7.2 Bore materials . 6
5.8 Design and materials of the connection . 7
5.8.1 Design . 7
5.8.2 Materials . 7
5.9 Requirements of operating device and actuators . 7
5.10 Surface treatment . 7
5.11 Welding and heat treatment . 8
5.11.1 Welding . 8
5.11.2 Heat treatment. 8
5.12 Repair welding . 8
6 Test and inspection . 8
6.1 General . 8
6.2 Material test . 8
6.3 Non-destructive inspection . 8
6.3.1 General. 8
6.3.2 Radiographic testing (RT) . 9
6.3.3 Dye penetrant testing (PT) . 9
6.3.4 Ultrasonic Testing (UT) . 9
6.3.5 Retest .10
6.3.6 Submission of inspection results .10
6.4 Dimension check .10
6.5 Visual inspection .10
6.6 Heat treatment inspection .10
6.7 Operating tests .10
6.8 Pressure test .10
6.8.1 Pressure test in ambient temperature .10
6.8.2 Test procedure and method .11
6.9 Fire-resistance test (if necessary) .11
6.10 Anti-static testing.11
6.11 Cryogenic tests .11
6.11.1 General.11
6.11.2 Scope of tests .12
6.11.3 Test procedure .12
6.11.4 Submission of test results .13
7 Marking .13
Annex A (informative) Examples of butterfly valve construction .14
iv © ISO 2018 – All rights reserved

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
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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
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on the ISO list of patent declarations received (see www .iso .org/patents).
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URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 3, Piping and machinery.
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.
INTERNATIONAL STANDARD ISO 21159:2018(E)
Ships and marine technology — Butterfly valves for use
in low temperature applications — Design and testing
requirements
1 Scope
This document specifies requirements for design, manufacture, and test methods of cryogenic butterfly
valves in order to have an excellent quality leakage stability in a very low temperature service (−196 °C
to 80 °C).
It is applicable to valves of nominal sizes: DN: 80, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600
corresponding to nominal pipe size (NPS): 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24.
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 5208, Industrial valves — Pressure testing of metallic valves
ISO 5209, General purpose industrial valves — Marking
ISO 5211, Industrial valves — Part-turn actuator attachments
ISO 28921-1, Industrial valves — Isolating valves for low-temperature applications — Part 1: Design,
manufacturing and production testing
ISO 10497, Testing of valves — Fire type-testing requirements
API 609, Butterfly Valves: Double flanged, lug and wafer-type
ASME B 16.5, Pipe Flanges and Flanged Fittings
ASME B 16.10, Face-to-Face and End-to-End Dimensions of Valves
ASME B 16.25, Buttwelding Ends
ASME B16.34:2007, Valves — Flanged, Threaded, and Welding End
Sec ASME V, Non-destructive Examination
Sec ASME VIII, Pressure vessels
ASTM A182/A182M, Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings and Valves and Parts for
High-temperature Service
ASTM A193/A193M, Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature
or High Pressure Service and Other Special Purpose Applications
ASTM A194/A194M, Carbon and Alloy Steel Nuts and Bolts for High-Pressure and High-Temperature Service
ASTM A276, Standard Specification for Stainless Steel Bars and Shapes
ASTM A312/A312M, Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic
Stainless Steel Pipes
ASTM A320/A320M, Alloys-Steel Bolting material for Low-Temperature service
ASTM A351/A351M, Casting, Austenitic, Austenitic -Ferriti c (Duplex), for Pressure-Containing Parts
ASTM E186, Reference Radiographs for Heavy-Walled (2 to 4 1/2-in) Steel Castings
ASTM E446, Reference Radiographs for Steel Castings up to 2in. in Thickness
MSS SP-44. Steel pipeline flanges
MSS-SP-55. Quality Standard for steel Castings for Valves, Flanges and Fittings and other Piping Components
(Visual Method)
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at http: //www .iso .org/obp
3.1
nominal diameter
DN
alphanumeric designation of size for components of a pipe-work system, used for reference purposes,
comprising 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 1 to entry: The number following the letters DN does not represent a measure value and shall not be used
for calculation purposes except where specified in the relevant standard.
Note 2 to entry: In those standards which use the DN designation system, any relationship between DN and
component dimensions shall be given, e.g. DN/OD or DN/ID.
3.2
nominal pressure
PN
numerical designation relating to pressure that is a convenient round number for reference purposes
Note 1 to entry: It is intended that all equipment of the same nominal size (DN) designated by the same PN
number shall have the same mating dimensions appropriate to the type of end connections. The permissible
working pressure depends upon materials, design and working temperature and has to be selected from the
pressure/temperature rating tables in corresponding standards.
3.3
nominal pipe size
NPS
alphanumeric designation of size that is common for components used in a piping system, used for
reference purposes, comprising the letters NPS followed by a dimensionless number having an indirect
correspondence to the physical size of the bore or outside diameter of the component end connections.
Note 1 to entry: The dimensionless number may be used as a size identifier without the prefix NPS. The
dimensionless number does not represent a measurable value and is not used for calculation purposes.
Note 2 to entry: Prefix NPS usage is applicable to components bearing Class designations according to ISO 7268.
2 © ISO 2018 – All rights reserved

3.4
class
alphanumeric designation, used for reference purposes, related to a combination of mechanical and
dimensional characteristics of a component of a pipe-work system, comprising the word “class” followed
by a dimensionless whole number
4 Pressure-temperature rating
4.1 The types of typical fluid are shown in Table 1.
Table 1 — Types of typical fluid
Fluid Temperature (in atmospheric pressure) Liquid density (density)
LNG (Liquefied natural gas) −163 °C to −88 °C (434 to 478) kg/m
NG (Natural gas) −160 °C to −65 °C (0,7 to 0,89) kg/m
LN2 (Liquefied nitrogen) −196 °C 804 kg/m
N2 (Nitrogen) −196 °C to −65 °C 1,184 kg/m
4.2 The valve shall be designed to operate without failure or leakage at the extreme temperature and
pressure ranges expected in service. The maximum working pressure and design temperature are shown
in Table 2.
Table 2 — Maximum working pressure
Maximum working pressure
PN Class Note
MPa(psi)
20 150 2,0(290)
in ambient temperature
50 300 5,2(750)
NOTE The piping design condition including, but not limited to, working pressure, service temperature and
fluid is provided by the purchasers.
4.3 The manufacturers and purchasers may reach an agreement when Class exceeds 300.
4.4 Design temperature should be between −196 °C and 80 °C.
5 Structure
5.1 General
5.1.1 Structure
Butterfly valves can be divided into two types, with maintenance holes and without maintenance
holes. For butterfly valves with maintenance holes, the disc or seat sealing shall be removable from the
maintenance hole without removing the valve from the pipe. The butterfly valve is extended bonnet
type. The end connection of the body is welding ends type or flanged ends type. A wheel or levers
is used to apply the turning torque or thrust to open or close the valve. The butterfly valve may be
either soft-seated or metal-seated. Configuration and functions of the butterfly valve are shown in this
document. If there are some differences from this document, the manufacturers can make a decision
after reaching an agreement with the purchasers. General examples of the structure of the valve are
shown in Annex A.
5.1.2 Materials
Throughout this document, materials are specified for each of the various parts of the valve. In lieu of the
materials specified, other materials may be used provided they are manufactured by the same process
as the materials specified, such as forging, casting, bar, or seamless pipe. In addition, the material shall
be suitable for the operating temperatures and pressure of the valve and the metal materials shall have
mechanical properties, including low temperature impact resistance, and resistance to corrosion equal
to or better than the material specified for the specific valve part.
5.2 Design and materials of the body
5.2.1 Design
The body should be casting integrally, in case the valve contains suitably located lugs which have sufficient
strength to support the valve lift and valve support legs, they cannot affect the connection bolts.
5.2.2 Materials
Materials are shown in Table 3. Materials for ‘welding ends’ type valves may be used for ‘flange ends’
type material.
Table 3 — Materials by manufacturing method
Materials
Manufacturing method
Flange ends type Welding ends type
Casting ASTM A351 CF8M ASTM A351 CF3M
5.2
...