BS ISO 21157:2018,Ships and marine technology — Ball valves for use in low temperature applications — Design and testing requirements.
BS ISO 21157:2018 specifies requirements for design, manufacture and test methods of cryogenic ball valves in order to have an excellent quality leakage stability in a very low temperature service (−196 °C to 80 °C).
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.
All tests and inspections shall be conducted as per related standards, test procedures, inspection procedures and working drawings which are agreed to between the purchasers and the manufacturers.Also these procedures may be conducted by the purchasers or third parties whom the purchasers select.