This International Standard specifies the requirements for the design, manufacture and testing of non-reclosable pressure-relief devices for cryogenic service, i.e. for operation with cryogenic fluids in addition to operation at temperatures from ambient to cryogenic. This International Standard is restricted to bursting-disc and buckling-pin devices not exceeding a size of DN 200 designed to relieve single-phase vapours or gases. A bursting-disc or buckling-pin assembly may be specified, constructed and tested such that it is suitable for use with more than one gas or with mixtures of gases. NOTE This International Standard does not provide methods for determining the capacity of bursting-disc or buckling-pin devices for a particular cryogenic vessel. Such methods are provided in ISO 21013-3.