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.