Please note that any addenda or errata may not be included in translated editions of this standard.This standard is a purchase specification for flanged steel pressure-relief valves. Basic requirements are given for direct spring-loaded pressure-relief valves and pilot-operated pressure-relief valves as follows: — orifice designation and area; — valve size and pressure rating, inlet and outlet; — materials; — pressure-temperature limits; — center-to-face dimensions, inlet and outlet. Nameplate nomenclature and requirements for stamping are detailed in Annex A.