API Standard for Flanged Steel Pressure-relief Valves, 8th Edition
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 [metric units (SI)] and Annex E [U.S. customary units (USC)]