Specifies requirements for the design, construction, and testing of safety valves, liquid relief valves, liquid level gauges, blowdown valves, and other fittings for use on boilers and unfired pressure vessels and thus associated piping. It does not deal with the selection, operation, or application of valves and fittings, as these are covered in the Standard applicable to the equipment to which the valves and fittings are to be connected. Appendices include equations for the calculation of discharge capacity for single-phase flow through safety valves and liquid relief valves.