This specification covers self-contained, internally operated, globe style, pressure-reducing valves for use in steam service. In these valves, the downstream pressure feedback is sensed by a spring-loaded diaphragm to position a pilot valve-the pilot valve uses the inlet steam pressure to position the main valve plug via an operating piston.
ANSI/ASTM F1565:2000 history
2000ANSI/ASTM F1565:2000 Specification for Pressure-Reducing Valves for Steam Service