: Selection, specification, and application of piston (double-acting and spring-return) and diaphragm-actuated control valves. Key Considerations
: Strategies for multi-stage trim selection to drop fluid pressure gradually, keeping local pressure above the vapor limit. api 553 pdf
: Throttling devices modulated continuously by automated controllers to manage process pressure, temperature, flow rates, and liquid levels. api 553 pdf
Refinery fluids frequently subject control elements to extreme stress. API RP 553 provides targeted solutions to prevent sudden valve failures caused by fluid dynamics: api 553 pdf