API-RP-576

Types
Mediums
Limitations
Safety-relief Valve
Full lift; Liquid 10% or 25% overpressure, Gas/Vapor phase 10% overpressure
Conventional
Safety-relief Valve.
All phases
Valves should not be used; :
1. total built-up backpressure exceeds the allowable overpressure.
2. (CDTP) cannot be reduced to account for the effects of variable
backpressure.
3. ASME BPVC Section I steam boiler drums & superheaters.
4. as pressure control or bypass valves.
Whose operational characteristics are directly affected by changes in the backpressure.
Bonnet is pressure-tight cavity and is vented to the discharge side of the valve.
Balanced Safetyrelief
Valve.
All phases
valves should not be used:
1. on ASME BPVC Section I steam boiler drums or ASME BPVC Section I
superheaters, and
2. as pressure control or bypass valves.
valve that incorporates a bellows or other means for minimizing the effect of backpressure
on the operational characteristics of the valve. The bonnet may or may not be pressure
tight. Used where high backpressures are present at the valve discharge.
Fion Zhnag/ Charlie Chong