3 replies to this topic

[Sara Owens]

are bellows type relief valve prohibited for use in cryogenic applications?

i have a thermal relief valve in cryo service. the back pressure is high, therefore i cannot use conventional type relief valve. i have to use either pilot or bellows type. i have heard bellows are a big no no for cryo service? any ideas? pilot type relief valve are too stringent for thermal relief.

[fallah]

are bellows type relief valve prohibited for use in cryogenic applications?

i have a thermal relief valve in cryo service. the back pressure is high, therefore i cannot use conventional type relief valve. i have to use either pilot or bellows type. i have heard bellows are a big no no for cryo service? any ideas? pilot type relief valve are too stringent for thermal relief.

 

Sara,

 

As per following statement in API 520 2008 Ed. it's not allowed applying the bellows type PSV in cryogenic services:

 

4.2.1.3.9 It is important to remember that the bonnet of a balanced PRV shall be vented to atmosphere at all times. The user should be cautioned of the potential for freezing of atmospheric moisture inside the bonnet in cold service due to auto-refrigeration or cold ambient temperatures.

[Sara Owens]

can back pressure be ignored for thermal relief valves, so i can use conventional type relief valve? I prefer not to use pilot type for thermal relief. i cannot use bellows type for cryo service.

[fallah]

can back pressure be ignored for thermal relief valves, so i can use conventional type relief valve? I prefer not to use pilot type for thermal relief. i cannot use bellows type for cryo service.

 

No, the back pressure cannot be ignored...