1 reply to this topic

[cmp74]

Hello folks,

I have a PSV installed on a flash drum (degassing vessel) which is sized for steam service based on an external fire scenario.

Now, one more scenario is inlet control valve failure in open position, which would bring more liquid into the drum.The operating pressure on u/s side of the C/V is 9 times the design pressure of the drum, so PSV has to relieve the incoming liquid(mostly water).I calculated the orifice area required (based on API liquid equation) for liquid relief, which is much smaller than actual installed orifice for steam relief.

My question is this: Is a vapor-gas service valve good for liquid service (mechanically)? Any capacity certification required? What is guarantee that valve will work for liquid as a good as it will for steam ?

Any help is appreciated.

thanks.

[fallah]

Hello folks,

I have a PSV installed on a flash drum (degassing vessel) which is sized for steam service based on an external fire scenario.

Now, one more scenario is inlet control valve failure in open position, which would bring more liquid into the drum.The operating pressure on u/s side of the C/V is 9 times the design pressure of the drum, so PSV has to relieve the incoming liquid(mostly water).I calculated the orifice area required (based on API liquid equation) for liquid relief, which is much smaller than actual installed orifice for steam relief.

My question is this: Is a vapor-gas service valve good for liquid service (mechanically)? Any capacity certification required? What is guarantee that valve will work for liquid as a good as it will for steam ?

Any help is appreciated.

thanks.

A vapor-gas service relief valve may be used for liquid service,provided that 25% overpressure (required for full lift and stable operation)is being allowed.

Pressure relief valve should be specified for the fluid the valve is normally exposed to.Therefore,based on your result shows much smaller area needed for liquid relief,seems there is no need to capacity certification.