9 replies to this topic

[james.corrobro@gmail.com]

hi, 

 

i have a gas injection line from compressors to wells which is operating at high pressure (around 2000 psig).

We have added a manual depressurization line to flare downstream of the last block valve on the injection line. for manual depressurization ball valve...is it fine to have a spec break at the ball valve ? please see sketch attached? or should we have a globe valve for better control??

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[Bobby Strain]

You will need more than you have shown.

 

Bobby

[fallah]

 

i have a gas injection line from compressors to wells which is operating at high pressure (around 2000 psig).

We have added a manual depressurization line to flare downstream of the last block valve on the injection line. for manual depressurization ball valve...is it fine to have a spec break at the ball valve ? please see sketch attached? or should we have a globe valve for better control??

 

Hi,

 

In general, spec break should be at the point you have shown on the sketch...but it's better the last valve to be globe type..

Built up pressure after the last valve (toward flare) during depressurizing should be considered in line class determination hence it might the line class to be 300# or more rather than 150#...

 

Anyway more info needed to specify the line class after the last block valve in depressurizing line to flare...

[AlertO]

For that such huge differential pressure between process and flare header empowered with the large open area at ball valve, you may need to consider providing RO on this depressuring line to ensure that the flow from well injection line will be not over the flare capacity.

[SyedAhmed]

Its safe to add RO with globe valve because careless operation can be disaster. You need to show more in the sketch.

[Sharma Varun]

If you are going with ball valves an RO should be provided in between, else you may do away with globe valve. Spec break location is fine, just check the temperature drop also.

[SyedAhmed]

Single isolation may cause leak problem to flare header. Should have DBB.

[james.corrobro@gmail.com]

If you are going with ball valves an RO should be provided in between, else you may do away with globe valve. Spec break location is fine, just check the temperature drop also.

 hi varun, 

 

you mean ball valve and then RO and then the second ball valve?

or we should have the ro after the two ball valves?

[Sharma Varun]

 

If you are going with ball valves an RO should be provided in between, else you may do away with globe valve. Spec break location is fine, just check the temperature drop also.

 hi varun, 

 

you mean ball valve and then RO and then the second ball valve?

or we should have the ro after the two ball valves?

 

yes first option is better, put RO between the two isolation valves

[nasr91]

I think the RO should be after the two ball valves. You also should consider the minimum distance between RO and the last valve to prevent ice buildup.