5 replies to this topic

[aniljani]

What is basis for Maximum Built up back pressure for different types of PSVs viz., conventional, balanced and pilot operated safety valves.I have just entered into the Flare header audit assignment.
For conventional <=10%, balanced <=30% and for pilot operated <=50% of Set pressure.

[fallah]

What is basis for Maximum Built up back pressure for different types of PSVs viz., conventional, balanced and pilot operated safety valves.

-Having stable operation (no chattering,...)
-Maintaining specified capaciy of the PSV
-.........

[ashetty]

To elaborate a little more on the 2nd point of Fallahs response.

For conventional PSVs the PSV would start to close if the back pressure gets too high.Upto 10% of the set pressure there is no tendency for the valve to close.At higher back pressures it may tend to close and will lose some or all of its capacity, thereby compromising the protected equipment.Similar is the case for balanced bellows at over 30% and pilot operated at over 50% of set pressure.

Thanks.

[aniljani]

To elaborate a little more on the 2nd point of Fallahs response.

For conventional PSVs the PSV would start to close if the back pressure gets too high.Upto 10% of the set pressure there is no tendency for the valve to close.At higher back pressures it may tend to close and will lose some or all of its capacity, thereby compromising the protected equipment.Similar is the case for balanced bellows at over 30% and pilot operated at over 50% of set pressure.

Thanks.

Thank you all for response.....

[Traileum]

I have a question on MABP on flarenet. After a run, I noticed that my node pressures (in the pressure profile view) is most of the time higher than my allowable back pressure. Is this a problem? Do I need to increase pipe size?

[JoeWong]

I have a question on MABP on flarenet. After a run, I noticed that my node pressures (in the pressure profile view) is most of the time higher than my allowable back pressure. Is this a problem? Do I need to increase pipe size?

MABP is what you specified in FLARENET based on whatsoever reasons and node pressure is the calculated pressure.

If the node pressure exceeded MABP which you have specified, obviously there is a problem base on MABP defined by yourself.