6 replies to this topic

[powerox6]

Hello Professionals,

 

I am sizing a PSV attached to a TEG filter, where the selected overpressure scenario is Fire Case. There are several heat and material balance (HMB) cases, which have varying operating conditions and fluid properties. Just for the sake of comparing I have run all cases with the reference stream taken at the inlet of my vessel. The results are as follows. My question is, how would I know how to screen for the HMB cases in order to get the maximum relief load and/or orifice area? By the trend in the table below, it seems that the maximum relief occurs with the case which has the highest overall MW and highest liquid fraction. Is this always the case? Are there any other fluid properties which I must look for in order to determine the governing HMB case?

Attached Files

•  Screenshot 2026-08-21 204751.png   156.75KB   0 downloads

Edited by powerox6, 21 August 2026 - 07:43 AM.

[latexman]

Maximum relief load is relevant, but maximum orifice area is what you are really after!

[powerox6]

Yes. I've had cases where the relief load for a particular case is higher, but the maximum orifice area is in another case with lower relief rate.

Maximum relief load is relevant, but maximum orifice area is what you are really after!

[carlos infante]

Power

 

You must choose the case with the higher orifice area for the PRV. API 521 defines it as the worst-case scenario.

 

Carlos

[powerox6]

Thanks Latex & Carlos

[breizh]

Hi,

Consider reading these documents.

Breizh

Attached Files

•  safety valve sizing adequacy method API 521 for pressure vessel filled with gas..pdf   4.27MB   5 downloads
•  sizing Pressure-Relief devices.pdf   1.36MB   6 downloads

[powerox6]

Hi,

Consider reading these documents.

Breizh

Thanks Breizh