Please give me the suggestion & comment.

I come across one case for 24” gas blow down. Due to the process design concept for blow down, velocity = 540 ft/sec, A = 24”, density = 0.9865 lb/ft3. So the momentum force at elbow is 11,980 Kg (F= density x V^2 x A) and the reaction force at the exhaust is 43,816 kg (from API 520). You can see that the force is very high. I analyze by input the reaction force(F1) at the tip of stack and input the momentum force(F1) at all elbow. The load cases similar as below

1) W+T1+P1 (OPE)
2) W+T1+P1+F1 (OPE)
3) W+P1 (SUS)
4) L1-L3 (EXP)
5) L2-L1 (OCC)
6) L3+L5 (OCC)

Is the acceptable method for static analysis?

I am waiting for your comment.
Best Regards,
Kach

Random Thoughts

load case 5 is unused
load case 6 is scalar


Be carefull which node on the elbow you put the force on. i always put it on the first node (0deg)in the direction of the force vector
If you put it on the last node (90)deg, strange things happen.
On close elbows, forces cancel out ( but you will struggle to have someone define what 'close' is.
(I input this opposing force onto the opposing elbow,effectively stretching the pipework whilst i am unsure as to its validity, i have yet to have anyone argue against it.)

Don't forget the DLF.
Do have the PRV manufacturer give relief load values as these can be very much lower due to
orifices etc.
Read the excellent course notes on prv relief systems if available.
Use the Relief force Calculator.

If this is the first time you have done this, have your work validated by a second party.

I like this work too!!!!

goog luck