Dear all,

Im about to analyze PSV down stream lines.

I have started to analyze from the discharge flange & i m applying the Reaction force in this flange & i have providedthe structral deflections on this flange.

Now while looking at the restraint summay ill be getting some forces in X,Y,Z directions. My question starts here..........how am i going to check tht the generated values are ok & PSV never fails!!!!!!!!!!!!!!!!

Dear Sir

please tell me that whether you are analysing open system or closed system.
(refer p&id)

Dear Shabeer,

Your query is not clear.But it seems that you are spliting your PSV line into two different calculations. One calculation for inlet piping and other calculation for discharge piping.

For PSV discharge line calculation-Make your model by including PSV inlet piping upto the first support (usually trunnion)and apply thermal displacements to free end point.The thermal displacement you have to calculate manually taking into consideration applicable length of the piping between this end and the equipment/header to which your PSV inlet line connects.Apply reaction forces as per the company practise and make load cases to comply with code's primary(sustained and occational)and secondary(expansion)stress limits.
Apply same method to analaysie other side of the PSV(inlet piping).

Restraint summary is not used the way you have asked in your question.It is used for support design and nozzle evaluation.

I hope this will help.

Hello Shabeer,

I would recommand you to do the anlaysis of both inlet and outlet pipes in the same model. There are a ot of complication when you divid the systm.

Dear Shabeer,

How are you?
I believe that your PSV system is closed system.

Please don't divide PSV as two system.However I answering your query.

Thrust loads due OPEN and CLOSED to PSV discharge shall be calculated in accordance with ASME/ANSI B31.1 Appendix II or API RP-520. The suction/ discharge piping shall be adequately supported to restrain the pressure thrust loads. A dynamic load factor of 2 shall be used in calculating the reaction forces.

If you follow above procedure your PSV system will not be get failure.

Dear Shabeer,

I would like to add one more point,
Calculate the thrust load force of the relief valve and place a concentrated load equal to the thrust force at the appropriate place downstream such as the first bend node or intersection node of a Tee. Also place an equal force, but in opposite direction on the back of the reliev valve.