Dear all,

I'm asking about Pressure Force developed by full vacuum in the expansion joint as mentioned by NEMA 23 para. 8.4.6.3. As per Sample Problem 8B, this force is calculated separately and is compared to the allowable which is 15.5 times the nominal exhaust area.

Can we input this force to CAESAR directly (like PSV discharge force during popping) then we get the F/M which is already covering this pressure force? do we need to calculate it separately?

Yes, you can enter a force set in your model and include that force set in any analysis.

But be sure that the pressure thrust forces which may pull your XJ apart are not also included in that analysis. This all depends on how you modeled your expansion joint.