flexMen,

I'm afraid I'm having trouble understanding some of the terms you are using as they are very different from what I'm used to hearing here in Texas. I'm making some guesses at what you're trying to say. Can you clarify these terms:

butts (I think your meaning is restraints, line stops, guides)

dilations (thermal expansion?)

escape run (I can't figure this one out from the context)

However, assuming that butts does mean restraints and dilations refers to thermal expansion, then you are saying pretty much exactly what I said with this part:

"Now, here's the big if that I think had been hinted at - if you can justify that your occasional load case can only occur when your system is at T=25°F, then I think you could make a case for checking your occasional stresses based on Sh at 25°F. Quite frankly, I can't think of what kind of loading that would be, certainly niether wind nor seismic. If this is your situation, I'd like to hear it in detail."

It sounds like your seismic2 case won't have thermal expansion (dilations) becuase it won't be at a high temperature and you therefore want to be able to use the Sh at the lower temperature to check you occasional stresses for this case.

The only dispute that I have, and I think Mr. Luf agrees, is, how can you justify that your seismic2 case won't occur when the system is hot? There's not usually any warning for a seismic event like there would be with a hurricane, such that you could have an orderly shutdown of the unit and get the temperature down.