the calculated sustained stresses assuming no non-linearity calculated for T1 T2 and T3 with P being the same for all three temperatures should be identical, however the allowed code stress varies as a function of the metals strength at the 3 different temperatures. The higher the temperature the lower the code allowable.

So if the sustained stresses calculated are the same then the % of the code allowable varies. Thus for instance a system may not be over-stressed @ T2=25Deg.... it is possible with the same calculated stresses to be over-stresed at T1 and T3.

Now if it is possible for the plant to be operating during a seismic event (most probable) then the calculated Occasional stress level must be below the code allowable stresses for all the possible temperatures the event may occur at...

The bottom line is if Dave, Ed or myself checked your worked you would be quickly be re-doing it... the last time I did a literature review on the codes or flexibilty analysis I did'nt see a "flexmen" authoring any papers nor did I see "flexmen" as a member of any code comittee so read this final reply.

Take a look through the member list of B31.3 and finally I quote Plato...

"Wise men speak because they have something to say; Fools because they have to say something."

http://en.thinkexist.com/quotation/wise_men_speak_because_they_have_something_to_say/218003.html