Dear All,

I am a beginner in learning stress. I have some basic questions i hope you will help me to resolve my confusions.
My first question is when the software calculate the stress for thermal expansion & compare it with code equation f(1.25sc+0.25sh) then the calculated stress is for the complete cycle or from ambient/installation to operating point. If it is for cycle then it seems to be ok as per texts but if it is the other way then the basic idea that stress should not exceed the yield in hot or cold condition is not valid.

My second question is are theories of failure such as rankine von n tresca are applicable for thermal failure of pipe. or above theories are for primary stress only.