It just came to my notice that on activating App P, the allowable for Expansion Stress range are affected.

This should not have happened as I can't figure out any relation b/w App P & the allowable for Expansion Stress Range.

Does anyone can please throw some light on this?

Additionally, if App P is activated, the allowable are reduced by 15%.However, for the material in my case A106 Gr B, ratio b/w min specified yield strength to min specfied tensile strength is 0.58 (doesn't exceed 0.8)but still the allowable are reduced. Checking on the help file,it states that the checkbox for "reduction of ope allowable for App P" is kept activated by default for 31.3 & it reduces the allowable only if the codition as specified by code are met.But still its doing it.
The B31.3 code edition I'm referring to is 2010 & Caesar version is Caesar V6.10.