Temp. & Pr. Conditions of Piping Material Spec sometimes depends on actual Pr. &
Temp. conditions, Flange Pr.& Temp. rating as decided by ANSI B 16.5 according to
Group Material & Category of fluid used. Out of these three which one to use while
developing spec & why?Give other criterion if any.(Site Location- U.S.Refinery &
Work.Station.- India)

Regards
PME

Your question(s) is/are not clear and some of your statements seem nonsensical to me. I don't know what you're trying to say when you state.



Temperature & pressure conditions ALWAYS depend on actual conditions. If you mean DESIGN T and P, then yes, there is a connection between actual and design T & P. The exact nature of that connection is normally stated in your company's design guidelines. When you state,



I don't know what you mean. ANSI B16.5 is a standard that aids YOU in selecting appropriate flange ratings. Your design temperature and pressure and your selected material are inputs into that decision process. Nothing is "decided" by ANSI B16.5.



I assume "these three" means T, P, and material of construction. All three are instrumental in developing the piping specs, as I stated above. This interrelationship is clearly shown in the standard. Work and site locations don't appear to be relevant unless additional standards govern your situation.

I've read several of your posts and would wish to offer a general observation. You seem to be in a great hurry to post your questions. They tend to be short and use a lot of abbreviations and shorthand. To get the best out of this forum it really is in your best interests to pose your questions carefully. take the time to state the question clearly giving all the relevant information.

Why should forum members spend their time on replying where it appears obvious that the poster hasn't been prepared to spend time on the questions?

This is a clear case of "more is best"