Some posts in the forum seem to imply that a short term excursion in temperature can be ignored from a thermal displacement analysis point of view. Seeking to add clarity to the codes I put in this RFI (my wording was once more improved upon as shown below)at our last meeting in Phoenix Az

Question:
Does ASME B31.3-2004 Edition require that the duration of an operating cycle be considered when evaluating displacement stress range in accordance with para. 319.2.3

Reply:
No

I will send this inquiry in to B31.1 and when they respond I'll post back here the results.

We all look forward to your inquiry to B31.1 Code Committee with keen interest.

Of particular relevance is an observation that the time-dependent CREEP effect imposes a direct impact upon the FATIGUE STRENGTH of a pipeline. Consequently, a prolonged exposure, or DURATION, at an elevated temperature will result in a physical reduction of the fatigue cycle life in the pipe.

B31.3 Code's "NO" opinion does not seem to have considered this fact, or facet, of pipe life, and it behooves to solicit a second opinion from B31.1 Code, as you are proceeding.

Thanks for sharing thoughts from inside the minds of ASME Code Committees with the outside hard labors of this forum.

Your welcome, my unhidden agenda is to have us all playing from the same sheet music.

Actually having been a participant on B31.3 I will say that RFI's are responded to on the basis of this is what the code says now. Not what the code should say but doesn't. Sometimes RFI's will jog the comittee into taking out an AI to revise or add to the code to cover a topic in a manner that the RFI could not.

In this case the code is truly silent as far as thermal displacement stresses versus time is concerned. Creep is quite a problem, but as far as displacement stresses are concerned for their calculation time is not an esential variable per se.

I have to send it along to B31.1 however they are quite slower in their reponse time, our highest priority is answering RFI's promptly theirs I can't say!

RFI = Request for Interpretation
AI = Agenda Item, Once a topic has a AI its recorded and worked on until some sort of conclusion is reached on it. Some AI's go on to be code revisions, some AI's go extinct.

Look at the orginial Markl papers. Creep is considered in the allowable stress basis. The criteria is designed to result in elevated temperature shakedown, and essentially a single relaxation cycle over the life, so that hold time creep damage is not a signficant consideration.

The B31.1 response should be essentially the same as the B31.3 response, because that is the way these codes are written.