Temperature gradients B31.1 & VIII

[Gapinspect]

We have a B31.1 weld (pipe to nozzle) to a very short nozzle on a section VIII vessel which is going to require alot of heat to go into the shell to meet the PWHT requirements. B31.1 is very vague on PWHT and temperature gradients but section VIII UW-40 is very clear about harmful gradients.

Both the vessel (HP heater) and piping (feedwater) are new.

I have found an old interpretation that asks "Q)If a piping system falls within the scope of B31.1 & is attached to a piping system or vessel, the construction of which is within another code, which code governs the requirements of the weld connecting the two systems? R)It is the opinion of teh committee that the weld connecting the two systems shall comply with the requirements of B31.1 unless there are specific rules in the other code making that the governing code.

The question is 1) does the PWHT fall under only B31.1 when it is going to effect the Section VIII vessel?
2) When considering the applicable code (B31.1) do you have to take into consideration the adjoining codes? If so, is this referenced anywhere?

 

[bernoullies123]

The end prep of the nozzle falls under the scope of VIII. The pipe to nozzle weld itself will fall under your B31.1 code.

Refer to

http://www.eng-tips.com/viewthread.cfm?qid=278025&page=4

and

http://www.eng-tips.com/viewthread.cfm?qid=262542&page=1

Since the weld is out of the scope I would think that there is no specific requirement for it to be considered. With that said the vessel is still a designed piece of equipment which considered the anticipated loading of which UG-22(h) considers temperature gradients. Based on this I would ensure that area around the heat treatment is sufficently protected to prevent harmful temperature gradients as highlighted in UW-40(a)(7).