Hi Aaron,

I don't think you ignore the fire condition temperature, I think you consider the pipe to be in a faulted condition (subject to mandatory examination - per fire recovery procedure) if there is a fire or if for any other reason the pipe temperature goes to 350 C. And as Don says, there are a lot of things that must be examined. For design, I would go with the design temperature of 235 C.

I have been in the industry for over 40 years and I still do not consider a fire "quite nornal" (I have done fire recovery for 4 or 5 companies). Yes, fires happen but (thankfully) they happen less often due to the industry's commitment to safety. Don't build the church for the Easter crowd.

I have some photos of an NPS 6 steam system (mostly horizontal) after an upstream desuperheater failure and it looks like home made pasta hanging (drooping) out to dry. Sometimes hot catalyst gets into piping that was not designed for it too. In these cases (no fire) the piping must be examined and its temperature embrittlement must be quantified (albeit, if it is carbon steel pipe (relatively inexpensive) the owner may opt to replace it as NDE adds nothing to the value of the pipe).

There will be some report that documents the design and that is the place to declare the design parameters and state the assumptions. One of the assumptions would be that if there is any over pressure or over temperature event (greater than "variations") the system must have an orderly and well documented examinine per a specific recovery procedure.

Regards, John.