Section VIII Pressure Boundary Scope

[anolan23]

Can a branch pipe nozzle that is welded to a larger run pipe be considered external piping and not be included in the geometrical scope of the vessel as stated in U-1(e)(1)?

 

[Afox88]

I would say that the branch nozzle is considered part of the vessel if it is welded to the nozzle before the first flange/circumferential weld.

 

[anolan23]

My question was misleading. Only two pipes in this case. One run pipe. One branch pipe.
Branch pipe welded to run.

My question: Can the first circumferential joint be the joint that connects the branch to the run?

 

[anolan23]

This would in turn exempt me from any nozzle calculations as the manufacturer

 

[Afox88]

I would not consider the nozzle attachment weld to be a circumferential joint. You should be running nozzle calculations on the branch. You should be running nozzle reinforcement calcs on the branch nozzle. I would take exception to any external nozzle loads on that branch nozzle though.

 

[anolan23]

Yeah just found UW-3 describing welding joint categories. I agree I must do UG-45 nozzle thickness calcs. I believe I am exempt from reinforcement calcs per UG-36(c)(3)(-a). Could you explain why I could take exception to any external nozzle loads?

 

[Afox88]

Anolan, what I mean to say is that I would not perform any external nozzle load calculations provided by specifications or the such. ASME Code does not set the loads to be run. Unless you have a large nozzle with a small branch, you might have a hard time getting it to pass. Of course, I do not know anything about your design and you are more than welcome to try.

Personally, from a fabricator standpoint, I will not run external nozzle load calculations (again, not a COde requirement) on any nozzles other than the main process connections only. No vents, drains, relief connections, etc.