Pressure Vessel Boundary / U-2 Partial Data Report

[posershadow]

A question came up regarding a pressure vessel we are manufacturing. I included a sketch below for clarity.

We are supplying vessel #1 (blue) which is installed inside a drum (vessel #2). Vessel #1 carries a U-stamp. It has some piping connected to it which is designed to B31.3, the parts in orange are what we are considering as piping. We are also supplying transition joints designed per B31.3 (marked orange with an X), as the metals are dissimilar between our piping (in orange) and the piping (in red) shown. Lastly the SA-106B piping in red is in our scope, but we are going to subcontract the supply of the material to subcontractor #1. The weld in green will be performed by subcontractor #1. So essentially subcontractor #1 is only buying a piece of seamless pipe and performing the weld in green, that is the entirety of their scope.

The vessel #2 will also carry a U-stamp and is being supplied by subcontractor #2, who will take the entire assembly mentioned above and install it inside the drum to finish off the fabrication. They will perform the welds where the piping in red passes through the dished head.

We view the piping (in red) which passes through the dished head as part of vessel #2 and believe it should be designed per Sec. VIII like the rest of the vessel #2. Therefore one of the questions is: does the piping in red need a U-2 partial data form completed by subcontractor #1? If so, then it would likely mean that subcontractor #1 needs a U-stamp. The way we interpret U-1(e)(1)(a) is that the weld in green is beyond the boundary of vessel #2, therefore since subcontractor #1 is only supplying a piece of seamless pipe without any work on the pipe itself inside the vessel boundary, then an MTR is probably the only thing required.

We are hoping a U-2 form isn't required because it will open up additional possible subcontractors who don't carry a U-stamp.

 

[SnTMan]

Makes my head hurt

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Geoff13]

Wasn't sure if Sub #1 was supplying Vessel 1. I don't think so, and thus in my head they're Sub #3.

Since the ASME scope of Vessel 1 stops where the blue stops, the red parts cannot be considered to be part of Vessel 1. Plus you said orange is B31.3 piping, so red is even further removed from being part of Vessel 1.

The red pipes are nozzles in the Vessel 2 head. They are not B31.3 piping at that point. They will need MTR's for Sub #2 to include with their data book for Vessel 2.

The green weld is the inside limit of the Vessel 2 ASME scope. Presumably there's a weld somewhere outside that will be the outside limit of ASME's scope. Since the green weld is outside the ASME scope it doesn't need a U-2. Thus the green weld is a B31.3 weld, with whatever paperwork and subcontractor restrictions that requires.

 

[r6155]

IMO, all is ASME VIII.

Regards
r6155