Removal of Section VIII Vessel Support

[bozworth]

Would a permanent removal of a Section VIII pressure vessel support (welded to the vessel) have any restriction under the original design (code requirements?). The Owner of the vessel has requested removal of the support and a new support configuration be installed (non welded)

Thanks

 

[CodeRef]

Yes, the original design requirements were established for the complete vessel. (including the supports in accordance with UG-22(d)(2)of ASME VIII-1)

Repairs/Alterations to existing ASME stamped items will require compliance to the rules specified by the governing administrative authority at the vessel location. More than likely if the vessel is installed in the US or Canada, a National Board "R" Stamp Certificate Holder would be required to conduct this work. Thus, changes to the original design would require compliance to the original Code of Construction, which in this case would be ASME VIII-1.

ASME VIII-1 paragraph UG-22 lists those loadings which shall be considered. Recommended guidance for designing Vessel supports is currently published in Appendix G of ASME VIII-1.
Also see Paragraph U-2(g)

FAQ731-376

 

[bozworth]

Thanks CodeJackal.

The support appearently is not apart of the original design of the vessel. It looks as if it was welded to the vessel in the past. There are no R reports or plates to support the attachment being welded. The support runs under the bottom of an exchanger ( which is stacked above another exchanger.) The original drawing does not show this support as apart of the original design.

 

[brandonb73]

Sounds like an unauthorized alteration. Get rid of it. I would still get an R stamp holder involved if your state requires it in order ensure the integrity of the vessel after the support is removed. They should probably do some NDE of the previously welded areas.

 

[CodeRef]

If the support was not part of the original design (as far as you can tell) then a redisign is necessary. Supports must be considered as required by ASME VIII-1 paragraph UG-54.
I remember sitting in a review where the question was asked "....how is this heat exchanger supported?....", the reply was that the support was inherent in the nozzles, and upon further look into the calculations it was determined that the nozzles could not sustain the loads imposed upon them, the solution was to support the vessel with U bolt clamps around the exchanger shell bolted to a rigid support. This information was added to the remarks section of the Data Report as it would help others in the future determine the support requirements.
A thorough check on the history of the vessel should reveal something of value, if not, then a redesign of the support is necessary.

FAQ731-376

 

[JStephen]

I have seen a situation on piping where the design loading didn't require a support, but unanticipated vibration resulted without the support. I would have to wonder if there wasn't some good reason for it to be added, whether authorized or not.

 

[GenB]

Your new alteration can be brought to the AI supported by design.-
a support was not authorized and you want to fix the problem,
make a lot of sense. alteration has to be by an R stamp holder.