ASME B31.3/ASME BPE / DIN????

Discuss the matter directly with the Engineer/Surveyor from the company that is to supply burst/collapse indemnity insurance cover for the equipment, and go from there.

I agree with the above. I don't work in Bio-pharm industry but in my industry we would have agreed on the standards applicable during the tendering phase of a project which would then be reviewed again during the execution phase.

Things to also watch out for are spec breaks. You might find that for a system you need to apply different specs to different assemblies and this can also cause some degree of discussion/argument between people.

One real life example of this was we had a piece of kit which was attached to a pipeline, the pipe was subject to ASME B31.3 therefore this piece of kit (I won't go into the detail of the design) was also subject to B31.3, however, I argued it was actually a pressure vessel and should be subject to API 6A & 17D or ASME BPVC. I lost that arguement because the other party said they were right and walked away! Hey, you have to pick your battles.

So my advice would be that you need to choose your spec based on your knowledge of the actual design (we don't have details so can't really do that here) then get your client (be it internal or external) to verify this is the correct one.