Welding After Hydro

[innovation2]

Quick question, is it permissible to weld insulation pins onto 2205 or 904L after hydro test on Section VIII Div. 1 equipment? What are the restrictions on types of welds, tig, mig, resistance, etc. The pins are 3.5" long and the equipment has a long trip to job site and may require us to put on insulation pins depending on where the code stands. Any help is appreciated.

 

[metengr]

innovation2;
Simple answer is no, not for Section VIII because of impact concerns and the loss of benefit from a hydrostatic test (local yielding of material and work hardening), for new fabrication. There was a request for code revision regarding Sect I on this same issue and the folks from Section VIII shot it down in flames.

 

[vesselguy]

metengr is right. no welding on vessel after hydrotest and if you have to weld then re-hydro. The code is clear (in a way) see UG-99a(1). However, you said insulation pins and that leads me to think you are welding to a skirt (ie. a non pressure part) or support. Is that correct? If so, then it would be OK to weld onto non-pressure membrane parts after hydro.

How many times have we hear this request from fabricators who try to induce/trick the owner/EPC responsible equipment engineer to "interpret" the code meaning? LOL.

 

[innovation2]

The QC is certain there is an exception for capacitor discharge welding. I am under the assumption that it is not allowed after hydro. Section VIII is vague on capacitor discharge welding. Only reference I see is UW-37(h).

 

[innovation2]

It is allowable in Section 1 and Section 4 vessels but not in regard to Section 8.

 

[JoeTank]

API-650 permits a limited amount of post-hydro welding. Maybe your QC guy is thinking of that?

Joe Tank

 

[mizzoueng]

Guys,

I am looking for information on this as well for a utility boiler. Does anyone have the specific line in Section 8 that says this?