Grinding after hydro
Grinding after hydro
(OP)
We are building a new pressure vessel per ASME Sect VIII Div 1. We have completed the vessel and pressure tested the vessel with AI present and stamped. Now we noticed the Client drawings call for the internal welds ground flush. Do we have to re-hydro the vessel if we just grind the welds smooth and flush?





RE: Grinding after hydro
I consider it as part of fabrication as it would affect your weld reinforcement, and it could have been done prior to testing thus hydrotesting has to be redone.
UG-99 STANDARD HYDROSTATIC TEST
(a) A hydrostatic test shall be conducted on all vessels
after:
(1) all fabrication has been completed, except for
operations which could not be performed prior to the test
such as weld end preparation [see U-1(e)(1)(a)], cosmetic
grinding on the base material which does not affect the
required thickness;
RE: Grinding after hydro
RE: Grinding after hydro
RE: Grinding after hydro
The above is self explanatory.
RE: Grinding after hydro
RE: Grinding after hydro
RE: Grinding after hydro
RE: Grinding after hydro
Regards,
Mike
RE: Grinding after hydro
However, I would like to put a bit of a different slant on it by way of a query.
Would you have to perform MT or PT again if it was originally required ?
IMHO, yes it would have to be retested.
A volumetric discontinuity may be acceptable if it is sub surface but if the reinforcement is ground off and the same discontinuity is exposed to the surface it may be not acceptable.
Also, internal defects (elongated cavities, slag, porosity etc) that could not be detected on the initial test may very well be surface breaking defects after grinding off the reinforcement.
Your thoughts ?
Cheers,
DD
RE: Grinding after hydro
RE: Grinding after hydro