Repair of surface indications after Hydro test 1

[LittleEd]

Large (5" thk) ASME Sect. I Header section (PART). One end of header has TEE on the end, so temporary flat heads were welded-in for hydro testing in shop. After successful hydro test, the temporary flat heads were removed and ID surfaces where temporary weld was removed were examined by MT. A few small linear indications were observed and removed by grinding, MT examined again to verify indication has been removed. I am not sure of depth of areas where indications were removed, expect maybe 3/32" max.

Question: Can the excavated areas be repaired by welding without having to hydro test again? The repaired areas would have final MT examination (same method which found the indications) performed. PW-54 only seems to address repairs found by hydro test, repaired, then rehydro tested (and some exceptions noted in PW-54.3)? This repair doesn't really fit PW-54.3 exceptions.

Since the Header is actually only a segment of the Header, there will be butt-welding and another hydro test performed in field. Due to the thickness of the header and small size and depth of the indications after removal, just seems final MT examination should be sufficient. It seems it would be more detrimental to weld temporary flat heads back in to re-hydro, and have to go through removal process again, all for such minor surface indications after removal of temporary attachment (flat head for hydro test only)?

Other option would be to just "blend-out" excavtions to at least 3:1 taper and MT.

 

[metengr]

Yes, you can weld perform weld repairs after hydrostatic testing without re-hydrostatic testing. Review PW-54.3 of Section I. Keep in mind, the flat head attachment welds are temporary welds and as such are not considered part of the component after hydrostatic testing because they have been removed. In this case, making repairs using PW-40.3 can be done.

The issue of weld repairs to base material would apply if during hydrostatic testing a leak were to be found, and a repair is made as a result of the leak - the hydrostatic test would need to be performed to ensure the pressure retaining base material does not leak at the repair location.

 

[LittleEd]

That was exactly as I was thinking. I considered repair of these "surface indications" really no different than those allowed by PW-40.2/40.3 and PW-54.3 (even though they are not exactly as described by those paragraphs, the logic for allowance would be the same). These surface indications were found by MT after removal of "temporary" welds, indications will be removed, MT to verify removal, weld repaired, blended and final MT examination to close the NCR which was opened when indications were found.

I just really appreciate having second opinions on such issues (some might call gray areas). There was just nothing logical or to be gained by having to weld in temporary flat heads and rehydro and then have to remove again...just for such minor surface indications.

Thanks!