Whether Grinding or filling is allowed on the Final pass (on capping) for Welder performance qualification test (WPQT) for Plate or Pipe. Since qualification is done based on ASME Sec IX, so need reference only as per ASME Sec IX.
ASME Sec 9 - QW194, which only mentions the Complete joint penetration for visual examination for WPQT. But it is not more specific in case of Grinding or filling and also some other (acceptable limits?) parameters like Reinforcement, undercut, underfill, etc..
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Codes do not specify about the grinding & filling, on not only final but even in filler passes. It is the discrepancy of the Inspection authority who witnesses the test. Some allow it while few do not. They feel it is lack of skill on the part of the welder concerned if he is allowed to grind such surface defect.
But, it need not be a fact. Say if it is a surface pore due to sudden breeze or to other reasons where welder is not at fault, he takes the Inspector into confidence to remove such defects by grinding or other means. So it is a selective thinking.
More attention is given in initial visual inspection for root defects like. LP, LF, UC, Ex. Penetration , Oxidation (in TIG process), Cavities, under flush etc., than on surface defects on cap runs.
ASME Sec IX do not address this issue.
As far as I know, the only code which allows grinding of completed welds is AWS D1.5 - 2002 (Bridge Welding Code) See Clause 3.2.2.1, 2nd para, Point # 4.
(4) grinding the completed weld smooth and flush with the adjacent surface to produce a workmanlike finish (see 3.6.3).
Further, 3.6.3 says : Unless otherwise approved by the Engineer, all reinforcement shall be removed where the weld forms a part of a faying surface. Any reinforcement shall blend smoothly into the plate surfaces with transition areas free from weld edge undercut. Chipping may be used, provided it is followed by grinding.
IMO, grinding of the completed welds should be applicable only for removing sharp notches, bulbous contours, overlaps only with prior approval and presence of concerned Inspector/Engineer, especially qualification welds.
No welder should be allowed to grind the completed welds on their own, as they make it mess sometimes. I have seen welders try to "remove" external undercuts by grinding the base metal and bringing it to the level of surface of undercut, which may reduce the minimum specified wall thickness of the base metal.
Filing a completed weld for good visual appearance, is not a problem, I think.
I'm also waiting for opinion of the experts of this forum.