My company has occasionally allowed welders to remove the backing bar after welding, then grind a groove in the root and backweld. The WPS says no root treatment required when using backing bars. It's my understanding that for certification purposes, the welder removes the backing bar, grinds the root and cap smooth, then we section and test. No back welding is allowed. Is this typical, or are we in error. Any thought on this matter:
Thanks.
Gamma
In the codes such as ASME, backing is backing whether it be a bar, back welded, or a backing weld. As far as performance qualification "Requirements" I know of nothing that prohibits this other than an inspectors reason to doubt the skill of someone unable to weld a joint on metal backing without having to reweld the back side.
What do you do if during the backing strip removal process, the root side of the weld gets a gouge in it ? I myself let the welder weld it up since the code does NOT prohibit such action. However if they removed the backing strip and there was a line of NON fusion at the root I may look them out.
Have a nice day
Gerald
I would say it is not typical to allow welding after removal of a backing bar. If that is the desired weld joint, why not just use a BU-2 type open root joint, backgouge the other side, and weld?
If after welding a coupon with a backing bar,...and the backing bar is removed, and root defects are detected visually that require gouge and weld, ...it seems to me the welder has failed part of the original intent of the test, which is to make a sound root pass with a backing bar.
Under D1.1 and D1.5, at least, if you qualify with backing, then you are only qualified to weld with backing.
Good Luck
brad
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