matschka
Materials
- Apr 23, 2002
- 53
Years ago while working as a welding engineer for the biggest construction contractor, we ran into a problem with not having enough welders for the nuclear project. The union could not supply us so we brought in (non-union people, non welding people) and trained and tested them to weld only socket welds. I was directly involved with this program as an instructor. Of course we trained the people on how to 'walk the cup' by simply laying the wire in the throat of the socket and proceeding to consume the filler wire and there by producing a good looking fillet weld. No weld wire dipping was required. When we started to test the coupons we sawed them in sections and polished them. We then performed a macroetch examination. Under magnification we found that very few test specimens had penetrated the 'root'.They got close but not enough penetration. We changed our training technique to melt out the root a little dip the filler rod in and move ahead, melt out the root, dip the filler rod. But after the root was deposited in this way they could 'walk' the cup to finish the socket weld. The test specimens were then cut, bent, and then macroetched. 'WOW" what a difference. Complete penetration plus, no question.
We came to the conclusion that simply laying the filler wire in the throat and welding over it, consuming the wire was stopping complete penetration but the finished weld looked pretty.
It is my opinion that this is the cause of some of the socket weld failures around the globe.
I also believe that their are pipe welds out there that have been welded using the same technique of just consuming over the filler wire and they have been x-rayed and look ok but
have cold lap where one weld bead lays over an underlying bead but is not completly fused. The defect is laying in a plane where the x-ray goes through but does not show the lack of fusion. However, ut would show this type of defect.
We came to the conclusion that simply laying the filler wire in the throat and welding over it, consuming the wire was stopping complete penetration but the finished weld looked pretty.
It is my opinion that this is the cause of some of the socket weld failures around the globe.
I also believe that their are pipe welds out there that have been welded using the same technique of just consuming over the filler wire and they have been x-rayed and look ok but
have cold lap where one weld bead lays over an underlying bead but is not completly fused. The defect is laying in a plane where the x-ray goes through but does not show the lack of fusion. However, ut would show this type of defect.