Remova of Defects

A defect should be clearly marked by the inspector or supervisor so that the metal can be excised with a minimum of material loss. Normally surface defects and those of reasonable depth can be removed by grinding or gouging. Defects that go into the weld are removed by the gouging method; the weld must be preheated to the required tem­perature and maintained as such. The preheating temperature is the same as that used for making the weld.

There are two stages of repair: (a) removal of defects and (b) prepa­ration of the defective area for welding. The cavity, which has been pre­pared by gouging, must now be dressed by a grinder or a burring tool that can effectively remove the rough surface in the cavity. The repair cavity must be wide enough so that electrode can fully access the defec­tive area.

A weld that is fully prepared should be as follows:

1. The prepared cavity surface must be smooth without peaks and valleys.

2. All traces of oxide must be removed.

3. All spatter and globular deposits in the groove during each welding pass should be removed repeatedly.

Preperaiion of weld repair

As shown in the figure below, the root opening is reestablished. This part of the root bead must first be deposited, because the base metal is that of a medium alloy composition. If the root pass was originally deposited by the gas tungsten arc welding process, it should again be applied here. However, if the machine to be used for welding has an attachment for pulse arc, then it should be used instead to control bum through. The second pass should be slightly wider than the first, using the pulse arc. From there on, the shielded metal arc process can be used to deposit stringer beads of a limited size. All slag particles and dust should be removed from the cavity after each deposit. As shown in Fig the figure below, the starting point should be approximately 3/16 of an inch on the base metal. It should then be either ended or discontinued the same distance on the base metal. Stringer beads should be used until it is filled, and then two weave passes or a single, wider weave can complete the weld.

Remova of Defects

•Starting Point

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