Courtesy of the Hobart Brothers Co.

Fig. 8-29. Weaves used to weld the cover pass. A. Slant weave used for 12 to 5 o’clock positions. B. Horseshoe weave used for 5 to 6 o’clock positions.

Poor Fit-up. When a poor fit-up is encountered, the necessary corrective action to be taken is similar to that used when welding by the downhill method. If the root opening is too wide, nuggets are deposited on both edges of the weld until a bridge is built across the wide gap, over which the arc can travel to tie the two edges together. The welding current should be reduced slightly when welding over­spaced joints. An important difference in the welding method occurs in welding the root bead. In order to be able to carry the arc across the wide root opening, the root bead should be started against a tack weld and the bead should be deposited by using a loop-shaped weave, as shown before in Fig. 8-24. After the root bead has filled the root opening with sound weld metal, the intermediate beads and the cover bead are deposited by using the same procedures as used over a normal size root opening.

When the root opening is too narrow, the tack welds and the root bead are made by dragging the electrode as previously described; however, a higher current setting is necessary to obtain the required amount of weld penetration. Usually the current setting should be about 15 amps more than for a correctly spaced joint. During welding, the welder should pay attention to the penetration obtained. If overpenetration occurs, the electrode angle should be decreased slightly and the speed of travel can be increased. When insufficient penetration occurs, the speed of travel should be de­creased slightly and, if this does not help, the current setting must be increased. Again, the remaining layers are welded in the manner described for a correctly spaced root opening.

When the root face is too wide, the root bead is deposited by dragging the electrode, using a sufficiently higher current setting to obtain the required amount of penetration. For a narrow root face, the electrode is dragged to deposit the root bead, using a current setting that is about 10 amps less than normal to prevent over­penetration. If excessive penetration or burn-through occurs, the welding current is further decreased.

Pipe Axis at 45-Degree (6G) Position. On some jobs it is necessary to weld a pipe joint with the pipes positioned at an approximately 45-degree angle. While the welding procedure used in this case is similar to welding in the 5G position, there are still some differences that will be described in the following paragraphs.

As shown in Fig. 8-30, the root bead is deposited by dragging the electrode from the top to the bottom of the pipe, as before. Deposit­ing the hot pass is also done by using the same method as when the pipe is in the 5G position.

Intermediate beads are deposited in a slightly different manner than in the case where the pipes are in the 5G position. First, the electrode must be held so that it points toward the high side of the joint, as shown in Fig. 8-31. With respect to a perpendicular Hn<> from the surface of the weld, the electrode angle in a plane cutting through the weld joint should be 10 to 15 degrees, as before. The side angle should be 25 to 30 degrees, as shown; as it is in respect to a plane passing through the weld joint. The current setting and the

arc length (one electrode diameter) are the same as used when the pipes are in the 5G position.

In the flat welding position on top of the pipe, a loop or oval­shaped weave, as shown in Fig. 8-32, is used. The electrode should pause where the dots are shown at the upper edge in order to deposit sufficient metal there and to obtain good fusion against this edge. If possible, this weave should be continued around the side of the weld to the 5 o’clock position; however, in the vertical welding position between 2 and 4 o’clock, the puddle may start to roll downward excessively. If this happens, the electrode angle should be increased to 20 to 25 degrees and the weave pattern changed to a slant weave (see Fig. 8-25). It may also be necessary to increase the welding speed slightly, in order to keep the electrode ahead of the puddle. The arc force should be used as effectively as possible to hold back the molten metal, also the electrode movement should be kept slow and steady. When the overhead position is reached, a horseshoe weave, similar to that shown before, in Fig. 8-27, is used to finish the weld.

If necessary, stripper beads should be deposited on the sides of the weld before welding the cover bead. The same angles as in Fig. 8-31 are used to hold the electrode for depositing the cover bead. This layer is deposited entirely by using an oval weave, illustrated in Fig. 8-32. At each side of the bead, the center of the electrode should pass over the edge of the previous layer, pausing at the upper edge to obtain good edge fusion.