9 Square-Groove
Butt Joint The
reinforcement of square-groove welds tends to increase with the plate thickness.
However, with suitable backing,
the reinforcement can be controlled somewhat by increasing the root gap slightly.
In this way, single-pass
welds of good quality can be made in plate up to 5/16-in. thick. The excessive
reinforcement shown
in Figure 32 was caused by too narrow a root gap. Thicknesses
greater than 5/16-in. require a vee preparation or may be welded from both sides
up to about 5/8-in.
thickness. Steel-Backed
Welds Figure 33
illustrates the effect of improper spacing and fit-up on welds with integral steel
backing. The welds are
single-pass with square groove butt joint preparation. Although not indicated
in the illustration, the effect mentioned
in the preceding section is also present here: widening the root gap lowers the
weld reinforcement.
FIG. 32 - Effect of Improper Fitup
in Square Butt Weld
