Figure 7-32.Lap joints on plates of different thickness.
Figure 7-33.Horizontal butt joint.
Figure 7-34.Multiple passes.
Figure 7-35.Vertical weld plate positions.
(fig. 7-32). Be careful not to overheat or undercut the
thinner plate edge.
BUTT JOINTS. Most butt joints, designed for
horizontal welding, have the beveled plate positioned on
the top. The plate that is not beveled is on the bottom
and the flat edge of this plate provides a shelf for the
molten metal so that it does not run out of the joint (fig.
7-33). Often both edges are beveled to forma 60-degree
included angle. When this type of joint is used, more
skill is required because you do not have the retaining
shelf to hold the molten puddle.
The number of passes required for a joint depends
on the diameter of the electrode and the thickness of the
metal. When multiple passes are required (fig. 7-34),
place the first bead deep in the root of the joint. The
electrode holder should be inclined about 5 degrees
downward. Clean and remove all slag before applying
each following bead. The second bead should be placed
with the electrode holder held about 10 degrees upward.
For the third pass, hold the electrode holder 10 to 15
degrees downward from the horizontal. Use a slight
weaving motion and ensure that each bead penetrates
the base metal.
A vertical weld is defined as a weld that is applied
to a vertical surface or one that is inclined 45 degrees or
less (fig. 7-35). Erecting structures, such as buildings,
pontoons, tanks, and pipelines, require welding in this
position. Welding on a vertical surface is much more
difficult than welding in the flat or horizontal position
due to the force of gravity. Gravity pulls the molten
metal down. To counteract this force, you should use
fast-freeze or fill-freeze electrodes.
Vertical welding is done in either an upward or
downward position. The terms used for the direction of
welding are vertical up or vertical down. Vertical down
welding is suited for welding light gauge metal because
the penetration is shallow and diminishes the possibility
of burning through the metal. Furthermore, vertical
down welding is faster which is very important in pro-
Current Settings and Electrode Movement
In vertical arc welding, the current settings should
be less than those used for the same electrode in the flat
position. Another difference is that the current used for
welding upward on a vertical plate is slightly higher than
the current used for welding downward on the same