When welding in the overhead position, keep a
short arc of about one-eighth inch, hold the arc at
an angle of 90 to the base metal, and avoid
weaving. Butt joints in the overhead position are
most easily made with backing straps. If backing
straps are not permitted, the root can be welded
from the top of the joint. Each bead must be
cleaned and any rough places should be removed
before the next pass is made. Figure 10-16 shows
the correct electrode angle and the correct sequence
for running beads when making a butt joint in the
Figure 10-15.--Order of making stringer beads for a T-joint
in heavy plate.
Figure 10-17 shows the fillet welding of a T-joint
in the overhead position. The welding should be
done with a short arc, using stringer beads. Hold
joined make a 90-degree angle with each other.
First weld a tack at each end to hold the pieces in
the electrode about 30 from the vertical plate, and
position. To make the fillet weld, use a short arc
move it uniformly in the direction of welding.
and hold the electrode at a work angle of 45 to the
Control the arc motion so as to get good root
plate surfaces. Tilt the electrode to a lead angle of
penetration and good fusion with the side walls. If
about 15. Light plate can be welded in one pass,
the pool of molten metal gets too large and begins
without any weaving motion of the electrode.
to sag, shorten the arc and speed up the travel rate
Heavier plate may take two or more passes, and you
of the electrode. Then return the electrode to the
must use a semicircular weave motion with the
crater, and continue the welding. On heavy plate,
several passes may be required to make either
second pass to get good fusion without undercutting.
T-joints or lap joints in the overhead position.
To weld plate that is one-half inch or more in
thickness, use stringer beads in the order shown in
Make the second, third, and fourth passes of a weld,
figure 10-15. Lap joints in the flat position are
like the one shown in figure 10-18, with a slight
made in the same way as T-joints, except that the
circular movement of the end of the electrode. The
electrode should be held so as to form a 30-degree
lead angle should be about 15. Each bead must be
angle with the vertical.
cleaned of all slag and oxides before the next bead
Welding in the vertical position is difficult
because molten metal tends to run down. A short
arc and careful control of voltage are particularly
important for welding in the vertical position.
Current setting (amperage) is lower for welding in
the vertical position than it is for welding in the flat
position. Also, less amperage is used for welding
down than for welding up in the vertical position.
When welding up in the vertical position, hold the
electrode at an angle of 90 to the vertical.
Welding with dc involves a special problem
known as arc blow (also known as magnetic arc
blow). It is important that you understand what arc
blow is and that you know how to recognize it and
what to do about it.
Figure 10-16.--Bead sequence and electrode angle for welding
Arc blow is caused by distortion in the
a butt joint in the overhead position.
field that surrounds a