WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 1
(2) Lap Joint (figure 19, views B and C, on the previous page).
(a) In making lap joints, two overlapping plates are tack
welded in place and a fillet weld in the horizontal position is
deposited along the joint.
(b) The procedure for making this weld is similar to that used
for making fillet welds in tee joints. The electrode should be
held so as to form an angle approximately 30 degrees from the
vertical and tilted 15 degrees in the direction of welding. The
position of the electrode in relation to the plates is shown in
figure 19, view C. The weaving notion is the same as that used
for tee joints, except that the pause at the edge of the top
plate is sufficiently long to ensure good fusion and no under
cut.
Lap the joint by depositing a series of overlapping beads
on top of each other.
(c) In making lap joints on plates of different thicknesses as
shown in figure 20, view A, on the following page, the electrode
is held so as to form an angle of 20 to 30 degrees from the
vertical.
Care must be taken not to overheat or undercut the
thinner plate edge. Also, the arc must be controlled to wash up
the molten metal to the edge of this plate.
h.
Vertical Position Welding.
(1) Bead Welds (figure 20, views B through E).
(a) Welding on a vertical surface is more difficult than
welding in the flat position.
Because of the force of gravity,
the molten metal tends to flow downward.
(b) When metal-arc welding in the vertical position, current
settings should be less than those used for the same electrode in
the flat position.
The currents used for welding upward on a
vertical surface are slightly higher than those used for welding
downward on the same surface.
(c) The proper angle between the electrode and the base metal
is also necessary in order to deposit a good bead weld when
welding vertically.
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