WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 1
(c) When using any of the weaving motions, the electrode should
be oscillated or moved uniformly from side to side with slight
hesitation at the end of each oscillation and, as in bead
welding, the electrode should be inclined 5 to 15 degrees in the
direction of welding.
If the weaving motion is not properly
performed, undercutting will occur at the joint as shown in
figure 16, view C, on the previous page. Excessive welding speed
will also cause undercutting and poor fusion at the edges of the
(2) Butt Joints in Flat Position with Backup Strips (figure 16,
(a) Backup or backing strips are used when welding 3/16 inch
plate or heavier to obtain complete fusion at the root of the
weld and to provide better control of the arc and the weld metal.
The edge of the plates to be welded are prepared in the same
manner as required for welding without backing strips.
backing strips, 1 inch wide and 3/16 inch thick for plates up to
3/8 inch thick, 1 1/2 inch side, and 1/4 inch thick for plates
over 1/8 inch thick, are tack welded to the base of the joint.
The backing strip will act as a cushion for the first bead or
layer deposited in the joint.
(b) The joint should be completed by adding additional layers
of metal using the procedures prescribed in paragraphs 5e, on
pages 35 and 36.
(c) After the joint is completed, the backup strip may be
washed off or cut away with a cutting torch and, if necessary, a
sealing bead may then be applied along the root of the joint.
(3) Plug and Slot Joints (figure 17 on the following page).
(a) Plug and slot welds, shown in figure 17, views A and B, are
used to join two overlapping plates, by depositing and filling a
hole or slot in the upper plate.
Slot welds are used in butt
straps to join face hardened armor plate edges from the back or
soft side. They are also used to fill up holes in plates and to
join two overlapping plates where it is impossible to join them
by any other method.