Chapter 29 Shielded Metal Arc Welding 787
Copyright Goodheart-Willcox Co., Inc.
control of heat input and the amount of fi ll deposition is critical to a
successful bonding. By its nature, an edge joint may only be welded from a
single side.
Lap Joint
A lap joint is a bond between two overlapping parts. Lap joints are
often welded along the edge of one piece where it contacts the surface of the
second part. If the pieces need to be welded at a location that is not on an
edge, they can be welded together through a hole created in one piece. This
is called a plug weld. Whether the joint is welded along an outside edge or the
edge of a hole, the resulting weld is a fi llet weld.
Welding Positions
The welding position is determined by the location of the electrode
in relation to the welded joint. The American Welding Society recognizes
four basic welding positions—fl at, horizontal, vertical, and overhead. See
Figure 29-15. The AWS designates welding positions with numbers and
letters. The numbers represent the positions—1 for fl at, 2 for horizontal,
3 for vertical, and 4 for overhead. The letters F and G stand for fi llet welds
and groove welds, respectively. Welding fl at is known as position welding, and
all other orientations are known as out-of-position welding.
In industrial applications, weld engineers analyze the materials and joint
characteristics to determine weld specifi cations. These specifi cations include
the information a welder needs to perform a specifi c job, including how
to position the weld. For many agricultural welding jobs, the welder must
decide how to make the weld. Selecting the correct welding position can
greatly affect the quality of the work. The following sections briefl y describe
each position.
Flat Position
In the fl at position, the electrode is kept more or less in a vertical
alignment and directed down toward the weld pool. AWS designations for
welding in the fl at position are 1G (groove weld in plate) and 1F (fi llet weld
with the joint down).
Flat welding is the easiest position for the beginning welder to master.
When welding in this position, the welder has the benefi t of the force of
gravity. It is usually preferable, even for experienced welders, to weld in the
fl at position, and the work is repositioned to allow this if possible. The fl at
position is best for welding beads that require the addition of large amounts
of fi ll. In these instances, a fast-fi ll electrode is used.
Horizontal Position
In the horizontal position, the electrode is held in a mostly horizontal
position, and the weld progresses from side to side in a horizontal weld. In
a horizontal groove weld (2G), the two parts are aligned approximately in