Chapter 29 Shielded Metal Arc Welding 811
Copyright Goodheart-Willcox Co., Inc.
Vertical Fillet and Butt Welds
When welding in the vertical position (3G or 3F), keep in mind the effect
of gravity on the molten pool as well as the effect of heat rising through the
base metal. The trick to vertical welding is preventing the molten pool from
dripping out of the joint. Vertical welding can be performed by traveling up
or down. Uphill welding provides better penetration than downill welding,
but the downhill technique can be used on thinner plate because less
penetration is required. Whether running vertical-up or vertical-down welds,
the welder should always begin by setting the amperage in the lower end of
an electrode’s amperage rating as published by the manufacturer.
Vertical uphill welding is a layering operation in which a welded base
is built from the bottom up. Each new layer acts as a base on which the
following layer is built. Each solidifi ed section of the bead should be one and
one-half to two times the diameter of the electrode.
Using a 1/8″ electrode, the weld pool should be about 1/4″ across. The
weld pool should freeze in time to support the next weld. With an E7018
electrode, control the heat by weaving the electrode from side to side, mostly
focusing on the sides of the joint. This motion allows the bead below the
weld pool to cool just enough to form a supporting platform for the next
section of the bead. Hold the electrode with the back tilted slightly down
from perpendicular. Maintain the correct arc length to ensure penetration,
Figure 29-60. The slag should drip away from the molten weld pool to ensure
a strong weld that is free from slag inclusions.
Vertical uphill welding can also be performed
with fast-freeze electrodes such as an E6011. When this
electrode is used, the AWS recommends a whipping
technique in which the electrode is positioned rapidly
in and out of the weld pool. Using an E6011 electrode
requires a stacking technique, rather than the weaving
performed with an E7018. The bead will resemble a
stack of dimes, with each “dime” supporting the next.
Refer again to Figure 29-30. To stack a vertical-up
weld, keep the electrode in the root of the material.
The technique requires the welder to maintain the arc
while whipping the electrode up, away from the weld
pool. As the weld pool freezes, the electrode is returned
to the molten pool to build another level of the weld.
Whipping with an E6011 requires a higher level of skill
than weaving with an E7018.
Controlling Distortion
The biggest factor infl uencing the amount of distortion produced by a
weld is the amount and distribution of heat input. The faster a weld is made,
the less heat is absorbed into the base metal. Simply speeding up the welding
process can greatly reduce the introduction of heat. Using a higher amperage
setting to achieve a faster travel speed may actually result in a lower overall
Wes Hancock, Caldwell High School
Figure 29-60. Welding in the vertical position. Note
the position of the electrode.
Safety Note
Due to the effects of
gravity, the risk of dripping
molten metal is increased
when 3G and 3F welds
are performed. When
welding in these positions,
stand to the side and wear
full protective gear. Check
the surrounding area for
potential fire hazards and
have a properly charged
fire extinguisher nearby.