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Recommended Angles for Overhead Fillet Welds
15˚
Multi-run horizontal fillets have each run made
using the same run lengths (run length per
electrode table). Each run is made in the same
direction, and care should be taken with the shape
of each, so that it has equal leg lengths and the
contour of the completed fillet weld
is slightly convex with no hollows in the face.
Vertical fillet welds can be carried out using
the upwards or downwards technique. The
characteristics of each are: upwards – current
used is low, penetration is good, surface is slightly
convex and irregular. For multiple run fillets large
single pass weaving runs can be used. Downwards
– current used is medium, penetration is poor,
each run is small, concave and smooth (only BOC
Smootharc 13 is suitable for this position).
The downwards method should be used for making
welds on thin material only. Electrodes larger than
4.0 mm are not recommended for vertical down
welding. All strength joints in vertical plates 10.0
mm thick or more should be welded using the
upward technique. This method is used because
of its good penetration and weld metal quality.
The first run of a vertical up fillet weld should be
a straight sealing run made with 3.15 mm or 4.0
mm diameter electrode. Subsequent runs for large
fillets may be either numerous straight runs or
several wide weaving runs.
Correct selection of electrodes is important for
vertical welding.
46
45˚
30˚
In overhead fillet welds, careful attention to
technique is necessary to obtain a sound weld of
good profile. Medium current is required for best
results. High current will cause undercutting and
bad shape of the weld, while low current will cause
slag inclusions. To produce a weld having good
penetration and of good profile, a short arc length
is necessary. Angle of electrode for overhead
fillets is illustrated above.
11.7 Typical Defects Due to
Faulty Technique
Manual metal arc welding, like other welding
processes, has welding procedure problems
that may develop which can cause defects in
the weld. Some defects are caused by problems
with the materials. Other welding problems may
not be foreseeable and may require immediate
corrective action. A poor welding technique and
improper choice of welding parameters can cause
weld defects. Defects that can occur when using
the shielded metal arc welding process are slag
inclusions, wagon tracks, porosity, wormhole
porosity, undercutting, lack of fusion, overlapping,
burn through, arc strikes, craters, and excessive
weld spatter. Many of these welding technique
problems weaken the weld and can cause cracking.
Other problems that can occur which can reduce
the quality of the weld are arc blow, finger nailing,
and improper electrode coating moisture contents.
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