This document discusses common welding defects such as blow holes and worm holes, their causes, and how to prevent them. Blow holes can be caused by an unclean base metal surface, rusty wire or wet flux, improper spot welding or wire size, excessively long arc length or insufficient gas shielding, or welding in windy conditions without a shield. Worm holes are caused by a wet, unclean, or damaged electrode, base metal covered in oil or rust, over traveling speed, over currents, excessively long or short arc length, or a base metal that is too thick or cools too quickly. To prevent these defects, welders should properly clean the base metal, maintain equipment, use proper currents

1. Causes and Cures of Common Welding defects
Welding Type
worm hole
Defect: Blow Hole
worm holeblow hole
Why What to Do
SMAW
CO2/MAG
1.Unclean base metal surface.
2.Rusted wire or wet flux.
3.Improper spot welding or wire.
4.Excessively long arc length or
insufficient gas shielding.
5.Welding in the windy surrounding
without trailer shield.
Welding Type
1.Wet, unclean or damaged
electrode.
2.Base metal surface covered
with oil, rust, etc.
3.Over travelling speed.
4.Over currents
5.Excessively long or short arc
length.
6.Too thick base-metal or too
fast cooling rate.
Why What to Do
SMAW
1.Properly maintain and store
electrode.
2.Properly clean base metal
prior to welding.
3.Reduce travel speed.
4.Use proper welding current.
5.Maintain proper arc length.
6.Proceed proper pre-heating.
CO2/MAG
1.Properly clean base metal
prior to welding.
2.Properly maintain and store
wire and flux.
3.Choose wire size properly
and proceed spot welding
correctly.
4.Maintain proper arc length
and gas flow rate.
5.Add trailer shield.
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