Just as there is no universal medicine
that will cure all ailments, some cast iron repairs lend themselves to
gas welding better than arc welding. In other cases, arc welding is
more practical than gas welding. Types of applications where
oxyacetylene welding is generally preferred:
Small parts, such as a broken lever.
Repairs such as a fracture where
both parts to be joined are loose and free to move.
Welds where the weld metal must have
the exact, or almost exact, same properties as the base material. For example, a glass mold where a weld with dissimilar coefficient
of expansion and contraction could cause a spot or flaw in the
In some machine applications where
heat, corrosion, color or other reasons require that the weld metal
have the same properties as the base metal. For example, valve ports
in cylinder heads.
Most engineers would prefer to
oxyacetylene weld any part where facilities are available and it is
practical to preheat, especially on parts where the crack cannot be
reached by an electrode but the iron must be melted in order to obtain
access. For example a crack between valve ports. Here usually only the
top of the crack is reachable. It is therefore necessary to melt down
into the crack in order to weld the complete crack. In such case, the
oxyacetylene torch is naturally used.