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Fastening
& Joining Methods
Oxyfuel
gas welding (OFW)
Oxyfuel gas welding (OFW) is a group of
welding processes which join metals by heating
with a fuel gas flame or flares with or
without the application of pressure and
with or without the use of filler metal.
OFW includes any welding operation that
makes use of a fuel gas combined with oxygen
as a heating medium. The process involves
the melting of the base metal and a filler
metal, if used, by means of the flame produced
at the tip of a welding torch. Fuel gas
and oxygen are mixed in the proper proportions
in a mixing chamber which may be part of
the welding tip assembly. Molten metal from
the plate edges and filler metal, if used,
intermix in a common molten pool. Upon cooling,
they coalesce to form a continuous piece.
There are three major processes within
this group:
- oxyacetylene welding
- oxyhydrogen welding
- pressure gas welding.
There is one process of minor industrial
significance, known as air acetylene welding,
in which heat is obtained from the combustion
of acetylene with air. Welding with methylacetone-propadiene
gas (MAPP gas) is also an oxyfuel procedure.
Process
Advantages
(1) One advantage of this welding process
is the control a welder can exercise over
the rate of heat input, the temperature
of the weld zone, and the oxidizing or
reducing potential of the welding atmosphere.
(2) Weld bead size and shape and weld
puddle viscosity are also controlled in
the welding process because the filler
metal is added independently of the welding
heat source.
(3) OFW is ideally suited to the welding
of thin sheet, tubes, and small diameter
pipe. It is also used for repair welding.
Thick section welds, except for repair
work, are not economical.
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