torch has certain advantages over the low-pressure type
because the flame can be more readily adjusted, and
since equal pressures are used for each gas, the torch is
less susceptible to flashbacks.
The welding tips are made of hard, drawn,
electrolytic copper or 95-percent copper and 5-percent
tellurium. They are made in various styles and types,
some having a one-piece tip either with a single orifice
or a number of orifices, and others with two or more tips
attached to one mixing head. The diameters of the tip
orifices differ to control the quantit y of heat and the type
of flame. These tip sizes are designated by numbers that
are arranged according to the individual manufacturers
system. In general, the smaller the number, the smaller
the tip orifice.
No matter what type or size tip you select, the tip
must be kept clean. Quite often the orifice becomes
clogged with slag. When this happens, the flame will not
burn properly. Inspect the tip before you use it. If the
passage is obstructed, you can clear it with wire tip
cleaners of the proper diameter, or with soft copper wire.
Tips should not be cleaned with machinists drills or
other sharp instruments. These devices may enlarge or
scratch the tip opening and greatly reduce the efficiency
of the torch tip.
HOSE.The hose used to make the connection
between the torch and the regulators is strong,
nonporous, light, and flexible to make the torch
movements easy. It is made to withstand high internal
pressures, and the rubber used in its manufacture is
chemically treated to remove sulfur to avoid the danger
of spontaneous combustion.
The oxygen hose is GREEN, and the acetylene hose
is RED. The hose is a rubber tube with braided or
wrapped cotton or rayon reinforcements and a rubber
covering. The hoses have connections at each end so
they can be connected to their respective regulator outlet
and torch inlet connections. To prevent a dangerous
interchange of acetylene and oxygen hoses, all threaded
fittings used for the acetylene hookup are left-handed
threads, and all threaded fittings for oxygen hookup are
right-handed threads. The hoses are obtainable as a
single hose for each gas or with the hoses bonded
together along their length under a common outer rubber
jacket. This type prevents the hose from kinking or
becoming entangled during the welding operation.
LIGHTERS.A flint lighter is provided for igniting
the torch. The lighter consist of a file-shaped piece of
steel, usually recessed in a cuplike device, and a piece
of flint that can be drawn across the steel, which
produces the sparks required to light the torch.
Matches should never be used to ignite a
torch; their length requires bringing the
hand too close to the tip to ignite the gas.
Accumulated gas may envelope the hand
and, when ignited, cause a severe burn.
GOGGLES.Welding goggles are fitted with
colored lenses to keep out heat and light rays and to
protect the eyes from sparks and molten metal.
Regardless of the shade of lens used, goggles should be
protected by a clear cover glass. The welding operator
should select the shade or density of color that is best
suited for his/her particular work. The desired lens is the
darkest shade that will show a clear definition of the
work without eyestrain. Goggles should fit closely
around the eyes, and should be worn at all times during
welding and cutting operations. Special goggles, using
standard lenses, are available for use with spectacles.
WELDING (FILLER) RODS.The use of the
proper type of filler rod is very important in
oxyacetylene welding operations. This material not only
adds reinforcement to the weld area, but also adds
desired properties to the finished weld. By selecting the
proper type of rod, either tensile strength or ductility can
be secured in a weld. Similarly, rods can be selected that
will help retain the desired amount of corrosion
resistance. In some cases, a suitable rod with a lower
melting point will eliminate possible cracks from
expansion and contraction.
Welding rods are classified as ferrous and
nonferrous. The ferrous rods include carbon and alloy
steel rods as well as cast iron rods. Nonferrous rods
include brazing and bronze rods, aluminum and
aluminum alloy rods, magnesium and magnesium alloy
rods, copper rods, and silver rods. The diameter of the
rod used is governed by the thickness of the metals being
joined. If the rod is to small, it will not conduct heat away
from the puddle rapidly enough, and a burned weld will
result. A rod that is to large will chill the puddle. As in
selecting the proper size welding torch tip, experience
will enable the welder to select the proper diameter
The welding flame is classified as neutral,
carburizing, or oxidizing. Each type of flame has its own
special function The operator can adjust the torch to
produce the type of flame best suited for the job at hand.