Oxy-Acetylene Welding and Cutting | Page 9

being of intense
heat, is of very small size.
_Cutting._--The process of cutting metals with the flame produced
from oxygen and acetylene depends on the fact that a jet of oxygen
directed upon hot metal causes the metal itself to burn away with great
rapidity, resulting in a narrow slot through the section cut. The action is
so fast that metal is not injured on either side of the cut.
_Carbon Removal._--This process depends on the fact that carbon will
burn and almost completely vanish if the action is assisted with a
supply of pure oxygen gas. After the combustion is started with any
convenient flame, it continues as long as carbon remains in the path of
the jet of oxygen.
_Materials._--For the performance of the above operations we require
the two gases, oxygen and acetylene, to produce the flames; rods of
metal which may be added to the joints while molten in order to give
the weld sufficient strength and proper form, and various chemical
powders, called fluxes, which assist in the flow of metal and in doing

away with many of the impurities and other objectionable features.
_Instruments._--To control the combustion of the gases and add to the
convenience of the operator a number of accessories are required.
The pressure of the gases in their usual containers is much too high for
their proper use in the torch and we therefore need suitable valves
which allow the gas to escape from the containers when wanted, and
other specially designed valves which reduce the pressure. Hose,
composed of rubber and fabric, together with suitable connections, is
used to carry the gas to the torch.
The torches for welding and cutting form a class of highly developed
instruments of the greatest accuracy in manufacture, and must be
thoroughly understood by the welder. Tables, stands and special
supports are provided for holding the work while being welded, and in
order to handle the various metals and allow for their peculiarities
while heated use is made of ovens and torches for preheating. The
operator requires the protection of goggles, masks, gloves and
appliances which prevent undue radiation of the heat.
_Torch Practice._--The actual work of welding and cutting requires
preliminary preparation in the form of heat treatment for the metals,
including preheating, annealing and tempering. The surfaces to be
joined must be properly prepared for the flame, and the operation of the
torches for best results requires careful and correct regulation of the
gases and the flame produced.
Finally, the different metals that are to be welded require special
treatment for each one, depending on the physical and chemical
characteristics of the material.
It will thus be seen that the apparently simple operations of welding
and cutting require special materials, instruments and preparation on
the part of the operator and it is a proved fact that failures, which have
been attributed to the method, are really due to lack of these necessary
qualifications.

OXYGEN
Oxygen, the gas which supports the rapid combustion of the acetylene
in the torch flame, is one of the elements of the air. It is the cause and
the active agent of all combustion that takes place in the atmosphere.
Oxygen was first discovered as a separate gas in 1774, when it was
produced by heating red oxide of mercury and was given its present
name by the famous chemist, Lavoisier.
Oxygen is prepared in the laboratory by various methods, these
including the heating of chloride of lime and peroxide of cobalt mixed
in a retort, the heating of chlorate of potash, and the separation of water
into its elements, hydrogen and oxygen, by the passage of an electric
current. While the last process is used on a large scale in commercial
work, the others are not practical for work other than that of an
experimental or temporary nature.
This gas is a colorless, odorless, tasteless element. It is sixteen times as
heavy as the gas hydrogen when measured by volume under the same
temperature and pressure. Under all ordinary conditions oxygen
remains in a gaseous form, although it turns to a liquid when
compressed to 4,400 pounds to the square inch and at a temperature of
220° below zero.
Oxygen unites with almost every other element, this union often taking
place with great heat and much light, producing flame. Steel and iron
will burn rapidly when placed in this gas if the combustion is started
with a flame of high heat playing on the metal. If the end of a wire is
heated bright red and quickly plunged into a jar containing this gas, the
wire will burn away with a dazzling light and be entirely consumed
except for the molten drops that separate themselves. This property of
oxygen is used in oxy-acetylene cutting of steel.
The combination of