CHAPTER II

OXY-ACETYLENE WELDING AND CUTTING MATERIALS


_Welding._--Oxy-acetylene welding is an autogenous welding process, in
which two parts of the same or different metals are joined by causing the
edges to melt and unite while molten without the aid of hammering or
compression. When cool, the parts form one piece of metal.

The oxy-acetylene flame is made by mixing oxygen and acetylene gases in a
special welding torch or blowpipe, producing, when burned, a heat of 6,300
degrees, which is more than twice the melting temperature of the common
metals. This flame, while 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.