Figure 8-8.--Characteristics of the oxyacetylene flame.
flame. The carburizing flame bums with a temperature
of molten metal is quiet and clear, and the metal flows
without boiling, foaming, or sparking.
of about 5700F at the tip of the inner cone. When it is
used for welding steel, the metal boils and is not clear.
The REDUCING (or CARBURIZING) flame is
A carburizing flame is best for welding high-carbon
produced by burning an excess of acetylene. You will
steels, for hard-surfacing, and for welding nonferrous
be able to recognize it by the feather at the tip of the
alloys such as Monel.
inner cone. At the end of the inner cone, this feathery
The OXIDIZING flame is produced by burning an
tip has a greenish color. The degree of carburization
excess of oxygen. The oxidizing flame bums with a
can be judged from the length of the feather. For most
temperature of about 6300F at the tip of the inner
welding operations, the length of the feather should be
cone. You can identify this flame by the short outer
about twice the length of the inner cone. You can
flame and the small, white, inner cone. It takes about
always recognize the carburizing flame by its three
distinct colors. These are the bluish-white inner cone,
two parts of oxygen to one part of acetylene to produce
this flame, and you will find that the adjustment for the
a white intermediate cone, and the light-blue outer
8-8