Figure 5-11.Welding operation with backhand technique.
FUSION WELDING PIPE
In oxygas welding of pipe, many tests have proved
that fusion welded pipe joints, when properly made, are
as strong as the pipe itself.
For success in oxygas welding of pipe, three essen-
tial requirements must be met: there must be a conven-
ient source of controlled heat available to produce rapid
localized melting of the metal, the oxides present on the
surface or edges of the joints must be removed, and a
metal-to-metal union between the edges or surfaces to
be joined must be made by means of molten metal.
One method used for welding steel and wrought iron
pipe is known as FUSION WELDING. This method
involves melting the pipe metal and adding metal from
a rod of similar composition. The welding operation
performed at the top of a joint in a horizontal pipe is
shown diagrammatically in figure 5-11. This shows the
BACKHAND welding technique. The rod and flame are
moved alternately toward and away from each other, as
shown in figure 5-12. Full strength oxygas welds can be
made in any welding position.
The cohesiveness of the molten metal, the pressure
of the flame, the support of the weld metal already
deposited, and the manipulation of the rod all combine
Figure 5-12.Flame and rod motion with backhand technique.
to keep the molten metal in the puddle from running or
The soundness and strength of welds depend on the
quality of the welding rod used. If you have any doubt
about the quality of the rods or are not sure of the type
to use, then it would be to your advantage to contact the
manufacturer or one of his distributors. If the rod is
supplied through the federal stock system, supply per-
sonnel should be able to look up the information based
on the federal stock number of the rod.