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 TM 55-1905-222-14
6-23
REPAIR PROPELLER AND PROPELLER SHAFT (Continued).
k. Multiple-Layer Gas Welding. The multiple-
layer gas welding method is an approved
for major and minor repairs of propellers.
The edges to be welded are beveled to
form a 75 degree, single V-groove weld
for thicknesses less than 1-1/2 inches. A
75 degree double V-groove is used if the
thickness of the section is greater than 1-
1/2 inches (381 cm) A copper-zinc, low-
fuming, welding rod of the proper size
and
in accordance with
Military
Specification MIL-R-19631 is used with a
suitable brazing flux for repair of
manganese-bronze propellers. A carefully
adjusted oxidizing flame is essential for
sound welds.
A forehand method of
welding should be used and the weld metal
deposited in beads with limited oscillation
not exceeding 1-1/2 times the diameter of
the welding rod.
l.
Welding-Preheat
and Stress Relief
Because copper-zinc alloys are susceptible
to stress-corrosion or season cracking,
stress must be relieved, as the propeller
can crack after being returned to service
The use of local preheat above 400
F
(204C), preferably between 600 and
F
800F (315C and 427C), will preclude
the accumulation of harmful stresses. Hot-
flow welds and large gas welds are
automatically preheated and slowly cooled,
and stress relief can be safely omitted after
welding. Arc welds and small gas welds
should be preheated with a torch or other
suitable means and then cooled slowly.
If it is considered more desirable to stress
relief after welding, the following procedure
is recommended. Heat slowly to 750F
(399C) and hold at this temperature for at
least 1 hour per Inch of thickness of metal
In the welded area, cool slowly,
approximately 2F (1C), per minute,
6-126
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