c. Pass the flame over the metal several times in order to preheat the metal
slightly; then direct the flame steadily upon the spot where the weld is to begin.
d. Keep the end of the luminous cone about one-sixteenth of an inch away from
the metal.
e. Just before the metal begins to melt, bring the end of the welding rod
under the flame. If this action is timed correctly, both the rod and base metal
will melt at the same time and form a puddle of molten metal.
f. Care should always be taken to keep the rod within the molten puddle since
the rod will stick to the plate if it touches the cooler edges.
g. On metal of 1/8-inch thickness, the bead should be approximately 3/8-inch
wide.
h. The filler metal from the welding rod is added by dipping the end of the
rod into the molten puddle of metal. Movement of the torch should be styled to
suit the individual.
i. Before moving forward, be sure that the added material is actually being
fused to the base metal and not merely being laid on the surface in droplets. If
the weld is carried forward too rapidly, the metal will not fuse together, if
progression is too slow, the metal is very likely to be burned.
j. Penetration of the weld all the way through the seam to the bottom edge is
one of the most important requirements of welding.
EXERCISE
36.
What advantage does a two-stage oxygen regulator have over a single-stage
regulator?
a.
Better adjustment can be obtained with a single-stage regulator
b.
Working pressure is held constant during welding operations
c.
Two-stage regulator is safer
37.
To prevent dangerous interchange of oxygen and acetylene hoses what measures
have been taken?
a.
Threaded fittings for oxygen hookup are right-handed
b.
Threaded fittings for acetylene hookup are right-handed
c.
Oxygen hoses are red and acetylene hoses are green
38.
When adjusting the oxygen acetylene torch flame, which type of flame would
have a ratio of slightly less than one volume of oxygen mixed with one volume of
acetylene (0.85 to 0.95)?
a.
Neutral
b.
Oxidizing
c.
Reducing or carburizing
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