14.
SHUTTING DOWN WELDING APPARATUS.
a. Shut off the gases. First close the acetylene valve and then the oxygen
valve on the torch. Then close the acetylene and oxygen cylinder valves.
b. Drain the regulators and hoses by the procedures outlined below.
(1) Open the torch acetylene valve until the gas stops flowing; then close
the valve.
(2) Next open the torch oxygen valve to drain the oxygen regulator and
hose. When gas stops flowing, close the valve.
(3) When the above operations are performed properly both high- and low-
pressure gages on the acetylene and oxygen regulators will register zero.
c. Release the tension on both regulator screws by turning the screws to the
left until they rotate freely.
d. Coil the hoses without kinking them and suspend them on a suitable holder
or hanger. Avoid upsetting the cylinders to which they are attached.
15.
WELDING RODS.
a. Welding rods are drawn or cast metal rods of various diameters for various
classes of work. Oxyacetylene welding rods may be grouped into two classes:
ferrous and nonferrous. In the first group are rods of steel and cast iron, while
the latter covers the so-called bronzes, copper, aluminum, and nickel. The welding
rod acts as a filler metal and during the process of welding is fused with the base
metal. Metal from such rods forms a large portion of the actual weld metal;
consequently, the rod plays a most important part in determining the quality of the
finished weld.
b. Good welding rods must be of correct chemical composition and, equally
important, free from foreign matter or "dirt". The metal from the rod changes
somewhat in its chemical composition and its properties after passing through the
welding flame. A good welding rod, naturally, has its composition so fixed as to
provide for these changes; therefore, the metal in the weld will be of as good
quality, or better than, the parts being joined. Good rods will melt and flow
freely and will unite readily with the base metal producing sound, clean welds.
c. The behavior of a welding rod in the blowpipe flame gives a good
indication of its quality. It must melt quietly and without excessive sparking.
Welding rods are made in various diameters from 1/16 inch to 3/8 inch. As a rule,
the diameter of the welding rod should correspond with the thickness of the
material being welded.
d. Welding rods should be stored in such a way that the different kinds of
rods will not get mixed up. Steel and cast iron rods should be kept dry so they
will not rust. Some manufacturers apply a very thin coating of copper or grease to
prevent rust.
e. In fusion welding, the welding rod is generally similar to the base metal.
In bronze welding, however, the same kind of rod is used for a wide variety of base
metals.
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