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welded by the process, provided that the proper amount of heat is applied.
Welds must be vertical, varying to either side by a maximum of 15 degrees.
Like other arc welding processes, EGW requires that the operator wear a
welding helmet and proper attire to prevent exposure to molten metal and the
bright welding arc. Compared to other processes, a large amount of molten
metal is present during welding, and this poses an additional safety and fire
hazard. Since the process is often performed at great heights, the work and
equipment must be properly secured, and the operator should wear a safety
harness to prevent injury in the event of a fall. EGW uses a constant voltage,
direct current welding power supply, and the electrode has positive polarity.
A wire feeder is used to supply the electrode, which is selected based on the
material being welded. The electrode can be flux-cored to provide the weld
with protection from atmospheric contamination, or a shielding gas can be
used with a solid wire electrode. The welding head is attached to an apparatus
that elevates during the welding process. Also attached to the apparatus are
backing shoes which restrain the weld to the width of the workpieces. To
prevent them from melting, they are made of copper and are water-cooled.
They must be fit tightly against the joint to prevent leaks.
Stud welding is a form of spot welding where a bolt or specially formed nut
is welded on to another metal part. The bolts may be automatically fed into
the spot welder. Weld nuts generally have a flange with small nubs that melt
to form the weld. Studs have a necked down, unthreaded area for the same
purpose.
10 Write a brief summary to the text in the previous activity.
11 Say if the following is true or false. Correct the false sentences.
1. Electrogas welding is less hazardous than electroslag welding.
2. Electroslag welding is more frequently used to weld in a horizontal
orientation.
3. Carbon Arc Welding is broadly used in industry in the present time.
4. Filler metal is always necessary in Atomic Hydrogen Welding.
5. Quenched and tempered steels are not welded using Electrogas welding.
6. Carbon Arc Welding is the newest arc welding process.
12 Answer the following questions.
1. What kind of electrodes are used in Electrogas and Atomic Hydrogen
Welding processes?
2. What structures can be welded by Electrogas welding?
3. Can thick workpieces be easily welded by Electroslag welding?
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