Figure 3-2.0xyfuel gas welding (OFW).
source is called a welding machine or simply, a welder.
This should not be confined with the same term that is
also used to describe the person who is performing the
welding operation. The welder (welding machine) is
either electric- or motor-powered. In the Naval Con-
struction Force (NCF), there are two main types of
arc-welding processes with which you should become
familiar. They are shielded metal arc welding and gas
shielded arc welding.
Shielded Metal Arc Welding
Shielded metal arc welding (fig. 3-3) is performed
by striking an arc between a coated-metal electrode and
the base metal. Once the arc has been established, the
molten metal from the tip of the electrode flows together
with the molten metal from the edges of the base metal
to forma sound joint. This process is known as fusion.
The coating from the electrode forms a covering over
the weld deposit, shielding it from contamination;
Figure 3-3.Shielded metal arc welding (SMAW).
therefore the process is called shielded metal arc
welding. The main advantages of shielded metal arc
welding are that high-quality welds are made rapidly at
a low cost. You will learn more about shielded metal arc
welding in chapter 7.
Gas Shielded Arc Welding
The primary difference between shielded metal arc
welding and gas shielded arc welding is the type of
shielding used. In gas shielded arc welding, both the arc
and the molten puddle are covered by a shield of inert
gas. The shield of inert gas prevents atmospheric con-
tamination, thereby producing a better weld. The pri-
mary gases used for this process are helium, argon, or
carbon dioxide. In some instances, a mixture of these
gases is used. The processes used in gas shielded arc
welding are known as gas tungsten arc welding