include an extension tube to make the connection be-
tween the tip and the mixing head. When used with an
extension tube, removable tips are made of hard copper,
brass, or bronze. Tip sizes are designated by numbers,
and each manufacturer has his own arrangement for
classifying them. Tip sizes differ in the diameter of the
The term filler rod refers to a filler metal used in gas
welding, brazing, and certain electric welding processes
in which the filler metal is not a part of the electrical
circuit. The only function of the filler rod is to supply
filler metal to the joint. Filler rod comes in wire or rod
form that is often referred to as welding rod.
As a rule, filler rods are uncoated except for a thin
film resulting from the manufacturing process. Filler
rods for welding steel are often copper-coated to protect
them from corrosion during storage. Most rods are
furnished in 36-inch lengths and a wide variety of di-
ameters, ranging from 1/32 to 3/8 inch. Rods for weld-
ing cast iron vary from 12 to 24 inches in length and are
frequently square, rather than round. You determine the
rod diameter for a given job by the thickness of the metal
you are joining.
Except for rod diameter, you select the filler rod
based on the specifications of the metals being joined.
These specifications may be federal, military, or Navy
specifications. This means that they apply to all federal
agencies, the Military Establishment, or the Navy, re-
spectively. Filler metals are presently covered by one or
more of these three types of specifications. Eventually,
all Navy specifications will be rewritten as military
(MIL) specifications. For that reason, some of the speci-
fications for welding materials presented in this section
may subsequently be published as military, rather than
Many different types of rods are manufactured for
welding ferrous and nonferrous metals. In general,
welding shops stock only a few basic types that are
suitable for use in all welding positions. These basic
types are known as general-purpose rods.
OPERATION AND MAINTENANCE OF
This section discusses basic procedures involved in
setting up oxygas equipment, lighting off, adjusting the
flame, and securing the equipment. Information also is
provided on the maintenance of oxygas welding equip-
SELECTING THE WELDING
TORCH TIP SIZE
Welding torch tip size is designated by a number
stamped on the tip. The tip size is determined by the size
of the orifice. There is no standard system of numbering
welding torch tip sizes; each manufacturer has his own
numbering system. In this manual, the tip size is given
in the number drill orifice size. Number drills consist of
a series of 80 drills, number 1 through 80. The diameter
of a number 1 drill is 0.2280 of an inch and the diameter
of a number 80 drill is 0.0135 of an inch.
NOTE: As the drill size number increases, the size
of the drill decreases.
Once you become familiar with the use of a specific
manufacturers torch and numbering system, it becomes
unnecessary to refer to orifice number drill size. The
orifice size determines the amount of fuel gas and oxy-
gen fed to the flame; therefore, it determines the amount
of heat produced by the torch. The larger the orifice, the
greater the amount of heat generated.
If the torch tip orifice is too small, not enough heat
will be available to bring the metal to its fusion tempera-
ture. If the torch tip is too large, poor welds result from
the following: the weld is made too fast, control of the
welding rod melting is difficult, and the appearance and
quality of the weld is unsatisfactory.
For practice purposes, using an equal-pressure
torch, the welding rod sizes and the tip sizes shown in
table 5-1 should give satisfactory results.
Setting up the oxygas equipment and preparing for
welding is identical to setting up for oxygas cutting
(chapter 4) except for the selection of the torch tip.
Select the correct tip and mixing head (depending on
torch manufacturer), and connect them to the torch body.
Tighten the assembly by hand, and then adjust to the
proper angle. After the desired adjustment has been
made, tighten the tip. On some types of equipment, the
tip is tightened with a wrench, while on other types, only
hand tightening is required.
TORCH LIGHTING AND FLAME
When lighting the torch and adjusting the flame, you
should always follow the manufacturers directions for
the particular model of torch being used. This is neces-
sary because the procedure varies somewhat with