personal protective clothing and equipment shall be worn
by personnel performing welding operations. Helmets,
shields, aprons, gloves, gauntlets, or other items of
clothing of approved design may be used. Goggles shall
be carefully selected on the basis of lens shade which will
provide complete protection for type of welding involved.
(2) Ventilation. Forced ventilation should be provided
concentration of injurious fumes produced in welding
operation below harmful levels. Suitable respiratory
equipment shall be worn when concentration of injurious
fumes cannot be kept below maximum allowable
(3) Fire hazard. Welding shall not be permitted in the
vicinity of flammable or explosive substances. A suitable
fire extinguisher shall be provided for all welding units.
(a) Flammable material. All flammable material
shall be removed from the immediate vicinity of welding
operations. Wooden floors and other combustible
material which may be subjected to excessive heat or
contact with the flame shall be adequately protected.
Where removal of flammable material is impractical, a
suitable fire-resistant shield shall be placed between
flammable material and welding operation. A thorough
inspection of surrounding area shall be made upon
completion of a welding operation to detect any potential
prohibited where flammable liquids and gases create a
fire or explosion hazard. In confined areas with
inadequate ventilation, it is possible for the welding
operation itself to produce flammable and explosive
(c) Fire protection. Where a fire hazard
continues to exist despite reasonable precautionary
measures, a fire guard provided with suitable fire
extinguishing equipment shall be stationed near welding
(4) Welding of containers. Tanks, cylinders, and
other containers shall never be welded until it has been
ascertained that they do not contain flammable or
(a) Sealed containers. Sealed containers shall
not be worked on until it has been determined that
their contents do not present a hazard and venting is
(b) Draining. Prior to welding gas tanks and
other containers which have contained flammable liquids,
all liquid shall be drained from tank. Precautions shall be
taken to prevent draining process from creating a fire
hazard. The tank shall then be thoroughly washed,
steamed, and filled with water. Provide a vent to permit
release of pressure which is generated in tank by heat of
welding process. Accomplish repairs as soon as possible
after tank has been drained and cleaned.
3-3. Types of Welding. There are three general types of
welding: gas, electric arc, and spot welding. The following
paragraphs describe the three types.
Gas Welding. Gas welding is accomplished by
heating the ends or edges of metal parts to a molten state
with a high temperature flame. The flame is produced
with a torch burning pure oxygen with acetylene or
hydrogen. The metals, when in a molten state, flow
together to form a union.
(1) Gas welding precautions. The oxygen,
acetylene, and the flame used in oxyacetylene welding
requires careful handling to prevent injury or damage.
Observe the following precautions:
Do not allow oil or grease to contact welding
apparatus. Oil or grease in contact with oxygen
equipment, in particular, is extremely dangerous and
may result in fire or explosion.
Do not use acetylene from cylinders at pressures in
excess of 15 psi. The special T-wrench provided for
opening acetylene cylinders will be left in place while
cylinder is in use to permit quick shutoff in an
Acetylene and oxygen cylinders will be hand- led with
care to prevent damage to cylinders, regulators, or
valves. Cylinder valves will be in an immediately
accessible location when cylinders are in use to
permit quick shutoff in
an emergency. All cylinders to which a hose is not
attached will be provided with protective caps.
Protect hose from mechanical damage or con- tact
with hot metal, open flame, and other destructive
agents. Inspect hose periodically for leaks by
submerging in water. Do not use a flame to test for
leaks. Use only standard ferrules or clamps to secure
hose to nipples.