happens to be bent or badly worn, replace it with a new
A symptom of LEAKY VALVES is a continuous
flow of gases after the valves are closed. Leaky valves
are often caused by a dirty or damaged seat. To clean
the seat, remove the valve assembly and wipe the
seating portions of both the valve stem and the valve
body with a clean rag. If the leak continues, try closing
the valve tightly several times. When these measures
fail to stop the leak, you may have to replace parts, or
the valve body may have to be reseated. These repairs
should be made only by qualified personnel.
Leaks in the MIXING-HEAD SEAT of the torch
cause oxygen and MAPP-gas leaks between the inlet
orifices leading to the mixing head. This defect can
cause improper mixing of the gases and result in
flashbacks. This defect can be corrected by reaming
out the seat in the torch head and by truing the mixing-
head seat. You may have to send the equipment to the
manufacturer for these repairs, since special reamers
are required for truing seats.
With regulators, gas leakage between the
REGULATOR SEAT and NOZZLE is a common type
of trouble. This defect can be detected by a gradual rise
in pressure on the working-pressure gauge when the
adjusting screw is fully released or is in position after
adjustment. Frequently, this trouble, known as
CREEPING REGULATOR, is caused by worn or
cracked seats. It can also be brought on by foreign
matter lodged between the seat and the nozzle.
Regulators with leaks across the seats must be repaired
at once; otherwise, damage to other parts of the
regulator or apparatus may result. Leaks are
particularly dangerous in acetylene regulators because
acetylene, at very high pressure in the hose, becomes
an explosive hazard. To ensure the safety of personnel
and equipment, see that regulators with such leaks are
removed from service and turned in for repair.
Another important aspect of welding safety is
protecting your eyes and the vision of helpers,
chippers, or inspectors where someone is soldering or
silver brazing. Ensure you are aware of hazards, such
as stray flashes, reflected glare, flying sparks, and bits
of molten metal. Ensure that you are using the proper
eye protective lenses. If you are not sure, ask your crew
leader or project supervisor.
For hand protection, you may have to use either
gauntlet gloves or mitts. Some of the important safety
precautions in working with acetylene and oxygen
cylinders are provided below. Quite a number of
precautions apply to cylinders, so the following
precautions are NOT a complete listing.
Store all cylinders carefully under prescribed
storage procedures. Cylinders should be, stored in dry,
well-ventilated, well-protected places, away from
heat, and away from combustible materials: Do NOT
store oxygen cylinders in the same compartment where
acetylene or other fuel-gas cylinders are stored. All
cylinders should be stored upright, rather than
horizontally. If acetylene cylinders are not stored
upright (valves at top), they must not be used until they
have been allowed to stand upright for at least 12 hours
to prevent acetone discharge. This tendency to
discharge acetone depends largely upon the type of
porous filler; however, 12 hours is ample time,
regardless of the condition of the filler.
When the cylinder is empty, the letter E should be
written on the cylinder with a piece of soapstone, keel,
or crayon. Store empty cylinders separately from
charged ones. Storage spaces must have adequate
ventilation and must not be exposed to fire hazards,
extremes of weather, continuous dampness, or
accumulations of snow or ice.
The term galvanized means that wrought-iron and
steel pipe are protected to resist corrosion. Wrought-
iron and steel pipe are made in the same manner.
Wrought iron is about twice the cost of galvanized
steel, and it is used more for waste systems than for
water service. Almost all steel and wrought-iron pipe
are galvanized on the outside and on the inside at the
Black iron pipe (not galvanized) is cheaper than
galvanized pipe. Black iron pipe is suitable for heating
(both steam and hot water) and compressed air
systems. It is also used for gas and oil pipelines
exclusively. Black iron pipe is NOT suitable for use,
either in a water-supply system or a drainage system.
This is because black iron pipe rusts and causes
stoppages or leaks within a short time.
Galvanized wrought iron and steel pipes are cut,
measured, and threaded in the same manner. Both
types of pipe come in lengths from 18 to 22 feet. The
20-foot length is about average. These pipes are
classified into weights, such as standard, heavy, and
extra heavy and refer to the wall thickness of the pipe.
The wall thickness is a factor that bears directly on the
amount of pressure the pipe can withstand.