-- When lighting the torch, open the acetylene
-- Do not place anything on top of an acetylene
valve first and ignite the gas before introducing
cylinder that may interfere with the quick
oxygen to the flame.
closing of the cylinder valve.
-- Never allow unburned acetylene to escape into
-- Always use regulators to reduce compressed
small or closed spaces.
gases to a suitable working pressure.
-- Report any safety discrepancy or unsafe act to
-- Copper tubing should not be used with acetylene
your immediate supervisor.
gas because of the potential of an explosive
chemical reaction.
4. BACKFIRE AND FLASHBACK: Unless the
system is thoroughly purged of air and all connections
3. OPERATIONS: The improper operation of
in the system are tight before the torch is ignited, the
oxyacetylene equipment is the major cause of accidents.
flame is likely to bum inside the torch instead of outside
Follow these basic safety precautions when operating
the tip. The difference between the two terms backfire
oxyacetylene equipment:
and flashback is this: in a backfire, there is a momentary
-- Check all gas connections for leakage.
burning back of the flame into the torch tip; in a
flashback, the flame bums in or beyond the torch mixing
-- Do not use defective or damaged equipment.
chamber. A backfire is characterized by a loud snap or
-- Never use petroleum-based products (oil or
pop as the flame goes out. A flashback is usually
grease) to lubricate oxyacetylene equipment.
accompanied by a hissing or squealing sound. At the
Oil or grease in the presence of oxygen under
same time, the flame at the tip becomes smoky and sharp
pressure will ignite violently.
pointed. When a flashback occurs, immediately shut off
the torch oxygen valve, then close the acetylene valve.
NOTE: Glycerin is a suitable lubricant for
By closing the oxygen valve, the flashback is stopped at
oxyacetylene equipment.
once. The occurrence of a flashback indicates that
-- Do not use vice grips, adjustable wrenches,
something is radically wrong either with the torch or
pliers, or other similar tools to tighten
with the manner of handling it. A backfire is less serious.
connections or to open gas cylinder valves. You
Usually the flame can be relighted without difficulty. If
will only damage the connections rendering
backfiring continues whenever the torch is relighted,
check for these causes: overheated tip, gas working
them unusable in an emergency.
pressures greater than that recommended for the tip size
-- Always leave the apparatus wrench on the
being used, loose tip, or dirt on the torch tip seat. These
acetylene cylinder valve so the cylinder can be
same difficulties may be the cause of a flashback, except
secured quickly in an emergency.
that the difficulty is present to a greater degree. For
example, the torch head may be distorted or cracked.
-- Never open an acetylene cylinder valve more
than 1/4 to 1/2 of a turn.
In most instances, backfires and flashbacks result
from carelessness. These difficulties can be avoided
-- Fully back out the adjusting screw on a regulator
by making certain that (1) all connections in the system
and stand to one side when pressurizing a
are clean and tight; (2) torch valves are closed (not
compressed gas system. Regulators have been
open or merely loosely closed) when the equipment is
known to explode if pressurized improperly.
stowed; (3) the oxygen and acetylene working
pressures used are those recommended for the torch
-- Never run oxyacetylene hoses on the deck. The
employed; and (4) the system is purged of air before
hoses should always be run in the overhead.
the apparatus is used. Purging the system of air is
When running hoses through hatches, doors, or
especially necessary when the hose and torch have
scuttles, locate the connection near the access
been newly connected or a new cylinder is
and block open the door to prevent the hose from
incorporated into the system. Purging a system is
being cut.
accomplished as follows: Close torch valves tightly,
-- Never use matches, lighters, or any open flame
then slowly open the cylinder valves. Next, open the
to light your torch; use a friction lighter only.
regulator slightly. Open the torch acetylene valve and
Butane lighters have been known to explode if
allow acetylene to escape for 5 to 15 seconds,
exposed to excessive heat or if the casing melts.
depending on the length of the hose. Close the
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