Specifications

7
confined space only while it is being ventilated and, if necessary, while
wearing an air-supplied respirator. Vapours from chlorinated solvents can be
decomposed by the heat of the arc (or flame) to form PHOSGENE, a highly
toxic gas, and other lung and eye irritating products. The ultraviolet (radiant)
energy of the arc can also decompose trichloroethylene and
perchloroethylene vapours to form phosgene. DO NOT WELD or cut where
solvent vapours can be drawn into the welding or cutting atmosphere or
where the radiant energy can penetrate to atmospheres containing even
minute amounts of trichloroethylene or perchloroethylene.
C) FIRE AND EXPLOSION PREVENTION
Causes of fire and explosion are:
1. combustibles reached by the arc, flame, flying sparks, hot slag or heated
material;
2. misuse of compressed gases and cylinders;
3. short circuits.
BE AWARE THAT flying sparks or falling slag can pass through cracks, along
pipes, through windows or doors, and through wall or floor openings, out of
sight of the goggled operator. Sparks and slag can fly 10m.
To prevent fires and explosion: keep equipment clean and operable, free of
oil, grease, and (in electrical parts) of metallic particles that can cause short
circuits. If combustibles are in area, do NOT weld or cut. Move the work if
practicable, to an area free of combustibles.
Avoid paint spray rooms, dip tanks, storage areas, ventilators. If the work
cannot be moved, move combustibles at least 10m. away out of reach of
sparks and heat; or protect against ignition with suitable and snug fitting, fire-
resistant covers or shields.
Walls touching combustibles on opposite sides should not be welded on (or
cut).
Walls, ceilings, and floor near work should be protected by heat resistant
covers or shields. Fire watcher must be standing by with suitable fire
extinguishing equipment during and for some time after welding or cutting if:
a. appreciable combustibles (including building construction) are within 10m.
b. appreciable combustibles are further than 10m but can be ignited by
sparks.
c. openings (concealed or visible) in floors or walls within 10m can expose
combustibles to sparks.
d. combustibles adjacent to walls, ceilings, roofs or metal partitions can be
ignited by radiant or conducted heat.
After work is done, check that area is free of sparks, glowing embers, and
flames. An empty container that held combustibles, or that can produce