4-2.3
Fire and Explosion Prevention.
a.
Causes of fire and explosion are: combustibles reached by the arc, flame, flying sparks, hot slag or
heated material; misuse of compressed gases and cylinders; and short circuits.
b.
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
35 feet.
c.
Keep equipment clean and operable, free of oil, grease, and (in electrical parts) of metallic particles that
can cause short circuits.
d.
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 35 feet away out of reach of sparks and heat; or protect against
ignition with suitable and snug-fitting, fire-resistant covers or shields.
e.
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.
f.
Fire watcher must be standing by with suitable fire extinguishing equipment during and for some time
after welding or cutting if:
(1)
Appreciable combustibles (including building construction) are within 35 feet.
(2)
Appreciable combustibles are further than 35 feet but can be ignited by sparks.
(3)
Openings (concealed or visible) in floors or walls within 35 feet may expose combustibles to
sparks.
(4)
Combustibles adjacent to walls, ceilings, roofs, or metal partitions can be ignited by radiant or
conducted heat.
g.
Hot work permit should be obtained before operation to ensure supervisor's approval that adequate
precautions have been taken.
h.
After work is done, check that area is free of sparks, glowing embers, and flames.
i.
An empty container that held combustibles, or that can produce flammable or toxic vapors when heated,
must never be welded on or cut, unless container has first been cleaned as described in AWS Standard
A6.0, listed 3 in Standards index (para. 4-4).
4-3
