Safety in Welding, Cutting, and Allied Processes

ANSI Z49.1:1999
The supply air line for respirators shall be a dedicated
line that is not capable of being valved to any other line
which could allow hazardous or toxic gases into the respirator
air line.
7.1.5 Prohibited Ventilation Gases. Oxygen, or any
other gas or mixtures of gases, except air, shall not be used
for ventilation.
7.1.6 Ventilation in Areas Immediately Dangerous
to Life or Health (IDLH). When welding, cutting, or related
processes are performed in areas immediately dangerous
to life or health, positive pressure, self-contained
breathing apparatus or combination airline respirators with
auxiliary air supply shall be used.
E7.1.5 Air may be natural air or synthesized air for
breathing purposes.
E7.l.6 See 7.5.1 for information on attendant
responsibilities.
7.2 Location of Service Equipment E7.2 The purpose of this provision is to prevent contamination
of the atmosphere of a confined space by possible
leaks from gas cylinders or fumes from welding power
sources or similar equipment and to minimize the possibility
of electric shock.
7.2.1 Compressed Gas Cylinders and Welding Power
Sources. When welding or cutting in confined spaces, gas
cylinders and welding power sources shall be located outside
the confined space.
7.2.2 Heavy Portable Equipment on Wheels. Heavy
portable equipment mounted on wheels shall be secured
in position to prevent accidental movement before operations
are started in a confined space.
7.2.3 Ventilation Ducts. Ducts used to provide local
exhaust ventilation for welding, cutting, or related operations
shall be constructed of noncombustible materials.
These ducts shall be inspected as necessary to insure proper
function and that the internal surfaces are free of combustible
residuals.
7.3 Adjacent Areas. When welding or cutting is to be
done over, or adjacent to, any confined space, personnel
shall be made aware of the hazards in the confined space
and shall not enter such spaces without first following the
precautions specified in ANSI Z117.1 and OSHA 29 CFR
1910.146.
7.4 Emergency Signal. When a person enters a confined
space through a manhole or other small opening, means
shall be provided for signaling outside personnel for help.
7.5 Attendants in Areas Immediately Dangerous to Life
or Health (IDLH). When operations are carried on in
confined spaces where atmospheres immediately dangerous
to life or health may be present or may develop,
attendants shall be stationed on the outside of the confined
space.
7.5.1 Attendants Responsibilities. Attendants shall
have a preplanned rescue procedure for quickly removing
or protecting those working inside in case of emergency,
E7.2.3 When welding or cutting activities occur near
ventilation ducts, or conveyor systems, care should be
taken to see that sparks and spatter are not carried to locations
with combustible or explosive material.
E7.5.1 Rescue operations should take into consideration
such elements as the number of workers requiring
rescue, the time available to perform the rescue given dif-
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