(B) Definitions.
(1) "Fire-resistive construction" means a
method of construction which prevents or retards the passage of hot gases or
flames, as defined by the fire-resistance
rating.
(2) "Fire-resistance
rating" means the measured time in hours, or
fractions thereof, that the material or
construction will withstand fire exposure, as determined by fire tests
conducted in conformity to recognized standards.
(C) Responsibility.
(1) The employer shall verbally, and through demonstration, instruct the employee in the safe operation and
maintenance of cutting and welding equipment.
(2)
It
Employees shall
be
have the
duty of the employee to operate such
equipment in accordance with such
instructions provided by the employer in paragraph (C)
(1) of this rule.
(E) Gas welding and cutting.
(1) Equipment.
Only approved equipment, such as torches, regulators, or
pressure-reducing valves, acetylene generators, manifolds, cylinders, and
containers shall be used.
(2) Cylinders and containers.
(a) Marking.
Compressed gas cylinders shall be legibly marked, for the
purpose of identifying the content, with either the chemical or the trade name
of the gas. Such marking shall be by means of stenciling, stamping, or
labeling, and shall not be readily
removed.
(b) Storage.
(i) Oxygen cylinders in storage shall be
separated from fuel-gas cylinders or combustible materials
(
, especially
oil or grease), a minimum distance of
twenty feet (6.1 meters) or by a noncombustible
barrier no less than five feet (1.5 meters) high,
having a fire-resistance rating of no less than one-half hour.
(ii) Cylinders, when not in use, shall be
protected from any heat-radiating objects or open flame which could cause the
cylinder to rupture or could cause the
fusible plug to melt.
(c) Valve protection caps.
(i) All cylinders with a water weight
capacity of over thirty pounds (13.6 kilograms)
shall be equipped with means of connecting a valve protection cap or with a
collar or recess to protect the valve.
(ii) Employees shall be responsible for using
valve protection caps when cylinders are moved from place to place or put in
storage.
(iii) Where carriers are
provided for moving cylinders which are connected for use, capping shall not be
required, but employees shall be responsible for
seeing that cylinder valves are closed, and
pressure is released from regulators, hoses, and torches.
(d) Regulator protection.
Welders and cutters shall be instructed to close valves on
oxygen and acetylene cylinders and bleed off hose pressure at the end of each
workshift
work
shift, to prevent malfunction of the regulators.
(e) Transporting cylinders by crane or
derrick.
When cylinders are hoisted, they shall be secured on a cradle,
slingboard, or pallet. They
Cylinders shall
not be hoisted or transported by means of magnets or choker slings.
(f)
Facilities
Employer
responsible to provide facilities for securely fastening cylinders
; responsibility.
The employer shall provide facilities for securely fastening
cylinders of compressed gas in an upright position.
(3) Hose and hose connections.
(a) Hose.
(i) Identification.
The color red shall be used for acetylene and other fuel-gas
hose. The color green shall be used for oxygen hose. The color black shall be
used for inert-gas hose and air hose.
(ii) Hose in which flashback has
occurred.
Any length of hose in which a flashback has occurred and burned
in the hose shall be taken out of service.
(iii) Single hose with more than one gas
passage.
The use of a single hose having more than one gas passage, in
which a wall failure would permit the flow of one gas into the other gas
passage, is prohibited.
(iv) Hoses taped together
,
- limitation.
When parallel lengths of oxygen and acetylene hoses are taped
together for convenience and to prevent tangling, no more than four inches
(10.2 centimeters) out of twelve inches
(30.5 centimeters) shall be covered by
tape.
(v) Damaged or
defective hose.
Hose showing leaks, burns, worn places, or other defects
rendering it unfit for service shall have the damaged portion removed.
(b) Hose connections
and couplings.
(i) Hose connections for oxygen
and fuel-gas shall be distinguished from each other. Hose connections shall be
clamped or otherwise securely fastened in a manner that will withstand, without
leakage, twice the pressure to which they are normally subjected in service,
but in no case less than three hundred pounds per square inch
(2068.4 kilopascal).
(ii) Hose couplings shall be of the type that
cannot be unlocked or disconnected by means of a straight pull without rotary
motion.
(c) Pressure
reducing regulators.
Oxygen and fuel-gas pressure regulators, including their
related gauges, shall be in proper working order while in use.
(F) Arc
welding and cutting.
(1) Manual electrode
holders.
(a) Only manual electrode holders
which are specifically designed for arc welding and cutting, and are of a
capacity capable of safely handling the maximum rated current required by the
electrodes, shall be used.
(b) Any
current-carrying parts passing through the portion of the holder which the arc
welder or cutter grips in his
by hand, and the outer surfaces of the jaws of the
holder, shall be fully insulated against the maximum voltage encountered to
ground.
(2) Welding
cables and connectors.
(a) All arc welding and
cutting cables shall be of the completely insulated, flexible type,
and be capable of handling the maximum current
requirements of the work in progress, taking into
account
considering the duty cycle under
which the arc welding or cutting unit is working.
(b) Cables with splices within ten feet
(three meters) of the holder shall not be
used, except that cables with standard insulated
connectors, or with splices whose insulating
quality is equal to that of the cables, are
permitted.
(c) When
it becomes necessary to connect or splice
lengths of cable one to another, substantial insulated connectors of a capacity
at least equivalent to that of the cable shall be used. If connections are
effected by means of cable lugs, they
the connections shall be securely fastened
together to give good electrical contact, and the exposed metal parts of the
lugs shall be completely insulated.
(d) Cables in need of repair shall not be
used.
(3) Ground returns
and machine grounding.
(a) A ground return
cable shall have a safe current-carrying capacity equal to or exceeding the
specified maximum output capacity of the arc welding or cutting unit which
it
the ground
return cable services. When a single ground return cable services more
than one unit, the safe current-carrying capacity shall equal or exceed the
total specified maximum output capacities of all the units which
it
the ground
return cable services.
(b)
Pipelines containing gases or flammable liquids,
or conduits containing electrical circuits, shall not be used as a ground
return.
(c) When a structure or
pipeline is employed as a ground return circuit, it
shall be determined that the required electrical contact
exists
has to
exist at all joints. The generation of an arc, sparks, or heat at any
point shall cause rejection of the structures
structure or
pipeline as a ground circuit.
(d) When a structure or pipeline is
continuously employed as a ground return circuit, all joints shall be bonded,
and periodic inspections shall be conducted to ensure that no condition of
electrolysis or fire hazard exists by virtue of such use.
(e) The frames of all arc welding and cutting
machines shall be grounded either through a third wire in the cable containing
the circuit conductor or through a separate wire which is grounded at the
source of the current. Grounding circuits, other than by means of the
structure, shall be checked to ensure that the circuit between the ground and
the grounded power conductor has resistance low enough to permit sufficient
current to flow to cause the fuse or circuit breaker to interrupt the
current.
(f) All ground connections
shall be inspected to ensure that they
the ground connections are mechanically secure
and electrically adequate for the required current.
(4) Operating instructions.
Employers shall instruct employees in the safe means of arc
welding and cutting as follows:
(a)
When electrode holders are to be left unattended, the electrodes shall be
removed, and the holders shall be so placed or
protected that they
the holders cannot make electrical contact with
employees or conducting objects.
(b) Hot electrode holders shall not be dipped
in water.
(c) When the arc welder
or cutter has occasion to leave
leaves or stops work or to stop work for any appreciable length of time,
or when the arc welding or cutting unit is to be moved, the power supply switch
to the equipment shall be opened.
(5) Shielding.
Arc welding and cutting operations shall be shielded by
noncombustible or flameproof screens which will protect employees working in
the vicinity from the direct rays of the arc.
(6) Overcurrent protection.
All welding machines shall be protected by an overcurrent
device.
(7) Disconnecting
means.
(a) A disconnecting means shall be
provided in the supply for each alternating-current transformer and
direct-current rectifier arc welder which is not equipped with a disconnect
mounted as an integral part of the welder.
(b) The disconnecting means shall be a switch
or circuit breaker, and its rating shall be no less than that necessary to
accommodate overcurrent protection.
(G) Welding or cutting of containers.
No welding, cutting, or work utilizing a torch shall be
performed on used drums, barrels, tanks, or other containers until they have
been cleaned and purged of materials which, when
subjected to heat, might produce flammable or
toxic vapors.
(I)
Protection from sparks or falling objects.
(1)
Cutting or welding shall be permitted only in areas that are, or have been made,
fire safe.
(2) Screens or shields
shall be provided for the protection of employees or combustible materials
exposed to falling objects or sparks.
