29 Cfr 1910.255

§ 1910.255

29 CFR Ch. XVII (7–1–05 Edition)

§ 1910.255 Resistance welding.
(a) General—(1) Installation. All equipment shall be installed by a qualified
electrician in conformance with subpart S of this part. There shall be a
safety-type disconnecting switch or a
circuit breaker or circuit interrupter
to open each power circuit to the machine, conveniently located at or near
the machine, so that the power can be
shut off when the machine or its controls are to be serviced.
(2) Thermal protection. Ignitron tubes
used in resistance welding equipment
shall be equipped with a thermal protection switch.
(3) Personnel. Workmen designated to
operate resistance welding equipment
shall have been properly instructed and
judged competent to operate such
equipment.
(4) Guarding. Controls of all automatic or air and hydraulic clamps shall
be arranged or guarded to prevent the
operator from accidentally activating
them.
(b) Spot and seam welding machines
(nonportable)—(1) Voltage. All external
weld initiating control circuits shall
operate on low voltage, not over 120
volts, for the safety of the operators.
(2) Capacitor welding. Stored energy
or capacitor discharge type of resistance welding equipment and control
panels involving high voltage (over 550
volts) shall be suitably insulated and
protected by complete enclosures, all
doors of which shall be provided with
suitable interlocks and contacts wired
into the control circuit (similar to elevator interlocks). Such interlocks or
contacts shall be so designed as to effectively interrupt power and short circuit all capacitors when the door or
panel is open. A manually operated
switch or suitable positive device shall
be installed, in addition to the mechanical interlocks or contacts, as an added
safety measure assuring absolute discharge of all capacitors.
(3) Interlocks. All doors and access
panels of all resistance welding machines and control panels shall be kept
locked and interlocked to prevent access, by unauthorized persons, to live
portions of the equipment.
(4) Guarding. All press welding machine operations, where there is a possibility of the operator’s fingers being

under the point of operation, shall be
effectively guarded by the use of a device such as an electronic eye safety
circuit, two hand controls or protection similar to that prescribed for
punch press operation, § 1910.217 of this
part. All chains, gears, operating bus
linkage, and belts shall be protected by
adequate guards, in accordance with
§ 1910.219 of this part.
(5) Shields. The hazard of flying
sparks shall be, wherever practical,
eliminated by installing a shield guard
of safety glass or suitable fire-resistant
plastic at the point of operation. Additional shields or curtains shall be installed as necessary to protect passing
persons from flying sparks. (See
§ 1910.252(b)(2)(i)(C) of this part.)
(6) Foot switches. All foot switches
shall be guarded to prevent accidental
operation of the machine.
(7) Stop buttons. Two or more safety
emergency stop buttons shall be provided on all special multispot welding
machines, including 2-post and 4-post
weld presses.
(8) Safety pins. On large machines,
four safety pins with plugs and receptacles (one in each corner) shall be provided so that when safety pins are removed and inserted in the ram or platen, the press becomes inoperative.
(9) Grounding. Where technically
practical, the secondary of all welding
transformers used in multispot, projection and seam welding machines shall
be grounded. This may be done by permanently grounding one side of the
welding secondary current circuit.
Where not technically practical, a center tapped grounding reactor connected
across the secondary or the use of a
safety disconnect switch in conjunction with the welding control are acceptable alternates. Safety disconnect
shall be arranged to open both sides of
the line when welding current is not
present.
(c) Portable welding machines—(1)
Counterbalance. All portable welding
guns
shall
have
suitable
counterbalanced devices for supporting
the guns, including cables, unless the
design of the gun or fixture makes
counterbalancing impractical or unnecessary.

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Occupational Safety and Health Admin., Labor
(2) Safety chains. All portable welding
guns, transformers and related equipment that is suspended from overhead
structures, eye beams, trolleys, etc.,
shall be equipped with safety chains or
cables. Safety chains or cables shall be
capable of supporting the total shock
load in the event of failure of any component of the supporting system.
(3) Clevis. Each clevis shall be capable
of supporting the total shock load of
the suspended equipment in the event
of trolley failure.
(4) Switch guards. All initiating
switches, including retraction and dual
schedule switches, located on the portable welding gun shall be equipped with
suitable guards capable of preventing
accidental initiation through contact
with fixturing, operator’s clothing, etc.
Initiating switch voltage shall not exceed 24 volts.
(5) Moving holder. The movable holder, where it enters the gun frame, shall
have sufficient clearance to prevent
the shearing of fingers carelessly
placed on the operating movable holder.
(6) Grounding. The secondary and
case of all portable welding transformers shall be grounded. Secondary
grounding may be by center tapped secondary or by a center tapped grounding
reactor connected across the secondary.
(d) Flash welding equipment—(1) Ventilation and flash guard. Flash welding
machines shall be equipped with a hood
to control flying flash. In cases of high
production, where materials may contain a film of oil and where toxic elements and metal fumes are given off,
ventilation shall be provided in accordance with § 1910.252(c) of this part.
(2) Fire curtains. For the protection of
the operators of nearby equipment,
fire-resistant curtains or suitable
shields shall be set up around the machine and in such a manner that the
operators movements are not hampered.
(e) Maintenance. Periodic inspection
shall be made by qualified maintenance
personnel, and a certification record
maintained. The certification record
shall include the date of inspection, the
signature of the person who performed
the inspection and the serial number,
or other identifier, for the equipment

§ 1910.261

inspected. The operator shall be instructed to report any equipment defects to his supervisor and the use of
the equipment shall be discontinued
until safety repairs have been completed.

Subpart R—Special Industries
AUTHORITY: Sections 4, 6, and 8 of the Occupational Safety and Health Act of 1970, 29
U.S.C. 653, 655, and 657; Secretary of Labor’s
Order No. 12–71 (36 FR 8754), 8–76 (41 FR
25059), 9–83 (48 FR 35736), 1–90 (55 FR 9033), 6–
96 (62 FR 111), or 3–2000 (65 FR 50017), as applicable, and 29 CFR part 1911.

§ 1910.261 Pulp,
board mills.

paper,

and

(a) General requirements—(1) Application. This section applies to establishments where pulp, paper, and paperboard are manufactured and converted.
This section does not apply to logging
and the transportation of logs to pulp,
paper, and paperboard mills.
(2) Standards incorporated by reference.
Standards covering issues of occupational safety and health which have
general application without regard to
any specific industry are incorporated
by reference in paragraphs (b) through
(m) of this section and in subparagraphs (3) and (4) of this paragraph and
made applicable under this section.
Such standards shall be construed according to the rules set forth in § 1910.5.
(3) General incorporation of standards.
Establishments subject to this section
shall comply with the following standards of the American National Standards Institute, which are incorporated
by reference as specified in § 1910.6:
(i) Practice for Industrial Lighting,
A11.1—1965 (R–1970).
(ii) Scheme for the Identification of
Piping Systems, A13.1—1956.
(iii) Safety Code for Elevators,
Dumbwaiters, and Moving Walks,
A17.1—1965,
including
Supplements
A17.1a—1967, A17.1b—1968, A17.1c—1969,
and A17.1d—1970.
(iv) Practice for the Inspection of
Elevators (Inspector’s Manual), A17.2—
1960, including Suppelements A17.2a—
1965 and A17.2b—1967.
(v) Safety Code for Conveyors,
Cableways, and Related Equipment,
B20.1—1957.

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