1915.71—Scaffolds or staging.
(a) Scope and application.
The provisions of this section shall apply to all ship repairing, shipbuilding and shipbreaking operations except that paragraphs (b)(8) through (b)(10) and paragraphs (c) through (f) of this section shall only apply to ship repairing and shipbuilding operations and shall not apply to shipbreaking.
(b) General requirements.
(1)
All scaffolds and their supports whether of lumber, steel or other material, shall be capable of supporting the load they are designed to carry with a safety factor of not less than four (4).
(2)
All lumber used in the construction of scaffolds shall be spruce, fir, long leaf yellow pine, Oregon pine or wood of equal strength. The use of hemlock, short leaf yellow pine, or short fiber lumber is prohibited.
(3)
Lumber dimensions as given in this subpart are nominal except where given in fractions of an inch.
(4)
All lumber used in the construction of scaffolds shall be sound, straight-grained, free from cross grain, shakes and large, loose or dead knots. It shall also be free from dry rot, large checks, worm holes or other defects which impair its strength or durability.
(5)
Scaffolds shall be maintained in a safe and secure condition. Any component of the scaffold which is broken, burned or otherwise defective shall be replaced.
(6)
Barrels, boxes, cans, loose bricks, or other unstable objects shall not be used as working platforms or for the support of planking intended as scaffolds or working platforms.
(7)
No scaffold shall be erected, moved, dismantled or altered except under the supervision of competent persons.
(8)
No welding, burning, riveting or open flame work shall be performed on any staging suspended by means of fiber rope.
(9)
Lifting bridles on working platforms suspended from cranes shall consist of four legs so attached that the stability of the platform is assured.
(10)
Unless the crane hook has a safety latch or is moused, the lifting bridles on working platforms suspended from cranes shall be attached by shackles to the lower lifting block or other positive means shall be taken to prevent them from becoming accidentally disengaged from the crane hook.
(c) Independent pole wood scaffolds.
(1)
All pole uprights shall be set plump. Poles shall rest on a foundation of sufficient size and strength to distribute the loan and to prevent displacement.
(2)
In light-duty scaffolds, not more than 24 feet in height, poles may be spliced by overlapping the ends not less than 4 feet and securely nailing them together. A substantial cleat shall be nailed to the lower section to form a support for the upper section except when bolted connections are used.
(3)
All other poles to be spliced shall be squared at the ends of each splice, abutted, and rigidly fastened together by not less than two cleats securely nailed or bolted thereto. Each cleat shall overlap each pole end by at least 24 inches and shall have a width equal to the face of the pole to which it is attached. The combined cross sectional area of the cleats shall be not less than the cross sectional area of the pole.
(4)
Ledgers shall extend over two consecutive pole spaces and shall overlap the poles at each end by not less than 4 inches. They shall be left in position to brace the poles as the platform is raised with the progress of the work. Ledgers shall be level and shall be securely nailed or bolted to each pole and shall be placed against the inside face of each pole.
(5)
All bearers shall be set with their greater dimension vertical and shall extend beyond the ledgers upon which they rest.
(6)
Diagonal bracing shall be provided between the parallel poles, and cross bracing shall be provided between the inner and outer poles or from the outer poles to the ground.
(8)
Platform planking shall be in accordance with the requirements of paragraph (i) of this section.
(9)
Backrails and toeboards shall be in accordance with the requirements of paragraph (j) of this section.
(d) Independent pole metal scaffolds.
(1)
Metal scaffold members shall be maintained in good repair and free of corrosion.
(2)
All vertical and horizontal members shall be fastened together with a coupler or locking device which will form a positive connection. The locking device shall be of a type which has no loose parts.
(3)
Posts shall be kept plumb during erection and the scaffold shall be subsequently kept plumb and rigid by means of adequate bracing.
(4)
Posts shall be fitted with bases supported on a firm foundation to distribute the load. When wooden sills are used, the bases shall be fastened thereto.
(5)
Bearers shall be located at each set of posts, at each level, and at each intermediate level where working platforms are installed.
(7)
Platform planking shall be in accordance with the requirements of paragraph (h) of this section.
(8)
Backrails and toeboards shall be in accordance with the requirements of paragraph (j) of this section.
(e) Wood trestle and extension trestle ladders.
(1)
The use of trestle ladders, or extension sections or base sections of extension trestle ladders longer than 20 feet is prohibited. The total height of base and extension may, however, be more than 20 feet.
(2)
The minimum dimensions of the side rails of the trestle ladder, or the base sections of the extension trestle ladder, shall be as follows:
(i)
Ladders up to and including those 16 feet long shall have side rails of not less than 1 5/16 ×2 3/4 inch lumber.
(ii)
Ladders over 16 feet long and up to and including those 20 feet long shall have side rails of not less than 1 5/16 × 3 inch lumber.
(3)
The side rails of the extension section of the extension trestle ladder shall be parallel and shall have minimum dimensions as follows:
(i)
Ladders up to and including 12 feet long shall have side rails of not less than 1 5/16 ×2 1/4 inch lumber.
(ii)
Ladders over 12 feet long and up to and including those 16 feet long shall have side rails of not less than 1 5/16 ×2 1/2 inch lumber.
(iii)
Ladders over 16 feet long and up to and including those 20 feet long shall have side rails of not less than 1 5/16 ×2 3/4 inch lumber.
(4)
Trestle ladders and base sections of extension trestle ladders shall be so spread that when in an open position the spread of the trestle at the bottom, inside to inside, shall be not less than 5 1/2 inches per foot of the length of the ladder.
(5)
The width between the side rails at the bottom of the trestle ladder or of the base section of the extension trestle ladder shall be not less than 21 inches for all ladders and sections 6 feet or less in length. For longer lengths of ladder, the width shall be increased at least 1 inch for each additional foot of length. The width between the side rails of the extension section of the trestle ladder shall be not less than 12 inches.
(6)
In order to limit spreading, the top ends of the side rails of both the trestle ladder and of the base section of the extension trestle ladder shall be beveled, or of equivalent construction, and shall be provided with a metal hinge.
(7)
A metal spreader or locking device to hold the front and back sections in an open position, and to hold the extension section securely in the elevated position, shall be a component of each trestle ladder or extension ladder.
(8)
Rungs shall be parallel and level. On the trestle ladder, or on the base section of the extension trestle ladder, rungs shall be spaced not less than 8 inches nor more than 18 inches apart; on the extension section of the extension trestle ladder, rungs shall be spaced not less than 6 inches nor more than 12 inches apart.
(9)
Platform planking shall be in accordance with the requirements of paragraph (i) of this section, except that the width of the platform planking shall not exceed the distance between the side rails.
(10)
Backrails and toeboards shall be in accordance with the requirements of paragraph (j) of this section.
(f) Painters' suspended scaffolds.
(1)
The supporting hooks of swinging scaffolds shall be constructed to be equivalent in strength to mild steel or wrought iron, shall be forged with care, shall be not less than 7/8 inch in diameter, and shall be secured to a safe anchorage at all times.
(2)
The ropes supporting a swinging scaffold shall be equivalent in strength to first-grade 3/4 inch diameter manila rope properly rigged into a set of standard 6 inch blocks consisting of at least one double and one single block.
(3)
Manila and wire ropes shall be carefully examined before each operation and thereafter as frequently as may be necessary to ensure their safe condition.
(4)
Each end of the scaffold platform shall be supported by a wrought iron or mild steel stirrup or hanger, which in turn is supported by the suspension ropes.
(5)
Stirrups shall be constructed so as to be equivalent in strength to wrought iron 3/4 inch in diameter.
(6)
The stirrups shall be formed with a horizontal bottom member to support the platform, shall be provided with means to support the guardrail and midrail and shall have a loop or eye at the top for securing the supporting hook on the block.
(7)
Two or more swinging scaffolds shall not at any time be combined into one by bridging the distance between them with planks or any other form of platform.
(8)
No more than two persons shall be permitted to work at one time on a swinging scaffold built to the minimum specifications contained in this paragraph. Where heavier construction is used, the number of persons permitted to work on the scaffold shall be determined by the size and the safe working load of the scaffold.
(9)
Backrails and toeboards shall be in accordance with the requirements of paragraph (j) of this section.
(10)
The swinging scaffold platform shall be one of the three types described in paragraphs (f)(11), (12), and (13) of this section.
(11)
The ladder-type platform consists of boards upon a horizontal ladder-like structure, referred to herein as the ladder, the side rails of which are parallel. If this type of platform is used the following requirements shall be met.
(ii)
The side rails of ladders in ladder-type platforms shall be equivalent in strength to a beam of clear straight-grained spruce of the dimensions contained in Table E-2 in § 1915.118.
(iii)
The side rails shall be tied together with tie rods. The tie rods shall be not less than 5/16 inch in diameter, located no more than 5 feet apart, pass through the rails, and be riveted up tight against washers at both ends.
(iv)
The rungs shall be of straight-grained oak, ash, or hickory, not less than 1 1/8 inches diameter, with 7/8 inch tenons mortised into the side rails not less than 7/8 inch and shall be spaced no more than 18 inches on centers.
(v)
Flooring strips shall be spaced no more than 5/8 inch apart except at the side rails, where 1 inch spacing is permissible.
(12)
The plank-type platform consists of planks supported on the stirrups or hangers. If this type of platform is used, the following requirements shall be met:
(iii)
The planks shall be tied together by cleats of not less than 1×6 inch lumber, nailed on their undersides at intervals of not more than 4 feet.
(iv)
The planks shall extend not less than 6 inches nor more than 18 inches beyond the supporting stirrups.
(v)
A cleat shall be nailed across the platform on the underside at each end outside the stirrup to prevent the platform from slipping off the stirrup.
(13)
The beam-type platform consists of longitudinal side stringers with cross beams set on edge and spaced not more than 4 feet apart on which longitudinal platform planks are laid. If this type platform is used, the following requirements shall be met:
(i)
The side stringers shall be of sound, straight-grained lumber, free from knots, and of not less than 2×6 inch lumber, set on edge.
(ii)
The stringers shall be supported on the stirrups with a clear span between stirrups of not more than 16 feet.
(iii)
The stringers shall be bolted to the stirrups by U-bolts passing around the stirrups and bolted through the stringers with nuts drawn up tight on the inside face.
(iv)
The ends of the stringers shall extend beyond the stirrups not less than 6 inches nor more than 12 inches at each end of the platform.
(v)
The platform shall be supported on cross beams of 2×6 inch lumber between the side stringers securely nailed thereto and spaced not more than 4 feet on centers.
(vii)
The platform shall be formed of boards 7/8 inch in thickness by not less than 6 inches in width, nailed tightly together, and extending to the outside face of the stringers.
(viii)
The ends of all platform boards shall rest on the top of the cross beams, shall be securely nailed, and at no intermediate points in the length of the platform shall there be any cantilever ends.
(g) Horse scaffolds.
(1)
The minimum dimensions of lumber used in the construction of horses shall be in accordance with Table E-3 in § 1915.118.
(2)
Horses constructed of materials other than lumber shall provide the strength, rigidity and security required of horses constructed of lumber.
(3)
The lateral spread of the legs shall be equal to not less than one-third of the height of the horse.
(4)
All horses shall be kept in good repair, and shall be properly secured when used in staging or in locations where they may be insecure.
(5)
Platform planking shall be in accordance with the requirements of paragraph (i) of this section.
(h) Other types of scaffolds.
(1)
Scaffolds of a type for which specifications are not contained in this section shall meet the general requirements of paragraphs (b), (i), and (j) of this section, shall be in accordance with recognized principles of design and shall be constructed in accordance with accepted standards covering such equipment.
(i) Scaffold or platform planking.
(1)
Except as otherwise provided in paragraphs (f)(11) and (13) of this section, platform planking shall be of not less than 2×10 inch lumber. Platform planking shall be straight-grained and free from large or loose knots and may be either rough or dressed.
(2)
Platforms of staging shall be not less than two 10 inch planks in width except in such cases as the structure of the vessel or the width of the trestle ladders make it impossible to provide such a width.
(3)
Platform planking shall project beyond the supporting members at either end by at least 6 inches but in no case shall project more than 12 inches unless the planks are fastened to the supporting members.
(j) Backrails and toeboards.
(1)
Scaffolding, staging, runways, or working platforms which are supported or suspended more than 5 feet above a solid surface, or at any distance above the water, shall be provided with a railing which has a top rail whose upper surface is from 42 to 45 inches above the upper surface of the staging, platform, or runway and a midrail located halfway between the upper rail and the staging, platform, or runway.
(2)
Rails shall be of 2×4 inch lumber, flat bar or pipe. When used with rigid supports, taut wire or fiber rope of adequate strength may be used. If the distance between supports is more than 8 feet, rails shall be equivalent in strength to 2×4 inch lumber. Rails shall be firmly secured. Where exposed to hot work or chemicals, fiber rope rails shall not be used.
(3)
Rails may be omitted where the structure of the vessel prevents their use. When rails are omitted, employees working more than 5 feet above solid surfaces shall be protected by safety belts and life lines meeting the requirements of §§ 1915.159 and 1915.160, and employees working over water shall be protected by buoyant work vests meeting the requirements of § 1915.158(a).
(4)
Employees working from swinging scaffolds which are triced out of a vertical line below their supports or from scaffolds on paint floats subject to surging, shall be protected against falling toward the vessel by a railing or a safety belt and line attached to the backrail.
(5)
When necessary, to prevent tools and materials from falling on men below, toeboards of not less than 1×4 inch lumber shall be provided.
(k) Access to staging.
(1)
Access from below to staging more than 5 feet above a floor, deck or the ground shall consist of well secured stairways, cleated ramps, fixed or portable ladders meeting the applicable requirements of § 1915.72 or rigid type non-collapsible trestles with parallel and level rungs.
(3)
Ladders shall be so located or other means shall be taken so that it is not necessary for employees to step more than one foot from the ladder to any intermediate landing or platform.
(4)
Ladders forming integral parts of prefabricated staging are deemed to meet the requirements of these regulations.
(5)
Access from above to staging more than 3 feet below the point of access shall consist of a straight, portable ladder meeting the applicable requirements of § 1915.72 or a Jacob's ladder properly secured, meeting the requirements of § 1915.74(d).