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Subchapter 18. Ship Building, Ship Repairing and Ship Breaking Safety Orders
Article 5. Scaffold Construction
(a)(1) Scaffolding shall be erected in bents, set not over 12 feet apart, center to center, parallel with the building ways. The bents shall consist of uprights adequately bolted together in pairs, with suitable sized spacers and set from 3 feet to 5 feet apart, center to center, transverse with the building ways.
(2) Uprights less than 30 feet in length shall be of not less than 3-inch by 6-inch lumber or stock of equivalent strength and rigidity. Uprights 30 feet or over in length shall be of not less than 3-inch by 8-inch lumber.
(3) Scaffolding shall be adequately braced both transversely and longitudinally. Bracing shall be of not less than 1-inch by 8-inch lumber or stock of equivalent strength and rigidity.
(4) The feet of the uprights shall be securely fastened to the dock or the flooring of the building ways by means of suitable connections.
(b) Spalls or needle beams shall be of not less than 3-inch by 8-inch lumber, and shall not overhang more than 5 feet unless additional support is provided.
(c) Spall pins shall be of not less than three-fourths-inch round steel, and shall project not less than 2 inches beyond the uprights at each end. The diameter of the holes for the spall pins when bored shall not exceed the diameter of the spall pins by more than one-sixteenth inch (1/16 ").
(d)(1) Staging shall be not less than two 10-inch structural planks in width except in such cases as the structure of the vessel or in the case of trestle ladder scaffolds, the width of the trestle ladders makes it impossible. In cases where material or equipment is on the staging or more than one employee is working, it shall be wide enough to provide a clear passageway where required at least 20 inches wide throughout the work area.
(2) Planks shall be laid edge to edge. Where due to warping the space between the planks exceeds 1-inch, the planks shall be rearranged to reduce such space or they will be withdrawn from staging use. The safe concentrated center loads for scaffold plank shown in the table below shall not be exceeded.
SAFE CONCENTRATED CENTER LOADS (Lbs.) FOR SCAFFOLD PLANK OF 1,900 PSI FIBER STRESS
LUMBER DIMENSIONS IN INCHES
SPAN IN FEET
2 x 10
1 1/2 x 9 ¼
2 x 12
1 1/2 x 11 ¼
3 x 8
2 1/2 x 7 ¼
3 x 10
2 1/2 x 9 ¼
3 x 12
2 1/2 x 11 ¼
(e) Staging shall not clear the hulls by a distance of more than 8 inches except at the bow and stern where the converging hull lines prohibit. In all cases, however, the space between hull and staging shall be held to a minimum.
(f) Staging shall be supported by at least 3 spalls whenever possible. Planks shall overlap the spalls by 2 feet or be secured to the spalls.
(g) Staging at the bow and stern shall be so arranged that the outboard plank of the lower platform shall extend under the inboard plank of the upper platform immediately above.
(h) Standard guardrails shall be installed on the open sides and ends of all staging 5 feet or more in elevation above the dock or building ways. Guardrails shall be attached securely to the scaffolding upright or horse. The guardrails shall be in the same vertical plane as the outside edge of the outboard staging planks and the toeboards, where required, shall be installed so that tools or material cannot make their way between them and the staging planks.
(i) Where staging passes over established aisles, runways, or passageways, toeboards shall be installed on the side of such staging farthest from the hull. Toeboards shall be of not less than 1-inch by 4-inch lumber or stock of equivalent strength and rigidity.
(j) Independent Wood Pole Scaffolds.
(1) Ribbons shall extend over three consecutive uprights and shall overlap the uprights at each end by not less than 4 inches. They shall be left in position to brace the uprights as the platform is raised with the progress of the work. Ribbons shall be level and shall be securely nailed or bolted to each upright and shall be placed against the inside face of each upright.
(2) Diagonal sway bracing not less than 1 x 6-inch lumber or equivalent, shall be provided between the parallel poles. Cross bracing shall be provided between the inner and outer poles or from the outer poles to the ground.