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1917.121(a) Definition. "Spiral stairway" means one with closed circular form, uniform sector-shaped treads and a
supporting column.
1917.121(b) Requirements. Spiral stairways shall meet the following requirements:
1917.121(b)(1) Stairways shall conform to the minimum dimensions of Figure F-1;
| Spiral Stairway -- Minimum Dimensions |
| |
A (half-tread width) |
B |
| Normal use by employees |
11 inches (27.94 cm) |
6 inches (15.24 cm) |
| Limited access |
9 inches (22.86 cm) |
5 inches (12.7 cm) |
1917.121(b)(2) Stairway risers shall be uniform and shall range from 6½ to
10½ inches (16.5 to 26.67 cm) in height;
1917.121(b)(3) Minimum loading capability shall be 100 pounds per square foot (4.79 kN), and minimum tread center
concentrated loading shall be 300 pounds (1334 N);
1917.121(b)(4) Railings shall conform to the requirements of
§ 1917.112(c)(1). If balusters are used, there shall be a minimum of
one per tread. Handrails shall be a minimum of 1¼ inches (3.18 cm)
in outside diameter; and
..1917.121(b)(5)
1917.121(b)(5) Vertical clearance shall be at least 6 feet, 6 inches (1.98 m) above the top step.
1917.121(c) Maintenance. Spiral stairways shall be maintained in safe condition.
[62 FR 40141, July 25, 1997; 65 FR 40942, June 30, 2000]
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Regulations (Standards - 29 CFR) - Table of Contents
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