• Part Number:
    1917
  • Part Number Title:
    Marine Terminals
  • Subpart:
    1917 Subpart F
  • Subpart Title:
    Terminal Facilities
  • Standard Number:
  • Title:
    Spiral stairways.
  • GPO Source:
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)
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]