437-004-0330 Fixed Industrial Stairs (1) Definitions. Unless otherwise stated, fixed industrial stair terms mean: (a) Handrail. A single bar or pipe supported on brackets from a wall or partition, and used as a handhold for persons on stairs or ramps. (b) Nose, nosing. That part of a tread projecting beyond the face of the riser. (c) Open riser. The space between the treads of stairways without upright parts (risers). (d) Platform. An extended step or landing breaking a continuous run of stairs. (e) Railing. A vertical barrier along exposed sides of stairs and platforms to prevent people from falling. The top rail usually serves as a handrail. (f) Rise. The vertical distance from the top of a tread to the top of the next higher tread. (g) Riser. The upright part of a step at the back of a lower tread and near the leading edge of the next higher tread. (h) Stairs, stairway. A set of steps with three or more risers, from one level or floor to another, or leading to platforms, pits or around machinery, tanks, and other equipment. (i) Tread. The horizontal part of a step. (j) Tread run. The horizontal distance from the leading edge of a tread to the leading edge of an adjacent tread. (k) Tread width. The horizontal distance from front to back of tread including nosing. (2) Application. This section has specifications for the safe design and construction of fixed stairs. This includes interior and exterior stairs around machinery, tanks, and other equipment, and stairs leading to or from floors, platforms, or pits. This section does not apply to stairs used for fire exits, private residences or articulated stairs, the angle of which changes with the rise and fall of the base support. (3) Where fixed stairs are required. There must be fixed stairs where work requires regular travel between floors or levels, and access to operating platforms at any equipment that requires frequent attention. There also must be fixed stairs for daily access to elevations or for access at each shift for such purposes as inspection, regular maintenance, etc. There must be fixed stairs where work may expose employees to acids, caustics, gases, or other harmful substances, or where employees normally must carry tools or equipment by hand. (It is not the intent of this section to preclude using fixed ladders for access to elevated tanks, towers, and similar structures, etc., where their use is common practice.) Spiral stairs are not legal except for special limited use and secondary access situations where it is not practical to provide a conventional stairway. Winding stairs are acceptable on tanks and similar round structures where the diameter of the structure is at least five (5) feet. (4) Stair strength. Fixed stairs must be able to carry a load of five times the normal live load anticipated but never less than a moving concentrated load of 1,000 pounds. (5) Stair width. Fixed stairs must be at least 22 inches wide. (6) Angle of stairway rise. Fixed stairs must be at angles to the horizontal of between 30° and 50°. Use any uniform combination of rise/tread dimensions that will result in stairs at an angle to the horizontal between 30° and 50°. Table 1 gives rise/tread dimensions that will produce stairs within this range. However, other allowable rise/tread combinations are possible. [Table not included. See ED. NOTE.] (7) Stair treads. All treads must be slip-resistant and the nosings must be a nonslip finish. Welded bar grating treads without nosings are acceptable if the leading edge can be readily identified by people descending the stairs and if the tread is serrated or is of nonslip design. Rise height and tread width must be uniform throughout any flight of stairs including any foundation structure used as one or more treads of the stairs. Treads must not be loose. Replace or repair defective treads quickly. (8) Stairway platforms. Stairway platforms must be no less than the width of the stairway and a minimum of 30 inches long measured in the direction of travel. (9) Railings and handrails. There must be standard railings on the open sides of exposed stairs and stair platforms. There must be handrails on at least one side of closed stairs preferably on the right side going down. Stair railings and handrails must comply with OAR 437-004-0320. (10) Vertical clearance. Vertical clearance above any stair tread to an overhead obstruction must be at least 6-1/2 feet measured from the leading edge of the tread. [ED. NOTE: Tables referenced are available from the agency.] Statutory/Other Authority: ORS 654.025(2) & 656.726(3) Statutes/Other Implemented: ORS 654.001-654.295 History: OSHA 4-1998, f. 8-28-98, cert. ef. 10-1-98