Wash. Admin. Code § 296-24-740
This section contains specifications for the safe design and construction of fixed general industrial stairs. This classification 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 exit purposes, construction operations, stairs on scaffolds, stairs designed into machines or equipment, articulated stairs, such as may be installed on floating roof tanks or on dock facilities, the angle of which changes with the rise and fall of the base support, or to stairs on self-propelled motorized equipment.
Wash. Admin. Code § 296-24-740
Order 73-5, § 296-24-765, filed 5/9/73 and Order 73-4, § 296-24-765, filed 5/7/73.