Section 408.10342. Step bolts and manhole steps; specifications.

(1) This rule applies to step bolts and manhole steps used on structures such as towers, stacks, conical manhole sections, and vaults. This rule does not apply to individual rung ladders.

(2)   Step bolts and manhole steps shall  be  continuous   and  spaced uniformly not less than 6 inches (15 cm) and not more than 18  inches  (46 cm) apart.

(3)   The minimum clear step width of step bolts shall be 4 1/2 inches (14.4 cm). The minimum clear step width  of  manhole steps shall be 10 inches (25.4 cm).

(4)   The minimum toe clearance for manhole steps shall be 4 inches (11.1 cm) from the point of embedment on the wall to the outside face of the step. The toe clearance in the center of the manhole step shall be a minimum of 4 1/2 inches (11.4 cm) measured to the outside face of the step.

(5)   The minimum toe clearance for step bolts shall be 7 inches (17.8 cm). Where obstructions cannot be avoided, toe clearances may be reduced to 4 1/2 inches (11.4 cm).

(6)   Step bolts and manhole steps shall be designed  to  prevent  an employee's foot from slipping or sliding off the end of the step  bolt  or manhole step.

(7)   Manhole steps and step bolts which are installed after the effective date of this rule and which are used in corrosive environments shall be constructed of, or coated with, a material that will retard  corrosion of the step or bolt.

(8)   All manhole steps installed on or after the effective date of this rule shall be provided with slip-resistant surfaces, such as  corrugated, knurled, or dimpled surfaces.

(9)   Each step bolt shall be capable of withstanding, without failure, not less than 4 times the intended load to be applied to the bolt.

(10)   Manhole steps installed before the effective date   of  this  rule shall be capable of supporting their maximum intended load.

History: 1994 AACS.