Definition of Confined Space, as it may apply to large product heating and aging furnaces (OSHA LOI)

Background

Product parts are heated in the furnaces using natural gas to temperatures ranging from 700ºF to 2200ºF to facilitate material processing. The furnace doors are actuated remotely from either the cab of a forklift or a control panel. Parts are loaded and unloaded from the furnaces using forklifts during production runs. The furnaces range in size from 8 feet x 8 feet x 8 feet to 18 feet x 18 feet x 18 feet. Furnace access is provided through large garage door type units on the front of the units that move upward on a track system. The floor (hearth) of the furnaces range from 22 to 29 inches above the floor of the building depending on the size of the unit.

Question 1: Do these types of furnaces meet the definition of a confined space? Ingress and egress only require stepping up from the building floor to the hearth of the furnace.

Question 2: Is there a threshold limit to the height of the furnace hearth above the ground that is allowed before the space would be considered “limited or restricted means for entry or exit”? For example, if the furnace is less than 30 inches above the ground, it would not be considered to have “limited or restricted means for entry or exit”. Conversely, if the furnace hearth is greater than 30 inches above ground level, it would be considered “limited or restricted means for entry or exit”.

Question 3: Regardless of furnace hearth threshold height, would using a small access stool be acceptable for ingress and egress of the furnace? If used, would this then meet the definition “limited or restricted means for entry or exit”?

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