When can a permit-required confined space be reclassified?

In accordance with 1910.146(c)(7), the space may be reclassified as a non-permit confined space if the space poses no actual or potential atmospheric hazards and if all hazards within the space are eliminated without entry into the space.

OSHA discusses reclassification in a November 15, 1993 Letter of Interpretation (LOI) in which the agency discusses a metal curing oven by saying:

“An employer who eliminates the hazards from a permit space, as provided by paragraph (c)(7) of the standard, can reclassify that space as a non-permit confined space. That reclassification, which would remain in effect as long as the hazards remain eliminated, would allow employers to have employees enter the curing ovens without implementing a permit space program.

”Item 1 of your letter addresses using Lockout-Tagout (1910.147) procedures to eliminate the hazards of moving machinery and natural gas. We agree that through the application of 1910.147, the hazards of stored energy and moving machinery would be eliminated. We do not agree that lockout-tagout would eliminate the natural gas hazard. Hazard elimination in that case would require one of the techniques (blanking, blinding, misaligning or removing sections of lines or pipe, and double block and bleed system) referenced in the definition of “isolation” (see paragraph (b) of 1910.146).

“Item 2 indicates that a cool down time is allotted so that the latent heat of the oven does not create a heat exposure hazard. We concur with the cool down practice to eliminate this heat stress potential. However, we suggest the actual job safety practice indicate a maximum oven temperature allowable or other measurable parameter (period of time) allotted before entry.

”Item 3 describes your process for verifying that there are no atmospheric hazards. The standard does not specify a duration of time over which verification monitoring must be done. However, we do not see a problem with the documented baseline monitoring program being conducted over an 8 hour period of time as long as the employer can prove that atmospheric hazards have been eliminated from the ovens before an employee enters. Verification monitoring with the ventilation system off will be needed to establish that atmospheric hazards have been eliminated. OSHA agrees that spot air monitoring for atmospheric monitoring for atmospheric hazards is not necessarily required by paragraph (c)(7), however, it is the most appropriate way of determining that atmospheric hazards have not manifested themselves.

“Item 4 prohibiting solvents or welding during non-permit entries is a sound practice and should be continued.”

Another LOI dated December 02, 2005 includes the following:

“If the source has been truly removed, i.e. no piping, containers, residual, etc., and the flammable material is not brought into the space by any mechanism, then there would not be a potential atmospheric hazard for that material.”

If the hazards are eliminated for the length of the entry through lockout and blanking, etc., the space may be reclassified as a non-permit according to the criteria in 1910.146(c)(7).