Eliminating hazards before reclassifying a permit-required confined space

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

November 6, 1996
William K. Principe
Constangy, Brooks, & Smith, LLC
[Recipient address omitted]
Dear Mr. Principe:
This is in response to your letter of July 23, to Mr. John B. Miles, Jr. requesting interpretative guidance for paragraph (c)(7) of 29 CFR 1910.146 - Permit-Required Confined Spaces (PRCS) standard. The responses to questions raised are set forth below.
Question 1: Is there a distinction under 29 CFR § 1910.146(c)(7) between "eliminating" and "isolating" a hazard or are these terms synonymous?
Answer: There is no reference to the term "isolating" in paragraph (c)(7). In the context of paragraph (c)(7) these terms are not synonymous.
Question 2: May mechanical hazards be eliminated by compliance with § 1910.147?
Answer: Yes
Question 3: May mechanical hazards be eliminated by compliance with Subpart O covering machine guarding requirements?
Answer: Yes, as long as the guarding method chosen effectively protects the entrant performing tasks within the space.
Question 4: May electrical hazards be eliminated by compliance with § 1910.147?
~~Answer: Yes~~
[This document was edited on 10/25/99 to strike information that does not reflect OSHA policy. Please see 1910.333(b)(2) Note 2 for the current policy.]
Question 5: May natural gas hazards be eliminated by isolating such hazards by the means set out in the definition of "isolation" in § 1910.146(b)?
Answer: Only the means identified in the definition of isolation which address a fluid flowing through pipe, lines or ducts would be appropriate. They are blanking or blinding the pipe or conduit; misaligning or removing sections of lines, pipes, or ducts; as well as a double block and bleed system. The other means of isolation identified in the definition, lockout or tagout of all sources of energy or blocking or disconnecting all mechanical linkages would not be appropriate.
Question 6: May hydraulic energy hazards be eliminated by compliance with § 1910.147? If not, please describe how such hazards may be eliminated.
Answer: Yes, if the frame of reference is that the hydraulic energy is the source of power to drive or activate a device within the space. No, if the hydraulic (stored) energy in question is a fluid being prevented from flowing into the space by a single in-line valve (i.e., the hydraulic energy developed from an elevated tank). See discussion in question 5.
Question 7: Please describe how atmospheric hazards can be eliminated from a permit-required confined space in a manner to comply with § 1910.146(c)(7).
Answer: Paragraph (c)(7) does not apply where a permit space presents an atmospheric hazard or the potential to pose an atmospheric hazard. Therefore, the elimination of present or potential atmospheric hazards would not constitute compliance with paragraph (c)(7).
Question 8: May the potential for heat stress be eliminated by allowing a sufficient cool-down time before employees or contractors enter the confined space?
Answer: A qualified yes. The sufficiency of the cool-down time taken has to include not only the latent heat within the space but the active heat created by the anticipated work activities of the employees within the space and any personal protective equipment being worn.
Should you have further question on this response, please contact [the Office of General Industry Enforcement at (202) 693-1850].
Sincerely,
John B. Miles, Jr., Director
[Directorate of Enforcement Programs]
[Correction 10/22/2003]

[Requester letter reproduced on OSHA page; omitted here.]