Standard Interpretations - Table of Contents Standard Interpretations - (Archived) Table of Contents
• Standard Number: 1910.146; 1910.147
• Status: Archived

Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.


OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.


November 6, 1996

William K. Principe
Constangy, Brooks, & Smith, LLC
Suite 2400
230 Peachtree Street, N.W.
Atlanta, GA 30303-1557

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]



July 23, 1996

John B. Miles, Jr.
U.S. Dept. of Labor/OSHA
Room N-3468 F-P Building
200 Constitution Avenue, NW
Washington, DC 20210

Dear Mr. Miles:

I would like to request an interpretation of 29 CFR 1910.146(c)(7).

Many of our clients attempt to re-classify permit-required confined spaces to non-permit-required confined spaces by isolating or eliminating the hazards within the permit spaces. It would be helpful if OSHA could clarify the conditions under which a permit-required confined space may be re-classified. Please address the following:

(1) Is there a distinction under 29 CFR 1910.146(c)(7) between "eliminating" and "isolating" a hazard or are these terms synonymous?

(2) May mechanical hazards be eliminated by compliance with 1910.147?

(3) May mechanical hazards be eliminated by compliance with Subpart O covering machine guarding requirements?

(4) May electrical hazards be eliminated by compliance with 1910.147?

(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)?

(6) May hydraulic energy hazards be eliminated by compliance with 1910.147? If not, please describe how such hazards may be eliminated.

(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).

(8) May the potential for heat stress be eliminated by allowing a sufficient cool-down time before employees or contractors enter the confined space?

I look forward to receiving your response.

Sincerely,

William K. Principe


Archive Notice - OSHA Archive

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.


Standard Interpretations - Table of Contents Standard Interpretations - (Archived) Table of Contents