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 https://www.osha.gov.

July 13, 1993

Mr. Dean Davenport
3269 Ezell Pike
Nashville, Tennessee 37211

Dear Mr. Davenport:

Thank you for your letter of February 23, to the Occupational Safety and Health Administration's (OSHA) Nashville Area Office requesting an interpretation of the 29 CFR 1910.146 Permit - Required Confined Space (PRCS) as it applies to work performed in conjunction with your insulated enclosures Please accept our apology for the delay in this response.

Based on the literature and data sheets you submitted, it is our opinion that the 1910.146 standard should not normally apply to your insulated water piping enclosures for their intended use, for the following reasons.

1. When the enclosures (large or small) are removed, the work area could not be considered a confined space.

2. Normal access to the water pipe for inspection and testing purposes is from the outside by reaching into the enclosure with no whole-body entry. This type of activity is not covered by the standard.

3. Even though it may be possible to get into one of the larger enclosures, which could technically be considered a confined space, in the applications you describe, there should not be any anticipated hazard characteristic such as engulfment, lack of oxygen, or atmospheric toxins which would make the enclosure a permit required confined space subject to the 1910.146 standard.

If during the manufacturing process, however, an employee of Hydrocowl were to work within a completely assembled unit and become exposed to a hazardous condition, a permit-required confined space would exist which would be subject to the 1910.146 standard.

Should you have further questions in this matter please contact Mr. Don Kallstrom in the Office of General Industry Compliance Assistance on (202) 219-8031.


Roger A. Clark, Director
Directorate of Compliance Programs

April 1, 1993

                   Directorate of Compliance Programs

THROUGH:            LEO CAREY, Director
                   Office of Field Programs

FROM:               R. DAVIS LAYNE Regional Administrator

SUBJECT:            Permit - Required Confined Spaces for General Industry
                   (29 CFR 1910.146)

The attached letter is from Mr. Dean Davenport, of Hydro Cowl, Inc. Mr. Davenport requests an interpretation regarding coverage under the new confined space standard (29 CFR 1910.146) for enclosures manufactured by his company. Hydro Cowl enclosures are distributed throughout the country. An interpretation regarding this matter will have nationwide implications. Therefore, we are forwarding Mr. Davenport's request for your response.

Please reply directly to Mr. Dean Davenport of Hydro Cowl, Inc. with copies to the Assistant Regional Administrator for Technical Support, Region IV and Mr. Cois Brown, Area Director, Nashville, Tennessee.

If you have any questions, please contact the Acting Assistant Regional Administrator for Technical Support or Terry Wilkins of my staff, at (404) 347-2281.


February 23, 1993

Mr. Cois M. Brown
Area Director
U.S. Department of Labor-OSHA
2002 Richard Jones Road,
Suite C205
Nashville, TN 37215

Dear Mr. Brown:

We are the manufacturer of insulated enclosure that is installed outside over a water piping assembly to prevent the water inside the piping from freezing and also to provide security to help prevent vandalism.

The piping assembly consists of piping and a series of double check valves or backflow preventers. The assembly contains water from the public utility to the end user.

The HydroCowl enclosures Models #100-#200 are designed to be completely removed from the assembly and set aside. They are one-piece designed, do not have an access opening and are too small to be entered.

The larger enclosures Model #300 thru #1000T are constructed to be assembled in panels that are removable. The enclosures will have a large removable panel on the front to use for testing and maintenance and a large removable panel on the back that also serves as the drain panel in case the backflow preventer dumps water.

As you can see in our literature, the removable panel has to be set aside to gain access to the piping assembly for testing and maintenance. If complete replacement of the assembly is required additional panels can be removed or the top of the enclosure can be removed to provide additional working space. We recommend that these enclosures be mounted on a concrete base approximately 4 inches thick.

Does the Permit Required Confined Space Standard 1910.146 apply to this operation? If a permit is required, what portion of the standards would apply to this operation?


HydroCowl, Inc.

Dean Davenport