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NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.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

February 1, 1994

                   Regional Administrator

THROUGH:            ROGER A. CLARK, Director
                   Directorate of Compliance Programs

FROM:               ROY F. GURNHAM, Director
                   Office of Construction and Maritime
                   Compliance Assistance

SUBJECT:            Guarding of Flush Manholes with U-Guards during Ship
                   Repair and Shipbuilding Operations

This memorandum is the written follow-up to our previous verbal response to your August 30, 1993 memorandum requesting OSHA to rescind a long-standing written interpretation that the proper use of "U" bar guards to temporarily guard flush manholes opened during shipbuilding or ship repair operations meets the intent and requirements of 29 CFR 1915.73(b). We apologize for the delay in providing you with this written response.

Section 1915.73(b) states:

"(b) When employees are working in the vicinity of flush manholes and other small openings of comparable size in the deck and other working surfaces, such openings shall be suitably covered or guarded to a height of not less than 30 inches, except where the use of such guards is made impractical by the work actually in progress."

We believe it would be inappropriate at this time for OSHA to rescind its long-standing interpretation regarding this matter for the following reasons.

1. The use of the "U" bar guard has been widely used throughout the ship repair and shipbuilding industry during the last 30 years as an accepted and suitable method for guarding open flush manholes when permanent guards would be impractical or when the use of a permanent guard would in itself constitute or contribute to a hazard.

2. Since its introduction in 1962, the use of the "U" bar and similar guards have proven to be a practical and suitable solution to various deck opening guarding problems. During this period (over three decades), there have been no known serious injuries attributed to their use. These two factors are the primary reason for their popularity and continued use over such a long period of time.

3. We have received no indication from any other region that this policy of the last three decades has caused them any compliance or abatement problems, nor have they requested that it be changed or modified.

4. It should also be noted that OSHA's predecessor agency (the Bureau of Labor Standards) participated in the development of the "U" bar guard and publicly encouraged its use in a 1962 article in the Agency's national publication (the "Marine Safety Digest").

In light of the long history and extensive use of this method of temporary guarding and the lack of a historical record indicating that a number of substantial injuries have occurred from their use, OSHA will continue to consider the "U" bar guard as a suitable compliance method for the temporary guarding of flush manholes opened during shipbuilding and ship repair operations.

It is noted that this issue is addressed in the proposed rules for Shipyard Employment Safety Standards, 29 CFR Part 1915, published in the Federal Register, Volume 53, Number 229, Tuesday, November 29, 1988 (Pages 48170 through 48175).

In order to further clarify the use and suitable applications of "U" bar guards, the following information is provided:

1. On certain vessels, particularly tankers and bulk liquid barges, there are a considerable number of manholes, inspection plates and other deck openings such as butterworth holes. These openings are used during construction and repair for the entry of men and materials as well as for ventilation, either forced or natural. Uncovered openings may exist for very short periods of time, such as for inspection, or may exist for longer periods of time, as during construction or major repairs. The "U" bar guard was designed to allow for immediate installation whereas a welded guard would take a longer period of time to fabricate than the manhole would be uncovered for work or for inspection.

2. The "U" bar guard provides a substantial hand hold for employees entering or leaving the tank or compartment and results in a safer entry and exit; whereas a fixed periphery guard necessitates climbing over the upper rail, thereby contributing to the hazardous condition. Likewise, a three sided guard, with removable chain for entry and exit, has proved to be inadequate.

3. Unsecured portable type periphery guards, similar to those used in guarding street utility manholes, would be subject to slipping and sliding on the steel deck when struck by materials or men working in the vicinity.

4. A portable or fixed periphery guard would have to be removed to permit materials to be lowered or hoisted into the space, during which time no protection would be provided. In most cases, a "U" bar guard does not require removal for similar operations, thus providing the greatest amount of protection to the employee.

5. In tanker and liquid barge repair, where manhole access is necessary into those tanks classified by the Marine Gas Chemist as "Safe for men, Not safe for fire", and where no hot work is permitted, the "U" bar guard is particularly suitable in that no hot work is required for its installation.

6. Due to the configuration and standardization of the "U" bar guard, safe storage and handling is achieved, reducing the likelihood of injury.

7. Recognizing that manholes are generally of standard size, as are bolt and thread size, "U" bar guards designed and fabricated in conformity with general manhole size standards can be used consistently from vessel to vessel, thereby heightening their acceptability and ready use. These standard sizes apply worldwide and are summarized as follows:

a. The world wide shipbuilders standard size for manhole openings is 15" X 23", of oval shape which is considerably less in area than if a rectangle of the same dimensions. This is a small opening, through which a many large persons cannot pass and through which any person has to carefully pass.

b. The maximum allowable opening in a ballast or similar tank, for any purpose, is 23" diameter. If a larger opening were to be used, the vessel would lose her tonnage exemption, which for the layman translates to paying a lot more taxes and insurance. Hence, larger openings are not to be expected in this application.

c. Cargo tank hatches on tanker vessels are either 30" X 24" or 30" X 36", depending on the vessel's frame spacing. These have inclined ladders and coamings at least 36" in height, usually more. Thus, they pose no problem at all except possibly during construction if the coaming was not installed before erection (normally installed in the shop before erection). Furthermore, the standard is not intended for such a protected opening in the first place.

d. While manholes are almost always of the oval variety, there may also be found deck access plates which are square, rectangular or round. These shapes are usually not for personnel access but for other specialized purposes such as grain feeders, butterworth openings, etc. Most of these will be smaller than the oval 15" X 23" manhole opening.