Confined Space Safety

Nov. 13, 2002

Following the proper safety precautions when entering or working in confined spaces is an important function for anyone who subjects himself to the hazards of this kind of vocation. We all know of the horror stories of persons getting buried alive or of those who die from lack of oxygen in confined spaces, and yet these accidents and deaths continue to occur; mostly because people are in too much of a hurry or feel that they are not in any danger when working in these situations. In some cases, people fail to read the condition of excavations and think that they can work without the aid of a trench box or proper shoring, only to become another statistic.

Before a person tries to learn any safety precautions he must first know which conditions or circumstances constitute a confined space and what sort of rules apply to working in these spaces. Once this is known, he then can proceed to follow the regulations that relate to a particular situation so he is working safely presuming, of course, that he knows the proper safety regulations.

Knowing and understanding the proper safety precautions is only a part of following safety procedures. Having the proper equipment necessary to prevent accidents and save lives and practicing with this equipment also is important.

Defining Confined Spaces

A confined space as defined by OSHA in Part 1910.146(b) of the Federal Register ( is any space that is large enough for an employee to enter and perform work, has a restricted means of entry and exit and is not designed for continuous occupancy. Additionally, the space may contain a hazardous atmosphere that can result in employee injury or death. A hazardous atmosphere is defined as one with a flammable gas, vapor or mist at 10 percent or more than the lower flammable limit as well as an atmospheric oxygen concentration below 19.5 percent or above 23.5 percent or other gasses such as hydrogen sulfide or carbon monoxide above 10 ppm or 35 ppm, respectively.

It is not relevent whether the space is a below-grade vault or an above-ground building with a door. It is the interior space and atmosphere that determines if it is a confined space. There are, however, some considerations that can be taken into account in order to determine if the space can be considered "confined."o:p>

For example, a chlorine room or other chemical feed/storage room can be a confined space because of the possibility of chlorine or other chemical fumes existing if the ventilation fan was not turned on to clear the space before entering. At the same time, if chemical solutions or chlorine tanks are being changed or handled, the atmosphere could have vapors or trace gasses that would qualify the room as a confined space.

On the other hand, an open trench could be considered a confined space if it was deep enough and had limited escape access ladders and restricted movement in the bottom because of pipe structures and shoring supports.

Another consideration that must be taken into account when dealing with confined spaces is the determinaton of whether or not the space may or may not require a permit for entry. Some spaces may be entered without a permit and by anyone who has a need to enter the space. On the other hand, many spaces cannot be entered by anyone (even those that are authorized) without a permit that is signed by a responsible person.

Though this may seem like a complicated issue, there is some guidance provided by the Federal Register under Section 1910.146—Appendix A: Permit-required confined space decision flow chart (see left) and Appendix C: Examples of permit-required confined space programs.

Appendix A (decision flow chart) begins with the utility as a whole entity, asking the question, "Does the workplace contain confined spaces as identified by 1910-146(b)?" If it does not, there is no problem. However, if it does, then there are a series of checks and determinations that must be made in order to determine if an entry permit is required. It also requires that the employees be informed of the hazard and procedures necessary to work in the space including safety equipment and evacuation or emergency procedures. The appendix also covers outside contractors that may work in the space.

At this point, it is important to note that any outside contractor working within your premises is under your responsibility, whether he reports directly to you or not. You are responsible for his well-being even though he is not on your payroll. If he enters a permit required space, he must get a permit from you, and you must have someone around the job sites to make sure that he follows all of the necessary work and safety procedures.

Addendix C uses examples to show when a permit is or is not required. Basically, it states, "entry into a space can be made without a permit or attendant, providing the space can be maintained in a safe condition with the use of mechanical ventilation as provided in 1920-146(c)(5)." Of course, a fully trained and qualifed employee must do a pre-check of the space to check for any hazardous gasses or conditions. He also is required to fill out a Confined Spaces Pre-Entry Check List to ensure that all of the necessary procedures are being followed. This includes testing of the atmosphere in the space, blocking off (where possible) of any lines that could bring contaminants into the space and the surveillance of the surrounding area for drifting vapors.

Entering Confined Spaces

Whenever entering any confined space, it is important to remember the need for safety and to follow recommended safety procedures that correspond to each area. Although confined space entry may be briefly separated into permit and non-permit entry, there are many circumstances listed in 1920-146 that provide flexibility in exactly how to define a confined space. Therefore, any employer should thoroughly investigate the statute to ensure that his employees are following the proper procedures when entering any sort of confined space.

For example, non-permit entry previously was described and referenced as Appendix C of the code. Appendix E of 1910.146 goes one step further to explain sewer entry and its requirements. It states that only employees that are trained for this work should be used, and that the air should be tested for specific substances (CO, ft, LLC and combustibles such as LEL) before entry and at regular intervals while the employees are working. Also, continuous ventilation should take place. Additionally, in large bore sewers, employees should be equipped with audible alarm devices and an escape self-contained breathing apparatus (ESCBA) with at least a 10-minute air supply or some other NIOSH-approved self-rescuer and other emergency equipment such as flashlights and radios.

Permit-required entry into confined spaces is more clearly defined in 1910.146(c) of the Federal Register. It starts out with the requirement that an employer must evaluate the workplace to determine if a space is a permit-required area. If so, all employees should be notified and a sign reading "Danger: Permit Required--Confined Space, Do Not Enter" be posted. (There also are other sections of the OSHA Code that refer to other vocations--mining, shipyard and meat packing--that have their own specific regulations that define hazardous work environments.)

Once a space has been designated as a permit-required area, the employer may or may not permit employees to enter the space. If entry is permitted, then the employer must develop and implement a written space permit program that complies with 1910.146(c) regulations. This regulation, however, can be side-stepped if the space only has a potential hazardous atmosphere that can be eliminated by forced air ventilation as defined in 1910.146(c)(S).

The details of implementing 1910.146(c) are further spelled out in 1910.146(d). These include such items as identifying the hazard, specifying acceptable entry conditions, providing protection barriers, providing testing, communications, personal protection equipment, ladders and emergency rescue equipment. It also includes the requirements that each employee be able to observe and know the results of any tests that were made prior to entering the space.

Additionally, the regulation requires that an entry supervisor be present to determine if entry is allowable and then remain at the site or have another person available as an attendant during the time when an employee is working in the confined space. It also is suggested that a third person be nearby in case an emergency arises. The regulation spells out the procedures for calling for assistance as well as the actions to be taken by the crew for extracting a worker from the confined space.

Safety Precautions

Most confined space safety procedures are just common sense. You would not attempt to change a tire on a vehicle without setting the brakes and blocking at least one wheel to prevent the vehicle from moving. The same rules apply to the procedures that should be followed before entering a confined space and are spelled out in the Federal Register 1910.146.

As previously mentioned, proper ventilation, sample air testing and the use of protective safety equipment all are necessary before entering a confined space. However, there are some specific items that should be pointed out because their selection depends on the conditions within the confined space. The following are examples of some of these selection possibilities.

Ventilation equipment is available in both "suction" and "blow-in" styles. If a suction style is used, then the ventilator must be placed somewhere other than the work area in order to provide fresh air at the work area and to eliminate other fumes from entering. If a blow-in style is used, then the blower must be located away and downwind of the work area. Also, the blower discharge hose must extend to the bottom of the confined space to permit full purging of the atmosphere. The amount of time for the air purge that is required can be calculated by dividing the manhole volume (cubic feet) by the cfm of the blower. The air also must be tested for purity.

C3 as detectors are available in a variety of styles. However, those that most often are used measure specific gasses such as CO, O2, H2S and combustibles (LEL). Additionally, there are audible warning devices that can be worn by the worker as added protection against an unexpected surge of hazardous gas.

Remember that the test equipment/device is only as good as its calibration. Therefore, the device must be checked and calibrated at regular intervals if it is to provide the required data. Also, the permit entry form requires that the gas test equipment be identified as well as the person performing the test.

The selection of hoisting equipment depends upon whether the confined space is a ladder or ladderless entry and whether or not the hoist is used for materials or personnel. Work winches should never be used to hoist personnel. Various manufacturers have different stipulations on how their winches should be used and are reflections of OSHA regulations published under several different rulings.

For example, 1910.146(k)(3)(ii) requires a mechanical-type device for rescue in vertical conditions more than 5 feet deep. On the other hand, OSHA 1910 general industry and 1926 construction industry standards stipulate specific requirements for the selection of a tripod/manually operated winch system. Additionally, 1910.28 and 1926.451 require the use of a backup fall arrest system for use when entering ladderless structures. Both regulations also require that the tripods and winches be tested and listed by a nationally recognized testing laboratory (Underwriters or Factory Mutual). The winches also may require testing by the manufacturer after a period of use or operation.

Backup fall systems are good ideas for any structure that is deep and can be considered a hazard to enter even if they have rungs—especially, if the structure is old and the ladder rungs are not in the best condition. The backup fall system can be a rope grab kit or a self-retracting lifeline but must be connected to the "D" ring of the full body harness that the worker wears when entering the work space.

If the confined space contains a hazardous gas that cannot be effectively purged or reduced to an acceptable level, then some sort of breathing appartus will be required before the worker can be allowed to enter the space. Again, the existing conditions will determine which kind of breathing assistance/apparatus will be required.

For most conditions where the worker must enter and remain for a period of time before he can complete his task, a 30- or 60-minute self-contained breathing apparatus (SCBA) would be required. While some are rated for fire-fighting situations, there are others that are rated for industrial use. Both styles have similar features and are acceptable under OSHA regulations. Keep in mind that the 30- or 60-minute air time cannot be fully used by the wearer. Usually, a 5- or 10-minute warning system permits the wearer to egress the space before the air runs out.

There also are other SCBA units available that have more limited escape time from 5 to 15 minutes. These devices are not worn when entering, and only are used to permit an emergency exit from the space. In addition to these devices, some manufacturers have limited-use respirators that can be used by workers in atmospheres that contain hazardous gasses at low levels.

Regardless of how much and which kind of equipment you provide, it is useless if the employees are not trained and proficient with it. Training (not just talking about it but doing it) is the most important part of any confined space entry program. It also is required as part of the OSHA regulations and can be used to certify the employees performance of various tasks that they will perform. There are many training programs available for this purpose as well as OSHA compliance and accident-prevention manuals that can help you determine how to understand and meet the regulations. WWD

About the Author

Don Renner

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