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29 CFR 1910 Subpart J, Occupational safety and health standards
Application of the Permit-Required Confined Spaces (PRCS) Standards, 29 CFR 1910.146. OSHA Directive CPL 02-00-100 [CPL 2.100], (1995, May 5).
NOTE: Employers in states with state-run safety and health plans should check with their state agency. Their state may enforce standards that, while "as effective as federal standards," may not be identical to the federal requirements.
A confined space has limited or restricted means of entry or exit, is large enough for an employee to enter and perform assigned work, and is not designed for continuous occupancy by the employee.
Examples of confined spaces are:
Because of the difficulties of entry and exit from confined spaces, employees who work in them may also face increased risk of exposure to serious injury from hazards such as entrapment, engulfment, and hazardous atmospheric conditions.
The atmosphere in a confined space can be hazardous due to the presence of chemicals that are either man-made, such as toxic fumes from welding operations, or naturally occurring, such as hydrogen sulfide or methane that can result from decomposing organic material. The oxygen level in a confined space may be reduced below that required for normal breathing. Gases that are heavier than air, such as carbon dioxide, may sink to the bottom of a confined space and reduce the level of oxygen breathed by a worker. Or chemical processes such as the formation of rust or bacterial action, as in the fermentation process, can use up the oxygen in a confined space.
In addition, the presence of flammable liquids or gases in a confined space presents a fire or explosion hazard
Work in confined spaces may keep employees closer to machinery components and power-driven equipment, such as augers, than they would be otherwise.
Heat, noise, vibration, and structural hazards such as scaffolding installed for maintenance, overhead structural members, or baffles also contribute to potentially unsafe conditions in confined spaces.
OSHA regulates confined spaces that have one or more of the following characteristics:
Such confined spaces are defined as "permit-required confined spaces" or "permit spaces" and are regulated by OSHA's standard 29 CFR 1910.146. See Confined Space vs. Permit-Required Confined Space.
Confined Space Case
The tank was located on the second floor and was part of a chicken processing operation at a rendering plant. The inside of the tank measured 8 feet high by 6-1/2 feet in diameter. The bottom of the tank was cone-shaped and sloped outward at a 120-degree angle. The to of the tank was covered with loose plate steel, one-third of which had been removed just prior to employee’s entry. Employee was to enter the tank to repair a hole in the bottom. The only witnesses to this operation were two other employees who observed from outside the tank. Upon entering the tank, the employee was immediately overcome by a gaseous, oxygen-deficient atmosphere. When he tried to climb out, he fell backward into the tank and apparently lost consciousness. Local authorities were unable to revive him. The gas present in the tank was identified as methane.
The following are examples of areas in poultry processing that need to be evaluated to see if they meet the definition of a "permit-required confined space" (View examples):
Floor hole in feather pit - Confined space with a moving screw-augur in the bottom
An actual case (see Confined Space Case) involved an employee who entered a tank that had contained chicken blood.
OSHA's standard requires employers to determine whether there are any permit-required confined spaces in their facility.
If there are, employees must be informed of them and of the dangers posed by them. See Confined Space Requirements.
If employees are not to enter and work in permit spaces, the employer must take effective steps to prevent employee entry.
If employees are to enter permit spaces, the employer must develop a written permit space program, which will (see Permit System and Entry Permit Requirements):
Before initial work assignments, employees must be trained in the understanding, knowledge, and skills necessary for the safe performance of their duties.
Additional training is required when:
Rescue team members must have also been trained in:
The standard also requires coordination with contractors. See Multi-Employer Requirements.
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