A confined space consists of any one of the following characteristics:
- Limited openings for entry and exit
- Unfavorable natural ventilation
- Not designed for continuous worker occupancy
Examples of confined spaces include, but are not limited to:
- Storage tanks
- Compartments of ships
- Process vessels
- Reaction vessels
- Furnaces, incinerators, boilers and steam drums
- Ventilation and exhaust ducts
- Underground utility vaults
- Includes construction confined spaces as of March 2015
- Isolated-Hazard Confined Space
- Controlled-Atmosphere Confined Space
- Permit-Required Confined Space
- Continuous System-Permit-Required Confined Space
Attributes associated with hazards:
- May contain a hazardous or potentially hazardous atmosphere (fuel storage tank).
- May contain a material which can engulf an entrant (grain silo)
- May contain walls that converge inward or floors that slope downward and taper into a smaller area which can trap or asphyxiate a person (coal silo)
- May contain physical hazards such as unguarded machines or exposed live wires (process vessels)
Confined spaces with these potential hazards are permit-required confined spaces that must be identified by the employer. Typically a sign or label will be used to identify permit-required confined spaces. Workers who are exposed to a permit-required confined space must be informed of their existence and location, and be informed about their hazards.
The existence of one or more permit-required confined spaces requires that the employer have a program for controlling, and where appropriate, for protecting employees from permit-required confined space hazards and for regulating employee entry into the permit-required confined spaces.
What should you do if you need to enter a permit-required confined space?
- Do not enter any confined space without being full informed about the space and the hazards of that confined space. Do not rely on there being a sign or label identifying a space as a permit-required confined space. Don't make assumptions.
- Do not enter permit-required confined spaces without having a permit to enter that space.
- Be sure you have the appropriate training before entering a permit-required confined space.
- Review, understand and follow the established procedures before entering a permit-required confined space.
- Identify and know how and when to exit the confined space.
- Before entry, identify any physical hazards.
- Before and during entry, test and monitor the atmosphere in the confined space for oxygen content, flammability, toxicity or explosive hazards.
- Follow the entry procedures for the permit-required confined space you are entering. Use the required fall protection, ventilation, air-monitoring, rescue, lighting and communication equipment.
- When in a confined space maintain contact at all times with a trained attendant either visually, using a wired phone, or using a two-way radio. If there is a problem, the communications system allows the attendant or entry supervisor to order you to get out of the confined space evacuate or to call on trained rescue personnel.