Many workplaces contain spaces that are considered “confined” because their configurations hinder the activities of workers who enter, work in, and exit them. For example, employees who work in process vessels generally must squeeze in and out through narrow openings and perform their tasks while cramped or contorted. The Occupational Safety and Health Administration (OSHA) uses the term “confined space” to describe such spaces. In some cases, confinement itself poses entrapment hazards. In other cases, confined work spaces keep workers closer to hazards, such as asphyxiating atmospheres or the moving parts of machinery. OSHA uses the term “permit-required confined space” (permit space) to describe those spaces that both meet the definition of “confined space” and pose health or safety hazards.

The following questions can help supervisors and workers evaluate a confined space to ensure that all hazards to workers are controlled.

  • Before entry, are confined spaces thoroughly emptied of corrosive or hazardous substances?
  • Before entry, are confined spaces checked for decaying vegetation or animal matter that may produce methane?
  • Are all utility lines to the confined space, containing inert, toxic, flammable, or corrosive materials, turned off and blanked or disconnected and separated before entry?
  • Are all impellers, agitators, or other moving parts and equipment inside confined spaces locked-out?
  • Is either natural or mechanical ventilation provided prior to entry into the confined space?
  • Are appropriate atmospheric tests performed to check for oxygen deficiency, toxic substances, and explosive concentrations in the confined space before entry?
  • Is the atmosphere inside the confined space frequently tested or continuously monitored?
  • Is adequate illumination provided in the confined space for the work to be performed?
  • When required, is there an assigned safety standby worker outside of the confined space whose sole responsibility is to watch the work in progress, sound an alarm if necessary, and render assistance?
  • Is the standby worker appropriately trained and equipped to handle an emergency?
  • Is the standby employee or other employees prohibited from entering the confined space without lifelines and respiratory equipment if there is any question as to the cause of an emergency?
  • Is approved respiratory equipment required when the atmosphere cannot be made acceptable?
  • Are portable electrical equipment used inside the confined space either grounded and insulated, or equipped with ground fault protection?
  • Before performing gas welding in a confined space, are hoses checked for leaks?
  • Are compressed gas bottles forbidden inside of the confined space,
  • Are torches lighted only outside of the confined area, and the confined space tested for an explosive atmosphere each time before a lighted torch is to be taken into it?
  • If employees will be using oxygen-consuming equipment, such as salamanders, torches, and furnaces, in a confined space,is sufficient air provided to assure combustion without reducing the oxygen concentration of the atmosphere below 19.5 percent by volume?
  • When combustion-type equipment is used in a confined space, are provisions made to ensure the exhaust gases are vented outside of the enclosure?

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