OSHA Handbook for Small Businesses

Entering Confined Spaces

Entering Confined Spaces

  • Are confined spaces thoroughly emptied of any corrosive or hazardous substances, such as acids or caustics, before entry?
  • Are all lines to a confined space, containing inert, toxic, flammable, or corrosive materials valved off and blanked or disconnected and separated before entry?
  • Are all impellers, agitators, or other moving parts and equipment inside confined spaces locked-out if they present a hazard?
  • Is either natural or mechanical ventilation provided prior to confined space entry?
  • Are appropriate atmospheric tests performed to check for oxygen deficiency, toxic substances and explosive concentrations in the confined space before entry?
  • Is adequate illumination provided for the work to be performed in the confined space?
  • Is the atmosphere inside the confined space frequently tested or continuously monitored during conduct of work?
  • Is there an assigned safety standby employee outside of the confined space, when required, whose sole responsibility is to watch the work in progress, sound an alarm if necessary, and render assistance?
  • Is the standby employee 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 if the atmosphere inside the confined space cannot be made acceptable?
  • Is all portable electrical equipment used inside confined spaces either grounded and insulated, or equipped with ground fault protection?
  • Before gas welding or burning is started in a confined space, are hoses checked for leaks, compressed gas bottles forbidden inside of the confined space, torches lightly only outside of the confined area and the confined area tested for an explosive atmosphere each time before a lighted torch is to be taken into the confined space?
  • 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?
  • Whenever combustion-type equipment is used in a confined space, are provisions made to ensure the exhaust gases are vented outside of the enclosure?
  • Is each confined space checked for decaying vegetation or animal matter which may produce methane?
  • Is the confined space checked for possible industrial waste which could contain toxic properties?
  • If the confined space is below the ground and near areas where motor vehicles will be operating, is it possible for vehicle exhaust or carbon monoxide to enter the space?