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Contractor Safety Advisory


Confined Spaces

A confined space is defined as any space that is large enough to enter and perform work, has a limited means of entry or egress (exit), and is not designed for continuous employee occupancy. Examples of confined spaces include pits, tanks, certain tunnels, and underground vaults.

Contractors should be familiar with relevant portions of 29 CFR 1926 Subpart C – General Safety and Health Provisions, and use appropriate entry procedures when working in confined spaces, including the following:

  • Before entry occurs, test the confined space's atmosphere using a direct reading instrument for oxygen content, combustible gases, and toxic air contaminants.
  • If entry is permissible, ensure ventilation is continuous, appropriate and adequate.
  • When required, assign a trained attendant to observe those working in the confined space.

When a confined space entry includes hot work (welding or cutting), the following additional procedures from 29 CFR 1926 Subpart J – Welding and Cutting should be followed:

  • Gas cylinders and welding machines should be left outside the space when work is performed in such spaces as tanks, boilers, or pressure vessels. Heavy portable equipment mounted on wheels should be securely blocked to prevent movement.
  • Whenever workers must enter the confined space through a manhole or other restricted opening, some means for his or her quick removal should be provided. This could include a body harness and lifeline attached to mechanical retrieval equipment. An attendant with a preplanned rescue procedure should be available to observe the welder and to initiate rescue should it become necessary.
  • When operations are suspended for any substantial period of time, such as lunch or overnight, electrodes should be remove from their holders and arc-welding machines should be disconnected from their power source. If gas welding or cutting is in use, fuel gas and oxygen supply should be shut off with the torch valves and at some point outside the confined space. Where possible hoses and torches should be removed from the space.
  • After operations are completed, the welder should mark the hot metal or provide for some other means of warning others working in the area.


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