Confined spaces, although on first appearance may seem relatively hazard free, contain many hazards that can pose a threat to entry personnel. This presentation will cover the major hazards that are likely to be encounter by entry personnel. The hazards discussed include the majority of common hazards you will find in any confined space operation. It is critical that each confined space in your facility be evaluated individually to determine that all hazards are identified.

The following categories cover the major hazard groups found in confined spaces:

  • Atmospheric

  • Content issues

  • Potential energy

  • Environment in the space

  • Configuration of the space

  • Nature of the work

  • External Hazards

  • Miscellaneous

Some of these hazards are relatively obvious, while others may be difficult to identify and challenging to assess. In addition to those hazards which are unique to confined spaces, we must also contend with the general safety hazards that are present in any work environment. We must also recognize that not all hazards that pose a threat to us in the space have originated in the space. The space itself may pose some of the hazards that threaten entry personnel. For ease of discussion the following section breaks hazards down into categories and individual groupings. Our evaluation must include an overall assessment of all of the potential hazards associated with the space and the development of techniques and methods to safely deal with the hazards that are present.

Ideally hazards should be eliminated. If this is not possible we must control the hazards to a level of acceptable risk.

Atmospheric Hazards
OSHA Definition of Hazardous Atmosphere (quoted directly from OSHA 1910.146)

Hazardous atmosphere means an atmosphere that may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue (that is, escape unaided from a permit space), injury, or acute illness from one or more of the following causes:

  1. Flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit (LFL);

  2. Airborne combustible dust at a concentration that meets or exceeds its LFL;

    Note: This concentration may be approximated as a condition in which the dust obscures vision at a distance of 5 feet (1.52 m) or less;

  3. Atmospheric oxygen concentration below 19.5 percent or above 23.5 percent;

  4. Atmospheric concentration of any substance for which a dose or a permissible exposure limit is published in Subpart G, Occupational Health and Environmental Control, or in Subpart Z, Toxic and Hazardous Substances, of this part and which could result in employee exposure in excess of its dose or permissible exposure limit;

    Note: An atmospheric concentration of any substance that is not capable of causing death, incapacitation, impairment of mobility to self-rescue, injury, or acute illness due to its health effects is not covered by this provision;

  5. Any other atmospheric condition that is immediately dangerous to life or health.

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