Oxygen-deficient atmospheres are the leading cause of
confined space fatalities in the shipyard. While normal atmosphere
contains between 20.8 and 21 percent oxygen, OSHA defines as oxygen deficient any
atmosphere that contains less than 19.5 percent oxygen, and as oxygen enriched, any
atmosphere that contains more than 22 percent.
Oxygen-deficient atmospheres may be created when
oxygen is displaced by inerting gases, such as carbon dioxide, nitrogen,
argon, or the ship's inert gas system or firefighting system. Oxygen can
also be consumed by rusting metal, ripening fruits, drying paint, or
coatings, combustion, or bacterial activities.
Oxygen-enriched atmospheres may be produced by
certain chemical reactions, but in a shipyard they are typically caused by
leaking oxygen hoses and torches. Oxygen enriched atmospheres present a
significant fire and explosion risk.
| Requirements and Example Solutions |
- The following spaces must be tested for oxygen
content before entry: [29 CFE 1915.12(a)]
- Spaces that have been sealed, such as spaces that
have been coated and closed up, and non-ventilated spaces that
have been freshly painted;
- Spaces and adjacent spaces that contain or have
contained combustible or flammable liquids or gases;
- Spaces and adjacent spaces that contain or have
contained liquids, gases, or solids that are toxic, corrosive, or
irritant;
- Spaces containing materials or residues of
materials that create an oxygen-deficient atmosphere.
- Spaces that are oxygen deficient must be labeled
"Not Safe for Workers", and spaces that are oxygen enriched
must be labeled "Not Safe for Workers —
Not Safe for Hot
Work." [29 CFR 1915.12(a)]
 Back to Top |
|
Newsletter
RSS Feeds
