Fatal Incident Involving a Temporary Enclosure at a
Chemical Facility
From an OSHA Technical Information Bulletin
PurposeProvide informationHazard alertRequirements and regulationsRecommendations and guidanceOther information
Incident DescriptionFacility unit undergoing a turnaround.2 workers to inspect the flange surfaces
of an open 48-inch piping system.Piping system opened to remove a
piece of process equipment for cleaning.
Incident Overview
N2
Injection
Reactor w/new catalyst
Open 48" Piping
Open Valve
Closed Valve
N2 Venting
Note: Actual process/piping significantly more complex. N2 injection point 150' and several stories in elevation from pipe opening.
North
South
Incident Overview
Nitrogen Purge
Reactor with Catalyst
Open valves to north side open piping
In-Line Mixer (removed)
Black Tarp
Incident DescriptionSouthside open pipe & enclosure
Midday black light inspection. Black tarps draped to block light. Workers entered enclosure. No problems with inspection.
Incident DescriptionNorth side open pipe & enclosure
Midday backlight inspection. Black tarps draped to block light. Workers entered enclosure. Workers overcome upon entering.
Incident Conclusions One worker died, another hospitalized.N2 throughout system.
Piping system was not straightforward.OSHA cited the employer for 1910.146
Permit-Required Confined Space violations.
Permit RequiredConfined Space Hazards
Oxygen deficiency Flammable atmosphere Toxic atmosphere Oxygen enrichment Chemical exposure Thermal hazards Electrical shock Temperature extremes
Engulfment Mechanical hazards Trapping/Pinch points Physical hazards Slips, Trips, Falls Unstable working surface Structural failure Other recognized hazards
Nitrogen HazardCan’t be detected by human sensesN2 displaces oxygen in enclosures
(confined spaces) resulting in oxygen-deficient atmospheres
Human Response to Oxygen-Deficient Atmospheres
Atmospheric Oxygen Concentration [%O2]
Possible Consequences
19.5Meets OSHA minimum requirements for worker protection
8-10Unconsciousness without warning; so quickly that individuals cannot help or protect themselves
6-8 Fatal injury < 6 minutes
4-6 Coma < 40 seconds with subsequent death
Requirements, Recommendations & Guidance
If space meets the definition of a PRCS, must follow 1910.146.
Even if not technically a PRCS, 1910.146 recommended.
Other OSHA standards may apply: 1910.134 – Respiratory Protection
IDLH Atmospheres
Recognition that temporary enclosures may be PRCSs.
Requirements, Recommendations, & Guidance
Comprehensive confined space training. Particular attention on hazardous
atmospheres
Related Information OSHA Technical Information Bulletin on
incident at: http://www.osha.gov
CSB Morten Report at: http://www.csb.gov/reports/1998/union_carbide/98005lafr.htm
OSHA PRCS Standard, Directive and Interpretation at: http://www.osha.gov