# Presentation: 680394

## Fatal Incident Involving a Temporary Enclosure at a Chemical Facility

- From an OSHA Technical Information Bulletin

## Purpose

- Provide information
- Hazard alert
- Requirements and regulations
- Recommendations and guidance
- Other information

**Notes:**
The purpose of this presentation is to provide information on hazards within temporary enclosures by talking about an actual workplace incident at a chemical facility. This presentation is designed to be used as a short training tool for employees and first-line supervisors who may be exposed to similar hazards. This presentation contains information (PowerPoint “notes”) intended to aid a facilitator during the course of presenting the material to employees. 

This incident can alert workers and their supervisors to the potential existence of hazardous substances in enclosures that are in contact with or near to facility equipment.

This presentation will also talk about permit-required confined space regulations and requirements in order to provide guidance to workers and supervisors who work inside enclosures and permit-required confined spaces.   It will also provide information and links to other websites related to the incident.

## Incident Description

- Facility 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 Description

- Plastic-wrapped pipe
- New moisture-sensitive catalyst upstream

**Notes:**
To protect the open piping, plastic sheeting was wrapped around the ends of the pipe. 
Upstream from the open piping, new catalyst was installed in a reactor. 
As the catalyst was moisture-sensitive, on the night before the incident nitrogen gas (N2) was injected into the process. The injection point was some 150 feet upstream and several stories in elevation from the two open flanges.

## Incident Overview

## Incident Overview

- Nitrogen
- Purge

- Reactor with
-     Catalyst

**Open valves to north side open piping**

- In-Line Mixer (removed)

- Black Tarp

## Incident Description

- Southside open pipe & enclosure
- Midday black light inspection.
- Black tarps draped to block light.
- Workers entered enclosure.
- No problems with inspection.

**Notes:**
At midday, the two workers were to conduct a black light inspection of the 48-inch open flange surfaces for any oily residues which might contaminate the process.
To block out the sun, black tarps were draped over the ends of the 48-inch pipes.
The two workers entered the black tarp enclosure on the south side of the opening.
This inspection encountered no problems; a block valve between the injection point and the south pipe opening was closed, preventing the flow of N2.

## Incident Description

- North side open pipe & enclosure
- Midday backlight inspection.
- Black tarps draped to block light.
- Workers entered enclosure.
- Workers overcome upon entering.

**Notes:**
The two workers attempted to inspect the flange on the north side opening.
They were overcome almost immediately due to an oxygen-deficient atmosphere inside the temporary black tarp enclosure.
The oxygen deficiency existed because nitrogen flowing from the injection point to the north opening had displaced the oxygen inside the black tarp enclosure; no valve had been closed on this portion of the system.

## 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.

**Notes:**
N2 was flowing not only to the reactor, as intended, but throughout the entire piping system, including the open 48-inch north flange.
Because the piping system was complex, the worker: 
1) could have forgotten the N2 was in the process, or 
2) may not have realized that the process configuration would allow N2 to be at the open piping location.
This could have occurred despite the fact that one of the involved workers reportedly directed the nitrogen injection the evening prior to the incident.
OSHA cited Union Carbide for violations of 1910.146, Permit-Required Confined Space standard with respect to the incident. 

## Permit RequiredConfined 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 Hazard

- Can’t be detected by human senses
- N2 displaces oxygen in enclosures (confined spaces) resulting in oxygen-deficient atmospheres

## Human Response to Oxygen-Deficient Atmospheres

| Atmospheric Oxygen Concentration [%O2] | Possible Consequences |
| --- | --- |
| 19.5 | Meets OSHA minimum requirements for worker protection |
| 8-10 | Unconsciousness 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.

**Notes:**
Where an OSHA-defined permit-required confined space exists, employers must follow OSHA’s Permit-required Confined Spaces (PRCS) standard, 29 CFR 1910.146.
Even though all enclosures/spaces may not meet the OSHA regulatory definition for a permit-required confined space, when employees need to work in these types of enclosures, it is recommended that the OSHA PRCS requirements be followed to the extent practicable.
For temporary enclosures, other OSHA standards, such as 1910.134, Respiratory Protection, may apply. As it relates to this incident, all oxygen-deficient atmospheres must be considered immediately dangerous to life or health (IDLH) and 1910.134 applies. This standard requires the employer to develop and implement a written respiratory protection program which must address, among other things, respirator selection and emergency rescue procedures, along with respirator-related employee training. 
An employer’s permit-required confined space program needs to address the potential for temporary permit-required confined spaces in a facility. Temporary enclosures are most often created during maintenance and construction activities.

## Requirements, Recommendations, & Guidance

- Comprehensive confined space training.
- Particular attention on hazardous atmospheres

**Notes:**
The confined space training program needs to alert personnel to potential hazards which can be created by changes in the configuration of the workplace. Training needs to be provided to supervisors, employees and contract employees, etc.
When the potential exists for enclosure/confined space hazards, such as oxygen deficiency, toxic atmospheres, flammable atmospheres, etc., training must be conducted accordingly.

## Related Information

- OSHA Technical Information Bulletin on incident at: _[http://www.osha.gov](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