|
|
EPA investigated an explosion and fire
that occurred at the Accra Pac Group, Inc., North Plant Facility located
in Elkhart, Indiana. The incident took place on June 24, 1997 killing one
employee, injuring 59 others and prompting the evacuation of a 1-mile
radius around the plant. The Accra Pac facility produces various
pressurized containers, most of which are consumer aerosol products such
as hair sprays and deodorants.
The explosion took place in the Gas House, which
consists of a feed system where ethylene
oxide liquid from a storage tank is brought through a stainless steel pipe
to the Gas House at 55-65 pounds-per-square-inch-gauge pressure (psig). In
the Gas House, ethylene oxide is fed into the Graco pump, which is a
feed-booster pump, where ethylene oxide is pressurized to 600-650 psig and
then sent to the "under-the-cup" filling machine.
In the afternoon of June 24, 1997, the pump
that supplied breathing air to the operator in the Gas House stopped.
Unable to breathe without supplied breathing air, the operator was forced
to quickly shut down the filling operation and leave the Gas House. When
the pump was fixed and the operator returned to restart the process, he
noticed that an alarm indicating a high level of hydrocarbon vapor had
been triggered, exceeding 40% of the lower explosive limit (LEL). As the
operator exited the Gas House to investigate the alarm, a large explosion
occurred. The EPA Chemical Accident Investigation Team (CAIT) believes
that the explosion was caused by ethylene oxide vapor that had accumulated
in the Gas House. The vapor exceeded the LEL and contacted an ignition
source that initiated the explosion.
Root Causes
EPA identified the following root causes to
the incident:
-
Inadequate shut-down procedure
-
Location of the reclamation tank
inside the occupied Gas House
-
Lack of instrumentation to indicate
the level of ethylene oxide in the tank
- Lack of sufficient barriers or separation spacing between the Gas
House and the Production Building
-
Insufficient explosion venting to
permit adequate pressure release
-
Inadequate door design
- Use of electrical equipment that did not meet National Electrical
Code (NEC) requirements
Recommendations
- Establish safe emergency shutdown
devices and procedures for all operations.
- Relocate the reclamation tank to a
location outside the Gas House to reduce the amount of hazardous
material inside the occupied building.
- Develop a way to monitor the quantity of
material in the reclamation tank.
- Install a non-return check valve on the
reclamation tank.
- Properly locate and provide sufficient
barriers between units that have a potential for explosion from other
processes in accordance with NFPA 30, 5-3.2.2.
- Provide adequate deflagration venting
capability for the Gas House.
- Evaluate doors to ensure outward swing
action and latches that easily release under slight internal pressure.
- Limit the electrical equipment in the
Gas House to those that meet the NEC rating for the type of material
being processed.
- Ensure the maximum reliability of
breathing air systems.
- Relocate the feed charge pump (Graco or
similar).
- Perform process hazard analysis.
A copy of the full report is available at
the EPA web site, but be prepared for long load times (.PDF,
11 MB).
AcuSafe is a presentation of
AcuTech Consulting,
©2002, All Rights Reserved
|
