Preliminary Findings Confirm Blast
at West Pharmaceutical Services in Kinston, NC, Was a Dust Explosion
Fueled by Plastic Powder Used in Manufacturing
(Kinston, NC - June 18, 2003) Investigators
from the U.S. Chemical Safety Board (CSB) told a community audience
here tonight that last January's massive blast at medical device
maker West Pharmaceutical Services, which killed six workers and
injured dozens more, was in fact an explosion of fine plastic powder
used in the manufacturing of rubber products.
The dust explosion occurred above an
area where rubber strips were coated with moistened polyethylene
powder, investigators told the audience at the Kinston High School
Performing Arts Center auditorium. Although made from a plastic
similar to that in milk jugs, the powder when dry is as fine as
talcum and is capable of forming explosive mixtures in air, according
to CSB test results made public today.
"We held this meeting to brief
the community on our findings to date and hear from members of the
public who were affected," said CSB Chairman Carolyn Merritt,
who presided at the session. "The full Board will convene here
in Kinston when the staff investigation is concluded to issue our
final safety recommendations in this case. The Board is deeply concerned
by this event and the subsequent plant explosion in Corbin, Kentucky,
which claimed seven lives. The dangers of explosive dust are not
well known, and helping industry to understand this insidious hazard
certainly will be a priority."
According to CSB lead investigator
Stephen Selk "Our testing has now confirmed that actual polyethylene
powder recovered from the plant ruins is explosive when mixed with
air. The material contains enough energy to account for the level
of destruction we observed," Selk continued. He also noted
the heavy damage had thus far prevented his team from determining
the source of the ignition that triggered the dust explosion.
"The polyethylene powder was used
as a nonstick coating for rubber sheeting made at the plant,"
Selk added. "During the production process, the plant's ventilation
system drew fine dust particles into the space above an unsealed,
suspended ceiling, where the dust settled and built up."
CSB Investigator Angela Blair told
the group that on January 29 the five conditions necessary for a
dust explosion were all met at the West plant: fuel, oxygen, dispersion,
confinement, and ignition. "The dust was the fuel. Dispersed
in the air, it formed an explosive mixture," Blair said.
Blair explained that by installing
a suspended or false ceiling years earlier, the company had inadvertently
created an area where dust could accumulate out of view, and also
created a space where a dust explosion could occur and spread. It
is for these reasons, Blair added, that unsealed ceilings are not
recommended where hazardous dusts may be present.
Blair said investigators had recovered
numerous ceiling tiles that were scorched exclusively on the upper
surface, confirming the origin of the dust explosion within the
overhead space. "Eyewitnesses heard a sound like rolling thunder,
as a rapidly expanding chain of explosions moved through the ceiling
space and literally tore the building apart."
Blair and fellow investigator Lisa
Long described the sequence of events that ultimately led to the
accumulation of dust. Raw materials from a ground-level process
area called the "kitchen" were conveyed to a large mixer
on the upper floor, where the rubber was blended. The rubber mass
was then dropped through a chute to a mill back on the lower level,
where it was rolled into flat strips. The rubber strips were then
fed through rollers and coated using a tank of polyethylene powder
slurried in water.
Ms. Blair said, "Once the rubber
was dry, what remained on the surface was a baby powder-like coating.
But in the course of drying the rubber, fans blew some of the fine
powder into the air. Much of the dust settled in the processing
area, where the company had a regular program to clean the dust
from equipment, walls, and floors. However, some dust also migrated
through small openings in the suspended ceiling, drawn by air conditioning
intakes located overhead. Over time the dust accumulated above the
ceiling -- out of normal view -- on tiles, conduits, ducts, and
Lead investigator Selk pointed out
that weeks prior to the explosion, maintenance workers had seen
layers of dust coating surfaces above the suspended ceiling. "Tragically
there was no recognition of the explosion hazard posed by this accumulated
dust," Selk said.
The CSB so far has conducted 93 detailed
interviews of witnesses to the West explosion, including plant workers
and residents, and participated in or reviewed the results of 177
additional screening interviews conducted by the Bureau of Alcohol,
Tobacco and Firearms (ATF). The ATF investigation found the blast
was not the result of any criminal act.
The CSB is an independent federal agency
that investigates chemical accidents, determines root causes, and
issues findings and safety recommendations to prevent recurrence.
Sandy Gilmour 202-251-5496 (cell) -
Daniel Horowitz 202- 441-6074 (cell) - North Carolina
Robert Wager 202-261-7636 - Washington, DC