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An explosion roughly equivalent to 15 tonnes (16.5 tons or
33000 pounds) of TNT was the price a chemical plant paid for a shoddy temporary
fix.
The Nypro chemical factory, located in the small town of Flixborough,
Lincolnshire, was set up in 1969 to provide caprolactam, a base ingredient for
the production of Nylon in the UK. According to reports, residents of
Flixborough were not happy with its installation so close to their homes, and
their expressed safety concerns were made a reality years later.
The Incident
On June 1, 1974, a temporary bypass pipe was ruptured. The
pipe was connected to tanks containing cyclohexane, and within a minute, 40
tonnes of the plant's 400 tonne store of cyclohexane leaked from the pipe,
forming a vapor
cloud 320-650 feet in diameter.
After coming in contact with an ignition source, the cloud exploded,
destroying the plant and damaging some 1,800 buildings within a mile radius of
the site. A BBC news
coverage video provides a glimpse of the aftermath.
The disaster, which occurred on a weekend, killed 28 plant
workers and injured
36 others. Observers indicated that, had the explosion
happened on a weekday, more than 500 employees could have died.
An extensive
news report covered by BBC news details the events and the reactions of
some of the affected residents.
(Image left): The Nypro plant, post-explosion.
The Cause
The accident was due to the faulty construction of a
temporary bypass pipe. More than two months prior to the incident, a vertical
crack in reactor No. 5 was discovered to be leaking cyclohexane. As the tanks
were designed in series, a bypass line was made to connect the No. 4 and No. 6
reactors. The faulty and hasty modification was made with limited calculations
on its structural integrity. No calculations were undertaken to account for its
dog-legged shape, and no drawing of the proposal was formally produced.
 The Effect
The effect on British industry after the disaster was
significant. The Times newspaper
reported on November 12, 1975 that the loss of the plant put 35,000 jobs at
risk and cost the UK around €60 million in imports.
Coincidently, the Nypro plant (against the protests of
residents) began reconstruction in 1976, although it closed just two years
later after a large drop in the price of Nylon due to recession.
Lessons Learned?
The Flixborough disaster was an example of the risks
associated with design and system modification made without thorough
assessment. The bypass line installed in the plant was made quickly, likely in
order to minimize the costs and losses associated with suspended plant
operation.
Time constraints which result in quick fixes are
unfortunately common in all kinds of situations, albeit on a smaller scale. The
pressure to finish a job or provide a finished product often supersedes the
priority of doing it right or to its full potential, especially when the
consequences of a late project fall on the heads of only a few individuals.
Have you been a part of or witnessed any projects where "quick
fixes" had some undesirable consequences?
Sources:
Health &
Safety Executive
NZ
Safety Council - Flixborough - UK
Image Source:
AcuTech Consulting
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Re: Costly Quick Fix - Flixborough Disaster 1974
