19 April 2012 17:12 [Source: ICIS news]
HOUSTON (ICIS)--The US Chemical Safety Board (CSB) will urge DuPont to require monitoring for flammable vapours inside chemical storage tanks in the wake of a New York state plant accident that killed one worker and injured another, the panel said on Thursday.
The 9 November 2010, accident at DuPont’s Tonawanda plant near Buffalo killed a contract welder and injured another.
The safety board said sparks or heat from the welding, which took place on top of the tank, most likely ignited flammable vinyl fluoride inside a large process tank.
The CSB said a primary cause of the blast was “the failure of the company to require that the interior of storage tanks – on which hot work [welding] is to be performed – be monitored for flammable vapour”.
The Tonawanda plant produces polymers and surface materials for countertops, the CSB said. The process for making the products involves transferring polyvinyl fluoride slurry from a reactor through a flash tank and then into storage tanks, which are connected by an overflow line.
Although the tank being worked upon had been locked out of production, the CSB said flammable vinyl chloride had flowed through the overflow line into the tank to reach explosive concentrations.
“Although DuPont personnel monitored the atmosphere above the tank prior to authorising hot work, no monitoring was done inside the tank to see if any flammable vapour existed there,” the CSB said.
The CSB plans to vote on the final recommendations on Thursday.
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