US CSB: runaway reaction caused Georgia chemical leak

16 April 2004 19:15  [Source: ICIS news]

HOUSTON (CNI)--The US Chemical Safety & Hazard Investigation Board (CSB) said Friday that the apparent cause of an accident that sent nearly 200 people to hospital in Georgia on Monday was a runaway reaction in MFG Chemical's effort to produce a new product.

The Washington, DC-based CSB said it will conduct a root-cause investigation of the 12 April accident that vented toxic allyl alcohol and hydrochloric acid into the Dalton, Georgia community near the MFG plant.

Based on initial data gathered by CSB investigators who have already visited the accident site, CSB reported that the incident began Monday evening when plant operators were preparing for the first full-scale batch of a new chemical product intended for use in the rubber industry. Seven plant employees were at the plant when the batch production process was initiated in a 4000/gal vessel.

CSB said the operators added allyl alcohol, cyanuric chloride and an unspecified catalyst to the vessel. "After the chemicals were added," the CSB reports, "the internal temperature in the vessel began rising rapidly. Increasing pressure burst the vessel's rupture disk, a safety device designed to protect a vessel from catastrophic over-pressurisation and failure."

"Heated chemicals were then forced through the vent line onto the first floor of the facility," CSB said, "forming a gas cloud that travelled out into the surrounding community." The runaway process generated hydrochloric acid which, along with allyl alcohol, was released into the community.

The release forced evacuation of residents within a quarter-mile of the plant and 184 persons were treated at local hospitals for possible chemical exposure. Six persons were kept overnight at hospital and released the following day.

CSB said the release also damaged vegetation in the vicinity of the plant and fish in a nearby stream were killed by contaminated water runoff from the accident site. Although there was no fire associated with the accident, responding fire fighters poured "a significant quantity" of water on the site to control the gas cloud and cool the processing vessel.

CSB board member Gerald Poje, who visited the accident site with CSB investigators, said in a statement: "The Board is seriously concerned about the public impact of a chemical release of this magnitude. Uncontrolled chemical reactions represent a significant safety problem throughout the country, and when toxic materials are involved there is a potential for serious adverse consequences for workers, residents and the environment."

A 2002 CSB investigation found that uncontrolled chemical reactions caused 167 serious accidents in the US between 1980 and 2001 and resulted in more than 100 fatalities and hundreds of millions of dollars in property damage.

The CSB said its root-cause investigation of the MFG accident will take several weeks. When completed, a report on the accident and lessons learned will be published, CSB said.

By: Joe Kamalick
+1 713 525 2653

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