Washington, DC, February 7, 2006 - Investigators from the U.S. Chemical Safety and Hazard Investigation Board (CSB) have returned to the site of the January 31 explosion at the Synthron Inc. facility in Morganton, NC, which fatally burned one worker and injured about a dozen others. Synthron's maintenance chief, who initially survived the blast, died Sunday of his injuries.
Lead investigator Jim Lay, PE, and two other team members will be interviewing additional witnesses and developing an agreement governing site access and the handling of physical evidence.
Investigators believe the explosion was related to the process inside a 1500-gallon batch reactor at the plant, which contained butyl acrylate along with the flammable solvents toluene and cyclohexane. Workers had also added a chemical known as an initiator to cause the butyl acrylate to polymerize, or form long chains, a reaction that typically produces significant amounts of heat. The reaction is also accelerated by higher temperatures. Such reactions can go out of control, or run away, if heat can not be removed quickly enough. Five of the 167 serious reactive chemical incidents examined in a 2002 CSB hazard investigation report involved either butyl acrylate or related acrylic monomers.
At Synthron, the temperature of the reactor was controlled by a water-cooled condenser as well as jacket that could receive steam or cooling water. Witness evidence to date is consistent with the theory that control of the reaction was lost, resulting in a pressure increase and the release of flammable vapor from the reactor. Most employees left the building before the explosion, but a number were nonetheless burned or injured when the blast occurred. Some who were outside were thrown as far as 20 feet.
"Gaining access to the wreckage will be important in unraveling precisely what happened," Mr. Lay said. "We need to establish the exact configuration of the equipment, determine what kind of pressure relief system was in place, and characterize the damage caused by the blast." Mr. Lay said there were a number of safety and health issues to be resolved before investigators can approach the blast site. Facility structures suffered catastrophic damage, and some off-site buildings were also impacted.
CSB Chairman Carolyn W. Merritt said, "This was a very serious explosion that caused loss of life and widespread damage. We will therefore be conducting a full investigation to understand what happened and help protect communities from similar accidents in the future." CSB investigations typically result in written investigation reports, safety bulletins, case studies, or other products designed to prevent future accidents.
The CSB is an independent federal agency charged with investigating industrial chemical accidents. The agency's board members are appointed by the president and confirmed by the Senate. CSB investigations look into all aspects of chemical accidents, including physical causes such as equipment failure as well as inadequacies in safety management systems.
The Board does not issue citations or fines but does make safety recommendations to plants, industry organizations, labor groups, and regulatory agencies such as OSHA and EPA. Please visit our website, www.csb.gov.
For more information, contact Daniel Horowitz, CSB Director of Public Affairs, at (202) 261-7614 / (202) 251-5496 cell or Lindsey Heyl, Public Affairs Specialist, at (202) 261-3614 / (202) 725-2204 cell.