Board to Conduct Full Investigation of Tank Explosion at Marcus Oil and Chemical

December 10, 2004

Washington, DC, December 10, 2004 - The U.S. Chemical Safety and Hazard Investigation Board (CSB) announced today that it is conducting a full investigation of last week's tank explosion at the Marcus Oil and Chemical facility in southwest Houston.

The blast on the evening of December 3 was felt up to 20 miles from the plant site. CSB investigators believe the accident occurred when a 40,000-gallon chemical storage tank exploded violently. The tank was approximately 10% full at the time of the event and contained a raw material used in the production of polyethylene wax. The explosion ignited large fires that burned for several hours, and two firefighters were injured during the emergency response. Off-site buildings near the facility including two churches, a house, and a social club exhibited structural damage, such as broken windows and cracked walls. One of the churches was also reportedly affected by smoke from a previous chemical fire at the facility in December of last year.

To determine the cause of the accident, CSB investigators will be examining fragments of the destroyed tank to determine the mode of failure; testing the quality of the nitrogen gas that was used to pressurize the tank; and analyzing records and other evidence to evaluate the physical integrity of the tank prior to the explosion. Preliminary information indicates that the tank had been welded and modified to install internal heating coils, and that the tank had no pressure-relief system, but no causal link has been established between these circumstances and the accident Friday night. Investigators are also drawing samples of chemical raw materials at the plant site.

According to Board member John Bresland, who accompanied the team, "An immediate priority will be to determine whether the tank simply failed due to excess pressure or if there was in fact an explosive event inside the vessel. In either case, this was a powerful blast that caused damage away from the facility and could readily have caused deaths or serious injuries. We will be working to determine the root cause of this accident in order to avoid similar accidents in the future."

CSB lead investigator Johnnie Banks will be available to the news media at 11 a.m. local time, Friday December 10, to discuss the announcement and the status of the investigation. The media availability will be conducted in the parking lot across the street from the plant entrance at 14549 Minetta, Houston. CSB media contacts for this event are (1) Jean Gonsoulin at 713-202-0972 cell; (2) Daniel Horowitz at (202) 261-7613 / (202) 441-6074 cell.

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. Typically, the investigations involve extensive witness interviews, examination of physical evidence, and chemical and forensic testing.

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. The Board designates formal responses to its recommendations as acceptable or unacceptable, open or closed. Further information about the CSB is available from


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