National Transportation Safety Board
Office of Public Affairs
Washington, DC - The National Transportation Safety Board today recommended that the U.S. Department of Transportation modify current federal regulations addressing the adequacy of mobile acetylene trailer design for protection during transport and the effectiveness and safety of current unloading procedures. Additionally, the Board asked the Compressed Gas Association to review its standard for fire suppression systems at loading and unloading facilities for these vehicles.
These three recommendations were part of a Safety Board special investigation report that involved highway vehicles transporting bulk quantities of acetylene, a colorless flammable gas used for welding and the heat treatment of steel, that becomes unstable at elevated pressures. The Board conducted a special investigation of mobile acetylene trailers to address the safety issues uncovered.
Acting Chairman Mark Rosenker noted, "Though accidents involving mobile acetylene trailers are not common, the consequences of a release of this gas could be catastrophic." Rosenker continued, "Not only must prescribed procedures for handling such hazardous materials be closely followed, but it is critical that all containers are secured and protected every step along the way."
The accidents included in the study occurred between July 25, 2007, and June 9, 2008. Two accidents addressed in the special investigation involved overturned vehicles and two occurred while the vehicles were being prepared for unloading.
During the overturn accidents, the cylinders mounted on each trailer were thrown from the vehicles, and their valves were broken off, releasing acetylene, which ignited. The cylinders in these two accidents had not been secured to the trailers to prevent their ejection during overturn. In one of the unloading accidents, the fire on the initial trailer spread to cylinders on an adjacent trailer, and in the other, the fire spread to cylinders on adjacent trailers, nearby buildings, and vehicles.
The failures of the cylinders on these mobile acetylene trailers and the resultant damage raise concerns about the accident protection provided by these vehicles and the adequacy of the minimum safety standards and procedures applicable to unloading these vehicles, the Board said.
A copy of the report, including a complete list of the conclusions and safety recommendations, can be found on the Board's website.
NTSB Office of Public Affairs: (202) 314-6100
The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.