Mobile Acetylene Trailer Accidents: Fire During Unloading in Dallas, Texas, July 25, 2007; Fire During Unloading in The Woodlands, Texas, August 7, 2007; and Overturn and Fire in East New Orleans, Louisiana, October 20, 2007

​Abstract: The National Transportation Safety Board investigated three accidents that involved highway vehicles transporting bulk quantities of acetylene gas that occurred in 2007 and reviewed reports of a 2008 overturn accident of another vehicle. The vehicles, called mobile acetylene trailers, carried up to 225 cylinders that were connected by a manifold system and filled with acetylene. Two of the accidents occurred as the vehicles overturned on public highways, and two of the accidents occurred while the vehicles were being prepared for unloading. In the two overturn accidents, cylinders were ejected from the trailers and damaged, releasing acetylene, which ignited. In one unloading accident, the fire on the initial trailer spread to cylinders on an adjacent trailer; in the other, the fire also spread to nearby buildings and vehicles. The failures of the cylinders on these trailers and the resultant damage raised concerns about the accident protection provided by these vehicles, the adequacy of the minimum safety standards and procedures applicable to unloading these vehicles, and the adequacy of fire suppression systems at loading and unloading facilities.

The safety issues discussed in this report are adequacy of mobile acetylene trailer design for protecting cylinders during transport, effectiveness and safety of unloading procedures for mobile acetylene trailers, and adequacy of fire suppression systems at mobile acetylene trailer loading and unloading facilities.

As a result of this special investigation, the Safety Board makes safety recommendations to the Pipeline and Hazardous Materials Safety Administration and the Compressed Gas Association.


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