Conventional fire on a CGH2 trailer

The trailer experienced a tire/wheel fire at the rear of the tube trailer. The fire deteriorated the hand valve packing on one of the tube causing a slow leak of hydrogen. The trailer consisted of 10 tubes and only 1 of the tubes leaked. The road was closed due to the fire.
[Note of the event validator: the PHMSA report does not mention any hydrogen ignition. However, the local news quote a fire birgade report which speaks of two fires: the one caused by the orignal conventional axle fire, easy to be extinguised, and a second one engulphing the trailer cabinet, which took much more time to get under control]

The INITIATING CAUSE was a conventional fire on tire following brake failure.
One gasket in the packing assembly was damaged by the heat, what resulted
in a very small hydrogen leak.
The ROOT CAUSE is unknown.

valve

DESCRIPTION OF THE UNIT
This trailer unit consisted of 10 tubes.
The individual report provides values in Gas-Pound, which are easy to convert into kg of hydrogen. According to this report, the total nominal transport capacity was 640 pounds (290 kg), but the quantity transported at the moment of the incident was 420 pounds (191 kg).

This small incident, almost a near miss considering the very low amount of hydrogen vented, did not have any noticeable consequence. Nevertheless, similar cases started with conventional fires caused the mass venting of the whole hydrogen load, because the pressure relief valve were thermally or pressure-activated. Such a case has to be avoided when the trailers are in a confined space, such as a tunnel.