Safe measures to mitigate the effects of a surrounding fire on gaseous hydrogen composite tube trailers.

Composite cylinders have been developed to increase the amount of hydrogen carried and higher pressure.

One of the major safety scenarios is a fire on a GH2 composite tube trailer which could be caused by a road accident or a large hydrogen leak, or a brake system fire.

When composite tubes are subjected to a surrounding fire, the mechanical performance of the multilayers and liner tightness degrades. Tubes will then leak or burst depending on pressure and temperature.

This enhances the need to depressurize the composite tubes in the event of a fire before degradation of the mechanical properties of tubes and burst. Due to the thermal insulation properties of the material, heat from the fire will not raise pressure in the cylinder significantly. Therefore, a pressure safety valve (opening in case of overpressure) is not suitable. A TPRD (Thermally activated Pressure Relief Device) is a right safety device to depressurize composite tubes in this case because TPRD opens automatically when its temperature threshold is reached (~110°C).

Recent road incidents showed the efficiency of TPRD to limit the consequences of a fire on GH2 composite trailers.