Release and ignition of hydrogen during CGH2 transfer

During a gaseous hydrogen trailer filling operation, a burst disc relieved, causing a gas release. The gas flow caused the vent pipe to separate at the flared tube fitting, resulting in a fire. The fire caused three additional tubes in the gas trailer to relieve pressure (through their burst discs) increasing the intensity of the fire.

The INITIATING CAUSE was the burst disc failure, but no reason was given for this. The pulling away of the tube from under the SAE flared fitting indicated faulty assembly.
Causes of faulty assembly include:
(1) flare on tube too short (short flare is squeezed, then due to smaller area, tube is loosened), (2) nut too loose, (3) tube end not squarely cut,
(4) foreign material in joint when tightened, (5) split flare.

This suggests that the ROOT CAUSES were a combination design and installation shortcomings, possibly assisted by not enough specific procedure.

burst disc