Over pressurisation of a LH2 trailer

An LH2 trailer had just delivered hydrogen to a customer. The vehicle exited the plant, weighted the trailer parked to get the weight receipt. While in the building, a safety device activated due to excessive internal vessel pressure. The vented hydrogen vapour ignited (possibly by static electricity) resulting in a vent stack fire.
Plant emergency responders, carrier safety departments, and shipper safety department were contacted. The incident was terminated successful, but the source does not explain how. Very probably, they left the fire extinguishing by itself. The hydrogen left in the tank after delivery was not in a liquid state, it was vapour only.

The investigation revealed that the trailer had lost the vacuum guaranteeing thermal insulation from external heat to the LH2 tank, resulting in an increase of the vapour pressure. The safety device functioned properly and no significant quantity of product was dispersed.
This trailer was safely removed from the site and taken to a qualified repair facility for further evaluation and repairs.

The INITIAL CAUSE was over-pressurisation of the LH2 tank, which triggered a hydrogen venting.
The ROOT or INTERMEDIATE CAUSE was a loss of the thermal insulation capacity of the tank, due to deterioration of the vacuum between the external and internal shells of the LH2 tank.

vacuum thermal insulation

The trailer was empty, having just delivered hydrogen to a customer site. Only gaseous hydrogen, no LH2 was left.

A negligible amount of hydrogen was released.