LH2 pump explosion and fire

The event occurred at a liquid hydrogen transfilling station, when filling a CGH2 tube trailer. The filling process had started 30 minutes before, and the tubes had reached a pressure of approximately 124 bar, when hydrogen started leaking from the cryogenic pump, causing an explosion followed by a fire. 

The operator executed the emergency procedure to shut down the pump and to close the pump supply line valves. The shutdown was followed by three smaller explosions, while apparently also a safety relief valve was venting hydrogen. The fires were extinguished by plant personnel before the arrival of the local 

There were no injuries.

The INITIATING CAUSE was a leak at the cold end packing of the liquid hydrogen pump. 
The IGNITION SOURCE was possibly static electricity or frictional energy on the cryogenic pump shaft. 
The event was investigated by experts, but the investigation report has not been shared publicly.  Based on the recommendation provided by H2TOOLS, it can be deduced that the probable ROOT CAUSE was a lack of timely and correct maintenance of the cryogenic pump. Factors enabling the maintain failure could be inadequate procedures, lack of effective training and lack of maintenance verification.

cryogenic pump,
tubes

There were no injuries from this incident and only a small amount of equipment damage with some floor charring.

The operator was notified by the noise of the loud explosion and saw flames and ripples from heat generation near the ground in the hydrogen fill area. 
The operator actuated the emergency alarm system, which shut down the pump and closed the pump supply line valves.
The local fire department was called to the scene and participated in the final shutdown of the hydrogen system as the fire was extinguished prior to their arrival. The partially filled tube trailer was disconnected and moved away from the incident area to a safe location. 

The timely and adequate response of the operator prevented the escalation to a more serious incident. The consequences were negligible. It shows that the training programme of the plant was effective. 
H2TOOLS provided the following recommendations: 

1. To verify maintenance procedures for liquid hydrogen systems and align them to manufacturer’s requirements. 
2. To ensure that personnel performing maintenance have the necessary training to work on liquid hydrogen pumps. 
3. To guarantee that maintenance works is documented and filed in the maintenance system.
4. To performed pump maintenance based on the number of service hours instead of on a fixed schedule. This can be facilitated by installing a hour meter on the pump.   
5. To communicate the incident inside the company, to discuss it at safety meetings, and to broadely share best practices .