Leak during LH2 transfer

During a transfer of liquid hydrogen from a commercial tanker to a stationary receiving vessel, a leak developed in the bayonet fitting at trailer-vessel connection. The leak produced a hydrogen spray which enveloped the rear of the truck where the hand-operated shutoff valve was located. Emergency trained personnel, wearing protective clothing, except for proper shoes, entered area and shut off flow control valve. The personnel suffered frost-bite of their feet when shoes became frozen to water-wetted rear deck of truck.
[Ordin, NASA (1974)]

INITIATING CAUSE
A loose hose flange connection allowed leakage of cold fluid through the hydrocarbon­lubricated bayonet seal. This caused the cold fluid to enter in contact and shrink the "O" ring seal, which was made of rubber. The shrinking of the rubber ring caused the liquid hydrogen to leak into the atmosphere.

ROOT and/or CONTRIBUTING CAUSES
The hand-operated shutoff valve was not accessible because affected by the cryo-spill. This was a design shortcoming.
Why was the hose flange loose? This could suggests failing to carefully follow the procedures.
Why did the responders crew accessed the LH2 leakage one without the proper shoes protection? This could hint at a procedure shortcoming and/or to human errors.

connection hose

The event does not provide the number of injured persons. It is assumed that the team was consisting of 4 members

(i) The hand-operated shutoff valve would have been a safe guard, but it was not accessible because affected by the cryo-spill. All tank trailers should have a safely accessible auxiliary shut off valve in case of spills.
(ii) Escaping liquid or cryogenic gaseous hydrogen can surrounding freeze air. Personnel should always ware the prescribed personal protective equipment (PPE).