Hydrogen fire in an industrial gas production and treatment plant

A hydrogen leak caused a fireball in in an industrial gas processing and conditioning plant.
The leak occurred at the end of a hose in a packaging or transfer station, where tube trailers are refilled, ready to be tracked away.
The sound typical of an explosion was heard. The site's hydrogen supply was automatically cut off thanks to safety devices. Transfer was suspended while the source of the incident was determined.

The operator had just disconnected the hose used to fill a semi-trailer. He had done so to replace a check valve that was vibrating noisily during filling. The hydrogen supply was off, the automation had been switched to manual mode, and the hose had been purged and disconnected. Nevertheless, pressurised hydrogen entered the disconnected hose, causing the leak. The ARIA report explains the presence of hydrogen in the hose by the fact that the hose's anti-whip cable remained attached. This however does not make much sense, because an anti-whip cable is not a high-pressure connection and does not carry any gas.

The INITIATING CAUSE was the accidental release of hydrogen from a hose which should have been disconnected and emptied.

The explanation provided by the sources used for this event is flawed and cannot be used to extract a ROOT CAUSE, which could be only tentatively appointed to a human error.

hydrogen trailer, connecting hose, non-return hydrogen valve

The trailer filling had been stopped and the hose disconnected, to replace a malfunctioning check valve.

The operator in charge of filling was unhurt but shocked and a psychological support team was set up for.
No property damge or environmental impact.

The filling process was suspended until the cause of the incident was found.

Due to the lack of clarity on the causes of the leak, it is impossible to draw a specific return of experience from this event.

In general, it can be observed that the incident occurred during a ‘non-standard’ situation. An employee had to replace a malfunctioning valve. To do so, the automatic system in places during the ‘normal’ filling operations had been switched off. It is impossible to attribute the cause of the hydrogen explosion to a human error or to unclear procedures. Nevertheless, it is known that probability of a mishap increases, when operating high-pressure systems in manual mode and when executing an action not belonging to the series of actions to which employees are used to and execute every day.

Another reflection concerns the fact that the employee in charge was “…shocked, and a psychological support unit was set up for the employees.”
Despite the familiarity of employees with handling hydrogen and hydrogen systems, an unexpected event felt has life-threatening has a strong psychological impact. Moreover, hydrogen releases are characterised by very loud noises, an additional ‘ frightening’ element on top of a fire ball.