CGH2 cylinders truck collision

The incident occurred during delivery of a bundle of 28 cylinders to a metal manufacturing company. A hydrogen leak occurred due to due to a wrong operation of the the truck crane. While loading an empty bundle, the piping of a full cylinder was hit, casuing the leak.
Since the release could not be stopped by intervening at the leaking point, the fire brigade decided to vent the whole content of the pallet (246 m3) by gradually opening the valves and by keeping the rack cool.

The rack of the bottles was empty after four hours and the rescue operation ends at noon after the cylinder rack has been checked by an expert from the gas supply company. The residents returned to their homes and the plant's activity restarted one hour later.

The INITIATING cause was the mechanical damage of one of the compressed hydrogen cylinders, by an erroneous manoeuvring of the operator .

The ROOT CAUSE had two components a manoeuvre error and an inadequate safety design of the load. it should be possible to isolate the individual cylinders of the pallet before shipping, to minimise the hazard related to a leak on one of them.

cylinders

The accident took place when replacing the empty cylinders with full ones.

No consequence.

Since the leak could not be stopped locally, The fire brigade decided to drain the whole content of the pallet (246 m3) by gradually opening the valves and by keeping the rack cool.

The rack of the bottles was empty after four hours and the rescue operation ends at noon after the cylinder rack has been checked by an expert from the gas supply company. The residents returned to their homes and the plant's activity restarted one hour later.

A specialized expert emergency support cell estimated the leakage rate at 0.48 kg/s. They also estimated the distance to the Low flammability limit (LFL) about 30 m and the effects of an explosion in the event of delayed ignition of the cloud in the open air at 50 and 20 mbar over-pressure, for respectively 80 and 130 m.

The ARIA report (see references) does not mention any corrective action following the incident, but improved (safer) loading/unloading procedure would certainly be required.