Release from hydrogen cylinders storage of a chemical plant

A leak occurred on a rack containing 12 cylinders of hydrogen (50 l at 200 bar each) delivered by a lorry inside the fenced storage area of a bulb manufacturing plant.

The plant’s safety manager closed access to the area, had the other lorry drivers on the site cut off their ignitions, and made them evacuate. The firefighters tested the air with an explosimeter and stopped the leak by closing the gate valve located on the outside of the rack. The valve was used to transfer hydrogen from the cylinders to their points of use.

The rack had been delivered by a crane lorry. Each of the top four corners of the rack was fitted with a steel ring that was used to lift the rack off the lorry. The gate valve was opened when one of the four lifting chains used to lift the rack off the lorry accidentally wrapped around it.

INITIATING cause was the accidental opening of the main hydrogen valve during unloading of the lorry.

cylinders

The lorry had been delivered to destination and the unloading of the rack of hydrogen cylinders was ongoing by means of the lorry crane

The ARIA report (see references) does not provide quantitative assessment of the amount of hydrogen released.

According to the ARIA report (see references), the operator took the following two corrective measures:
i) stopped deliveries of this type of rack ,
ii) replaced it by one with 16 cylinders, fitted with a cover and a central lifting ring.