Explosion in an industrial gas plant

Works at the power grid of a hydrogen production unit were at the origin of the following accedental sequence:
1. Fusion of a safe fuse triggering the closure of a valve on the manifold of a pistons compressor, whose function was to raise the pressure from 50 mbar at the exit of the gasometer to 250 bar.
2. As a consequence of the closure of the valve, the dome of the gasometer filled with hydrogen up to the maximal level, after which the regulation valve of the storage system closed.
3. At this moment, a zone of under-pressure at the aspiration pipe of the compressor, causing the suction of air from outside, which formed with hydrogen an explosive mixture which auto-ignited.
4. The explosion caused the failure of the pressurised system: two pressure vessels, pipes and other parts of the plant were largely damaged, including the brick building hosting the unit.
5. Three plant keepers, which were in the near building, were seriously injured by an iron pieces breaking into the building.

Human failure during repair works that led to the malfunctioning of the hydrogen-high pressure condenser.

pressure condenser, pipe, water trap, plastic tube, hydrogen production unit, hydrogen compressor,

Works were executed at the power grid of the of the installation.

Two plant keepers, which were in the near building, were seriously injured by an iron pieces breaking into the building.
More than 3 MEuro of material damage.

A local hydrogen fire on a near measurement pipe was extinguished.

The measurement and control systems necessary for the continuation of the electrolysis operation were examined, the pipes open towards hydrogen outlet and air inlet were closed. The electrical supply of the condenser plant was controlled.

reported by the referred source states: "The building of the compressor plant has to be remade in light structure (design change)."

It seems a rather limited conclusion, focussing to mitigate the consequence of similar accidents.