Hydrogen fire in a alcohols production plant

The fire occurred after a hydrogen released from a venting valve opened for inspection. The hydrogen was at 300 bar and 300C centigrade and between 200 and 300 bar. The hydrogen ignited probably spontaneously and killed 4 workers and injured additional 3.
A similar accident seems to have taken place in the same installation 5 years before. A safety study of the facility has been requested before the start-up of the plant

The INITIATING cause was the manual opening of a valve which released hydrogen

The root causes have not been identified even if a general test of the equipment involved in the fire and/or suspected to have caused the accident was carried out.

venting flange reactor(?)

DESCRIPTION OF THE PROCESS
The hydrogenation unit was part of an organic chemical industry for the production of raw hydrogenated alcohols from vegetable and animal raw materials.

4 causalities, 3 injured workers, 2.5 MEuro damage.

The isolation valves were shut-off and the Internal Emergency Plan was activated.
No emergency measures were required, neither on-site nor off-site.

An investigation was performed, which however it is not (anymore) publicly available.
Logic recommendations would be to improve the venting system to avoid mass release and fire, and to conduct a detailed analysis of previous similar event which seems to have taken place in the same installation 5 years previously (in 1984).