Fire and explosion in a chemicals plant

The process unit affected by the incident was a two-step production, consisting of i) hydrogenation of phenyl acetyl carbinol with benzyl amine in a isopropyl alcohol/water mixture by means of a catalyst ii) removal of the catalyst and further hydrogenation of the solution.

At the moment of the incident the operator was starting the first step of the hydrogenation. A first fire, detected by the automatic fire alarm, was followed by a hydrogen leak and explosion, fed by the release of additional chemical agents.

One fatality and three first responders were affected by the smoke.

According to the investigation described by the ARIA report, the most likely accident scenario was as follows:

a) the isopropanol pipe had been fitted with a bypass featuring steel/glass discontinuity with a double enclosure to protect the glass portion of the pipe. Despite the operating procedure notification, the steel side of the valve had never been closed, triggering a 3.5-bar pressure surge on the glass/metal discontinuity each time the pump started.

b) Rupture of the glass device caused an isopropanol leak, eventually forming an explosive atmosphere and resulting in an ignition.

c) The adjacent hydrogen pipeline, exposed to strong heat failed, and the released hydrogen caused an explosion.

d) Moreover, the fire led to a short-circuit, cited as the reason for a malfunctioning phenylacetylcarbinol pump, which in turn helped feed the blaze.

The INITIATING cause was the rupture of a pipe with iso-propanol release and ignition and domino effect to the hydrogen line and later to other chemicals.

However, various operative and design deficiencies were found during the investigation, so that the root cause is of an organizational nature

Low pressure hydrogenation unit in a chemical plant.

At the moment of the incident the operator was starting the first step of the hydrogenation process

One operator died and three members of the fire brigade were injured by smoke.
The plant has been destroyed completely. The costs of damage reached several million marks.

Investigation were difficult due to the complete destruction of the plant, including operation procedures and records.

One of the source reports that water was spayed on the tank during the emptying operation. It is unclear why.