Explosion in a pharmaceutical plant

A hydrogen gas holder exploded.
It is assumed that there was diaphragm leak in the hydrogen-oxygen electrolytic cell used to produce high purity hydrogen for a pharmaceutical hydrogenation.

The INITIATING CAUSE was a through the diaphragm of the electrolyser cell membrane, which caused injection of oxygen into the hydrogen stream flow, ending in the hydrogen storage.

The ROOT CAUSE is not reported, but it could be assigned to design (lack of measures of process parameters) and management (inadequate risk assessment).

electrolytic cell, diafragm, gasholder

The incident occurred at the hydrogen storage tank, but it was caused by a cross-over of oxygen into the hydrogen stream flow.
This incident occurred a lot of time before the incident reported in HIAD_970, occurred in Korea in 2019. Oxygen and hydrogen cross-over in the electrolytic cell is a well-known phenomenon. The severity of the occurrence depends on the electrolysis technology and the operative parameter, nevertheless it is a hazard which must be monitored, and its consequences prevented. Without proper diagnostic able to detect timely the formation of flammable mixture in the hydrogen line, this is not possible. Little is known about this incident, but an automatic system able to stop hydrogen production when concentrations trespass a threshold would have been able to avoid the creation of flammable mixture in the gas holder.