Explosion of a sulphuric acid tank - issue 225

An explosion occurred in an empty sulphuric acid tank as subcontractors attempted to open the manhole by shearing the seized bolts with a grinder. Two subcontractors and one plant technician were injured in the incident and the tank was completely destroyed.

The accident was caused by insufficient rinsing of the tank combined with a low concentration of sulphuric acid causing an acid attack on the metal. This led to the formation of hydrogen at the top of the tank, which ignited as the subcontractors carried out their work.