At a soaking facility of an industrial plant in the metallurgy sector, the pipeline between a supply tank and a feed pump became clogged and the autoclave only received sporadic feed. Problems had been experienced with the feed over several days. The pipeline was flushed with water to little avail. Because no feed was received in the autoclave, no oxygen could enter to maintain the pressure of the autoclave normally. The blockage was quickly cleared, as a result of which a large quantity of feed, and with it solids that were contained in the blockage, entered the autoclave. The autoclave had been fed with anolyte and sulfuric acid during the entire duration of the blockage. Additionally, the water used for flushing also entered into the autoclave.A powerful explosion occurred in an autoclave. The autoclave internals and five of a total of seven mixers sustained severe damage. The internals showed signs of warping, suggesting a sudden pressure increase inside the autoclave. Similarly, the damage to and dislocation of the entire section 1 cover, gear system and motor suggest that major forces have been involved. The explosion did not damage the externals of the pressure equipment.