Non Evaluated Plant Mods cause incident
Original Basis of safety
The original basis of safety had postulated that there could be a double charge of caustic to a batch, this had been experimentally checked and found to be safe.
Later on the plant was modified, there was no cross checking with the hazards group, and a charge of 40 times the correct one was made in error. This led to the ejection of the batch contents. Fortunately no-one was hurt.
When a hazard has been identified and made safe, it is essential that later plant amendments be re-evaluated to ensure that the basis of safety is still valid