An explosion occurred within the hydrogen processing system of a chemical plant that produces sodium chlorate for bleaching pulp and paper. The chemical process utilizes electrolytic cells and is pH-dependent. Hydrogen is produced as a byproduct and is utilized as a fuel.

At the time of the incident, the plant was at an abnormal operating level of 25% capacity. A non-routine maintenance operation to repair high-pH liquid piping was in progress. To assist, operations personnel rerouted the high-pH liquid stream to the plant sump. However, in doing this, the liquid eventually made its way back into the electrolytic process by design. Ultimately this created the root cause of the explosive condition in that the pH of the electrolytic process increased faster than the computer- view more

Overview
A solution of potassium carbonate was being drawn off to an inventory tank for a turnaround/shutdown maintenance activity at a refinery's hydrogen production unit. On the day of the incident, the solution level in the tower wasn't checked as it should have been, which resulted in hydrogen gas flowing back into the tank until the increased pressure caused the tank to explode. The direct cause of the incident was the workers neglecting to check the solution level in the tower. It is not known whether the potential for backflow of hydrogen gas into the inventory tank was understood beforehand or not.

Incident Synopsis
An explosion occurred due to unexpected backflow of hydrogen gas while a solution of potassium carbonate was being drawn off to an view more

Incident Synopsis
A technician was welding a cable suspended over a stainless steel H2 instrument line. During the welding process, two holes were accidentally burned through the hydrogen tubing. The operator heard a hissing sound and closed the valve, but the hydrogen had already ignited and it burned his hand while he was feeling for a leak.

Cause
A short during welding caused the pinholes in the tubing containing the gaseous H2.