A maintenance operation as underway in the wastewater treatment facility of a metallurgical plant. A pipe from the used caustic soda transfer system was leaking into its containment area. The site’s maintenance personnel carried out the repair, and a chemical waste collection company pumped out and cleaned up the containment area.

To purge the pipe, the maintenance technician actuated a valve, allowing the air to enter but also unknowingly activated the transfer pump. The pump’s outlet valve was closed and the pressure in the system increased until the pipe burst. The caustic soda was sprayed onto the door of the pump’s tank which opened. The caustic soda was sprayed a distance of 3 m high and 5 m long toward the building’s door, reaching one of the subcontractors, who was wearing protective eyewear, at the eye and lip level. A second maintenance technician closed the valve and assisted the injured individual.

The causal analysis performed by the operator revealed problems in the design of the transfer system, particularly difficulties concerning the maintenance of the piping. Furthermore, a lack of awareness regarding specific risks inherent in the design of the system, such as the air valve connected to the pump, was also called into question.

The operator plans to draft station operation procedures and train the personnel.