Three High Potential Incidents involving H2S in oily water treatment occurred in 2006. Incident 1: The maintenance team was to replace a leaking bellows (rubber device on the discharge pipe of the oily water treatment unit). While the flange was being unbolted, oily water dripped out (problem of passing valve). The Mechanic doing the job inhaled H2S dissolved in water, fainted but recovered almost immediately. As the bellows had only a small leak, it was decided not to replace it.
Incident 2: A month after incident 1, around 20 people were attending a permit to work meeting in the Control Room when the same leaking bellows burst, and oily water reached the airlock door of the control room as the operators were leaving it. The H2S detectors, all set at 50 ppm, were triggered, including those in the Control Room. As the operator initiated ESD1, the oily water system was isolated. Several spare bellows units were quickly ordered from a local company and two of them were installed 2 weeks later.
Incident 3: One and half months later, one of the two new bellows installed after incident 2 ruptured (see Photo 1). The operator who saw the water jet alerted the Control Room and asked for activation of ESD1. The nearest H2S detector was triggered.