On February 19, 1999, a process vessel containing several hundred pounds of hydroxylamine exploded at the Concept Sciences Inc. production facility near Allentown, Pennsylvania. Employees were distilling an aqueous solution of hydroxylamine and potassium sulfate, the first commercial batch to be processed at the facility. After the distillation process was shut down, the HA in the process tank and associated piping explosively decomposed, most likely due to high concentration and temperature. Four CSI employees and a manager of an adjacent business were killed. Two CSI employees survived the blast with moderate-to-serious injuries. Four people in nearby buildings were injured. The explosion also caused significant damage to other buildings in the Lehigh Valley Industrial Park and shattered windows in several nearby homes.

KEY ISSUES:
• HAZARDS OF PROCESSING HYDROXYLAMINE
• PROCESS HAZARDS EVALUATION
• CHEMICAL FACILITY SITING

ROOT CAUSES:
1. CSI’s process safety management systems were insufficient to properly address the hazards inherent in its HA manufacturing process and to determine whether these hazards presented substantial risks.
2. Inadequate collection and analysis of process safety information contributed to CSI’s failure to recognize specific explosion hazards.
3. Basic process safety and chemical engineering practices – such as process design reviews, hazard analyses, corrective actions, and reviews by appropriate technical experts – were not adequately implemented.
4. The existing system of siting approval by local authorities allowed a highly hazardous facility to be inappropriately located in a light industrial park.

Image Credit: CSB