E.35 - Spark Finds Fuel—Risk Planning

While cutting a section near the tank vent, a spark ignited vapors coming from the vent. The fire flashed back through the vent’s malfunctioning flame arrestor, igniting vapors in the headspace. The pressure from the resulting fire separated most of the connections from the tank, including the flame arrestor, the level transmitter, a level switch, and inlet and outlet piping. The flat bottom of the tank also bulged and pulled off its foundation. Flaming methanol vapor discharged from vapor-space connections, burning the two workers and the crane operator. One burned worker fell to his death, one died from his burns, and the third was hospitalized for more than four months.
The Chemical Safety Board (CSB) investigators (Ref E.5) determined the facility’s engineering contractor had selected the wrong materials of construction for the tank and the flame arrestor. Consequently, the aluminum flame arrestor had corroded to the point it no longer functioned and the plastic tank could not withstand the pressure and stresses of the internal and external fire. The investigators further discovered the facility did not have a permit-to-work system, that it was seriously overdue on equipment inspection, and that its frequency of safety training had been steadily decreasing over the prior eight years. Based on interviews, the last training involving methanol hazards had occurred twelve years earlier. In its investigation report, the CSB made recommendations to regulatory agencies, standards organizations, and the engineering company that installed the methanol system. However, it made no recommendations to the facility, which is ultimately responsible for worker and process safety. Which culture factors could CSB have explored in this investigation? Did facility management and workers understand the hazards and risks of its processes? What caused the decrease in training frequency? Was the imperative for safety weakening?