What happened

A cast-iron y-strainer ruptured during production of sulfurized isobutylene, releasing isobutylene that formed a flammable vapor cloud and ignited. The explosion killed one KMCO employee, seriously injured two others and injured at least 28 additional workers. Portions of the Crosby specialty-chemical facility were substantially damaged, and authorities imposed a one-mile shelter-in-place for more than four hours. The U.S. Chemical Safety Board found that the piping segment lacked pressure-relief protection, the brittle cast-iron component was unsuitable for the hazardous service, and KMCO lacked adequate remote isolation and emergency-response safeguards. The product was a lubrication additive; it should not be described as a confirmed gasoline or diesel additive.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.