On Thursday night, a storage tank at an aerospace manufacturing facility in Garden Grove, California began behaving in a way that fire officials had never seen at this scale in their careers. By Monday morning, the catastrophic outcome they had spent four days preventing had been ruled out. About 50,000 residents were told they could begin returning home.
What happened in between is the story most of the weekend coverage missed.
The tank at GKN Aerospace’s Garden Grove facility contained approximately 6,500 to 7,000 gallons of methyl methacrylate — a highly flammable, volatile chemical used in the production of aerospace-grade plastics. Methyl methacrylate has a property that distinguishes it from most industrial chemicals: it is self-reactive. When it gets hot, it begins polymerizing — a chemical reaction that generates its own heat, which accelerates the reaction, which generates more heat. It is a self-feeding cycle that cannot easily be interrupted from the outside. You cannot neutralize it. You cannot drain it, because the tank’s valve had failed. You can only cool the outside and hope the inside stabilizes before the pressure becomes uncontainable…