Early lessons from the Garden Grove chemical incident

In the suburban Los Angeles city of Garden Grove, California this past May, there was a rather unusual chemical manufacturing incident at GKN Aerospace. This facility housed large tanks of methyl methacrylate (one tank containing 24,700 litres), the monomer form of polymethyl methacrylate, a commonly used polymer. GKN management and Orange County first responders believed that the tank was overheating, and that it was reaching the temperature that methyl methacrylate would begin polymerising (over 40°C). That polymerisation is exothermic – that is, as those monomers were beginning to stitch themselves together in the tank, they were releasing heat. GKN could not empty the tank, nor stop the polymerisation. A chemical catastrophe was in the making.