A densely populated area of greater Los Angeles became intimately familiar this past weekend with the term “BLEVE” (rhymes with “levee”). BLEVE is an acronym for “boiling liquid expanding vapor explosion.” While BLEVEs can involve a vast range of materials, in this case, the BLEVE resulted from an unwanted polymerization reaction occurring at the GKN Aerospace factory in Garden Grove, CA.
The fire department spent days spraying water on the site, and 50,000 people were ordered to evacuate.
While the full details of this incident are yet to be determined, the well-known chemical characteristics and reactivity of the chemicals involved make it easy to provide the big picture of what occurred and what might have occurred had the diligent fire department not intervened.
The chemical process behind the incident
The GKN facility had an approximately 7,000-gallon tank for storing methyl methacrylate (MMA). The MMA would have been pumped to different equipment and used as part of a polymerization process. Pure MMA can start polymerizing by itself to create polymethyl methacrylate (PMMA), more commonly known by the trade name Plexiglas. Unfortunately for GKN, the MMA started polymerizing, and their storage tank unintentionally became a reactor. Why this started isn’t clear and may never be known. MMA typically contains inhibitors to prevent an auto-reaction, but they don’t appear to have worked in this case…