A CSB safety video about the June 21, 2019, fire, explosions, and toxic hydrofluoric acid (HF) release at the Philadelphia Energy Solutions refinery in Philadelphia, Pennsylvania. A severely corroded pipe elbow ruptured, releasing process fluid into the refinery’s HF alkylation unit, which then ignited. The incident caused the release of over 5,000 pounds of highly toxic HF, launched a 38,000-pound vessel fragment off-site, and resulted in an estimated property damage loss of 750 million dollars.