Mechanical and thermal effects of simultaneous LPG tanks explosions in Dagneux, France, may 7th 2007

On May 7th , 2007, two 20 m3 tankers of propane exploded simultaneously, whereas a third one was rocketed without rupture. Although those explosions should be considered as BLEVEs, damage was rather mechanical than thermal because the vessels were almost empty. In a way, the explosions behaved as pneumatic bursts, with overpressure effects up to 400 m, and fragments projection up to 900 m. The fragments projection widely differed from the usual pattern, with a very high number of fragments (6 to 7 per vessel), and a main direction of propagation perpendicular to the vessels axis. Observations are consistent with calculations based on classical BLEVE modelling. The analysis confirms that safety distances for BLEVEs and pneumatic bursts should be given by fragment projection. The propagation of glowing fragments should also be considered as a main hazard