Following a malfunction on a hydraulic pump used to test 115-m³ tanks, a subcontractor completed his operation with a bottle of compressed oxygen. A valve failed beneath one of the tanks undergoing testing and struck a pipeline connected to an adjacent tank. A liquefied gas leak ignited and the tank exploded (BLEVE-type explosion) 20 min later. Two workers died and 6 others were injured. Property damage was confined to the site boundary.