Guarda Streamingcommunity. This U.S. Chemical Safety Board (CSB) video uses expert testimony and computer-animated reenactments to describe and discuss its detailed investigation into the March 23 2005 explosion of the ISOM (isomerization) unit at the BP (British Petroleum) refinery at Texas City, Texas. The explosion killed 15 workers, injured 180 others, and cost BP billions of dollars.