The Technical Safety Authority of Saskatchewan (“TSASK”) has finalized its investigation into the December 24, 2013, explosion at the Co-op Refinery Complex (“CRC”) in Regina. The investigation has concluded that a bypass line of Polymerization Unit 27 froze following a maintenance procedure. The stress of the freezing process ruptured the bypass pipe. Once the air temperature warmed, the petroleum product was released through the line, resulting in an explosion and subsequent fire. The event was not related to a malfunction of pressure equipment.