ENBRIDGE ENERGY, LIMITED PARTNERSHIP

Incident Narrative

TANK 1607 WAS TAKEN OUT OF SERVICE IN ORDER TO PERFORM AN API 653 INSPECTION. THE TANK VALVE WAS REMOVED AND A BLIND FLANGE WAS INSTALLED (ON THE TANK SIDE END OF THE PIPING ASSEMBLY). TANK LINE HAD A CLAMP (DRESSER COUPLING) WITHIN THE TANK LINE PIPE ASSEMBLY. ON OCTOBOER 12, 2011 THE DRESSER COUPLING CONNECTION FAILED AND APPROXIMATELY 398 BARRELS OF OIL WAS RELEASED FROM THE PIPE COUPLING CONNECTION INTO THE BERM AREA. TANK INSPECTION WORK AT THE HARTSDALE TERMINAL WAS HALTED AND CREWS COMMENCED CLEAN UP AND TEMPORARY REPAIRS ON THE FAILED SECTION. AN INCIDENT INVESTIGATION COMMENCED AND IS ONGOING TO DETERMINE THE ROOT CAUSE AND POTENTIAL CONTRIBUTING FACTORS. CLEAN UP OF THE SITE HAS BEEN COMPLETED. UPDATE AUG 2012 THERE ARE TWO PRIMARY CAUSES FOR THIS INCIDENT: -LACK OF ADEQUATE LONGITUDINAL ANCHORAGE: THE LACK OF SUFFICIENT ANCHORAGE ALLOWED THE BLIND FLANGE PIPE PIECE TO SLIP OUT OF THE DRESSER COUPLING WHICH RESULTED IN A RELEASE OF CRUDE OIL WHEN THE LINE WAS PRESSURIZED. THE ANCHORAGE PROVIDED TO THE DRESSER COUPLING WAS TWO CHAINS, WHICH SPANNED ACROSS THE COUPLING AND WERE WELDED TO PIPES ON EACH SIDE. THESE CHAINS WERE NOT CAPABLE OF RESISTING THE END CAP FORCE GENERATED BY PRESSURE UP TO THE RATED CAPACITY OF THE FILL LINE PIPING (182 PSI). -FAILURE TO ISOLATE THE OUT-OF-SERVICE TANK LINE :THE DESIRED DOUBLE BLOCK AND BLEED CONDITION WAS COMPROMISED BY LEAVING THE ISOLATION VALVE THAT WAS CONNECTED TO THE TERMINAL MANIFOLD PARTIALLY OPEN FOR THERMAL RELIEF, WHILE EXECUTING A MANEUVER THAT PRESSURIZED THE MANIFOLD. UPDATE MAY 2013 APPROXIMATELY 512 TONS OF CONTAMINATED SOIL WAS REMOVED FROM THE SITE AND DISPOSED OF AT AN APPROVED LOCATION.