NUSTAR LOGISTICS, L.P.

Incident Narrative

NUSTAR OPERATIONS PERSONNEL DISCOVERED A LEAK INSIDE NUSTAR'S WICHITA FALLS TERMINAL FACILITY. THE LEAK ORIGINATED FROM A 6-INCH RELIEF LINE PIPE SEGMENT BETWEEN THE PIPELINE RECEIVER TRAP AND THE TANK MANIFOLD INSIDE THE TERMINAL. THE LEAK WAS ISOLATED USING VALVES INSIDE THE TERMINAL FACILITY, AND A SEGMENT OF PIPE CONTAINING THE FAILURE HAS BEEN REMOVED FOR ANALYSIS TO DETERMINE THE CAUSE OF THE RELEASE. UPDATE - THE FAILURE WAS THE RESULT OF UNDER DEPOSIT CORROSION CAUSED BY A SEQUENTIAL PROCESS OF EVENTS THAT CAUSED CONTINUAL LOCALIZED CORROSION AND WALL-LOSS OVER TIME, LEADING TO EVENTUAL FAILURE. THE PROCESSES WERE INTERNAL AND STRONGLY DRIVEN BY THE PRESENCE OF SULFIDES AND CHLORIDES IN THE CRUDE, WHICH LED TO THE CORROSION OF THE IRON FROM THE WALL SECTION. THE ATTACK WAS ALSO DRIVEN BY EROSION CORROSION FROM INTERMITTENT FLOW THROUGH THE LINE WHICH REMOVED LOOSELY ADHERENT CORROSION PRODUCTS FROM THE WALL INTERIOR SURFACE TO ALLOW FOR CONTINUED CORROSION ATTACK AND LOSS OF WALL THICKNESS.