MID - VALLEY PIPELINE CO

Incident Narrative

ON 7/5/23 AT APPROXIMATELY 16:18 ET THE CONTROL CENTER RECEIVED A LINE IMBALANCE ALARM AND BEGAN SHUTTING THE PIPELINE DOWN. INVESTIGATION INTO THE ALARM BEGAN WHILE THE LINE WAS SETUP FOR A STATIC PRESSURE TEST TO CONFIRM INTEGRITY. AERIAL PATROL WAS INITIATED, AND THE STATIC TEST WAS COMPLETED WITH NO INDICATION OF A RELEASE. THE LINE IMBALANCE WAS BELIEVED TO BE DUE TO A MEASUREMENT ISSUE. THE LINE WAS CLEARED FOR RESTART AT APPROXIMATELY 21:04. AT APPROXIMATELY 22:00 AERIAL PATROL IDENTIFIED A STAIN ON ROW NORTH OF CYGNET. LINE WAS SHUTDOWN AGAIN AT APPROXIMATELY 22:04. APPROXIMATELY 2 BARRELS OF CRUDE OIL RELEASED TO THE SOIL. OIL SPILL RESPONSE CONTRACTORS WERE MOBILIZED TO CLEANUP RELEASED PRODUCT. A PLIDCO CLAMP WAS INSTALLED ON 7/6/23 AND THE LINE WAS RESTARTED ON 7/7/23. AFTER ILI ASSESSMENT THE FAILED SECTION WILL BE CUT OUT AND REPLACED. THE FAILED SECTION WILL BE ANALYZED FOR CAUSE AND A SUPPLEMENTAL REPORT WILL BE FILED. SUPPLEMENTAL: THE FAILED SECTION OF PIPE WAS CUT OUT AND REPLACED IN JANUARY 2024. THE FAILED SECTION WAS SENT FOR METALLURGICAL ANALYSIS. THE CAUSE OF THE FAILURE WAS DETERMINED BY METALLURGICAL ANALYSIS TO BE A LEAK LOCATED AT A COLONY OF AXIALLY ORIENTED, INTERLINKED NEAR NEUTRAL PH STRESS CORROSION CRACKS THAT WERE LOCATED AT AN AREA OF EXTERNA CORROSION AND A DENT. AN ULTRASONIC CRACK TOOL ILI ASSESSMENT WAS CONDUCTED IN DECEMBER 2023. TOOL DATA WILL BE REVIEWED FOR SIMILAR ISSUES ONCE RECEIVED AND REMEDIAL MEASURES TAKEN ACCORDINGLY.