MID - VALLEY PIPELINE CO

Incident Narrative

ON 3/23/2023 AT APPROXIMATELY 01:03, THE KARNACK STATION SUCTION AND DISCHARGE VALVES CLOSED CAUSING AN OVERPRESSURE EVENT AND SHUTTING DOWN THE LINE. A TECHNICIAN WAS DISPATCHED AND UPON ARRIVAL CONFIRMED THE STATION VALVES WERE IN FACT CLOSED, BUT MAINLINE UNIT 1 WAS STILL RUNNING AND WOULD NOT SHUT DOWN UNTIL THE STATION VACUUM BREAKER WAS TRIPPED MANUALLY BY THE TECHNICIAN. APPROXIMATELY 12 GALLONS OF CRUDE OIL SPRAYED OUT INTO THE PUMP ROOM DUE TO PUMP SEAL FAILURE. ALL PRODUCT WAS CLEANED UP. INVESTIGATION DISCOVERED THAT A LOSS OF 48V D/C CONTROL POWER OCCURRED AND AS A RESULT THE STATION VALVES CLOSED INITIATING A STATION SHUTDOWN HOWEVER THE VACUUM BREAKER DID NOT TRIP WHICH IS NECESSARY TO SHUTDOWN THE PUMP UNITS AUTOMATICALLY. THE VACUUM BREAKER ALSO DID NOT TRIP DUE TO THE LOSS OF 48V D/C POWER. A 120V A/C PROTECTIVE TRIP CIRCUIT HAS BEEN INSTALLED IN PARALLEL TO THE EXISTING 48V D/C CIRCUIT TO PREVENT A FUTURE, SIMILAR OCCURRENCE IN THE EVENT OF A 48V D/C POWER SUPPLY PROBLEM. INSTALLED DUPLICATE CIRCUIT AND LOGIC AS WELL ON UNIT 2 AT KARNACK. ENGINEERING AND OPERATIONS HAS CONDUCTED ANALYSIS AT SIMILARLY DESIGNED STATIONS TO ENSURE THE SAME CONDITIONS WERE NOT PRESENT AND NO SIMILAR FINDINGS WERE IDENTIFIED. SUPPLEMENTAL REPORT: CHANGED ACCIDENT SUB-CAUSE TO MALFUNCTION OF CONTROL/RELIEF EQUIPMENT.