NATURAL GAS PIPELINE CO OF AMERICA (KMI)

Incident Narrative

ON THE AFTERNOON OF JUNE 24, 2020, EMPLOYEES AT NATURAL GAS PIPELINE COMPANY OF AMERICA, LLC (NGPL) STATION 199 WERE PERFORMING OPERATIONAL TESTS ON THE BACKUP COMPRESSOR UNIT. WHEN THE TESTS WERE COMPLETE, THE EMPLOYEES STARTED THE SHUTDOWN PROCESS ON THE UNIT AND CHECKED IN THE STATION PLC THAT ALL UNIT VALVES WERE IN THE PROPER POSITION BEFORE LEAVING THE SITE FOR THE DAY. WHEN EMPLOYEES ARRIVED ON SITE THE NEXT MORNING, JUNE 25, 2020 AT 8:07, THEY DISCOVERED THAT GAS WAS VENTING AND CONFIRMED DISCOVERY OF AN INCIDENT. THEY DETERMINED THAT THE 36 INCH DISCHARGE MANIFOLD VALVE ON THE UNIT WAS NOT FULLY CLOSED, DESPITE INDICATING CLOSED ON THE PLC. THIS THEREFORE ALLOWED GAS TO CONTINUE TO VENT. THE EMPLOYEES MANUALLY CLOSED THE VALVE TO STOPPED THE RELEASE AND INITIATED THE ERL PROTOCOL. DURING THE ERL CALL THE INCIDENT WAS DEEMED REPORTABLE AND THE CALL TO THE NRC WAS INITIATED AT 9:01. HOWEVER, DUE TO HOLD TIMES, THE REPORT WAS NOT TAKEN UNTIL 9:17. THE INVESTIGATION IN TO THE RELEASE REVEALED THAT A CRACKED AND PUNCTURED VALVE DIAPHRAGM WAS RESPONSIBLE FOR THE BLOCK VALVE'S FAILURE TO FULLY CLOSE. THE PILOT OPERATOR WAS REPAIRED BY REPLACING THE DAMAGED DIAPHRAGM WITH A NEW DIAPHRAGM. IN ORDER TO PREVENT A REOCCURRENCE, ALL CONTROL DIAPHRAGMS ON SIMILAR PILOT OPERATING VALVES AT THIS STATION WERE INSPECTED AND REPLACED. FINALLY, A PRESSURE MONITORING ALGORITHM WAS ADDED TO THE PLC AND WILL ISSUE A CALL OUT ALARM IF THE COMPRESSOR HAS NOT BLOWN DOWN AFTER A SET TIME