ANR PIPELINE CO

Incident Narrative

ON 12 AUGUST 2020, TC ENERGY/ ANR PIPELINE COMPANY (ANR) REPORTED AN INCIDENT TO THE NATIONAL RESPONSE CENTER (NRC) (NRC REPORT NUMBER 1284343) FOLLOWING THE UNINTENTIONAL RELEASE OF 50.2 MILLION CUBIC FEET OF GAS TO THE ATMOSPHERE FROM THE EUNICE COMPRESSOR STATION LOCATED AT 4202 FOURNERAT ROAD IN EUNICE LOUISIANA (30.46632200, -92.52257600). THE RELEASE WAS CAUSED WHEN THE STATION FIRE DETECTION SYSTEM RECEIVED AN INDICATION OF A FLAME AND INITIATED THE EMERGENCY SHUTDOWN (ESD) SYSTEM. WHEN THE ESD WAS INITIATED, THE GAS CONTROLLER RECEIVED A SCADA ALARM AND DISPATCHED A TECHNICIAN TO THE SITE TO INVESTIGATE. WHEN THE TECHNICIAN ARRIVED AT THE SITE, NATURAL GAS WAS DISCOVERED BEING RELEASED THROUGH THE STATION BLOWDOWN. IMMEDIATE ACTION WAS TAKEN TO STOP THE RELEASE BY CLOSING BLOWDOWN VALVE AND SECURING THE SITE. SINCE THE INCIDENT, EUNICE COMPRESSOR STATION HAS REMAINED STAFFED 24-HOURS A DAY UNTIL REPAIRS CAN BE COMPLETED ON THE ISOLATION VALVE. INVESTIGATION OF THE INCIDENT HAS INDICATED THAT THE ACTIVATION OF THE ESD SYSTEM AND FAILURE OF THE ISOLATION VALVE TO COMPLETELY OPERATE CONTRIBUTED TO THE GAS LOSS. NO EVIDENCE OF FLAME OR FIRE WERE OBSERVED IN THE COMPRESSOR BUILDING FOLLOWING THE INCIDENT THAT WOULD INITIATE THE ESD. ADDITIONALLY, AN AUTOMATIC ISOLATION VALVE FAILED TO COMPLETELY CLOSE RESULTING IN THE CONTINUING RELEASE OF GAS TO THE ATMOSPHERE THROUGH THE STATION'S BLOWDOWN STACK. INVESTIGATION HAS ALSO DETERMINED THAT THREE-WAY PILOT GAS VALVES AND END-OF-TRAVEL STOP VALVES ASSOCIATED WITH AUTOMATIC OPERATION CONTRIBUTED TO THE INCOMPLETE CLOSURE OF THE ISOLATION VALVE DUE TO AN INSUFFICIENT GAS SUPPLY. FIVE VALVES WERE IDENTIFIED DURING THE INVESTIGATION THAT REQUIRED REPAIR AND THE REPLACEMENT OF PILOT VALVES. ON 1 MARCH 2021, REPAIR AND REPLACEMENT WAS COMPLETED ON THREE ESD VALVES IDENTIFIED DURING THE INVESTIGATION. ON APRIL 21, 2021, THE TWO REMAINING VALVES WERE REPAIRED. FOLLOWING THE VALVE REPAIR, A SUCCESSFUL EMERGENCY SHUTDOWN SYSTEM TEST WAS COMPLETED. FOLLOWING THE ESD TEST, THE STATION WAS RETURNED TO UNMANNED OPERATION CAPABILITY.