ANR PIPELINE CO

Incident Narrative

ON JUNE 10 AT 12:29 CT, ANR PIPELINE'S GAS CONTROL RECEIVED AN EMERGENCY SHUTDOWN SYSTEM (ESD) ALARM AT DELHI COMPRESSOR STATION LOCATED AT 1984 HWY 80 W, DELHI, LA 71232 (32.46707, -91.59751). WHEN THE ALARM WAS DETECTED, A TECHNICIAN WAS DISPATCHED TO THE COMPRESSOR STATION TO INVESTIGATE. UPON ARRIVAL AT THE SITE AT 12:40 CT, THE TECHNICIAN DISCOVERED NATURAL GAS BEING RELEASED THROUGH THE STATION'S BLOWDOWN STACKS. IMMEDIATE ACTION WAS TAKEN BY VERIFYING NO EMERGENCY EXISTED AND CLOSING THE VALVES, WHICH ENDED THE RELEASE AT 12:45 CT. UNINTENTIONAL GAS LOSS WAS CALCULATED TO 5.7 MILLION CUBIC FEET (MMCF). NO PROPERTY DAMAGE OR INJURIES WERE DOCUMENTED AND NO EVACUATIONS WERE REQUIRED. THE CAUSE OF THE UNINTENTIONAL RELEASE WAS ATTRIBUTED TO A FLAME DETECTION EQUIPMENT (FIRE EYE) THAT INITIATED THE ACTIVATION OF THE ESD SYSTEM. WHEN THE SYSTEM ACTIVATED, STATION ISOLATION VALVE 501-14-16 FAILED TO FULLY CLOSE RESULTING IN THE RELEASE GAS. FOLLOWING THE INCIDENT, DELHI COMPRESSOR STATION WAS TAKEN OUT OF SERVICE DURING THE INVESTIGATION. VALVE 501-14-16 WAS LOCKED OUT OF SERVICE AND BY-PASSED TO ANOTHER ESD VALVE CAPABLE OF ISOLATING THE STATION. THE FLAME DETECTION EQUIPMENT WAS REMOVED FROM THE BUILDING AND REPLACED. DELHI COMPRESSOR STATION WAS PLACED BACK INTO SERVICE ON JUNE 10, 2019. THE COMPRESSOR ENGINE BUILDING WHERE THE SHUTDOWN WAS INITIATED REMAINED OUT OF SERVICE UNTIL JUNE 14 AT 15:45 CT. DURING THE SHUTDOWN PERIOD, NO ADDITIONAL FLAME DETECTION ACTIVATIONS WERE DETECTED. THE FLAME DETECTOR UNIT WAS SENT TO THE ORIGINAL MANUFACTURER FOR EVALUATION. THE MANUFACTURER REPORTED THAT THE UNIT MET ALL MANUFACTURING SPECIFICATIONS AND OPERATED AS INTENDED. THE MANUFACTURER RECOMMENDED THAT THE UNIT'S SENSITIVITY BE REDUCED FROM ""HIGH"" TO ""MEDIUM"". THIS RECOMMENDED CHANGE IS DUE TO THE OPERATIONAL AND ENVIRONMENTAL CONDITION IN THE RECIPROCATING ENGINE COMPRESSOR BUILDING. THE CHANGE IN SENSITIVITY DOES NOT AFFECT THE SAFETY OF THE PIPELINE FACILITY AND THE SYSTEM HAS BEEN TESTED ACCORDING TO PROCEDURES. THIS ACTION WAS COMPLETED ON JULY 26, 2019. ON 19 NOVEMBER 2019 INVESTIGATION AND REMEDIAL ACTION WAS TAKEN TO REPAIR VALVE 501-14-16, WHICH FAILED TO OPERATE FULLY CLOSED DURING A STATION ESD. THE 3-WAY PILOT VALVE, WHICH SENDS POWER GAS TO OPERATE THE VALVE WHEN PILOT PRESSURE DROPS OUT, WAS REPLACED. AN EXTRA POWER GAS BOTTLE WAS ALSO INSTALLED IN LINE WITH THE POWER GAS SUPPLY LINE TO ENSURE WE HAVE AN AMPLE AMOUNT OF POWER GAS TO FULLY STROKE THE VALVE. AN FULL EMERGENCY SHUTDOWN SYSTEM WAS CONDUCTED ON 11/19/2019 TO TEST REPAIRS ON VALVE 501-14-16. DURING THIS TEST, IT WAS DISCOVERED THAT PRESSURE TO THE POWER GAS SUPPLY ON THE ACTUATOR DROPPED OUT CAUSING THE VALVE TO NOT OPERATE. FURTHER INVESTIGATION REVEALED THAT THE PILOT GAS SUPPLY WAS INSTALLED INTO THE POWER GAS PORT AND THE POWER GAS SUPPLY WAS INSTALLED INTO THE PILOT GAS PORT ON THE OPERATOR. THE SWITCHING OF THESE SUPPLIES CAUSED AN INCOMPLETE OPERATION OF THE VALVE DUE TO RELIEVING PRESSURE OF THE PILOT GAS DURING AN ESD INITIATION. THESE LINES WERE SWITCHED TO THE CORRECT PORTS ON THE ACTUATOR AND PROPER OPERATION FOR VALVE CLOSURE WAS DOCUMENTED. VALVE 501-14-16 WAS PLACED BACK INTO SERVICE ON 22 NOVEMBER 2019.