ANR PIPELINE CO

Incident Narrative

ON JULY 9, 2014, OPERATOR PERSONNEL CONDUCTED THE ANNUAL TEST OF THE EMERGENCY SHUTDOWN (ESD) SYSTEM AT THE ANR PIPELINE COMPANY (ANR) PATTERSON COMPRESSOR STATION. THOUGH THE ESD SYSTEM TEST WAS CONSIDERED SUCCESSFUL WITH ALL VALVES AND ELECTRONICS OPERATING AS REQUIRED, THE STATION TECHNICIAN DECIDED THAT THE ACTIVATION PISTON OF THE ESD POPPET VALVE MOUNTED ON TOP OF THE VALVE ACTUATOR OF THE 8-INCH STATION SUCTION BLOWDOWN VALVE NEEDED ADDITIONAL LUBRICATION. THIS MAINTENANCE WAS PERFORMED ON JULY 11, 2014, THE DAY PREVIOUS TO THE REPORTED INCIDENT. TO PREVENT THE 8-INCH BLOWDOWN VALVE FROM ACCIDENTALLY OPERATING DURING THIS MAINTENANCE, THE PILOT GAS AND POWER GAS SOURCES TO THE BLOWDOWN VALVE OPERATOR WERE DISABLED BY CLOSING 1/2-INCH VALVES ON THE POWER GAS AND PILOT GAS TUBING LINES AT THE VALVE OPERATOR. AT THE COMPLETION OF THE VALVE OPERATOR MAINTENANCE, THE POWER GAS VALVE WAS REOPENED TO THE VALVE OPERATOR BUT THE PILOT GAS VALVE INADVERTENTLY REMAINED CLOSED WHEN THE BLOWDOWN VALVE AND OPERATOR WERE PUT BACK INTO SERVICE. BETWEEN COMPLETION OF THE VALVE OPERATOR MAINTENANCE ON JULY 11 AND 3:15 AM CDT ON JULY 12, 2014, THE PRESSURIZED GAS IN THE PILOT GAS TUBING, LOCATED BETWEEN THE PILOT GAS VALVE AND THE 8-INCH STATION SUCTION BLOWDOWN VALVE OPERATOR, MORE THAN LIKELY LEAKED FROM A FITTING. THIS RESULTED IN A LOSS OF PILOT GAS LINE PRESSURE AT THE OPERATOR, ALLOWED POWER GAS TO ACTIVATE THE ESD POPPET VALVE COMPONENT OF THE VALVE OPERATOR, AND RESULTED IN THE OPENING OF THE 8-INCH STATION SUCTION BLOWDOWN VALVE. THIS BLOWDOWN VALVE REMAINED OPEN UNTIL AN ON-DUTY STATION EMPLOYEE DISCOVERED THE OPEN VALVE AND MANUALLY CLOSED IT AT APPROXIMATELY 3:40 AM CDT. FOLLOWING CLOSURE OF THE BLOWDOWN VALVE, TRANSCANADA PERSONNEL CALCULATED THE ESTIMATED GAS LOST DURING THE EVENT TO BE APPROXIMATELY 1.84 MMCF, WHICH WOULD HAVE PUT THE EVENT BELOW THE REPORTING THRESHOLD OF 3.0 MMCF AS STATED IN 191.3 DEFINITIONS OF AN 'INCIDENT' (THE EVENT ALSO DID NOT MEET ANY OF THE OTHER REPORTING REQUIREMENT CRITERIA IN THE DEFINITION OF AN 'INCIDENT'). HOWEVER, UPON FURTHER REVIEW OF THE EVENT THE FOLLOWING MONDAY, JULY 14, 2014, IT WAS DISCOVERED THAT THE GAS LOSS CALCULATION HAD BEEN MISINTERPRETED, I.E., THE DECIMAL POINT WAS PLACED INCORRECTLY IN THE GAS LOSS RESULT. UPON DETERMINING THE CORRECT GAS VOLUME LOST TO BE 18.39 MMCF, THE INCIDENT WAS REPORTED TO THE NATIONAL RESPONSE CENTER (NRC) AS REQUIRED.