ANR PIPELINE CO — Gas transmission and gathering — incident on 2014-07-12

Gas transmission and gathering incident in PATTERSON, ST. MARY County, LA. Reported cause: INCORRECT OPERATION. Reported consequences: 0 fatalities, 0 injuries, 18390 NATURAL GAS released, $0 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20140084.

Operator ID: 405.

Reported incident date: 7/12/2014 3:15.

Location detail: PATTERSON CS

Cause detail: VALVE LEFT OR PLACED IN WRONG POSITION, BUT NOT RESULTING IN AN OVERPRESSURE

Cause detail: 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.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: INCORRECT OPERATION — INCORRECT VALVE POSITION.

PHMSA indexed costs: $75,950 reported total cost, $52,539.842 in 1984 dollars, $64,510.946 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.