ONEOK WESTEX TRANSMISSION, LLC — Gas transmission and gathering — incident on 2016-12-14

Gas transmission and gathering incident in Not Within a Municipality, ECTOR County, TX. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 12890 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: 20170003.

Operator ID: 31531.

Reported incident date: 12/14/2016 14:28.

Location detail: MP 0.00

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: ON 12/14/2016, AT THE RECENTLY CONSTRUCTED ECTOR COUNTY COMPRESSOR STATION, THE STATION EMERGENCY SHUTDOWN SYSTEM BLOW-DOWN VALVES OPENED UNEXPECTEDLY ALLOWING RELEASE OF NATURAL GAS TO THE STATION VENT LINE. GAS VENTED FOR AROUND 33 MINUTES UNTIL STATION ISOLATION VALVES WERE CLOSED TO SHUT OFF THE FLOW OF GAS FROM THE RED RIVER PIPELINE ALLOWING 12.89 MMCF TO VENT TO ATMOSPHERE. PARTIAL OPERATION OF THE VALVES HAS BEEN ATTRIBUTED TO A MOMENTARY LOSS OF OUTPUT FROM A DIGITAL OUTPUT CARD ON THE STATION PLC TO THE VALVES. THE STATION PLC PROGRAM WAS REVISED TO PREVENT THE RECURRENCE OF A PARTIAL ESD. ONEOK PERSONNEL FIRST BECAME AWARE OF GAS VENTING THROUGH THE STATION BLOW DOWN SYSTEM AT 12:59 PM. IT WASN'T UNTIL 14:28 THAT IT WAS DETERMINED THAT THE GAS RELEASE HAD EXCEEDED 3,000 MCF. DIFFICULTY IN ESTIMATING THE FLOW RATE DUE TO THE STATION BLOW DOWN PIPING CONFIGURATION WAS THE PRIMARY CAUSE OF THE DELAY.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — MALFUNCTION OF CONTROL/RELIEF EQUIPMENT.

PHMSA indexed costs: $47,693 reported total cost, $50,778.261 in 1984 dollars, $62,347.992 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.