ENABLE OKLAHOMA INTRASTATE TRANSMISSION, LLC — Gas transmission and gathering — incident on 2017-08-06

Gas transmission and gathering incident in CLAREMORE, ROGERS County, OK. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 6400 NATURAL GAS released, $558 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: 20170074.

Operator ID: 26330.

Reported incident date: 8/6/2017 18:00.

Location detail: CLAREMORE CS

Cause detail: THREADED CONNECTION/COUPLING FAILURE

Cause detail: AT 20:30 ON 8/6/17 THE ENABLE OKLAHOMA INTRASTATE TRANSMISSION (EOIT) SYSTEM CONTROL RECEIVED A CALL ABOUT AN ODOR OF GAS AT THE CLAREMORE COMPRESSOR STATION IN CLAREMORE, OKLAHOMA. WHEN THE EOIT O&M TECHNICIAN ARRIVED AT THE STATION, HE PERFORMED A COMPLETE INSPECTION AND FOUND A RELIEF VALVE BLOWING ON COMPRESSOR UNIT 433. IT WAS DISCOVERED A 1/4" TUBING FITTING FAILED ON THE PILOT OF THE UNIT 433 DISCHARGE VALVE CAUSING THE RELIEF TO VENT. THE UNIT WAS ISOLATED AND ULTIMATELY SHUT DOWN FOR REPAIR. WHEN IT WAS SAFE TO DO SO, THE AMOUNT AND DURATION OF GAS LOSS WAS CALCULATED TO BE A LITTLE OVER 3 HOURS AND ESTIMATED AT 6,400 MCF. THESE TOTALS WERE CONFIRMED AT 22:18 AND A CALL WAS PLACED TO NRC AT 22:50 (NRC#1186432). A FOLLOW UP CALL WAS PLACED WITH THE NRC ON 8/8/17 AT 07:04 (NRC#1186560). IT WAS DETERMINED THE FITTING FAILURE OCCURRED DUE TO UNIT VIBRATION. THE FAILED FITTING AND TUBING WAS REPLACED BY A 2000 PSIG STAINLESS STEEL HOSE. THIS REPAIR WAS PERFORMED FOR ALL THREE UNITS AT THE COMPRESSOR STATION. AS A SECONDARY PROTECTION, THE COMPRESSOR LOGIC WAS MODIFIED TO SHUT DOWN WHEN UNIT PRESSURE DROPS MORE THAN 1 PSIG IN A 1/3 OF A SECOND. WHILE REOCCURRENCE OF THIS INCIDENT IS NOT EXPECTED TO OCCUR, THE UPDATED LOGIC WILL ALMOST IMMEDIATELY SHUT THE UNIT DOWN, GREATLY REDUCING THE AMOUNT OF GAS RELIEVED INTO THE ATMOSPHERE.

PHMSA trend classification: not significant, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — THREADED CONNECTION/COUPLING FAILURE.

PHMSA indexed costs: $13,828 reported total cost, $12,757.704 in 1984 dollars, $16,152.242 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.