ONEOK GAS TRANSPORTATION, LLC

Incident Narrative

A LANDOWNER CALLED GAS CONTROL AT APPROXIMATELY 0630 HOURS ON JULY 28, 2013 TO REPORT A NATURAL GAS LEAK AT THE ONEOK GAS TRANSPORTATION'S HYDRO JUNCTION FACILITY IN CADDO COUNTY, OKLAHOMA. OPERATIONS PERSONNEL WERE DISPATCHED AT APPROXIMATELY 0640 HOURS AND VERIFIED THE LEAK TO BE ON ONEOK FACILITIES AT 0725 HOURS. THE HYDRO FIRE DEPARTMENT RESPONDED AND PROVIDED TRAFFIC CONTROL UNTIL THE LEAK COULD BE ISOLATED AT 0840 HOURS. THE LEAK WAS DETERMINED TO HAVE RESULTED FROM A FAILED 2 INCH VALVE ON THE PIPELINE DRIP. THE FAILED VALVE WAS REPLACED WITH A PLUG AND THE PIPELINE RETURNED TO SERVICE AT 1530 HOURS ON JULY 28, 2013. NO CUSTOMERS WERE IMPACTED. A FAILURE ANALYSIS IS BEING CONDUCTED ON THE FAILED 2 INCH VALVE. POST INCIDENT REVIEW OF SCADA DATA INDICATED THAT A SMALL PRESSURE DROP RECORDED AT 0142 HOURS ON JULY 28 WAS PROBABLY WHEN THE DRIP VALVE FAILED. THAT PRESSURE DROP WAS NOT OF SUFFICIENT MAGNITUDE TO BE JUDGED ABNORMAL WHEN IT OCCURRED. IT IS ESTIMATED THE UNINTENTIONAL GAS LOSS EXCEEDED 3 MILLION CUBIC FEET 83 MINUTES LATER THEREFORE MAKING THE LEAK REPORTABLE AT 0305 HOURS. THIS TIME IS USED IN PART A OF THIS INCIDENT REPORT AS THE TIME OF THE INCIDENT. THE OKLAHOMA CORPORATION COMMISSION WAS CONTACTED AT 0832 HOURS AND THE NATIONAL RESPONSE CENTER WAS CONTACTED AT 0842 HOURS - REFERENCE PHMSA INCIDENT NUMBER 1055311. UPDATE: THE FAILURE ANALYSIS CONDUCTED BY A THIRD PARTY STATED THE FAILURE MODE OF THE VALVE BOLTS WAS MOST LIKELY SULFIDE STRESS CRACKING, A FORM OF HYDROGEN EMBRITTLEMENT.