ONEOK WESTEX TRANSMISSION, LLC

Incident Narrative

AT APPROXIMATELY 0450 HOURS ON APRIL 10, 2014, ONEOK WESTEX TRANSMISSION (OWT) GAS CONTROL NOTICED A DROP IN LINE PRESSURE AT THE DORA ROBERTS COMPRESSOR STATION. OPERATIONS PERSONNEL WERE DISPATCHED AT 0500 HOURS TO LOCATE THE POSSIBLE LEAK. GAS CONTROL DID RECEIVE A CALL AT 0630 HOURS FROM THE PUBLIC REPORTING BLOWING GAS IN A RURAL AREA APPROXIMATELY 6 MILES SOUTH OF PENWELL, TX AND 1/2 MILE EAST OF ROAD FM 1601 IN ECTOR COUNTY. OWT PERSONNEL WERE DIRECTED TO THIS SITE AND WERE ABLE TO IDENTIFY THE SOURCE OF BLOWING GAS AS OWT LINE 4000-000, COMMONLY KNOWN AS THE JV OR JOINT VENTURE LINE. BLOCK VALVES UPSTREAM AND DOWNSTREAM OF THE SITE WERE MANUALLY CLOSED BY 0725 HOURS AND THE ISOLATED SECTION OF THE PIPELINE WAS ALLOWED TO BLOW DOWN TO ATMOSPHERIC PRESSURE. THE SITE IS RURAL AND THERE WERE NO BUILDINGS INTENDED FOR HUMAN OCCUPANCY WITHIN 1/2 MILE OF THE SITE. LOCAL EMERGENCY RESPONDERS WERE ON SITE WHEN OWT PERSONNEL ARRIVED AT 0645 HOURS. THERE WAS NO FIRE OR EXPLOSION DUE TO THE RELEASE. THE PIPE THAT FAILED WAS SECURED AND SENT TO A LAB IN TULSA, OK TO DETERMINE THE CAUSE OF THE FAILURE. UPDATE: THE FAILURE ANALYSIS PERFORMED BY ELEMENT LABS IN TULSA, OK CONCLUDED THAT THE CAUSE OF THE FAILURE WAS AN INITIAL DUCTILE FAILURE OF A FIELD MADE GIRTH WELD WHICH INITIATED THE FAILURE OF THE ADJOINING PIPE JOINT LONG SEAM. THE THIRD PARTY FAILURE ANALYSIS INDICATED THE CAUSE OF THE GIRTH WELD FAILURE WAS AN APPROXIMATELY ONE QUARTER INCH DIAMETER VOID LOCATED AT THE LOCATION OF AN ADJOINING LONGITUDINAL PIPE JOINT SEAM. THIS GIRTH WELD ALSO HAD AREAS OF INCOMPLETE FUSION AND FAILED DUE TO DUCTILE OVERLOAD IN THE VICINITY OF THE VOID. SIGNS OF FATIGUE WERE ALSO OBSERVED ON THE GIRTH WELD FAILURE SURFACES ALONG AREAS OF INCOMPLETE FUSION. WHEN THE GIRTH WELD FAILED, THE CRACK PROPAGATED INTO THE LONGITUDINAL SEAM AND THEN BY RAPID BRITTLE FRACTURE, IT PROCEEDED DOWN THE LENGTH OF THE LONGITUDINAL PIPE SEAM CAUSING THE PIPELINE RUPTURE.