TEXAS EASTERN TRANSMISSION LP (SPECTRA ENERGY CORP)

Incident Narrative

AT APPROXIMATELY 12:25 PM CDT ON JUNE 1, 2015, SPECTRA ENERGY WAS NOTIFIED BY JEFFREY SAND COMPANY, WHICH IS LOCATED ON THE NORTH BANK OF THE ARKANSAS RIVER AT THE TEXAS EASTERN TRANSMISSION, LP NATURAL GAS PIPELINE CROSSING, THAT IT APPEARED CONCRETE ANCHORING MATERIAL FROM THE PIPELINE HAD DAMAGED ONE OF THEIR TUG BOATS. SPECTRA ENERGY PERSONNEL WERE IMMEDIATELY DISPATCHED TO THE ISOLATION VALVES ON BOTH SIDES OF THE RIVER TO TAKE PRESSURE MEASUREMENTS ON THE AUXILIARY LINE. THE AUXILIARY CROSSING WAS FOUND TO BE AT ATMOSPHERIC PRESSURE. THE AUXILIARY LINE HAD BEEN ISOLATED FROM THE MAINLINE FOR SOME TIME AND SHOULD HAVE HAD NATURAL GAS PRESSURE IN EXCESS OF 700 PSIG. SPECTRA ENERGY PERSONNEL OPENED THE ISOLATION VALVES ON THE AUXILIARY LINE AND IMMEDIATELY OBSERVED BUBBLING ABOUT 100 FEET FROM THE NORTH BANK OF THE RIVER, THUS CONFIRMING A PIPELINE FAILURE. UPON CONFIRMING THE FAILURE, TEXAS EASTERN NOTIFIED THE NATIONAL RESPONSE CENTER, PHMSA, AND THE ARKANSAS PUBLIC SERVICE COMMISSION. ANALYSIS CONCLUDED HIGH WATER FLOW RATES IN THE ARKANSAS RIVER ERODED THE COVER OVER THE PIPELINE AND LED TO SCOUR OF THE SOIL SUPPORT UNDER THE PIPELINE. ONCE THE PIPELINE WAS EXPOSED AS A FREE SPAN, VORTEX-INDUCED VIBRATION (VIV) CAUSED VERTICAL OSCILLATION OF THE PIPELINE, CREATING CYCLIC BENDING STRESSES. THIS RESULTED IN A CIRCUMFERENTIALLY ORIENTED FATIGUE CRACK THAT INITIATED ADJACENT TO THE TOE OF A GIRTH WELD, WHICH CAUSED THE FAILURE.