TEXAS GAS TRANSMISSION, LLC

Incident Narrative

ON 9-2-2020 AT 12:06 PM, TEXAS GAS'S GAS CONTROL RECEIVED A CALL FROM THE SHERIFF'S DEPARTMENT REPORTING A POTENTIAL PIPELINE LEAK. GAS CONTROL CONTACTED OPERATIONS PERSONNEL AT 12:13 PM. A PIPELINE TECHNICIAN WHO WAS ALREADY IN THE FIELD PERFORMING MAINTENANCE WAS DISPATCHED TO THE SITE AT 12:15 PM. LOCAL OPERATIONS PERSONNEL ARRIVED AT THE HUN 4"" TAP VALVE AT APPROXIMATELY 12:30 PM. PERSONNEL SHUT THE TAP VALVE AND OPENED BLOWDOWN VALVE AT 12:33 PM. THE LINE WAS SECURED AND BLOWN DOWN AT 12:33 PM. NO ONE WAS INJURED. SOME GROUND DISTURBANCE OCCURRED. THE PIPELINE BLEW FOR 20 MINUTES AT 824 PSIG. AT THIS TIME THE FAILED PORTION OF PIPELINE IS STILL ATTACHED AND HAS NOT BEEN REMOVED. TEXAS GAS INTENDS TO ABANDON THIS PORTION OF PIPELINE AND REMOVE IT FROM SERVICE. CURRENTLY, THE AREA IS TOO WET TO COMPLETE THIS SCOPE AND, THEREFORE, TEXAS GAS HAS NOT YET HAD THE OPPORTUNITY TO COMPLETELY ASSESS THE CAUSE OF THIS INCIDENT ALTHOUGH IT APPEARS TO BE CORROSION RELATED. EVALUATION IS ONGOING AND A SUPPLEMENTAL/FINAL INCIDENT REPORT WILL BE REQUIRED. THE RESPONSE PROVIDED TO PART E, QUESTION 1A IS 1.0 BUT THE ACTUAL FLOW WAS TOO LOW TO CALCULATE. 3/15/2021 UPDATE REPORT FOLLOWING METALLURGICAL ANALYSIS. THE RUPTURE RESULTED FROM THE INITIATION OF MULTIPLE CRACKS AT THE EXTERNAL SURFACE OF THE PIPE. THE OBSERVED CRACKING WAS CONSISTENT WITH THE OCCURRENCE OF EXTERNAL HIGH PH STRESS CORROSION CRACKING. THE PIPE EXHIBITED MULTIPLE GOUGES AND DENTS IN ITS EXTERNAL SURFACE AND WAS PARTIALLY FLATTENED OVER A LENGTH OF APPROXIMATELY SIX FEET FROM THE GIRTH WELD OF THE ADJACENT JOINT. THE RUPTURE WAS CONTAINED WITHIN THIS FLATTENED LENGTH OF PIPE AND RESIDUAL STRESS IN THE PIPE WALL FROM THIS FLATTENING MAY HAVE CONTRIBUTED TO THE INITIATION AND GROWTH OF STRESS CORROSION CRACKS. THE INTERNAL SURFACE OF THE PIPE EXHIBITED LARGE SHALLOW CORROSION PITS. THE EXTERNAL SURFACE CONDITION SUGGESTS THAT THE OBSERVED GOUGES AND DENTS OCCURRED A SIGNIFICANT PERIOD OF TIME PRIOR TO THE RUPTURE. 10-20-22 UPDATED TO CORRECT LATITUDE AND LONGITUDE PER PHMSA REQUEST. A SUPPLEMENTAL REPORT WILL BE REQUIRED WHEN ABANDONMENT IS COMPLETE. 9-28-23 UPDATED TO SUBMIT FINAL REPORT. CURRENTLY, THIS SECTION OF LINE IS NOT SCHEDULED FOR FULL ABANDONMENT. UNTIL IT IS FULLY ABANDONED, THE LINE WILL REMAIN CUT, SEPARATED FROM ALL GAS SOURCES, AND UNPRESSURIZED.