ENABLE GAS TRANSMISSION, LLC

Incident Narrative

ON DECEMBER 18TH, 2020 AT 15:22 ENABLE GAS TRANSMISSION LINE A-SOUTH EXPERIENCED A FAILURE IN CADDO PARISH LOUISIANA. THE FAILURE WAS AT AN ORIGINAL ACETYLENE GIRTH WELD COMPLETED IN 1947. THE FAILED SECTION WAS REMOVED AND SENT TO A LAB FOR METALLURGICAL ANALYSIS. THE NRC WAS NOTIFIED ON 12/18/2020 (NRC # 1294597). A 48 HR FOLLOW UP CALL WAS PROVIDED TO THE NRC ON 12/20/2020 (NRC # 1294630). AT TIME OF REPORT SUBMISSION, ENABLE MIDSTREAM PARTNERS HAS NOT YET RECEIVED THE RESULTS OF THE LAB ANALYSIS. A SUPPLEMENTAL REPORT WILL BE FILED WHEN THE REPORT IS COMPLETED. 03.15.2021 UPDATE ON DECEMBER 18TH, 2020 AT 15:22 ENABLE GAS TRANSMISSION SYSTEM CONTROL DETECTED LOSS OF PRESSURE VIA SCADA FOR LINE A-SOUTH IN CADDO PARISH LOUISIANA. LOCAL OPERATIONS WAS IMMEDIATELY DISPATCHED TO LOCATE THE FAILURE. ENABLE RECEIVED A CALL FROM THE LOCAL EMERGENCY RESPONDER AT 16:02 NOTIFYING THEM OF THE EXACT FAILURE LOCATION. THE FAILURE WAS FOUND BY LOCAL PUBLIC WHO NOTIFIED THE LOCAL EMERGENCY RESPONDER. ENABLE OPERATIONS WERE ONSITE AT 16:40. THE FAILED SECTION WAS REMOVED AND SENT TO A LAB FOR METALLURGICAL ANALYSIS. THE LAB RESULTS PERFORMED ON THE SUBMITTED FRACTURED GIRTH WELD INDICATE THAT THE CAUSE OF FAILURE IS RELATED TO A TENSILE LOAD ACTING ON THE GIRTH WELD THAT HAD HOT CRACKING PRESENT IN THE ROOT AND CAP WELD METAL. THE INITIATION OF THE FRACTURE IS THOUGHT TO HAVE OCCURRED IN THE GIRTH WELD DUE TO THE REDUCED EFFECTIVE WALL THICKNESS IN THE GIRTH WELD METAL CAUSED BY THE PRESENCE OF HOT CRACKING AND STRESS RISERS CAUSED BY THE PRESENCE OF HOT CRACKING. THE TENSILE LOAD IS PRESUMED TO BE ASSOCIATED WITH CONSTRUCTION THAT OCCURRED ON A-SOUTH IN CLOSE PROXIMITY TO THE FAILED GIRTH WELD IN JUNE OF 2020. THE JUNE 2020 JOB CONSISTED OF INSTALLING 88 FEET OF PIPE TO REMEDIATE DRESSER COUPLES (DC) ON THE LINE. TO HELP STABILIZE THE LEGACY PIPE, 3 SLEEVES WERE INSTALLED UPSTREAM AND 3 SLEEVES WERE INSTALLED DOWNSTREAM ON ACETYLENE GIRTH WELDS (AGW) AND DC PRIOR TO THE NEW CONSTRUCTION. THE FAILURE LOCATION WAS A MISSED GIRTH WELD (FIRST ACETYLENE WELD DOWNSTREAM OF REPLACEMENT) WHICH WAS NOT IDENTIFIED PRIOR TO AND DURING CONSTRUCTION. TO INCREASE PIPE STABILITY THE STANDARD PRACTICE HAS BEEN TO INSTALL SLEEVES WHEN AGW ARE EXPOSED AND PRIOR TO CONSTRUCTION. THE 88-FOOT REPLACEMENT WAS PERFORMED IN JUNE 2020. THE SLEEVES WERE INSTALLED IN FEBRUARY OF 2020 IN ADVANCE OF THE PIPE REPLACEMENT PROJECT. THE PROCESS TO EXPOSE A GIRTH WELD IS TO REMOVE AS LITTLE DIRT AS POSSIBLE (TO LIMIT STRESS ON PIPE WHILE PRESSURIZED) UNTIL A AGW IS DISCOVERED AND A SLEEVE CAN BE INSTALLED. GOING FORWARD, ENABLE WILL UPDATE THEIR DC AND AGW PROCEDURES TO INCLUDE THE PRACTICE OF REMOVING ALL DIRT (WHILE THE PIPELINE SEGMENT IS FULLY EVACUATED) FROM THE LEGACY PIPE CUTOUT TO THE FIRST GIRTH WELD UPSTREAM AND DOWNSTREAM. THIS WILL ENSURE THE FIRST JOINT HAS NOT BEEN MISSED AND HAS THE REQUIRED INSTALLED SLEEVE PRIOR TO THE PIPE BEING RE-PRESSURIZED. 03.15.2021 SUPPLEMENTAL REPORT C.3E CHANGED TO SEAMLESS D.7D ADDED $27,000 G.2 ADDED HOT CRACKING H. UPDATED