ENABLE GAS TRANSMISSION, LLC

Incident Narrative

LOCAL OPS PERSONNEL RECEIVED A PHONE CALL FROM A HUNTER ON SATURDAY MORNING FEBRUARY 4TH, 2023. THE HUNTER WAS IN A VERY REMOTE LOCATION AND CAME ACROSS THE OM-1 PIPELINE ROW; HE NOTICED VAPOR COMING FROM THE GROUND AND SAW ICE COVERING THE GROUND IN THE PIPELINE ROW. OPS PERSONNEL DROVE OUT TO THE LOCATION TO VERIFY A POTENTIAL LEAK; AT 1030AM THAT MORNING OPS VERIFIED THAT WE HAD A POTENTIAL NATURAL GAS LEAK ON OM-1 AT THIS LOCATION. DUE TO THE HISTORY OF LAND MOVEMENT ON OM-1, OUR PERSONNEL BACKED AWAY FROM THE SITE OF THE LEAK AND NOTIFIED MANAGEMENT AND REGULATORY COMPLIANCE OF THE ISSUE. AN NRC NOTIFICATION (NRC#1359244) WAS MADE AT APPROXIMATELY 1045AM....ALTHOUGH THE LEAK WAS RELATIVELY MINOR, OPS KNEW THAT ANY REPAIR ON THE PIPELINE WOULD EXCEED $129,000 DUE TO THE REMOTE ACCESS AND RUGGED TERRAIN. OPS PERSONNEL MOBILIZED TO THE WINSLOW AND TURKEY FARM VALVE TO ISOLATE THE PIPELINE SEGMENT; THE PIPE WAS BROUGHT DOWN TO ROUGHLY 44# BY THAT AFTERNOON. COMMERCIAL BEGAN NOTIFYING CUSTOMERS OF THE OUTAGE, AS THE REPAIR WAS EXPECTED TO TAKE AN EXTENDED AMOUNT OF TIME. THE LINE WAS COMPLETELY FLAT BY NOON ON MONDAY, FEBRUARY 6TH AND THE CONTRACTOR BEGAN EXCAVATING LEAK SITE; EXCAVATION WORK WAS VERY SLOW, AS THE GROUND WAS HARD/FROZEN. ON 2-7-23, THE PIPE WAS EVALUATED AND IT APPEARS THE LEAK WAS CAUSED BY STRESS IN THE PIPE (LAB WILL CONFIRM CAUSE OF LEAK) ON 2-10-23, A SECTION OF THE EXCAVATED PIPE WAS SENT OFF TO A METALLURGICAL LAB FOR FURTHER ANALYSIS/RESEARCH OF THE LEAK CAUSE. ON 2-15-23, 2 40' REPLACEMENT PIPE JOINTS WERE HYDROTESTED IN PREPARATION FOR INSTALLATION. ON 2-17-23, NEW PIPE REPLACEMENT SECTION TIE-INS COMPLETED (X-RAYS PASSED) ON 2-21-23, THE LINE WAS PURGED AND RETURNED TO NORMAL OPERATING SERVICE. SUPPLEMENTAL REPORT DATED 8.30.2023 PART C HAS BEEN UPDATED WITH THE FOLLOWING INFORMATION: -CHANGED TYPE OF RELEASE FROM 'OTHER' TO 'CRACK' PART G HAS BEEN UPDATED WITH THE FOLLOWING INFORMATION: - APPARENT CAUSE WAS CHANGED FROM G8 TO G5 - SUB-CAUSE DETERMINED BY METALLURGICAL ANALYSIS - SUB-CAUSE IS ENVIRONMENTAL CRACKING-RELATED - ADDITIONAL FACTORS WERE 'OTHER' (DUCTILE OVERLOAD) - POST CONSTRUCTION PT WAS 1250 PSIG PART H HAS BEEN UPDATED WITH THE FINDINGS FROM THE LAB: EXAMINATION OF THE PIPE SAMPLE REVEALED SEVERAL COLONIES OF CIRCUMFERENTIAL CRACK-LIKE INDICATIONS. THE LEAK FRACTURE SURFACE APPEARED CONSISTENT WITH CIRCUMFERENTIAL STRESS CORROSION CRACKING (CSCC), PROGRESSING APPROX. 0.080 INCH DEEP. THE REMAINING FRACTURE APPEARED CONSISTENT WITH DUCTILE OVERLOAD, INCLUDING NECKING ALONG THE INTERNAL PIPE SURFACE. PIPE MATERIAL WAS CONSISTENT WITH API 5LX (1968) GRADE X60 MATERIAL.