ENABLE GAS TRANSMISSION, LLC

Incident Narrative

1635 - THIRD PARTY CALLED AND REPORTED A GAS LEAK NEAR HIS HOUSE AT 314 HARDING LANE IN JESSIEVILLE, AR. REPORTS THAT HE CAN SEE FOAM, SMELL GAS, AND HEAR A HISSING NOISE COMING FROM AN UNDERGROUND LINE. HE STATES THAT THIS HAS BEEN GOING ON FOR 3-4 DAYS. 1643 - SYSTEM CONTROL NOTIFIED MARK ATKINSON (MALVERN TEAM) AND RELAYED ALL INFORMATION. MARK REPORTS THAT IT WILL TAKE HIM APPROXIMATELY 2 HOURS TO GET ON-SITE AND NOTIFIED HIM THAT BT-1 AND BT-1-AN ARE CLOSE TO THE REPORTED LEAK. STATES THAT THIS MAY BE LOCAL DISTRIBUTION COMPANY LEAK. 1648 - SYSTEM CONTROL NOTIFIED LOCAL DISTRIBUTION COMPANY AND RELAYED INFORMATION. 1931 - TECHNICIAN REPORTS THAT THEY HAVE FOUND A TRANSMISSION LEAK ON EITHER BT-1 OR BT-1-AN. HE STATES THAT HE IS IN TOUCH WITH THE OPERATION MANAGER AND ARE TRYING TO GET A GAME PLAN IN ACTION ON GETTING THE LEAK DUG UP AND REPAIRED. 2005 - SYSTEM CONTROL MADE REPORT TO ARKANSAS SERC (#16826). 2010 - SYSTEM CONTROL NOTIFIED THE GARLAND COUNTY DISPATCH OFFICE AND MADE A REPORT. HE REQUESTED THAT WE NOTIFY THE JESSIEVILLE FIRE DEPARTMENT DISPATCH OFFICE AS WELL. 2015 - SYSTEM CONTROL NOTIFIED THE JESSIEVILLE FIRE DEPARTMENT DISPATCH OFFICE. 2018 - SYSTEM CONTROL MADE REPORT TO THE NRC (#1101914). 2100 - SYSTEM CONTROL SPOKE WITH FIELD PERSONNEL; HE STATES THAT THEY ARE GOING TO ISOLATE BT-1-AN AND WATCH FOR PRESSURE DROPS TO SEE IF IT IS THE LEAKING LINE. THEY ARE GOING TO VALVE OFF THE MAINLINE VALVES ON GM-232 AND GM-233 ON THE 24 INCH(BT-1-AN). 2320 - OPERATION MANAGER CALLED AND REPORTED THAT THEY HAVE CONFIRMED THAT BT-1-AN IS THE LEAKING LINE. THEY HAVE WORKED THIS PLAN FOR THE BLOW-DOWN. ESTIMATES APPROXIMATELY 4-5 HOURS FOR THE BLOWDOWN TO BE COMPLETE; GOAL IS TO GET TO 0# ON THE LINE, BUT WILL ACCEPT PRESSURES UNDER 50#. APPROXIMATE GAS RELEASED DURING BLOWDOWN WILL BE 15,732.2 MCF. LINE BACK IN SERVICE DECEMBER 7TH AT 17:05. UPDATE APRIL 10, 2015 - PIPE WAS SENT TO LAB FOR METALLUGIC REVIEW, COMPLETED REPORT RECEIVED APRIL 2, 2015. STRESS ENGINEERING'S TEST RESULTS ARE AS FOLLOWS: VISUAL, METALLOGRAPHIC, AND FRACTOGRAPHIC EXAMINATION OF THE SAMPLE INDICATED THAT CRACKS INITIATED ON THE OUTSIDE SURFACE OF THE PIPE. THE MORPHOLOGY OF THE CRACKS INCLUDED CLOSELY-SPACED CRACKS IN COLONIES, TRANSGRANULAR AND BRANCHED GROWTH PATH, CRESCENT-SHAPED CRACKS PARTIALLY COVERED WITH MAGNETITE, AND ENLARGEMENT OF THE CRACKS AT THE OUTSIDE SURFACE DUE TO CORROSION. THESE FEATURES SUPPORT THE CONCLUSION THAT THIS LEAK WAS THE RESULT OF NEAR-NEUTRAL PH STRESS CORROSION CRACKING (SCC). THESE CRACKS WERE ALIGNED PERPENDICULAR TO THE LONGITUDINAL AXIS OF THE PIPE AT THE EXTRADOS OF AN OVER-BEND AND WERE CREATED BY BENDING LOADS IN THE PIPELINE. THE FACT THAT THE FINAL FAILURE WAS DUE TO DUCTILE OVERLOAD ALSO SUPPORTS THE ASSERTION THAT THE LONGITUDINAL STRESSES WERE SIGNIFICANT AT THIS LOCATION. FURTHER, THE UPWARD MOVEMENT OF THE PIPE AFTER IT WAS CUT IN THE DITCH DURING EXCAVATION IS CONFORMATION OF THIS CONCLUSION. STRESS ENGINEERING DID NOT OBSERVE ANY MATERIAL FLAWS OR DEFECTS IN THE SAMPLE MATERIAL. THE MICROSTRUCTURE OF THE SAMPLE IS TYPICAL FOR A CARBON-STEEL PIPE MATERIAL. THE PROPERTIES OF THE MATERIAL ARE CONSISTENT WITH THE REQUIREMENTS OF API 5LX (1968) FOR GRADE X60 AND ARE NOT BELIEVED TO HAVE CONTRIBUTED TO THE FAILURE. 9/23/2015 ADDITIONAL ANALYSIS WAS CONDUCTED ON THE ILI DATA TO LOOK FOR SIMILAR CONDITIONS IN THE LINE SEGMENT AND THESE AREAS WERE OVERLAID WITH CIS DATA. THREE (3) LOCATIONS WERE SELECTED TO INVESTIGATE, THEY WILL DUG PRIOR TO THE END OF OCTOBER.