EAST TENNESSEE NATURAL GAS, LLC (SPECTRA ENERGY PARTNERS, LP)

Incident Narrative

ORIGINAL REPORT: AT APPROXIMATELY 2:09 P.M. CST ON DECEMBER 15, 2018, ETNG'S 22-INCH DIAMETER LINE 3100-1 TRANSPORTING NATURAL GAS FROM DIXON SPRINGS COMPRESSOR STATION TO GAINESBORO COMPRESSOR STATION IN TENNESSEE FAILED AT MP 49.147. THE FAILED PIPE IS 22 INCH DIAMETER BY 9/32 INCH WALL THICKNESS, X-42. THE FAILURE RESULTED IN A RUPTURE WITHOUT FIRE. THERE WERE NO INJURIES OR FATALITIES. APPROXIMATELY 12 RESIDENTS EVACUATED UNTIL LOCAL EMERGENCY RESPONDERS OPENED ACCESS TO THE AREA. THE COMPRESSOR UNITS AT THE DIXON SPRINGS COMPRESSOR STATION WERE SHUTDOWN REMOTELY BY THE CONTROL ROOM AT 2:19 PM CST. THE ESD AT THE DIXON SPRING COMPRESSOR STATION WAS ACTIVATED AT 2:56 PM CST. THE MLV AT GAINESBORO COMPRESSOR STATION WAS CLOSED AT 2:47 PM CST FOLLOWED BY ESD ACTIVATION, COMPLETING INITIAL ISOLATION OF THE FAILURE SITE. ETNG PERSONNEL WERE ALSO DISPATCHED TO CLOSE THE MAINLINE BLOCK VALVES IMMEDIATELY DOWNSTREAM OF THE FAILURE SITE WHICH WAS CLOSED AT APPROXIMATELY 4:30 PM CST. ETNG PERSONNEL ARRIVED AT THE FAILURE SITE AT APPROXIMATELY 5:00 PM CST. THE NRC WAS NOTIFIED AT 3:50 PM CST, AS SOON AS LOCATION INFORMATION FOR THE FAILURE SITE WAS AVAILABLE. THE LINE WAS REPLACED, TESTED, AND SUBSEQUENTLY PUT IN-SERVICE ON DECEMBER 29, 2018. A 3RD PARTY METALLURGICAL INVESTIGATION IS ONGOING. THE ROOT CAUSE IS PENDING. SUPPLEMENTAL REPORT 09/27/2020 THE FAILURE HAS BEEN DETERMINED TO BE DUE TO A RELATIVELY SMALL 0.09' DEEP X 0.44' LONG HYDROGEN INDUCED CRACK IN THE ERW SEAM HEAT AFFECTED ZONE AT A LOCATION WHERE HYDROGEN EMBRITTLEMENT HAD REDUCED THE MATERIAL TOUGHNESS TO A LEVEL SUCH THAT THE PIPE COULD NOT WITHSTAND RUPTURE AT MOP.