TRANSCONTINENTAL GAS PIPE LINE COMPANY

Incident Narrative

PIPELINE OPERATIONS RECEIVED AN AERIAL PATROL REPORT INDICATING A POTENTIAL LEAK ON MAY 5, 2021. THE LEAK WAS VERIFIED ON THE GROUND AT VALVE STATION 185-20 ON MAY 6, 2021 BY HAND DIGGING AND PROBING THE AREA BY WILLIAMS' PERSONNEL. INITIALLY IT WAS NOT SUSPECTED TO MEET THE REPORTING THRESHOLD AS THE LEAK WAS VERY SMALL. OPERATIONS BEGAN TO INVESTIGATE BY HYDROVACING AND PROBING AROUND THE SITE TO LOCATE THE LEAK. COST TO LOCATE THE LEAK BEGAN TO REACH $120K AND WAS REPORTED TO THE NRC ON JULY 21, 2021 (NRC #1311366). THE SUSPECTED AREA OF THE VALVE SITE CONTAINING THE LEAK HAS BEEN ISOLATED AND PURGED OF GAS. MOST RECENT DETAILS AS OF 8/19: -CURRENTLY: 0 PSI -EXCAVATING POSSIBLE SOURCES UNDERGROUND (FLANGES, VALVE THREADED FITTINGS) AND PROBING WITH GAS DETECTOR. -OPERATIONS STARTED INVESTIGATING MLA VALVE 185-A-20. IT WAS DISCARDED IT AS LEAK SOURCE AND WE ARE EXCAVATING FLANGES AND CROSSOVER VALVES IN CROSSOVER HEADER. NO CUSTOMERS AFFECTED. -CO7 VALVE EXCAVATED, VALVE THREADED GREASE FITTING FOUND LOOSE (POSSIBLE LEAK SOURCE) -185A20, CO1, CO2, A-LINE INSULATING FLANGES EXCAVATED AND RE-COATED. -POWER GAS LINE HEADER EXCAVATED, SECTIONS FOUND DAMAGED BY PRIOR EXCAVATION. NEXT STEPS: -REPLACE DAMAGED SECTIONS OF POWER GAS HEADER -REPAIR LOOSE GREASE FITTINGS ON CO7 ULTIMATELY, A FLIR CAMERA WILL BE USED IF WE ARE UNABLE TO FIND THE LEAK SOURCE. UPDATE: LEAK WAS FIXED AND SEGMENT WAS PUT INTO SERVICE ON AUGUST 31, 2021. GAS WAS FOUND TO BE COMING FROM UNDERGROUND THREADED CONNECTIONS ON THE CO8 (30"" CROSSOVER) VALVE. THE GREASE FITTING AND BODY BLOWDOWN CONNECTION POINTS WERE DISCOVERED TO BE HAND TIGHT. OPERATIONS APPLIED BELZONA 1111 WITH REINFORCING CLOTH TO ALL UNDERGROUND THREADED CONNECTIONS. GAS WAS REINTRODUCED TO THIS SEGMENT AND NO FURTHER GAS LEAKS WERE DETECTED.