TRANSCONTINENTAL GAS PIPE LINE COMPANY

Incident Narrative

FOUND GAS LEAKING FROM STATION YARD BY PICKING UP ON GAS MONITORS. PROBED HOLES AROUND THE AREA TO PINPOINT THE LEAK. FOUND STRONGER LEVELS OF GAS AND HAND DUG TO EXPOSE SOME PIPING AND VALVE WHERE THEN AN ICE BALL WAS FOUND WHERE THE LEAK WAS COMING FROM. PERFORMED ISOLATION AND BLOWDOWN OF THE STATION TO MAKE IT SAFE AND SCHEDULED CONTRACTOR TO COME IN TO BEGIN HYDROVAC AREA TO FIND THE LEAK. PERFORMED BLOWDOWN OF LEIDY A LINE FROM MLV 520LA1 TO 520LA10 TO REMOVE PRESSURE IN THE LINE TO INVESTIGATE LEAK AROUND 520S2 VALVE AND 24-INCH STATION HEADER PIPING. TIME LINE BELOW; 4/6/2018 16:30 IDENTIFIED A SMALL GAS LEAK NEAR VALVE 520S2. HAND-EXCAVATED GROUND AND IDENTIFIED ICE NEAR THE VALVE SITE AND LEAK INDICATIONS TOWARD LEIDY LINE A. OPERATIONS DECIDED TO BLOW-DOWN THE STATION YARD PIPING. BEGAN TO ASSEMBLE PERSONNEL AND EQUIPMENT. 18:00 TO 20:00 BLOWDOWN STATION YARD PIPING. STARTED LEAK INVESTIGATION. 4/11/2018 10:00 COMPLETED BLOWDOWN OF 2.5 MILES OF 24"" LEIDY LINE. GAS VOLUME WAS DRAWN BY METER STATIONS AND BLOWDOWN AT LOWER PRESSURE. CONTINUE LEAK INVESTIGATION. 4/12/2018 15:00 DECIDED TO REPLACE THE VALVE AND LOCATED SURPLUS VALVE. THE EXISTING 24"" BOLTED BODY VALVE WAS LEAKING AT THE BODY FLANGE AND THREADED DRAIN PLUG AT BOTTOM OF THE VALVE. THE EXISTING VALVE WAS INSTALLED IN 1965. OPERATIONS BEGAN TO ASSEMBLE PERSONNEL, MATERIAL, AND EQUIPMENT FOR THE VALVE REPLACEMENT. 4/16/2018 12:11 PIPELINE SAFETY WAS CONTACTED AND WILLIAMS - SECURITY OPERATIONS CENTER (SOC) CONTACTED THE NRC. ORIGINAL INCIDENT REPORT# 1209456. 4/18/2018 NEW 24"" VALVE ASSEMBLY WAS TESTED AND PLAN TO INSTALL ON 4/20/2018 4/19/2018 14:01 PIPELINE SAFETY CONTACTED NRC FOR THE FOLLOW-UP. WILLIAMS IS WORKING ON THE VALVE REPLACEMENT. NEW INCIDENT REPORT# 1209745. 4/20/2018 VALVE REPLACED WITH NEW 24"" BALL VALVE. EXISTING VALVE HAD BODY BLEED LEAK AND BODY FLANGE LEAK AT CONNECTIONS. CONTINUE TO INVESTIGATE PIPING AND HEADERS FOR CORROSION AND COATINGS WHILE COMPRESSOR STATION IS SHUT DOWN. 5/21/2018 13:30 LEIDY LINE A WAS RETURNED TO SERVICE FROM MLV 520LA0 - 520LA10. STATION 520 IS STILL OUT OF SERVICE, CONTINUE TO INVESTIGATE PIPING AND HEADERS FOR CORROSION AND COATINGS WHILE COMPRESSOR STATION IS SHUT DOWN. 6/22/2018 COMPLETED INVESTIGATION. 19:00 STATION 520 RETURNED TO SERVICE.