TRANSCONTINENTAL GAS PIPE LINE COMPANY

Incident Narrative

ON 2/18/2019, DURING PURGE AND PACK OPERATIONS ON THE MAINLINE D VALVE SETTING OUTAGE FROM MLV 185D0 (STATION 185) TO R9 AT THE POTOMAC RIVER VALVE SITE (APPROX. 20.41 MILES OF 42"" ML D), OPERATIONS PERSONNEL DETECTED A LEAK AT THE NEWLY INSTALLED MLV 185D14 VALVE SETTING AT 6:09 PM ET. THE SOURCE WAS THEN IDENTIFIED AS THE BACK WELD ON THE GREASE EXTENSION FITTING ON THE NEW 42"" BALL VALVE. THE PACK STOPPED AT 6:42 PM ET AND PIPELINE SECTION WAS ISOLATED. THIS IS CONSIDERED AS THE SHUTDOWN TIME. IMMEDIATELY PERSONNEL BEGAN TO BLOWDOWN THE SECTION OF MAIN LINE D, AT ~7:00 PM. THE LINE WAS THEN ISOLATED, AND DRAWN DOWN THE NEXT DAY BY WASHINGTON GAS, AND BLOWDOWN RESUMED AGAIN AT 2:06 PM ON 2/19/2019. THE BLOWDOWN WAS COMPLETED TO 0 PSIG AT 8:40 PM ON 2/20/2019. THE LINE WAS THEN SWEPT WITH AIR AND THE CRACKED WELD CONNECTION BETWEEN THE GREASE FITTING EXTENSION AND THE MAIN VALVE BODY WAS POSITIVELY IDENTIFIED AS THE SOURCE OF THE LEAK. THE WELD WAS SAND BLASTED AND INSPECTED, AND REPAIRED USING TIG WELDING. THE CAUSE OF THE EQUIPMENT FAILURE WAS A CRACKED WELD CONNECTION AT THE FITTING. WELD REPAIR, INSPECTION, AND RE-COATING WAS COMPLETED BY 12:16 PM ON 2/23/2019 AND THE PIPELINE SECTION WAS RETURNED TO SERVICE (PURGE AND PACK) BY 6:49 PM ON 2/23/2019. NO FURTHER REVIEW OR ROOT CAUSE ANALYSIS (RCA) HAS BEEN PERFORMED. THE INITIAL TOTAL REPAIR COSTS WERE COLLECTED, REVIEWED, AND WERE DETERMINED TO EXCEED THE $50,000 LIMIT AT 10:15 AM ET ON 2/26/2019 DURING A PROJECT MEETING. THEREFORE, THIS LEAK EVENT IS A DOT REPORTABLE INCIDENT DUE TO THE REPAIR COSTS. THE NRC WAS CONTACTED AT 10:26 AM ET ON 2/26/2019 - INITIAL NRC# 1238646. A 48-HOUR UPDATE WAS SUBMITTED ON 2/28/2019 - NRC# 1238845, AND CORRECTED TO ""WELD"" CONNECTION, NOT ""WELL"" CONNECTION. A 30-DAY INCIDENT REPORT (F 7100.2) IS REQUIRED TO BE SUBMITTED TO PHMSA. FINAL REPAIR COSTS ARE INCLUDED IN THIS REPORT.