TENNESSEE GAS PIPELINE COMPANY

Incident Narrative

ON 06/29/2019 AT 11:40-HOURS, THE TGP ON-CALL EMPLOYEE RESPONDED TO A GAS CONTROL CALL OUT CONCERNING A POSSIBLE ESD AT TGP STATION #563, JOELTON, TN. THE EMPLOYEE ARRIVED ON SITE AT APPROXIMATELY 12:20-HOURS AND PROCEEDED TO VERIFY SYSTEM STATUS. AT 12:45-HOURS, THE EMPLOYEE DISCUSSED WITH SUPERVISION AND CONFIRMED THE FACILITY ESD HAD OCCURRED WITH ALL VALVES WORKING AS DESIGNED. AT 13:00 HOURS, OPERATIONS ESTIMATED THE GAS LOSS FOR THE EVENT TO BE 4,005 MCF AND WAS REPORTED AS NRC #1250516 ON 06/29/2019 AT 13:34-HOURS. ENGINEERING PROVIDED REVISED ESTIMATED GAS LOSS ON 07/12/2019 AS 3,588 MCF. INVESTIGATION FOUND THERE WAS A MOMENTARY LOSS OF COMMERCIAL POWER AND THE STATION UPS SYSTEM DID NOT HOLD THE REQUIRED COMPRESSOR STATION VOLTAGE (120 VDC) IN THE INTERIM WHILE THE EMERGENCY GENERATOR WAS RAMPING UP TO COME ON-LINE. THIS INTERIM LACK OF VOLTAGE TRIGGERED THE COMPRESSOR STATION ESD. THE INVESTIGATION IDENTIFIED TWO BATTERIES IN THE UPS SYSTEM HAD IMPROPERLY DRAINED POWER. FURTHER INVESTIGATION FOUND SAID BATTERIES HAD NOT BEEN STORED AND MAINTAINED CORRECTLY DURING COMPRESSOR STATION CONSTRUCTION PRIOR TO OCTOBER, 2018. THE FAULTY BATTERIES WERE REPLACED. THE REPAIRS ALSO INCLUDED REPLACING SOME WIRING, FUSES, BREAKERS AND BATTERY CHARGERS. THE INVESTIGATION ALSO FOUND PREVIOUS AUTOMATION PROGRAMMING IN MAY, 2019 HAD INADVERTENTLY DISABLED AN ALARM CONCERNING ELECTRICAL POWER STATUS; SAID ALARM HAS BEEN REESTABLISHED. DURING THE INVESTIGATION AND REPAIR TIME PERIOD, THE STATION WAS IN MANNED OPERATION WITH THE EXCEPTION OF JULY 5, 2019, 14:40-HOURS TO JULY 10, 2019, 11:00-HOURS. JULY 5, 2019, INCLEMENT WEATHER IN THE AREA CAUSED ANOTHER LOSS OF COMMERCIAL POWER AND STATION ESD INCIDENT. (REFERENCE DOT REPORT #2019092) OPERATIONS KEPT THE STATION OFF LINE FOLLOWING THE JULY 5, 2019 INCIDENT UNTIL JULY 10, 2019 FOR CERTAIN TASKS RELATED TO BOTH INCIDENTS TO OCCUR. THE STATION THEN RESUMED MANNED OPERATION UNTIL OCTOBER 3, 2019, AT APPROXIMATELY 18:00-HOURS WHEN ALL REPAIRS FOR THE JUNE 29, 2019 INCIDENT WERE COMPLETED AND THE STATION RETURNED TO AUTOMATED OPERATION. THE 48-HOUR UPDATE IS NRC REPORT #1250639.