TEXAS EASTERN TRANSMISSION, LP (SPECTRA ENERGY PARTNERS, LP)

Incident Narrative

ORIGINAL REPORT: 48 HR NRC 1237186 AT APPROXIMATELY 11:00 AM EST ON JANUARY 31, 2019, A NATURAL GAS RELEASE WAS DISCOVERED FROM A RELIEF VALVE AT MARIETTA COMPRESSOR STATION ON THE TEXAS EASTERN TRANSMISSION (TETLP) SYSTEM IN LANCASTER COUNTY, PA. THE INITIAL GAS LOSS WAS DETERMINED TO BE LESS THAN THE REPORTING THRESHOLD. THE APPARENT CAUSE WAS A TUBING FITTING UNDER A RELIEF VALVE SNAPPING OFF DUE TO VIBRATION, WHICH CAUSED THE RELIEF VALVE 305-10 TO ACTIVATE AND VENT GAS TO ATMOSPHERE. THE GAS LOSS WAS LATER REVISED ON FEBRUARY 6, 2019 AFTER IT WAS DETERMINED THAT DURING STATION ESD, THE MARIETTA STATION 36""X30"" SUCTION VALVE #2-6290 DID NOT CLOSE AS INTENDED DUE TO FREEZING IN THE VALVE CONTROLS. THE REVISED GAS LOSS EXCEEDED THE REPORTING THRESHOLD. AFTER CONSULTATION WITH PHMSA ON FEBRUARY 6, 2019, PHMSA RECOMMENDED THAT ENBRIDGE MAKE THE NRC NOTIFICATION. THE AFFECTED PART OF MARIETTA STATION WAS RETURNED TO SERVICE BY 9:12 PM EST ON JANUARY 31, 2019. SUPPLEMENTAL REPORT: AT APPROXIMATELY 11:00 AM EST ON JANUARY 31, 2019, A NATURAL GAS RELEASE WAS DISCOVERED FROM A RELIEF VALVE AT MARIETTA COMPRESSOR STATION ON THE TEXAS EASTERN TRANSMISSION (TETLP) SYSTEM IN LANCASTER COUNTY, PA. THE ESD SYSTEM WAS ACTIVATED TO ISOLATE THE LEAK IMMEDIATELY AFTER THE LEAK WAS IDENTIFIED. THE INITIAL GAS LOSS WAS DETERMINED TO BE APPROXIMATELY 1,782 MCF, LESS THAN THE REPORTING THRESHOLD. THE APPARENT CAUSE WAS THE FAILURE OF A TUBING FITTING UNDER A RELIEF VALVE DUE TO VIBRATION, WHICH CAUSED THE RELIEF VALVE 305-10 TO ACTIVATE AND VENT GAS TO ATMOSPHERE. ON FEBRUARY 5, DURING THE INVESTIGATION OF THIS EVENT, IT WAS DETERMINED THE MARIETTA STATION 36""X30"" SUCTION VALVE #2-6290 DID NOT CLOSE AS INTENDED DUE TO FREEZING IN THE VALVE CONTROLS, RESULTING IN A GAS LOSS VOLUME GREATER THAN ORIGINALLY ESTIMATED. THE GAS LOSS WAS REVISED TO APPROXIMATELY 4,200 MCF ON FEBRUARY 5, 2019. THE REVISED GAS LOSS EXCEEDED THE REPORTING THRESHOLD. AFTER CONSULTATION WITH PHMSA ON FEBRUARY 6, 2019, PHMSA RECOMMENDED THAT ENBRIDGE MAKE THE NRC NOTIFICATION. THE NRC NOTIFICATION WAS MADE ON FEB. 6, AS RECOMMENDED BY PHMSA. THE AFFECTED PART OF MARIETTA STATION WAS RETURNED TO SERVICE BY 9:12 PM EST ON JANUARY 31, 2019.