GREAT LAKES GAS TRANSMISSION CO

Incident Narrative

ON FEBRUARY 2, 2020, AT 1000 (ALL TIMES ARE EASTERN STANDARD TIME), A FARWELL CS TECHNICIAN RESPONDED TO THE SOUND OF AN APPARENT NATURAL GAS RELEASE WITHIN THE COMPRESSOR STATION YARD. AT 1012, THE TECHNICIAN CONFIRMED THE RELEASE ASSOCIATED WITH THE 36 INCH HEADER INLET TO A GAS COOLER. AT 1013, THE TECHNICIAN ACTIVATED AN EMERGENCY SHUT DOWN (ESD) AND THE STATION WAS ISOLATED FROM ANY GAS SOURCES WITH THE BLOW DOWN SUCCESSFULLY COMPLETED. AT 1025 THE STATION WAS CONFIRMED ISOLATED. AT 1106, THE INCIDENT WAS REPORTED TO THE NATIONAL RESPONSE CENTER (NRC); REPORT # 1270167. THE INCIDENT WAS REPORTED DUE TO ANTICIPATED REPAIR COSTS EXCEEDING THE REPORTABLE THRESHOLD OF $50,000. FIELD INVESTIGATION INDICATED THE SOURCE WAS DUE TO A FAILED WELD ASSOCIATED WITH THE WELD-O-LET 2 INCH SIPHON DRAIN LINE CONNECTED TO THE 36 INCH HEADER. THE FAILED SIPHON DRAIN LINE WAS REMOVED AND PLUGGED. THE 2 INCH SIPHON DRAIN LINE ASSEMBLY WAS SENT FOR METALLURGICAL ANALYSIS TO DETERMINE THE CAUSE OF THE FAILURE. 20200514 UPDATE: RCFA RECEIVED ON 1 MAY 2020; WILL INCLUDE FINAL SUMMARY AFTER PAGE-TURN MEETING WITH MPSC ON 21 MAY 2020. 20200609 UPDATE: RCFA WAS RECEIVED AND RESULTS REVIEWED WITH THE MPSC ON 5/21. ADDITIONAL QUESTIONS WERE ASKED AND RESPONSES WERE PROVIDED ON 6/8. 20200625 UPDATE: METALLURGICAL ANALYSIS DETERMINED THE PIPE CRACKED DUE TO REVERSED BENDING FATIGUE, WHICH WAS A RESULT OF THERMAL LATERAL, AND THERMAL EXPANSION AND CONTRACTION OF THE FIXED (IN CONCRETE) 2"" DRAIN LINE.