FLORIDA GAS TRANSMISSION CO

Incident Narrative

ON JANUARY 16, 2023, AT APPROXIMATELY 07:00, A FLORIDA GAS TRANSMISSION TECHNICIAN DISCOVERED A COMPRESSOR UNIT VENT VALVE WAS VENTING NATURAL GAS TO ATMOSPHERE AT THE COMPRESSOR STATION 24, NEAR TRENTON, FL. THE TECHNICIAN ISOLATED THE COMPRESSOR AT APPROXIMATELY 0730 HRS. ACCORDING TO COMPANY SCADA, THE VENT VALVE HAD BEGUN VENTING AT APPROXIMATELY 13:00 ON JANUARY 15, 2023, BUT NO OTHER SCADA ALARMS WERE TRIGGERED. THE UNIT WAS SHUT DOWN REMOTELY BY GAS CONTROL AT 11:00 ON JANUARY 15, 2023. THE COMPRESSOR UNIT AUTOMATICALLY VENTS AFTER TWO (2) HOURS OF SHUTDOWN. THE SHUTDOWN AND ALL VALVE POSITIONS INDICATED CLOSURE; THEREFORE, NO ALARMS WERE TRIGGERED. THE VOLUME RELEASED WAS CALCULATED TO BE APPROXIMATELY 102.6 MMSCF NATURAL GAS. THE DETERMINATION TIME FOR THIS ESTIMATE WAS APPROXIMATELY 14:52 ON JANUARY 16, 2023, WHICH WAS FOLLOWED BY THE NRC NOTIFICATION THAT OCCURRED AT APPROXIMATELY 15:44. THE CAUSE OF THE INCIDENT WAS LATER CONFIRMED TO BE A SUCTION SIDE ISOLATION VALVE NOT FULLY SEATING AFTER THE COMPRESSOR UNIT WAS SHUTDOWN. SPECIFICALLY, IT APPEARS THAT THE VALVE ACTUATOR MALFUNCTIONED RESULTING IN THE VALVE NOT FULLY SEATING, THEREBY ALLOWING PIPELINE PRESSURE TO BLEED BY INTO THE COMPRESSOR UNIT CAUSING THE NATURAL GAS TO BE VENTED TO ATMOSPHERE. THE SUCTION SIDE VALVE WAS FULLY CLOSED MANUALLY BY THE TECHNICIAN TO STOP FLOW OF GAS THROUGH THE COMPRESSOR. THE LOGIC TO ALLOW MORE TIME FOR VALVE CLOSURE WAS DEVELOPED AND INSTALLED THE DAY OF THE RCFA INVESTIGATION TO PREVENT RECURRENCE.