FLORIDA GAS TRANSMISSION CO

Incident Narrative

ON JANUARY 2, 2023, AT APPROXIMATELY 1206 HOURS, AN FGT TECHNICIAN WAS NOTIFIED BY A DOWNSTREAM CUSTOMER THAT A RELIEF VALVE AT THE CLEARWATER SOUTH REGULATOR STATION WAS CURRENTLY ACTIVATED. THE CLEARWATER STATION IS SHARED WITH ANOTHER OPERATOR (CLEARWATER GAS COMPANY). THE FGT TECHNICIAN PROMPTLY RESPONDED TO THE AREA AND ISOLATED THE SOURCE AT APPROXIMATELY 1300 HRS. LOCAL FIRE DEPARTMENT AND POLICE RESPONDED TO A 3RD PARTY NOTIFICATION, AND THEY BLOCKED TRAFFIC IN BOTH DIRECTIONS UNTIL THE COMPANY TECHNICIAN ISOLATED THE REGULATOR RUN. ACCORDING TO SCADA, THE RELIEF VALVE BEGAN VENTING AT APPROXIMATELY 1030 HRS THAT DAY. THE PRESSURE EXCEEDED THE HI ALARM LIMIT THAT WOULD HAVE INITIATED CLOSER MONITORING BY GAS CONTROL HOWEVER THE PRESSURE DID NOT EXCEED THE HIHI CRITICAL ALARM LIMIT THAT WOULD HAVE GENERATED A CALL OUT AND FIELD INVESTIGATION. THE VOLUME RELEASED WAS CALCULATED TO BE APPROXIMATELY 3.45 MMSCF NATURAL GAS. THE DETERMINATION TIME FOR THIS ESTIMATE WAS APPROXIMATELY 1452 HRS. NRC NOTIFICATION OCCURRED AT APPROXIMATELY 1551 HRS. THE CLEARWATER SOUTH REGULATOR STATION DOES CONTAIN COVERED SEGMENTS IN THE COMPANY IMP, HOWEVER THE PIPING ASSOCIATED WITH THIS INCIDENT IS NOT A COVERED SEGMENT AS DETERMINED BY METHOD 2 (PIR). UPON INVESTIGATION THE CAUSE OF THE INCIDENT WAS CONFIRMED AS A DAMAGED DIAPHRAGM IN A MOODY PILOT ON THE REGULATOR WHICH ALLOWED HIGHER PRESSURE FLOW THROUGH THE STATION WHICH ACTIVATED THE RELIEF VALVE. THE RELIEF CAPACITY WAS VALIDATED DURING THE RELEASE VOLUME CALCULATION. THE DAMAGED EQUIPMENT WAS IMMEDIATELY REPLACED BY THE TECHNICIAN. TO PREVENT RECURRENCE THE COMPANY IS REVIEWING THE HIHI CRITICAL ALARM SETTING AT THIS LOCATION IN RELATION TO RELIEF VALVE SETTING AND WILL RESET THE HIHI ALARM AT A LEVEL BELOW THE RELIEF VALVE SETTING. THIS WILL RESULT IN A CALL OUT TO THE FIELD TO PERFORM INVESTIGATION BEFORE THE RELIEF ACTIVATES OR SHORTEN THE LENGTH OF TIME A RELIEF IS ACTIVATED.