NATURAL GAS PIPELINE CO OF AMERICA (KMI)

Incident Narrative

ON AUGUST 2, 2021 AT APPROXIMATELY 13:34 HOURS LOCAL TIME, NGPL COMPRESSOR STATION 388 EXPERIENCED AN UNPLANNED EMERGENCY SHUTDOWN (ESD) AND RELEASED AN ESTIMATED TOTAL OF 3,409 MCF OF NATURAL GAS TO THE ATMOSPHERE VIA THE ESD VENT STACK. DURING THE EVENT OPERATIONS, PERSONNEL WERE ON SITE WORKING AND CONFIRMED THE RELEASE. OUT OF AN ABUNDANCE OF CAUTION, NGPL NOTIFIED THE NRC OF THE EVENT AT APPROXIMATELY 14:23 HOURS LOCAL TIME (NRC REPORT NO. 1312544) BEFORE CONFIRMATION OF THE RELEASE VOLUME. UPON COMPLETION OF THE INVESTIGATION INTO THE EVENT, NGPL DETERMINED THAT THE ESD OCCURRED WHEN A FENWAL HEAT SENSOR FAILED AND THE ESD SYSTEM FUNCTIONED AS DESIGNED DUE TO THE DEVICE FAILURE. NGPL TESTED THE FENWAL DETECT-A-FIRE (D-A-F) SENSOR AND DISCOVERED AN ELECTRICAL SHORT DEFECT IN THE DEVICE. THE ELECTRICAL SHORT RESULTS IN A ""CLOSED"" SIGNAL, AND WHEN INTERPRETED BY THE ESD SYSTEM CONTROL LOGIC, WOULD COMMAND A STATION ESD SINCE THE STATION CONTROL LOGIC INTERPRETS A CLOSED SIGNAL AS A RAPID TEMPERATURE INCREASE, I.E., A FIRE BY THE ESD LOGIC. THEREFORE, THE STATION ESD SYSTEM TRIPPED AND VENTED THE STATION. NGPL REPLACED THE DEFECTIVE HEAT SENSOR. TO AVOID A REOCCURRENCE OF THIS TYPE OF EVENT, NGPL PLANS TO REPLACE THE STATION HEAT SENSORS AT A MINIMUM OF EVERY 10-YEARS AT THIS STATION OR REPLACE WITH SOME OTHER TYPE OF HEAT-SENSING DEVICE.