ANR PIPELINE CO

Incident Narrative

A SUSPECTED FALSE TRIGGER OF THE WINFIELD ESD SYSTEM FROM A NEW FIRE EYE(S) ACTIVATED THE STATION'S ESD SYSTEM. THIS FALSE TRIGGER ASSUMPTION IS BECAUSE THERE WAS NOT FIRE FOUND ONSITE AFTER A THOROUGH INSPECTION OF THE AREAS THAT THE FIRE EYES COVER. SUPPORTING THE IDEA OF THE FALSE FIRE EYE OUTPUT IS THE FIRE EYES ARE NEW AND ARE NOW GETTING REPLACED BECAUSE THE MANUFACTURE STATED THEY ARE TO SENSITIVE FOR OUR APPLICATION. THE ESD SYSTEM'S ACTIVATION, RESULTED IN A RELEASE OF THE COMPRESSOR STATIONS YARD PIPING GAS TO ATMOSPHERE. DURING THE ESD AN EXTENDED RELEASE OCCURRED WHEN THE LINE BLOCK VALVE (249-1-16) FAILED TO SHUT. THE VALVE WAS CLOSED BY THE ON-CALL TECHNICIAN. TC ENERGY HAS REPLACED ALL FIRE EYES AT THE WINFIELD STATION WITH NEW DETECTORS, WHICH WERE CALIBRATED AND TESTED. AFTER REPLACING DETECTORS, AN ESD SYSTEM INSPECTION WAS COMPLETED ACCORDING TO PROCEDURES ON APRIL 14, 2021. THE TEST WAS INITIATED BY TRIGGERING THE FLAME DETECTORS AND THEN MONITORING ALL EMERGENCY SYSTEMS VALVES FOR OPERATIONS AND TIMING. DURING THE TEST, ALL SYSTEMS VALVE PROPERLY OPERATED AND FULLY CLOSED. AN INVESTIGATION IS ONGOING AS TO WHY VALVE 249-1-16 FAILED TO SHUT. 20210526 UPDATE: DURING THE RELEASE EVENT VALVE 249-1-16 DID NOT CLOSE WHICH PROLONGED THE RELEASE OF GAS. THE ACTUATOR FOR THE VALVE HAS TWO STATES (MANUAL AND AUTOMATIC) AND THE VALVE WAS IN MANUAL. THIS MEANT THAT THE STATION CONTROL LOGIC WAS NOT ABLE TO CYCLE THE VALVE DURING THE FALSE TRIP OF THE FIRE EYE. PRIOR TO THE EVENT THE STATION VALVE CONFIGURATION WAS CHANGED FROM INJECTION MODE TO WITHDRAWAL MODE. THIS PROCESS FOR CHANGING MODES OF OPERATION REQUIRES LOCAL PERSONNEL TO MANUALLY CONFIGURE SEVERAL YARD VALVES AND IS NOT PART OF THE STATION CONTROL LOGIC. STATION PERSONNEL UTILIZED A MODE DIAGRAM TO VERIFY ALL VALVES ARE SET IN THE PROPER POSITION. VALVE 249-1-16 WAS LEFT IN THE MANUAL STATE AFTER THE YARD VALVES WERE RE-POSITIONED FOR WITHDRAWAL MODE. SUBSEQUENTLY A PROCEDURAL CHECKLIST HAS BEEN CREATED.