NATURAL GAS PIPELINE CO OF AMERICA (KMI)

Incident Narrative

ON 10/17/2021 AT APPROXIMATELY 6:48 AM, AN OPERATOR FROM NATURAL GAS PIPELINE COMPANY OF AMERICA (NGPL) ARRIVED AT STATION 346 AND HEARD GAS VENTING TO ATMOSPHERE. THE OPERATOR IMMEDIATELY STARTED THE INVESTIGATION AND DISCOVERED A FUEL GAS RELIEF VALVE OPEN ALLOWING GAS TO VENT. THE OPERATOR VERIFIED THE FUEL GAS PRESSURES MAKING SURE THEY WERE NORMAL AND THEN CLOSED THE ISOLATION VALVE BELOW THE RELIEF VALVE ENDING THE RELEASE. SUBSEQUENTLY AN EMERGENCY RESPONSE LINE (ERL) WAS INITIATED AND THE INCIDENT WAS DEEMED REPORTABLE. THE INVESTIGATION CONCLUDED THAT A GROVE FLEXFLOW REGULATOR WAS LEAKING INTERNALLY ALLOWING PRESSURE TO BUILD IN THE PIPING DOWNSTREAM. THE STATION HAS AN UPSTREAM PRESSURE MONITOR REGULATOR THAT CLOSES ON INCREASING DOWNSTREAM PRESSURE. HOWEVER, THE MONITOR REGULATOR IS NOT A POSITIVE SEAL VALVE. THUS, ALLOWED GAS TO CONTINUE TO FLOW TO THE GROVE FLEXFLOW REGULATOR. THE PRESSURE CONTINUED TO RISE UNTIL THE RELIEF VALVE ACTUATED AS DESIGNED. UPON ACTUATION, THE FUEL GAS RELIEF VALVE DID NOT RE-SEAT PROPERLY RESULTING IN A SLOW GAS RELEASE FOR APPROXIMATELY 23HRS. BECAUSE THE FUEL GAS RELIEF VALVE FAILED TO RE-SEATING PROPERLY, THIS INCIDENT WAS REPORTABLE DUE TO THE VOLUME RELEASE, WHICH WAS MORE THAN THE 3,000 MCF THRESHOLD. OPERATIONS DISCOVERED THAT THE RELIEF VALVE FAILED TO RE-SEAT DUE TO DEBRIS ACCUMULATION IN THE VALVE SEAT. IN ORDER TO PREVENT REOCCURRENCE OPERATIONS REPAIRED THE FLEXFLOW REGULATOR AND CLEANED THE FUEL GAS VALVE SEAT. IN ADDITION, CALLOUT ALARMS FOR HIGH FUEL GAS PRESSURE AND HMI CONFIGURATIONS HAVE BEEN INSTALLED FOR UNITS 1, 2 AND 3 AT NGPL COMPRESSOR STATION 346.