EL PASO NATURAL GAS CO

Incident Narrative

ON JULY 30, 2019, KEYSTONE COMPRESSOR STATION IN KERMIT CITY, WINKLER COUNTY, TEXAS LOST POWER AT 7:50 PM (CST). THE COMPRESSOR STATION SHUTDOWN DUE TO LOSS OF COMMERCIAL POWER. APPROXIMATELY 39 MINUTES AFTER THE LOSS OF POWER, THE PLANT B INLET SUCTION PIPING RELIEF VALVE, SET AT 585 PSIG, BEGAN RELIEVING PRESSURE INTERMITTENTLY UNTIL 8:55 PM DUE TO PRESSURE BUILD UP FROM UPSTREAM NATURAL GAS FLOW. GAS CONTROL NOTIFIED LOCAL OPERATIONS ABOUT THE RELIEF VALVE RELEASE AT 8:29 PM AND AT 8:30 PM PERSONNEL STARTED TO INVESTIGATE THE CAUSE OF THE RELIEF VALVE'S INTERMITTENT ACTIVATION. AT APPROXIMATELY 8:55 PM THE RELIEF VALVE SEAT MATERIAL PARTIALLY FAILED DUE TO THE INTERMITTENT ACTIVITY, ALLOWING THE VALVE TO LEAK GAS UNTIL 10:12 PM. DURING THIS EVENT FIELD PERSONNEL WERE IN CONTACT WITH THE CONTROL CENTER AND BOTH WERE TRYING TO DETERMINE IF THE RELIEF VALVE WAS TRULY ACTIVATING DUE TO AN OVERPRESSURE EVENT AND WERE TRYING TO DETERMINE HOW TO ELIMINATE OR DIVERT THE PRESSURE SOURCE. ONCE THEY DETERMINED WE DID NOT HAVE AN OVERPRESSURE EVENT LOCAL PERSONNEL OPENED A BYPASS VALVE AT 10:00 PM BETWEEN PLANT-B SUCTION AND DISCHARGE PIPING. THIS ACTION DIVERTED THE INCOMING FLOW OF GAS. ONCE THIS WAS ACCOMPLISHED FIELD PERSONNEL THEN ISOLATED THE RELIEF VALVE BY CLOSING ITS ISOLATION VALVE AT APPROXIMATELY 10:12 PM. THE POST INCIDENT INVESTIGATION DETERMINED THAT THE RELIEF VALVE SEAT WAS WEATHERED AND PARTIALLY TORN. THE RELIEF VALVE'S SEAT MATERIAL WAS REPLACED AND TESTED BEFORE B-PLANT WAS PUT BACK IN SERVICE.