EL PASO NATURAL GAS CO

Incident Narrative

GRESHAM STATION EXPERIENCED AN UNSCHEDULED EMERGENCY SHUT-DOWN (ESD) ON JUNE 11, 2018 AT APPROXIMATELY 9:35 AM LOCAL TIME. OPERATIONS PERSONNEL WERE DISPATCHED BY GAS CONTROL TO THE SITE AND CONFIRMED DISCOVERY AT 11:27 AM LOCAL TIME. THE STATION ESD EQUIPMENT FUNCTIONED AS INTENDED WITH A TOTAL OF 23,576 MSCF GAS VENTED TO ATMOSPHERE THROUGH A 4' BLOCK VENT VALVE DURING THE EVENT. THE GAS LOSS DURING THIS EVENT WAS CONFIRMED TO BE A REPORTABLE EVENT TO THE NRC - REPORT NO. 1214945 AND TO THE TECQ. A 48-HOUR UPDATE TO THE NRC - REPORT NO. 1215067 THE FOLLOWING DAY INCLUDING THE LATITUDE AND LONGITUDE FOR THE RELEASE LOCATION AND MAJOR CROSS STREETS. THE NORMAL ESD VOLUME FOR THE STATION SHOULD ONLY BE 135 MSCF. UPON INVESTIGATION, IT WAS DETERMINED THAT A MANUAL 2' BYPASS/LOADING VALVE LOCATED AT THE STATION DISCHARGE GAS BLOCK VALVE (VO-9113) WAS LEFT IN THE OPEN POSITION. DURING NORMAL OPERATION, THE POSITION OF THIS VALVE SHOULD BE CLOSED. HOWEVER, WITH THE 2-INCH VALVE IN THE OPEN POSITION, PIPELINE GAS WAS FREE TO BYPASS THE STATION ISOLATION VALVE VO-9113 AND ENTER THE ESD VENT PIPING CONTRIBUTING TO A REPORTABLE GAS RELEASE ABOVE THE NORMAL ESD VOLUME. TO DETERMINE THE ROOT CAUSE OF THE ESD ACTIVATION AND RELEASE OF NATURAL GAS, OPERATIONS COMPLETED AN INSPECTION OF THE ESD SYSTEM INCLUDING THE ALL OF THE ESD BREAK GLASS STATIONS, THE ESD PULL SWITCHES, THE FIRE DETECTION SYSTEM, THE GAS DETECTION SYSTEM, THE LOW SUCTION PRESSURE SWITCH, AND THE LOW INSTRUMENT AIR PRESSURE SWITCH. THE INSPECTION DETERMINED THAT THE IMMEDIATE CAUSE WAS AN ELECTRICAL SHORT IN THE ESD BREAK GLASS STAND NO. 3 WIRE THAT TRIGGERED THE ACTIVATION OF THE ESD SYSTEM. THE ROOT CAUSE OF THE ESD WAS THE SEEPAGE OF RAINWATER INTO AN OPEN ELECTRICAL CONDUIT CONTACTING AN EXPOSED ELECTRICAL WIRE RESULTING IN AN ELECTRICAL SHORTAGE TO THE CASING; TRIGGERING THE STATION ESD SYSTEM. CORRECTIVE ACTION INCLUDED REPLACING THE EXPOSED WIRE AND CONDUIT TO ELIMINATE THE SHORT ON THE NO. 3 ESD BREAK GLASS SWITCH STATION. IN ADDITION OPERATIONS WILL REPLACE EXPOSED WIRES ON THE ESD SYSTEM AND SEAL OPEN CONDUITS TO PREVENT WATER FROM ENTERING THE ELECTRICAL CONDUITS TO PREVENT ELECTRICAL SHORTING OF THE ESD WIRING AND AVOID INADVERTENT ACTIVATION OF THE ESD SYSTEM.