UGI PENN NATURAL GAS

Incident Narrative

A PRESSURE RELIEF VALVE ON A REGULATOR STATION OPENED AND VENTED AN ESTIMATED 3.5MM CUBIC FEET OF NATURAL GAS. ROOT CAUSE INVESTIGATION REVEALED THAT THE REGULATORS FOR THE CONTROL GAS TO THE POSITIONER ON THE CONTROL VALVE FAILED, WHICH RESULTED IN EXCESSIVE PRESSURE BEYOND THE CONTROL VALVE AND THE OPENING OF THE RELIEF VALVE PROVIDING OVER-PRESSURE PROTECTION TO THE DOWNSTREAM SYSTEM. AFTER THE RELIEF VALVE OPENED, THE VALVE FAILED TO RE-SEAT DUE TO A PIECE OF WELD SLAG ON THE SEAT OF THE RELIEF. IN RESPONSE TO THE INCIDENT, CREWS SHUT THE INLET VALVE TO THE REGULATOR STATION, HOWEVER THE RELIEF CONTINUED TO VENT DUE TO THE SLAG ON SEAT OF THE RELIEF. THE ISSUE WAS RESOLVED AT APPROXIMATELY 8:59 AM WHEN THE OUTLET VALVE TO THE STATION WAS CLOSED. THE INCIDENT IS BEING REPORTED ON THE BASIS OF THE VOLUMETRIC REPORTING CRITERIA. SUBSEQUENT TO THE INCIDENT, AND BEFORE RETURNING THE STATION TO SERVICE, A DEDICATED FILTER WAS PLACED IN FRONT OF THE REGULATORS TO THE INSTRUMENT GAS TO MINIMIZE THE PROBABILITY OF RE-OCCURRENCE. ADDITIONALLY, A RELIEF VALVE WAS ADDED TO THE INSTRUMENT GAS LINES AS SUPPLEMENTAL OVER-PRESSURE PROTECTION AND SUPPLY GAS TUBING LINES WERE RELOCATED TO MINIMIZE VIBRATION. FINALLY, ADDITIONAL PERIODIC MAINTENANCE HAS BEEN IMPLEMENTED TO INSURE THE REMEDIATION MEASURES TAKEN REMAIN ADEQUATE. 6/1/2018 SUPPLEMENTAL REPORT SUBMITTED TO INDICATE REPORT AS ""FINAL