COLUMBIA GAS TRANSMISSION CORP

Incident Narrative

AFTER AN INVESTIGAITON WAS COMPLETED INTO THIS REPORTABLE ICNIDENT, A CAUSAL FACTOR WAS IDENTIFED TO BE THE ROOT CAUSE BEHIND THIS REPORTABEL INCIDENT. THIS CAUSAL FACTOR WAS THE COMPRESSED AIR USED IN THE PILOT AIR SYSTEM THAT IS PART OF THE COMPRESSOR SATTION ESD SYSTEM. THE DEW POINT OF THE CONTROL AIR WAS ABOVE THE AMBIENT TEMPERATURE AT THE TIME OF THE INCIDENT DUE TO EQUIPMENT FAILURE DURING THE FALL OF 2011. INDICATIONS TO THE PRESENCE OF MOISTURE WAS FOUND IN THE BULK AIR STORAGE TANKS WHICH SUPPLY AIR TO ALL THE CONTROL SYSTEMS AT THE STATION. IN LIEU OF THIS FINDING, A NUMBER OF RECOMMENDATIONS WERE ISSUED AND IMPLEMENTED ACCORDINGLY. THE RECOMMENDATIONS WERE: (I) INSTALL NEW COMPRESSED AIR DRYING SYSTEM INCLUDING A NEW AFTERCOOLER, AIR DRYER AND WATER TRAPS. (INSTALLED AND FULLY FUNCTIONAL AS OF NOVEMBER 2, 2012.) (II) INSTALL FILTER/DRYER ON PILOT AIR SUPPLY SYSTEM. (INSTALLED AND WAS IN OPERATION AS OF JANUARY 31, 2013.) (III) ELIMINATE EXISTING MOISTURE IN THE ESD PILOT AIR SYSTEM. ACCUMULATED MOISTURE WAS REMOVED INTO OUTSIDE STORAGE TANKS. SMALL ESD STORAGE TANK CHECKED, NO WATER FOUND. PILOT AIR LINES TO BE PURGED WHEN NEW AIR SYSTEM IS INSTALLED. (COMPLETED ON DECEMBER 3, 2012.) (IV) TRAIN ADALINE COMPRESSOR STATION OPERATIONS PERSONNEL REGARDING THE IMPORTANCE OF THE AIR DRYING EQUIPMENT AND THE DOWNSTREAM SYSTEMS. (COMPLETED ON JANUARY 31, 2013.)