ENOGEX LLC

Incident Narrative

ON THE MORNING OF APRIL 3, 2012 A DISRUPTION OF PURCHASED POWER SERVING THE PERRY COMPRESSOR STATION AUTOMATICALLY ACTIVATED THE COMPRESSOR STATION EMERGENCY SHUTDOWN (ESD) SYSTEM, WHICH IS DESIGNED IN ACCORDANCE WITH 49 CFR PART 192.167. THE ESD SYSTEM IS DESIGNED TO ISOLATE THE COMPRESSOR STATION FORM THE INCOMING AND OUTGOING PIPELINES AND VENT ALL GAS INSIDE THE STATION TO A SAFE LOCATION. THE STATION INLET ESD VALVE FAILED TO CLOSE DUE TO A BLOCKAGE IN THE ESD VALVE ACTUATOR EXHAUST TUBING. THE BLOCKAGE, WHICH WAS IDENTIFIED AS POLLEN DEPOSITED BY INSECTS INSIDE THE TUBING, PREVENTED THE OPERATING PRESSURE INSIDE THE SPRING OPERATED VALVE ACTUATOR FROM VENTING TO ATMOSPHERE, THUS PREVENTING THE VALVE FROM OPERATING PROPERLY. THE ESD SYSTEM VENT VALVES DID OPERATE PROPERLY, THEREBY VENTING 3,368 MCF OF NATURAL GAS TO THE ATMOSPHERE UNINTENTIONALLY. GAS CONTROL DISPATCHED COMPANY PERSONNEL TO THE COMRPESSOR STATION. THE COMPRESSOR STATION WAS ISOLATED FORM THE PIPELINE VIA A MANUAL ISOLATION VALVE. THE NATURAL GAS REMAINING INSIDE THE STATION ESD VENT PIPING WAS THEN QUICKLY VENTED TO THE ATMOSPHERE. THE BLOCKAGE WAS REMOVED FROM THE ACTUATOR EXHAUST PORT TUBING AND THE STATION INLET ESD VALVE WAS RETURNED TO NORMAL OPERATION. THERE WAS NO DAMAGE TO THE ACTUATOR OR ESD VALVE. UPDATE MARCH 5, 2013: COMPLETED SECTION E.5.F.