SOUTHERN NATURAL GAS CO

Incident Narrative

UPON ARRIVING ON JUNE 30TH AT APPROXIMATELY 10AM CENTRAL TIME TO PERFORM DAILY COMPRESSOR STATION OPERATOR DUTIES AT THE YORK COMPRESSOR STATION, AN OPERATIONS SPECIALIST DISCOVERED THAT THE PRIMARY FUEL GAS RELIEF VALVE WAS VENTING GAS. AFTER APPROXIMATELY 5 MINUTES, THE SPECIALIST WAS ABLE TO STOP THE VENTING BUT DID NOT INFORM SUPERVISION OF THE ABNORMAL OPERATING CONDITION. THE OPERATIONS SPECIALIST, THINKING THAT THE REPORTABLE GAS LOSS FROM THE TIME HE NOTED IT UNTIL THE TIME HE ADDRESSED IT WAS UNDER THE PHMSA LIMIT OF 3000 MCF, DID NOT REPORT THE EVENT TO SUPERVISION. SEPARATELY, AND ALSO ON THE MORNING OF JUNE 30TH, THE MEASUREMENT TECHNICIAN RESPONSIBLE FOR THE YORK FUEL GAS METER RECEIVED A CALL FROM DATA INTEGRITY INFORMING HIM THAT THE DIFFERENTIAL PRESSURE TRANSMITTER FOR THE YORK FUEL GAS METER HAD OVER-RANGED OVER THE WEEKEND AND NEEDED TO BE INVESTIGATED. THE MEASUREMENT TECHNICIAN DROVE TO THE YORK C/S, ARRIVING AT 13:30 PM, BUT DID NOT FIND ANYTHING OUT OF THE ORDINARY. FURTHER INVESTIGATION AND DISCUSSION WITH DATA INTEGRITY, AS WELL AS A REVIEW OF SCADA DATA, DETERMINED THAT THE RELIEF VALVE HAD BEGUN VENTING ON FRIDAY, JUNE 27TH AT APPROXIMATELY 11 PM AND CONTINUED UNTIL THE OPERATIONS SPECIALIST ADDRESSED IT ON MONDAY, JUNE 30TH AT 10AM. IT WAS DETERMINED TO BE REPORTABLE AT 17:45 PM ON JUNE 30, 2014. EXAMINATION OF THE RELIEF VALVE AND REGULATOR DETERMINED THAT THE REGULATOR PILOT SEAT HAD BECOME WORN TO THE POINT WHERE IT ALLOWED GAS TO SEEP PAST IT UNTIL PRESSURE BUILT UP HIGH ENOUGH TO LIFT THE RELIEF VALVE.