EL PASO NATURAL GAS CO

Incident Narrative

AN UPSTREAM PRODUCER CALLED EPNG GAS CONTROL AT 8:30PM MTN ON AUGUST 8, 2015 REPORTING HIGHER THAN NORMAL PRESSURES (RESULTING FROM PURCHASE POWER LOSSES IN THE AREA IMPACTING EPNG COMPRESSION FACILITIES). DURING THAT CALL THE PRODUCER MENTIONED THAT A RELIEF VALVE WAS RELIEVING. THE PRODUCER DID NOT SAY THAT IT WAS EPNG'S RELIEF VALVE AND THE EPNG CONTROLLER BELIEVED THE REFERENCE WAS TO A PRODUCER RELIEF VALVE. FURTHER, MAOP WAS NOT EXCEEDED AND THERE WERE NO ALARMS ASSOCIATED WITH THE MONUMENT STATION SO THE GAS CONTROLLER DID NOT TAKE ANY ACTION RELATED TO THE RELIEF VALVE. THE PRODUCER CALLED AGAIN AT 2:13AM MTN ON AUGUST 9, 2015 TO REPORT THAT THEY HEARD AN EPNG RELIEF VALVE RELIEVING IN THE MONUMENT STATION. THE EPNG GAS CONTROLLER CALLED OUT THE LOCAL OPERATIONS SPECIALIST WHO ARRIVED AT THE STATION AT 2:40AM. BY 3:00AM MTN THE UNIT SUCTION AND DISCHARGE HAD BEEN CLOSED AND THE VENTING HAD BEEN STOPPED. THE GAS LOSS ORIGINALLY REPORTED TO THE NRC WAS REVISED TO 5521MCF BASED ON ENGINEERING CALCULATIONS (ORIGINALLY CALCULATED AS A 4"" ORIFICE BUT THE RELIEF VALVE IS A 1.28"" ORIFICE). AN INVESTIGATION INTO THIS INCIDENT DETERMINED THAT THE RELIEF VALVE ACTUATED AT A PRESSURE BELOW THE MAOP OF THE FACILITY AND VENTED GAS TO ATMOSPHERE FOR SEVERAL HOURS. THE RELIEF VALVE WAS INSPECTED ON AUGUST 12, 2015 AND THE CAUSE OF THE EQUIPMENT FAILURE COULD NOT BE DETERMINED. THE RELIEF VALVE SEAT WAS LAPPED, THE SET POINT RESET AND TESTED, AND PLACED BACK INTO SERVICE. CONTRIBUTING TO THE INCIDENT WERE THE CONTROLLERS ACTIONS. IT WAS FOUND THAT THE CONTROLLER LACKED AN UNDERSTANDING OF WHAT CONSTITUTES A POTENTIAL ABNORMAL OPERATION AND FAILED TO THOROUGHLY QUESTION WHICH RELIEF VALVE WAS VENTING TO ASCERTAIN WHETHER OR NOT THE DEVICE IN QUESTION WAS AN EPNG DEVICE. THE CONTROLLER'S OQ WAS REVOKED AND THE CONTROLLER WAS GIVEN EXTENSIVE RE-TRAINING WITH A FOCUS ON THE IDENTIFICATION OF ABNORMAL OPERATIONS AND THE APPROPRIATE TIMELY RESPONSE REQUIRED.