EL PASO NATURAL GAS CO

Incident Narrative

THE EPNG KEYSTONE CS (A.K.A. KEYSTONE ML OR KML) HAD A SCHEDULED OUTAGE ON 9/15/20 STARTING AT 9:00AM (START OF GAS DAY) TO PERFORM AN ANNUAL ESD TEST. ON 9/14/20, KEYSTONE AREA OPERATIONS WAS TOLD BY EPNG GAS CONTROL THAT THE EPNG WINK CS NEEDED TO BE ONLINE BEFORE THE OUTAGE TO ENSURE THAT THE PRESSURE DID NOT EXCEED MAOP. THE REQUIREMENT OF HAVING THE WINK CS OPERATING WAS NOT INCLUDED IN THE OUTAGE PLAN AND WAS NOT DISCUSSED DURING THE PRE-JOB OR JSA. ON 9/15/20 AT 8:15AM, EPNG OPERATIONS SPECIALIST MADE A CALL TO EPNG GAS CONTROL TO REQUEST PERMISSION TO TAKE KML DOWN EARLIER THAN PLANNED AS OPERATIONS HAD COMPLETED THE PRE-JOB / JSA REVIEWS WITH ALL OF THE KM/EPNG EMPLOYEES AND CONTRACTORS. THE EPNG GAS CONTROLLER STATED HE WOULD CHECK AND CALL THE EPNG OPERATIONS SPECIALIST BACK. AT 8:25AM, THE EPNG GAS CONTROLLER CALLED EPNG OPERATIONS SPECIALIST AND GAVE THE OKAY TO START THE OUTAGE AT 8:33 AM. THE WINK CS WAS NOT ONLINE. BASED ON THE INVESTIGATION INTO THIS EVENT IT WAS LATER DETERMINED THAT THE EPNG GAS CONTROLLER WAS REFERRING TO STARTING THE WINK CS IN PREPARATION FOR THE KEYSTONE ESD SYSTEM TEST. LOCAL OPERATIONS PERSONNEL PUSHED THE ESD BUTTON TO INITIATE THE ESD SYSTEM TEST AT KML. AT 8:41AM, A PRV ON THE 30-INCH PLANT SUCTION LINE, WHICH HAS A MAOP OF 575 PSIG, STARTED TO RELIEVE GAS DUE TO OVER PRESSURE (SET POINT 580 PSI). AT 8:45AM, A SECOND PRV LIFTED ON LINE 3026 (SET POINT 605 PSIG), WHICH HAS A MAOP OF 651 PSIG. AT 8:59AM, THE EPNG OPERATIONS SUPERVISOR FOR KML AND WINK CS CALLED KM KEYSTONE GAS STORAGE (KEYSTOR) TO STOP DELIVERING GAS TO EPNG LINE 3026. AT 9:20AM, THE THIRD PRV LIFTED ON LINE 3026 (SET POINT OF 630 PSIG). THE FOURTH PRV ON LINE 3026 (SET POINT 580 PSIG) DID NOT OPERATE. AT 9:50AM, IN CONFORMANCE WITH O&M PROCEDURE 159 ' EMERGENCY REPORTING AND INVESTIGATION, AN ERL CALL WAS HELD. DURING THE CALL IT WAS DETERMINED THAT THE UNINTENTIONAL GAS RELEASED THROUGH THE RELIEF VALVES WOULD MEET AND EXCEED THE 3,000 MCF REPORTABILITY THRESHOLD. THE ACTUAL GAS LOSS WAS UNKNOWN AT THE TIME. AT 9:55AM THE MAOP EXCEEDED 110% (632.5PSIG) WITH A PRESSURE OF 633 PSIG FOR APPROXIMATELY 1 MINUTE. IN ORDER TO REDUCE THE PRESSURES TO NORMAL AND STOP THE RELEASE OF GAS THROUGH THE RELIEF VALVES: - AT 9:05AM, KEYSTOR STOPPED WITHDRAWAL INTO THE EPNG SYSTEM - AT 9:20AM, THE GC LEADS WORKED WITH KEYSTONE CS SUPERVISION TO ISOLATE SUPPLY INTO KEYSTONE CS. THE L3006, L3028, AND L3082 WERE SHUTOFF AT THE KEYSTONE FIELD VALVE YARD. L1115 WAS OPENED AT GOLDSMITH TO DIVERT THE GAS NORTH TOWARDS PLAINS. ONCE THE WARREN WADDELL INTERCONNECT SHUTDOWN, L3146 VALVE 2 WAS OPENED, AND WINK WAS BROUGHT ONLINE, L1105 VALVE 0 WAS CLOSED. THESE TWO VALVE CLOSURES ISOLATE THE KEYSTONE CS SUCTION PIPING. - AT 10:01AM, KEYSTORE STARTED INJECTION - GAS CONTROL CALLED PERMIAN PRODUCERS ASKING THEM TO SHUT IN EARLY - AT 10:27AM, THE EPNG OPERATIONS SPECIALIST WAS SENT TO LINE 3026 TO CLOSE VALVE 3. - AT 10:14AM, A SECOND EPNG OPERATIONS SPECIALIST OPENED LINE 1115 TO ALLOW GAS TO FLOW NORTH TO PLAINS. BY 11:25AM, ALL OF THE RELIEF VALVES HAD RESEATED AND PRESSURES RETURNED TO BELOW MAOP BY 12:16PM. THE INVESTIGATION DETERMINED THAT THERE WAS A FAILURE OF CLEAR COMMUNICATIONS BETWEEN EPNG OPERATIONS AND THE CONTROL CENTER. NOTES: THE TIME ESTIMATE FOR INCIDENT REPORTING THRESHOLD IS A COMBINATION OF THE RELIEF VALVE ON THE INLET SUCTION PIPING AND ONE OF THE RELIEF VALVES ON LINE 3026 RELIEVING. 1) INLET SUCTION RV, RELEASE TIME: 8:41AM - 9:20AM, TOTAL 5936 MCF 2) RV L3026, RELEASE TIME: 8:45AM - 11:25AM, TOTAL 1586.7 MCF 3) RV L3026, RELEASE TIME: 9:20AM - 11:25AM, TOTAL 12363 MCF FOR PART E1 PRESSURE NOTED IS THE PRESSURE AT 8:55AM CENTRAL TIME WHEN THE GAS LOSS MET THE REPORTING THRESHOLD. A SEPARATE MAOP EXCEEDANCE REPORT (PHMSA REPORT 20-191933) WAS SUBMITTED TO PHMSA ASSOCIATED WITH THIS EVENT AND IN CONFORMANCE WITH 49CFR 191.25(B). L3026 MAOP OF 651PSIG WAS NOT EXCEEDED.