TENNESSEE GAS PIPELINE COMPANY

Incident Narrative

ON NOVEMBER 27, 2023 AT 11:07 (CST), STATION 527 IN PORT SULPHUR, LA EXPERIENCED AN EMERGENCY SHUT DOWN (ESD) EVENT. THE INITIAL NOTIFICATION WAS COMPLETED BY LOCAL TGP OPERATIONS PERSONNEL WHO WERE ONSITE AT THE TIME OF THE EVENT. UPON STATION WALKTHROUGH, IT WAS DISCOVERED THAT THE STATION BLOCK VALVE WAS NOT FULLY CLOSED, ALLOWING FOR VENTING OF GAS THROUGH THE BLOW-DOWN VALVE. AT 11:20 (CST), TGP OPERATIONS PERSONNEL CLOSED THE BLOW-DOWN VALVE TO STOP VENTING OF THE GAS. AT THE TIME OF THE EVENT, BOTH STATION 527 AND THE ASSOCIATED SCADA SYSTEM WERE OFFLINE. THE SCADA SYSTEM WAS UNDERGOING MAINTENANCE DUE TO A FLOW-REVERSAL PROJECT OCCURRING AT THE STATION. SINCE THIS EVENT, STATION 527 HAS REMAINED IDLE. THE INTERNAL INVESTIGATION DETERMINED THAT WHILE DOWNLOADING THE RTU, THE ESD TEST STAND WAS NOT REMOVED FROM SERVICE. UPON DOWNLOADING THE RTU, THE STATION ESD ACTIVATED. IT WAS DETERMINED THAT ONCE THE ESD ACTIVATED, THE STATION BLOCK VALVE WAS NOT ABLE TO FULLY CLOSE DUE TO A ROCK FILTER BECOMING CLOGGED ON THE PILOT GAS. THE GAS LOSS DUE TO THIS INCIDENT 16,319 MCF. IN ORDER TO PREVENT REOCCURRENCE, WRITTEN PROCEDURES ARE BEING DEVELOPED FOR TAKING THE ESD TEST STAND OUT OF SERVICE AND FOR DOWNLOADING THE RTU SAFETY. ADDITIONALLY, THE VALVE OPERATOR IS BEING ADJUSTED SO THAT THE POWER GAS DOES NOT HAVE REDUNDANT FILTRATION.