TRANSWESTERN PIPELINE COMPANY LLC

Incident Narrative

ON JUNE 19TH 2021 AT 23:23HRS MST, THE RELIEF VALVE AT THE LAGUNA 6 COMPRESSOR STATION ALONG THE TRANSWESTERN PIPELINE LIFTED AND BEGAN RELEASING NATURAL GAS. AT 03:20 MST ON THE MORNING OF JUNE 20TH, THE LOCAL POLICE CALLED THE CONTROL CENTER AND REPORTED THE COMPRESSOR STATION RELIEF WAS GOING OFF. AT 03:40 MST, THE LOCAL TECHNICIAN ARRIVED ON SCENE AND CONFIRMED THE RELIEF VALVE WAS OPEN. AT 03:50 MST THE PIPELINE WAS SHUTDOWN AND THE TECHNICIAN WAS ABLE TO GET THE RELIEF VALVE CLOSED. THE CAUSE OF THE RELEASE WAS A BROKEN SENSING TUBE ON THE RELIEF VALVE. THE SENSING TUBE HOLDS PRESSURE ON THE VALVE AND KEEPS THE RELIEF VALVE CLOSED. ONCE THE TUBE WAS BROKEN, THE RELIEF WAS ALLOWED TO ENGAGE. IT IS BELIEVED THE TUBE BROKE DUE TO EXCESSIVE VIBRATION. AT 05:30 MST OPERATIONS COMPLETED THEIR VOLUME RELEASED CALCULATIONS AND CONFIRMED THE 3MMCF LIMIT HAD BEEN MET. REGULATORY COMPLIANCE WAS NOTIFIED AND A NRC NOTIFICATION (1308279) WAS MADE AT 05:44 MST ON JUNE 20TH. THE 48HOUR NRC NOTIFICATION (1308368) WAS MADE ON JUNE 21ST AT 13:13 MST. ON JUNE 22ND AT APPROXIMATELY 13:45 MST, THE PIPELINE WAS RESTARTED AFTER REPLACING THE BROKEN TUBING ON THE RELIEF VALVE WITH TUBING THAT IS MORE FLEXIBLE TO ALLEVIATE VIBRATION INDUCED ISSUES.