KINDER MORGAN CO2 CO. LLC

Incident Narrative

THE SCADA CONTROLLER RECEIVED RATE OF CHANGE PRESSURE ALARMS AND NOTICED PRESSURE DROPS AROUND 15:31 - 15:34 CST ON THE INLET TRANSMITTER. THE CONTROLLER NOTIFIED CONTROL ROOM MANAGER AND AREA OPERATIONS SUPERVISOR OF THESE PRESSURE EVENTS. A PIPELINE OPERATOR ARRIVED ON SITE TO INVESTIGATE, AND CONFIRMED THAT A 4X6 INCH PILOT OPERATED RELIEF VALVE WAS RELIEVING INTERMITTENTLY, CAUSING CO2 TO RELEASE TO THE ATMOSPHERE. ACCORDING TO SCADA DATA THE RELIEF VALVE MALFUNCTIONED MULTIPLE TIMES BETWEEN 12:42 AND17:29 CST. THE OPERATOR ISOLATED THE RELIEF VALVE AT 17:33 CST BY CLOSING AN 6 INCH BLOCK VALVE UPSTREAM OF THE RELIEF VALVE. THE RELIEF VALVE WAS TESTED AND CALIBRATED THE FOLLOWING DAY ON 10/6 AND RESET TO THE CORRECT SET PRESSURE OF 2450 PSI. IN ADDITION, THE STATION PIPING WAS BLOWN DOWN ON 10/8 AS A MITIGATIVE MEASURE. THE PUMP STATION WHERE THE RELIEF VALVE WAS LOCATED HAS BEEN INACTIVE SINCE 2011. THE RELIEF VALVE WAS LAST SET AND CALIBRATED ON 10/9/2020 TO OPERATE AT 2450 PSI BUT RELIEVED AT A PRESSURE OF 2335 PSI. THIS RELIEF VALVE WAS INSTALLED TO PROTECT THE PIPELINE WHEN THE STATION PUMPS WERE RUNNING . THIS PUMP STATION HAS BEEN INACTIVE SINCE 2011 BUT REMAINED PRESSURED UP AT PIPELINE PRESSURE. THE RELIEF VALVE HAS BEEN SENT TO THE MANUFACTURE REPRESENTATIVE FOR TESTING. UPDATED 02/02/2022: DURING THE TEARDOWN OF THE VALVE THAT FAILED, IT WAS IDENTIFIED THAT A SUPPLY FILTER HEX NUT WAS LOOSE CREATING A PATH FOR CO2 TO LEAK TO THE ATMOSPHERE RESULTING IN A FREEZING CONDITION INSIDE THE RELIEF VALVE PILOT ASSEMBLY. THE FREEZING OF THE SUPPLY FILTER CREATED PRESSURE DIFFERENTIAL ACROSS THE MAIN VALVE WITH LOWER DOME PRESSURE CAUSING IT TO RELIEVE BELOW THE SET PRESSURE.