HARVEST MIDSTREAM COMPANY

Incident Narrative

"ON MAY 19, 2025, HARVEST INITIATED A ROUTINE FOAM PIGGING OPERATION ON THE PGGS SYSTEM AT APPROXIMATELY 11:00 AM AS PART OF STANDARD MAINTENANCE ACTIVITIES. THE PIG WAS LAUNCHED WITHOUT INCIDENT; HOWEVER, PRESSURE IN THE PG-02 SEGMENT BEGAN TO RISE UNEXPECTEDLY LATER THAT AFTERNOON. THIS SEGMENT IS EQUIPPED WITH A 6-INCH PRESSURE RELIEF VALVE (PRV) AND EMERGENCY SHUTDOWN VALVE (ESDV-1), MONITORED BY PRESSURE TRANSMITTER PT-201. DURING THE INVESTIGATION, IT WAS DETERMINED THAT THE PIG ARRIVED SIGNIFICANTLY EARLIER THAN ANTICIPATED. THE TRAVEL TIME HAD BEEN PROJECTED USING SCADA FLOW DATA. THE PIG WAS EXPECTED TO TAKE UP TO TWO DAYS TO REACH ITS DESTINATION BUT COMPLETED THE RUN WITHIN A FEW HOURS. THIS UNANTICIPATED ARRIVAL LED TO CONDENSATE ACCUMULATION IN THE LINE, WHICH TRAVELED INTO THE ACTUATOR SUPPLY TUBING OF ESDV-1, CONTRIBUTING TO VALVE MALFUNCTION. AT 5:14 PM, PT-201 REGISTERED A PRESSURE OF 526 PSI. THE HOUSTON CONTROL ROOM DETECTED THE TREND AND CONTACTED PIPELINE OPERATOR, WHO ADVISED THAT THE FOAM PIG WAS LIKELY STILL IN TRANSIT. HE INFORMED THE CONTROLLER THAT THE VALVE HAD PRESSURE RELIEF CAPABILITY AND INSTRUCTED THEM TO RESET THE VALVE IF NECESSARY AND NOTIFY HIM IF PRESSURE EXCEEDED 600 PSI. AS PRESSURE CONTINUED TO RISE, PIPELINE OPERATOR INITIATED MANUAL SHUT-IN COORDINATION WITH THE HILCORP PLATFORM. AT 5:54 PM, PRESSURE REACHED 550 PSI AND ESDV-1 RECEIVED A CLOSE COMMAND, SHUTTING THE VALVE AS DESIGNED. HOWEVER, CONDENSATE ACCUMULATION IN THE REGULATOR AND ACTUATOR TUBING SUBSEQUENTLY PREVENTED THE VALVE FROM REOPENING. THE CONTROL ROOM ISSUED MULTIPLE RESET COMMANDS TO ESDV-1 VIA SCADA, BUT THE VALVE REMAINED IN AN 'ERROR' STATE AND FAILED TO REOPEN. AT 6:37 PM, PRESSURE REACHED THE MAOP OF 606.2 PSI, PROMPTING THE CONTROLLER TO ESCALATE THE SITUATION TO OPERATIONS CONTROLS DIRECTOR, FOREMAN, AND PIPELINE OPERATOR. BY 6:43 PM, SCADA ENGINEER WAS CONTACTED FOR SUPPORT. HE DETERMINED THAT THE ISSUE WAS NOT DUE TO A SCADA MALFUNCTION BUT WAS LIKELY CAUSED BY CONDENSATE IN THE REGULATOR AND ACTUATOR TUBING, WHICH PREVENTED THE VALVE FROM RECEIVING SUFFICIENT ACTUATION PRESSURE. AT 6:50 PM, PRESSURE PEAKED AT 620.9 PSI, EXCEEDING MAOP BUT REMAINING BELOW 110%, AND THE PRV ACTIVATED TO RELIEVE PRESSURE. THE PRV VENTED NATURAL GAS TO ATMOSPHERE FOR APPROXIMATELY 22 MINUTES. AT 6:57 PM, FLOW THROUGH PG-02 DROPPED TO ZERO. AT 7:00 PM, A MANUAL CLOSE COMMAND WAS ISSUED TO ESDV-1, AND A PERMISSIVE SIGNAL WAS RECEIVED. PIPELINE OPERATORS AGREED TO KEEP THE VALVE CLOSED AND CONDUCT A STAND-UP PRESSURE TEST TO CONFIRM PIPELINE INTEGRITY. THE TEST BEGAN AT 7:18 PM, WITH PT-201 READING 594.5 PSI. BY 8:01 PM, PRESSURE HAD STABILIZED AT 594.0 PSI. ALTHOUGH THE LINE WAS DEEMED SAFE TO RESTART, REPEATED ATTEMPTS TO REOPEN ESDV-1 WERE UNSUCCESSFUL. AT 10:19 PM, PIPELINE OPERATOR AND I&E TECHNICIAN DECIDED TO KEEP THE SYSTEM SHUT-IN OVERNIGHT. THE ROOT CAUSE WAS IDENTIFIED AS A LIQUID-FILLED REGULATOR AND ACTUATOR TUBING, WHICH PREVENTED PROPER VALVE ACTUATION. PLANS WERE MADE TO ACCESS THE SITE THE FOLLOWING MORNING AND REPLACE THE AFFECTED COMPONENTS."