COLUMBIA GULF TRANSMISSION, LLC

Incident Narrative

ON JANUARY 11, 2015, STANTON COMPRESSOR STATION (CS) NIGHT SHIFT OPERATOR HEARD WHAT WAS NOTED TO BE A RELIEF VALVE (RV) VENTING MATERIAL INTO ATMOSPHERE. STANTON CS IS A TRANSMISSION FACILITY THAT IS OWNED, OPERATED AND MAINTAINED BY COLUMBIA GULF TRANSMISSION, LLC (COLUMBIA). THE FACILITY IS LOCATED IN THE TOWN OF STANTON IN POWELL COUNTY, KENTUCKY. THE STATION OPERATOR IDENTIFIED THE RV TO BE ON LINE 100 DISCHARGE PIPE. AFTER 25 MINUTES, THE OPERATOR WAS ABLE TO MANUALLY SECURE THE RV AND NO MATERIAL WAS NOTED TO BE VENTING INTO ATMOSPHERE THEREAFTER. INVESTIGATION INTO THIS INCIDENT WAS INITIATED THE FOLLOWING DAY WHERE IT INVOLVED A TEAM FROM COLUMBIA COMPRESSOR ENGINEERING SUPPORT AND COMPRESSOR OPERATIONS PERSONNEL. A CONTACT WITH THE RV ENGINEERING TECHNICAL SUPPORT WAS ESTABLISHED TO DETERMINE IF ANY HELP MAY BE PROVIDED TO DETERMINE THE PROBABLE CAUSE THAT LED TO THE INADVERTENT ACTIVATION OF THIS RV. THE RV ENGINEERING TECHNICAL SUPPORT INDICATED THAT BASED ON THE PROVIDED INFORMATION WHERE THE RV ACTIVATED BEFORE ACHIEVING THE SET POINT VALUE, IT WAS NOTED THAT IT MAY BE DUE TO THE PRESENCE OF FROST IN THE BODY OF THE RV THAT MAY HAVE INITIATED THIS UNINTENDED RELEASE. FURTHER INVESTIGATIONS ARE STILL ONGOING INTO THIS INCIDENT. THE FACILITY WAS RETURNED BACK TO SERVICE AFTER THE RV WAS BENCH TESTED AND EVALUATED WHERE ALL PERFORMED CHECKS DID NOT INDICATE OF ANY MALFUNCTIONS. HENCE, THE RV WAS RETURNED BACK INTO SERVICE. THE ROOT CAUSE ANALYSIS (RCA) REPORT FOR THIS INCIDENT IDENTIFIED THAT COLLECTED MOISTURE HAD SEEPED THROUGH A FAILED O-RING IN THE RV PISTON CAVITY. DUE TO THE REDUCED TEMPERATURE THAT WAS WIDESPREAD THROUGHOUT THE REGION (18 DEGREES F), THE COLLECTED MOISTURE FROZE, THENCE, FORCING THE RV TO UNSEAT AND RELEASING UNINTENTIONALLY MATERIAL INTO ATMOSPHERE. FOLLOW-UP ACTION ITEMS TO THE RCA REPORT WERE TO ENSURE THAT THE DRILLED VENT PASSAGE FOR THE SPRING CHAMBER OF THE RELIEF CONTROL CARTRIDGE SHOULD BE SEALED USING A SMALL AMOUNT OF GREASE SO THAT MOISTURE WILL NOT COLLECT IN THE CAVITY. VINTAGE RV ON THE DISCHARGE LINE OF CENTRIFUGAL COMPRESSORS WITH OBSOLETE SPARE PARTS, WILL BE REPLACED AND/OR PHASED-OUT FROM THE PIPELINE SYSTEM SUBJECT TO OPERATIONAL REQUIREMENTS. THIS WILL APPLY IF OVER PRESSURE PROTECTION AND OVER PRESSURE CONTROL STRATEGIES ARE IN PLACE WITH COMPREHENSIVE ENGINEERING ASSESSMENTS TO BE PERFORMED BEFORE ANY OF THESE STEPS ARE IMPLEMENTED.