COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON JUNE 15, 2014 AT 01:07 EASTERN STANDARD TIME, UNIT NO. 1 FAULTED AND BEGAN SHUTTING DOWN A COMPRESSOR STATION (CS) FACILITY. THE CS FACILITY IS OPERATED AND MAINTAINED BY COLUMBIA GAS TRANSMISSION, LLC (COLUMBIA) LOCATED IN WETZEL COUNTY, WV. COLUMBIA'S GAS CONTROL PERSONNEL NOTIFIED THE CS OPERATOR TO INVESTIGATE THIS EVENT. UPON ARRIVAL, THE CS OPERATOR OBSERVED GAS VENTING BEHIND THE CS BUILDING. THE GAS DETECTORS FOR UNIT #1 WERE ACTIVE INDICATING PRESENCE OF NATURAL GAS. UNIT #1 DISCHARGE RELIEF VALVE (RV) WAS FOUND TO BE VENTING. THE RV HAD VENTED FOR 77 MINUTES WITH GAS LOST ESTIMATED AT 4,664 MSCF. FURTHER INVESTIGATION BY THE CS OPERATOR SUPPORTED BY THE MEASUREMENT AND REGULATION MECHANIC IDENTIFIED THAT THE TUBING CONNECTING THE PILOT TO THE MAIN BODY OF THE RELIEF VALVE HAD CRACKED AND FAILED. THE TUBING WAS REPLACED AND THE UNIT WAS RETURNED TO OPERATION. THE UNIT WAS THEN TAKEN BACK OUT OF OPERATION BECAUSE OF OBSERVED MOVEMENT OF THE RV DUE TO UNUSUALLY HIGH VIBRATION. INVESTIGATION INTO THIS INCIDENT BY THE ENGINEERING DEPARTMENT, IDENTIFIED THAT EXCESSIVE VIBRATION INITIATED THE SEPARATION OF THE SENSING LINE THAT ACTIVATED THIS RV. INSUFFICIENT PIPE SUPPORT WITH THE OPERATING CONDITIONS OF THE ENGINES, ASSISTED IN ELEVATING THE VIBRATION LEVELS WITHIN THE FACILITY. A CORRECTIVE ACTION WAS TAKEN WHERE BASED ON THE EXPERIMENTAL DATA COLLECTED BY ENGINEERING SERVICES, IT WAS DETERMINED THE RVS WILL BE REMOVED AND ELECTRONIC SHUT DOWN DEVICES WILL BE INSTALLED TO PREVENT REOCCURRENCE OF THE RELIEF VALVE TUBING FAILURES. THIS ACTION WAS IMPLEMENTED ON UNITS NO. 1 AND 2. PIPELINE SUPPORTS WERE INSTALLED WITH A CLOSE MONITORING TO SMALL DIAMETER (SENSING LINES) WITHIN THE CS FACILITY WITH A CONSIDERATION TO PULSATION STUDY TO RECIPROCATING UNITS IN A CS IN PARTICULAR TO ABOVE GRADE PIPELINES. NO FURTHER ISSUES WERE NOTED IN THIS FACILITY AFTER THE CORRECTIVE ACTIONS WERE IMPLEMENTED.