COLUMBIA GAS TRANSMISSION CORP

Incident Narrative

A 4-IN RELIEF VALVE (RV) HAD FAILED WHERE IT RELIEVED NATURAL GAS INTO ATMOSPHERE BEFORE REACHING ITS SET POINT AT PAVONIA COMPRESSOR STATION, OH. TOTAL AMOUNT OF NATURAL GAS RELEASED INTO ATMOSPHERE WAS CALCULATED TO BE 9,303 MCF. A QUALITY INVESTIGATION CONSULTANT CONDUCTED A FULL ANALYSIS TO THE FAILED RV AND PROVIDED A ROOT CAUSE ANALYSIS DETAILING THE FOLLOWING: A DESTRUCTIVE/NON-DESTRUCTIVE TEST WAS PERFORMED TO THE REMOVED SOFT GOODS FROM THE FAILED RV AT A CERTIFIED RUBBER LABORATORY FACILITY WHERE IT WAS CONFIRMED THAT THE USED SOFT GOODS WERE PER THE MANUFACTURER'S RECOMMENDED MATERIAL LIST. A NEWLY PUBLISHED MAINTENANCE MANUAL OF THE FAILED RV PROVIDED ONLINE BY THE MANUFACTURER INDICATED THAT THE PRESSURE RATINGS FOR THE INSTALLED PILOT VALVE WERE REDUCED TO A LOWER LEVEL FOR ALL DIAPHRAGM-TYPE INSTALLATIONS. ALL HIGHER PRESSURE VALUES ABOVE THE ASSIGNED THRESHOLD MUST GO TO A PISTON-TYPE PILOT INSTALLATION. THIS INFORMATION THAT WAS RELEVANT TO THE PILOT VALVE WAS NOT PROVIDED TO THE MAINTENANCE FACILITY HENCE IT WAS NOT IMPLEMENTED ONTO THE FAILED RV. AN IN-HOUSE MEMORANDUM WAS ISSUED TO SEARCH FOR ALL SIMILAR INSTALLATIONS TO THE FAILED RV. A SIMILAR INSTALLATION WAS IDENTIFIED AT THE SAME FACILITY AND WAS REMOVED. A DIFFERENT TYPE OF RVS WAS INSTALLED AND NEW CAPACITY CALCULATIONS AND VERIFICATIONS WERE COMPLETED AND THE FACILITY WAS RETURNED BACK TO SERVICE.