COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON MARCH 25TH, 2015, AN 8-IN BLOW-OFF VALVE RELEASED INADVERTENTLY MATERIAL INTO ATMOSPHERE AT LOST RIVER COMPRESSOR STATION LOCATED IN THE TOWN OF MATHIAS, HARDY COUNTY, WV. THE COMPRESSOR STATION HEADER WAS ISOLATED AND THE SECTION WAS BLOWN DOWN TO STOP THE UNINTENDED RELEASE. PRELIMINARY INVESTIGATIONS INDICATED THAT THE SUPPLY TUBING HAD A LOW POINT THAT ALLOWED FOR THE COLLECTION OF MOISTURE WHICH, APPARENTLY, FROZE AND ISOLATED THE ACTUATOR FROM THE EMERGENCY SHUTDOWN (ESD) TRIGGER AIR SUPPLY. THEN, A NUISANCE LEAK WAS FOUND IN THE LAST TUBING CONNECTION TO THE ACTUATOR. THE COMBINATION OF THESE TWO FINDINGS, ALLOWED THE ESD TRIGGER PRESSURE ON THIS VALVE ACTUATOR TO LEAK DOWN TO THE POINT THE VALVE ACTUATED INADVERTENTLY, RELEASING MATERIAL INTO ATMOSPHERE. AS A RECOMMENDATION, (I) AN INSPECTION TO ESD VALVES WITH SIMILAR INSTALLATIONS WAS TO BE PERFORMED, (II) RE-ROUTING TO THE TUBING WAS INTRODUCED TO PREVENT THE COLLECTION OF THIS MOISTURE COLLECTION AND (III) RESEARCH THE INTRODUCTION OF AN ALARM WHENEVER ANY UPSET CONDITIONS DO EXIST TO SIMILAR VALVE INSTALLATIONS. THESE STEPS WILL NOT ALLOW THE CHAIN OF EVENTS LEADING TO THE ACTIVATION OF THE BLOW-OFF VALVE FROM FUTURE RE-OCCURRENCE.