COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

ON THE MORNING OF AUGUST 22, 2015, A DRIP INSTALLED ALONG LINE SL-2481 FAILED LEADING TO AN UNINTENDED AMOUNT OF NATURAL GAS (MATERIAL) TO VENT INTO ATMOSPHERE EXCEEDING THE INCIDENT REPORTING THRESHOLD. THIS PIPELINE IS LOCATED IN LAKEFIELD, HOLMES COUNTY, OHIO AND OWNED, OPERATED AND MAINTAINED BY COLUMBIA GAS TRANSMISSION, LLC (COLUMBIA), WITHIN THE HOLMES STORAGE FIELD (SF). THE FAILURE WAS IDENTIFIED BY A NEARBY COLUMBIA EMPLOYEE WHO WAS THE FIRST RESPONDER TO THE FAILURE SITE. NECESSARY SAFETY MEASURES WERE TAKEN TO ISOLATE ALL WELLS, SF LINES FOR HOLMES AND WAYNE SF. THE AFFECTED STORAGE LINE (SL) WAS ISOLATED AND MATERIAL STOPPED FLOWING INTO ATMOSPHERE IN LESS THAN AN HOUR FROM THE TIME THE FIRST RESPONDER ARRIVED ON SITE. THE DRIP WAS REMOVED WITH THE SECTION OF THE SL THAT IT WAS TAPPED INTO AND A NEW PRE-TESTED PIPE WAS INSTALLED, WHICH DID NOT INCLUDE A DRIP. THE REPAIRED SL WAS RETURNED BACK INTO SERVICE ON AUGUST 25, 2015. THE RESULTS OF THE METALLURGICAL FAILURE ANALYSIS INDICATE THAT THE METALLURGICAL CAUSE OF THE FAILURE WAS DUE TO INTERNAL PITTING CORROSION. THE LOCATION OF THE FAILURE POINT WAS AT THE 08:00 O'CLOCK POSITION AND THE PRESENCE OF SEVERE CORROSION AT THE 04:00 O'CLOCK POSITION, SUGGESTS THAT THE FAILED DRIP WAS PARTIALLY FILLED WITH SLUDGE/DEPOSITS AND THAT AN AQUEOUS PHASE WAS PRESENT ON TOP OF THE SLUDGE/DEPOSITS. THIS GEOMETRY IS CONSISTENT WITH A GAS-PHASE RELATED CORROSION MECHANISM. THE INITIAL INCIDENT REPORT WAS SUBMITTED ON SEPTEMBER 20, 2015.