ANR PIPELINE CO

Incident Narrative

ON 13 MARCH 2015 AT 11:22 CDT DURING A TRANSCANADA AVIATION FLIGHT OVER THE GULF OF MEXICO, A POTENTIAL LEAK WAS IDENTIFIED NEAR TC OFFSHORE (TCO) ASSETS IN THE OUTER CONTINENTAL SHELF (OCS) EUGENE ISLAND BLOCK 200 (EI-200). THE LEAK WAS REPORTED TO TRANSCANADA/ ANR PIPELINE, OPERATOR FOR TC OFFSHORE, AS A BUBBLING PATTERN OVER TCO'S 737 (20') TRANSMISSION PIPELINE NEAR MILE POST 15.6 (28.69737930, -91.84116430). NO SHEEN OR PRODUCT WAS OBSERVED AT THE LEAK LOCATION. THE NRC WAS NOTIFIED OF AN INCIDENT ON 13 MARCH 2015 AT 12:22 CDT (NRC REPORT #1110549). FOLLOWING THE REPORT OF THE INCIDENT TO THE NATIONAL RESPONSE CENTER, TRANSCANADA/ANR CONTACTED U.S. COAST GUARD, BSEE, AND PHMSA TO INFORM AND UPDATE THE AGENCIES ON THE INCIDENT. WHILE PREPARING TO DISPATCH AN INVESTIGATION AND REPAIR VESSEL TO THE SITE, A PIPELINE SEGMENT OF 18.4 MILES WAS ISOLATED AND BLOWN DOWN FROM 830 PSIG TO 200 PSIG FROM THE VALVES AT SOUTH MARSH ISLAND 76 TO EUGENE ISLAND 199. ADDITIONALLY, ANR SCHEDULED AERIAL PATROLS TO MONITOR THE LEAK. NO SHEEN OR PRODUCT WAS DOCUMENTED AT THE SITE FOR THE DURATION OF THE LEAK AND REPAIR. THE REPAIR VESSEL AND CONTRACT EMPLOYEES ARRIVED AT THE INCIDENT LOCATION ON 15 MARCH AT 13:27 CDT AND BEGIN EXPOSING THE PIPE FOR THE LEAK INVESTIGATION. FOLLOWING THE REMOVAL OF THE COVER MATERIAL, THE INVESTIGATION BY THE DIVERS DETERMINED THAT THE LEAK WAS CAUSED BY A DEFECT IN A BODY BLEED THREADED PLUG VALVE ON A 12-INCH SIDE VALVE. THE THREADED PLUG VALVE ON THE BODY BLEED WAS REPLACED ON 16 MARCH AT 17:59 CDT. FOLLOWING THE REPLACEMENT OF THE THREADED PLUG VALVE, THE LINE WAS INSPECTED TO CONFIRM THE REPAIR AND THE LINE AND VALVE WERE RE-COVERED. NO ADDITIONAL LEAKING WAS OBSERVED AND THE LINE WAS RETURNED TO SERVICE ON 17 MARCH 2015.