TDW Offshore Services has successfully completed a key subsea flex-joint isolation operation on the Independence Trail natural gas pipeline for Enterprise Products Partners L.P. in the Gulf of Mexico. The isolation operation allowed critical repairs to be made on the flex-joint assembly of the 20in export riser that had begun to leak in April 2008. Located approximately 85ft below sea level, the flex-joint allows the riser to withstand the movements of the platform. In order to facilitate the riser repair, Enterprise engaged TDW to isolate this flex-joint assembly, with its piggable, tetherless, SmartPlug isolation tool. The platform riser had previously been assessed by TDW for possible isolation with its remote-controlled SmartPlug high pressure pipeline isolation tool. The tool was launched and pigged (pumped by water) into the riser just below the flex joint. This allowed Enterprise to maintain pipeline pressure downstream of the flex-joint. With ambient pressure above the flex-joint, divers then replaced the o-ring gasket subsea and then after resealing, the entire riser was successfully pressure tested. Consequently, Enterprise was able to resume the gas flow from its production fields through the riser. The entire isolation operation was completed in 10 days.