T.D. Williamson S.A., has performed a complex subsea hot tap operation on the Temsah Concession gas pipeline network in Nile Delta, Egypt.

Situated in deep water, the 140-ton Temsah pipeline end manifold (PLEM) is connected to four 900-class pipelines. Petrobel began working on several replacement scenarios in 2007 to formulate the optimum approach to replacing the gas PLEM.

The decision was made to employ the Folding STOPPLE® technique which involved creating an alternative export pipeline network that began at a platform by-passing the gas PLEM, which enabled gas to flow to a subsea isolation valve (SSIV) before connecting with the 32-inch export sealine to an onshore gas plant.

TDW used its STOPPLE plug technology to isolate several lines, sidestepping the need to flood the entire network with salt water during the PLEM replacement. The operation was complex, demanding innovative engineering and very detailed subsea procedures. The operation required diving rotation, workforce flexibility and additional on-site training to ensure that procedures were understood, and that all safety requirements were fulfilled. In addition to working subsea, all hot tapping was carried out on pipeline walls of very high thickness (class 900). As a result, Petrobel was able to resume production with minimal interruption.