There are several methods for laying offshore oil and gas pipeline. The reel-lay process is fast and one of the most effective offshore pipeline installation methods for pipes with outside diameter of 16 inches or less. In the case of the reel-laying method, line pipes are subjected to plastic deformation multiply during reel-laying. Full scale reeling (FSR) simulations were performed to investigate the effect of the cyclic deformation on the mechanical properties of the line pipe. In the FSR simulations, the influences of the bending radius and repeated times of multiple plastic deformation were investigated.
There are mainly three methods, which are S-lay, J-lay and Reel-lay, for laying method of offshore pipeline. In case of S-lay, pipes are laid horizontally on the vessel. Girth welding, inspection of welded portion, coating and so on are performed continuously and simultaneously at several stations. Connected pipes are laid down on the seabed. Laying speed is comparatively fast. On the other hand, many operators are needed for this method because several operations (which are girth welding, inspection, coating and so on) are performed on the vessel. This method is named S-lay because pipeline shape during laying looks like the letter "S". In a deep water area, there is a concern of buckling because the shape like "S" of pipeline during laying becomes steeper. J-lay is an offshore installation method that one pipe or a few pipes, which are connected by girth welding, are stood vertically and then are connected to pipeline by girth welding. Connected pipes are installed in the sea vertically and laid down on the sea bed. Many operations can be performed continuously and simultaneously while pipes are laid horizontally. However, there is only one station for girth welding, inspection, coating after standing the pipes vertically.
