Pipe Layer (S-lay, J-lay, Reel-lay)

A pipe layer installs subsea pipelines by one of three methods, S-lay, J-lay, and reel-lay, each suited to a depth and pipe size. S-lay welds joints horizontally in a deck firing line and the pipe leaves over a curved stinger, forming an S to the seabed; it is fast for shallow to intermediate water but needs a long stinger when deep. J-lay welds in a near-vertical tower so the pipe leaves almost upright and bends only once at touchdown, which suits deepwater and fatigue-sensitive lines but is slower at its single station. Reel-lay spools pipe welded onshore onto a large reel, then unspools and straightens it offshore, the fastest method but limited to smaller diameters up to about 20 inches.