As a traditional offshore pipelay technology, S-lay is still frequently utilized even in the deep water pipelays. It has two important devices: stinger and tensioner. Stinger controls the overbend of pipeline. Its geometry, length, and curvature, are the function of water depth, lay tension requirement and geometry and material of the pipeline. In this paper, an analytical method and the finite element methods are presented for researching the relationships of these parameters. Suggestions on the conceptual design of a novel deepwater stinger and the upgrade of an actual stinger have been provided as a favor of decision-making.
As the exploration of oil and gas resources goes into deep and ultra deep water, subsea pipeline installation in such area has become a real challenge. Nowadays, S-lay and J-lay are two important pipelay techniques, which have made great success in shallow and moderate water depth respectively. These equipments include stinger, tensioner, and dynamic positioning system. These enhancements make the S-lay in ultra deep waters possible (Vermeulen, 2000). Other successful deep and ultra deep water pipelays were conducted by S-lay vessels Lorelay and Solitaire. They have laid the 12/14 inch pipeline into 932 meters in Oil Export Pipeline project in 1991, and laid the 8/12 inch pipeline in the water depth of 1676 meters in 2001. Even more success in 2005, they laid the 8/10 inch pipeline into 2750 meters in the Gulf of Mexico, and so on. The pipelay depth for S-lay is shown in Fig. 1. In the case of S-lay, there are several working stations located on the lay-barge, and pipes are welded, coated and tested horizontally, then pipe string passes through the stinger suspended from the back of barge into water in nearly a vertical slope. It is finally laid on the seabed.