Pipelay Systems offers cost effective, solutions for the S-lay, J-lay and Reel-lay deployment of rigid pipes. We offer a flexible source of supply for either individual pipelay components such as tensioners, clamps, straighteners, towers and stingers together with pipe storage facilities such as racks or reels, or fully integrated pipelay systems and the pipe handling equipment involved in the pipelay process.
Using the S-lay installation method, rigid pipe is welded, weld tested and a joint coating applied on the vessel deck at a series of stations prior to passing through the pipe lay tensioner(s) that support the outboard tension. From there the pipe leaves the tensioner(s) and deploys over a stinger that supports the curvature and weight of pipe as it is lowered to the seabed. S-Lay typically prepares double pipe joints before they enter the firing line, thus increasing the speed of the overall lay process.
S-Lay is the preferred option for laying large diameter pipe in shallow water thanks to its high production rate, and the ability to install concrete coated pipe. Some vessels with large radius stingers allow S-lay to be carried out in ultra-deep water where the stinger prevents the pipe from overbending during lay, however the stinger radius limits the pipe diameter that can be laid.
Using the J-lay installation method, rigid pipe is made up into stalks by welding 4 or 6 standard 12m pipe lengths together, and then weld testing and joint coating them on the vessel deck prior to it each stalk being moved into a loading arm and raised to the lay tower. In the tower the pipe is transferred to the firing line where it is held by a travelling clamp and aligned for welding by a series of alignment tools. Once aligned the pipe is welded, weld tested and coated in the work area where the outboard tension is being held on a fixed clamp mounted on the tower structure. On completion of the welded joint in the tower, the pipe tension is passed to the travelling clamp and the fixed clamp is opened allowing the travelling clamp to lower the new section. The pipe end is lowered to the work area where the tension is transfer back to the fixed clamp, allowing the travelling clamp to be raised in the tower in readiness to accept the next pipe stalk.
For deepwater pipeline installation, J-lay provides more tension capacity than the other lay methods allowing more flexibility with pipe diameters being laid. Additionally, J-lay only bends the pipe once at the catenary or sag bend between the vertical pipe and the seabed which can be advantageous when installing pipelines sensitive to fatigue. Compared to other lay methods, J-lay has a relatively low production rate due to the single welding station in the lay tower.
Using the Reel-lay installation method involves pre-welding, weld testing and joint coating lengths of pipe at a land based welding facility known as a spoolbase. The spoolbase will have storage racks that can support pre-welded pipe lengths of between 500m and 2500m long and have a quayside to moor the vessel. The longer the stored length of pipe, the less welds required when loading the vessel. A vertical (or horizontal) reel on the lay vessel deck is used to store the pipe as it is transferred from the spoolbase.
During pipelay, pipe is passed from the reel over the tower and through a pipe straightener before entering the tensioner(s). When the lay is complete the pipe is held in a clamp at the bottom of the tower and cut in the work area where end fittings and PLET’s can be connected by bolting or welding. Pipe storage capacity on the reel is limited, especially with larger diameter pipes above 12 inch or pipes with a large coating thickness.
Reel-lay is the fastest method of laying pipe, but it can mean travelling to and from the spoolbase several times to load pipe which adds time and expense to the lay operation. However, due to the controlled welding and inspection conditions onshore, this makes Reel-lay an efficient method for the installation of pipe diameters up to 20 inch.
The three pipe lay options described above are very much standalone systems, however on Reel-lay systems it is possible to mount a J-lay system to the same lay tower which allows more tension capacity if required. This is particularly useful when laying with Reel-lay from shallow water to deep water and the Reel-lay system capacity cannot cope with the final lay in the deepest water. In this instance J-lay completes the pipelay.