J-lay is used to install rigid pipelines in deep water. With a J-lay system, pipe stalks, consisting of up to six pipes with a total length of 72m, are upended and welded to the seagoing pipe in a near vertical ramp.
The ramp angle is adjusted so that it is in line with the pipe catenary to the seabed. This way bending of the pipe is kept to a minimum. The J-lay method is very suitable for deepwater because the pipe leaves the lay system in an almost vertical position and the pipeline is only bent (once) during installation (at the seabed). This reduced amount of bending is beneficial for installing pipelines that are sensitive to fatigue. Compared to other lay methods, J-lay has a relatively low production rate due to the single position welding of the pipe. The J-lay method is less suitable for shallow waters as this requires a departure angle close to horizontal.
We have solid experience in delivering complete J-lay systems including tower structures, tower angle adjustment systems, pipe handling equipment, line-up systems and the control system.