New type of bearings for new, longer stinger
For the Pioneering Spirit, Allseas required bearings to connect the stinger, the construction that guides the pipe lines into the sea, with the ship. The stinger, as well as the ship as well as the tensioner capacity are among the largest on Earth. The 150 metre long stinger is huge, as are the forces on the stinger-vessel connection. Because all components bend, move, flex and even move laterally, special spherical bearings, allowing lateral motion of the shaft, were the only feasible design option.
Subsea pipe lines are welded together on specialized vessels and eased off into the sea over a large roller conveyor, the stinger. This stinger allows the pipe to gradually bend down towards the up to 3000 metre deep sea floor and carries the load of the pipe and all dynamics involved. This puts huge demands on the stinger-vessel connection, where the force are enormous. Since the Pioneering Spirit is a catamaran, the stinger is connected to the inside of both bows, which move relative to each other, the bearings have to accommodate these motions.
The specially designed D-glide spherical bearings are not larger, but due to the efficient design and material choice, they are much stronger than any alternative. They are maintenance free and perfectly suited to meet the complex set of requirements in the harsh offshore environment.
With the new bearings, the stinger joints could remain compact. The bearings do not depend on lubrication for durability. They contribute to allowing this record ship, to lay record size pipe lines, in water depths never reached before; safely, sustainably and maintenance free.