Pipelaying vessel

is a specialized floating facility for submerged pipeline laying. It is widely used in offshore fields development for laying pipelines up to 1,420 millimeters in diameter down to 2,500 meters depth (Blue Stream gas pipeline). First pipelaying vessels were built in the 1940s and 1950s.
Submerged pipelines can be constructed on pipelaying vessels by stovepipe welding of pipe sections stored on the deck or by the reel method by which the pipeline produced onshore is wound onto reels beforehand. Winding onto the reel is possible for up to 90 kilometers of 100 to 400 millimeters diameter pipes. During pipeline laying the reel constantly rotates and the pipe is laid down to a 300 meter depth at a speed of up to 4 kilometers per hour. During lowering of the pipeline prepared on a deck a special device (a stinger) supports it to prevent from major bends when moving it from the vessel. The maintenance of all pipelaying vessel systems and welding equipment is performed by a computer (sea depth, wave and wind speeds are taken into account; pipelaying vessel stability is ensured).