Piloting of welded pipe line onto sea bed - suspends line to definite curvature between surface vessel and sea bed pilot module

摘要

The piloting system is used in laying a deep sea pipe line e.g. in laying a continuous weld-jointed line on the sea bed at depths of up to 1500 m. Pipes are welded together on a surface vessel or land, and the line is fed from the vessel to a pilot module on the sea bed, the line being suspended in a huge cateneric curve between the vessel and the pilot. The suspended line length is such that it can accommodate a relaxation of several tens of metres through elastic deformation. In addn. the apparent weight of the suspended length is such that reactions can be accommodated by the pilot module, and the stresses imposed on the line are within specified permitted values. The pilot may impose a definite adjustable curvature on the line, may be self-propelled by utilising sea bed or line reaction, may be suspended from surface vessels, and may lay the pipe to definite line and level.