Mfg. upwardly tapering support power for offshore platform - from polygonal ring sections with double-walled sides of trapezium-shaped flat steel plates, sections welded together in horizontal position

摘要

The method is intended for fabricating a tower, particularly to support an offshore drilling or production platform, and consisting of superimposed truncated conical steel rings welded together such that, after anchoring the lower end by piles driven into the seabed, the structure has optimum resistance to forces and moments at all levels. Each ring has a polygonal cross-section and consists of double-walled units each having a plane trapezium-shaped steel outer plate with inward plates rectangularly welded thereto and internal cover plates welded to the plates. At least a number of such units are positioned together in polygonal formation and their longitudinal edges are welded together. The length of the edges i.e. the height of the units, is selected to remain withi the maximum weight limit of the crane used. The ring portions thus produced have the ends of the outer and inner plates welded to those of a preceding ring with the tower axis in horizontal postion whilst at least the completed part is appropriately supported. This proceeds until completion of a horizontal tower.