On the Design and Fabrication of the Bends Used in Large Diameter Pipeline

With the absence of national and international specifications for the design and fabrication of bend pipes with large curvature radius for large diameter pipeline, it is suggested that, as long as the current code can be satisfied, smallest curvature radius shall be selected so as to minimize the sizes of the equipment and moulds for bend fabrication. When the bend and its adjacent straight line are of different materials, the wall thickness of the bend shall be multiplied by the ratio of their yield strengths. Bend wall thickness shall be reduced with care so as to cut down steel consumption. Longitudinally-welded (rather than spiral seamed) bend pipes of high strength and low alloy steel shall be used to guarrantee bend quality. Many more advantages exist in hot pushing pipes than in hot bent pipes : uniform wall thickness, small roundness, and no fold.