Selection of the Optimal Lifting Point for Submarine Pipeline

It is pointed out that two questions have to be answered in the submarine pipeline construction: the stresses in pipes and the location of the point to lift a pipe. The paper recommends that the stresses in pipe caused by lifting be below the allowable stress depending upon pipe strength, and that analysis on pipe stress and deformation during lifting operation be made to locate the most suitable point for pipe lifting. Analysis is made in the paper using the methods of mechanics of materials. In the stress analysis, such aspects are studied as the unaccompanied action of centralized loads, the unaccompanied action of uniform distributed loads and the conditions for pipe end displacement, with their calculation formula provided. For lifting point optimization, curves as well as formula are given, showing the maximum stress in pipe, the suspended length, and the variation of the suspended height of pipe end with the lifting force.