GB934151A - Improvements relating to laying submarine pipelines - Google Patents

Abstract

934,151. Laying pipelines. J. G. COULTRUP. Sept. 22, 1961 [Sept. 23, 1960], No. 32791/60. Class 99(2). In a method of constructing an underwater pipeline in which additional lengths of pipe 5 are joined at or near the water surface to the end of a pipe 1 already laid and extending from the water bed 3 upwards through the water, floats 7, 8 are attached to the length of pipe between the bed and the joint, the bouyancy and spacing, or both, of the floats along the pipe being arranged so that the lift per unit length on the portion of the pipe near the bed 3 is less than that on the portion nearer the joint and the longitudinal curvature of the pipe is limited so that it is not overstressed or buckled. As shown, the floats are so arranged that there is a point of contraflexure 10 in the longitudinal curvature of the pipe and the change in the bouyancy per unit length of the point occurs at substantially the point of contraflexure. The floats are attached to each new section 5 and may be equally spaced and alternately of larger and smaller size the latter being freed from the pipe, as the pipe-jointing, floating platform 9 moves to a new position, when they pass the point of contraflexure. The pipeline may first be laid on the bed and the end of each sunken pipe raised by the attachment thereto of water filled bouys which are subsequently pumped out by compressed air, the bouys being released from the pipe after jointing of the pipes.