METHOD OF REPAIR OF SAGGING AND WASHED-OUT SECTIONS OF UNDERWATER PIPE LINE Russian patent published in 1997 - IPC

FIELD: erection and repair of underwater pipe lines. SUBSTANCE: for repair of sagging and washed-out sections of underwater pipe line, washed-out section and sections adjacent to it are opened by parts whose length is equal to lines of intersection of water level with point of trench being dug out in direction of its raising. Trench is dug out along pipe line to depth exceeding design depth of trench at increased amount of opening of adjacent sections. Ground is removed from under pipe line by sections to ensure required bending radius of pipe line. The trench is filled with water forming cofferdams and intermediate supporting cofferdams which are removed, thus enhancing span of pipe line immersed in water. Cofferdams are cut by stages; after complete cutting of cofferdams limiting the bed portion, gas line is loaded to either side from center of washed-out section, after which trench is filled. EFFECT: enhanced reliability. 1 dwg