Underwater pipe laying method and apparatus

摘要

A method and apparatus for near vertical laying of a pipeline offshore by a pipe laying vessel includes a tower to which is attached a strongback that load pipe sections from a supply point on the vessel into the tower where the lower end of the pipe section is welded onto the upper end of a pipe line that extends into the sea while the strongback returns to the supply point for a second pipe joint. Where the pipe section includes a bulky item such as a valve assembly box, after the pipe section has been welded to the pipeline the pipe section is moved generally horizontally out of the tower and a hoisting cable lowers the pipe section to a predetermined depth below the tower. The hoisting cable then returns the pipe section and attached pipeline to their original position.