Patent ID: 7114881
Filing Date: 2006-10-03
Classification: B23K,C21D

Abstract:
1. A method of laying a pipeline underwater, in which pipe sections are welded together to form the pipeline, the method including the following steps: holding an end of a pipeline, providing a pipe section for extending the pipeline, arranging the pipe section adjacent to said end of pipeline thereby defining a circumferential joint to be welded, providing a plurality of welding heads, each head having at least one welding torch, and arranging the welding heads around the circumferential joint, welding the pipe section to the pipeline by simultaneously operating the welding heads and moving said heads along the circumferential joint, and laying the pipeline underwater, wherein the pipe section is made of steel having a carbon content of less than 0.1% by weight, and during the welding step the pipes are cooled in the region of the circumferential joint by means of introducing a cooling liquid into contact with an interior surface of the pipes.