Pipeline laying method - outer pipe casings are welded before inner flow pipes, and latter pushed into already laid pipe casing

摘要

When laying pipe line systems (2) the outer pipe casings (4) are welded together into one predetermined length and laid down and only then are the inner flow pipes (6) welded together into a substantially similar length medium pipe and pushed into the already laid pipe casing whilst observing a predetermined radial interspace. A pipe casing and/or medium pipe can be made of plastics. The pipe casings can be butt-welded together either before or during the actual pipe laying process. Spacers in the form of skids (8, 9) can be provided over the outer sleeve face of the inner medium pipe or over the inner sleeve face of the pipe lining (4). ADVANTAGE - The inner pipes can be easily inserted and the interspace allows inspection for leaks.