| 摘要 |
<p>The present invention relates to multi-wall pipelines particularly for transporting fluids over long distances under water. Such a pipeline comprises a plurality of pipe sections each of which comprises a plurality of concentric metal tubes 1, 2 which are radially spaced apart and the spaces filled with a filling material 3. At each end of each section the or each annular space between the tubes is closed by a metal ring 4 welded to the tubes, the ring 4 having a length such that the temperature attained at the level of the inner end of the ring during butt welding of the section to a like section is not such as will damage the filling material 3. <IMAGE></p> |
