| 摘要 |
<p>The present invention relates to a method of joining or repairing thermally-insulated line pipes that includes a plastic, weldable outer pipe (3) which encloses an inner pipe (1) embedded in an insulating layer (4), wherein the inner pipe lies generally exposed, or is laid bare, between two opposing outer pipe-ends. The methods comprises the steps of fitting over the exposed part of the inner pipe (1) and the opposing outer pipe-ends a slotted sleeve (7) which is made of weldable plastic material and has a length that exceeds the distance between the outer pipe-ends. The slit is widened (8), and an electrically conductive strip (9) which is permeable to molten plastic is placed between the outer pipe (3) and the sleeve (7), and the free ends (10) of the strip are passed-up through the slit (8). The sleeve is placed against the opposing outer pipe-ends and an electric current is applied to the ends (10) of the strip over a given length of time, wherewith the strip is heated and fuses with the plastic surfaces that lie against the strip, therewith to form a weld joint corresponding to the width of the strip. The invention also relates to a tool for a cirumferentially welding plastic pipe, wherein the tool includes a clamping device for pressing an outer plastic pipe against an inner plastic pipe. An electrical heating means is disposed between the plastic pipes for delivering the welding heat, and the outer plastic pipe is preferably slotted. The clamping device includes a flexible clamping strap which is formed into a loop around the pipe and the free ends of the strap can be connected to a tensioning device. The loop can then be caused to press the outer pipe against the inner pipe.</p> |
