| 摘要 |
<p>Thermoplastic pipes can be joined to each other by a thermoplastic sleeve which has along its inner walls two embedded electrical heating elements to fuse the adjacent walls. The resistance heating wires (11) are surrounded by a first layer (12) of a material which forms no connection with the sleeve material, pref. a lacquer or a suitable plastic, of max. 0.8 mm thickness. The second layer (15) can have a polygonal shape (20), e.g. trapezoidal and is the same material as the sleeve.</p> |
