| 摘要 |
<p>An electrically heated pipe assembly (10) includes a pipe (12) having an electrically insulative, longitudinally-extending outer surface. A pair of flat copper strip electrodes (18) are mounted in shallow recesses (20) extending longitudinally on the outer surface of the pipe (12) parallel to and spaced from each other. A heating layer (14) formed by an elongated electric heating tape (15) is wrapped tightly around the exterior surface of the pipe (12) and a plastic insulating sleeve (16) is either shrink-fitted or extruded over the exterior of the heating tape (15). The heating tape (15) is formed as a narrow, essentially transparent, polyester (Mylar) strip (22) printed with a plurality of spaced, parallel, longitudinally extending stripes (24) of semi-conductor material and is helically wrapped about the pipe (12) so that each of the semi-conductor stripes (24) extend generally helically of the pipe (12) and engage and electrically contact both of the conductors (18) at a plurality of spaced points thereof. For flexible pipes the strip electrodes are formed from soft tin-plated wire (118) bent into a serpentine shape able to accomodate bending.</p> |
