| 摘要 |
<p>1. Process for the production of pipelines by the butt welding of pipe sections molecularly oriented in the longitudinal direction, in which process rings having a diameter substantially equal to that of the sections are inserted between the successive sections, characterized in that the pipe sections and the rings are made of a thermoplastic material and in that the rings have undergone circumferential molecular orientation to a degree greater than the degree of longitudinal molecular orientation of the sections, so as to prevent the propagation of cracks from one section to another.</p> |
