| 摘要 |
A plastics pipe (1) comprises an inner wall (6) and an outer wall (5), being integral with longitudinal partitions (4) between them and bounding longitudinally extending channels (3) and a circumferential, helically or non-helically extending groove (10, 11, 12). The groove has been formed by closing the channels by pressing channel wall parts onto each other. A retaining ring (15) may be snapped into an external groove (10). |
