Welded joint for plastics coated tubes - uses connecting sleeve inside plastics coated flanges with countersunk holes for weld material

摘要

The joint between the smooth ends of two plastics coated tubes (1, 2) is formed by members which are welded together by heat. The two ends are first inserted inside a plastics sleeve (3) with tapered outside ends (3a, b) to locate against a shoulder (3d) inside. This can be welded at the ends to the plastics coating around the tubes. Two flanged, plastics coated collars (4, 5) are then fitted over the sleeve. These have countersunk holes (6) through their abutting flanges (4b, 5b). The horizontal flanges are heated welded onto the sleeve and also heat welded together, the joint being strengthened by plastics welding through the countersunk holes.