Abstract: A method for preparing an end of a thermoplastics tube (1) is provided, wherein the tube is manufactured by spirally winding and welding together of a hollow profile (1a) having a substantially rectangular cross section. The method includes the following steps: cutting the end of the tube by a planar transversal section; extruding a second hollow profile (2) having a rectangular cross section and an outer shape essentially similar to Fat of the hollow profile (1a) from which the tube (1) is manufactured; spirally winding the extruded second hollow profile (2) around a drum having a diameter corresponding to inner diameter of the tube (1); cutting a loop (2a) from the second hollow profile (2) in a length corresponding to circumference of the tube end; joining the ends of the loop (2a) to each other, whereby a ring (2b) is formed having the same inner and outer diameters as the spirally wound tube (1); placing the ring (2b) against the cut tube end; and welding the ring (2b) to the tube end.

Abstract: A method for joining thermoplastic pipes made by spiral winding a hollow profile with mainly rectangular cross section.

Abstract: The present invention relates to a welding method in the manufacture of a spirally wound tube having a thermoplastic profile (1) of a mainly rectangular cross-section. A hole profile (1) is wound in a screw line form manner on a welding drum (2) simultaneously as profile surfaces (1a, 1b), which are to be welded together are heated with hot air to a desired temperature, whereafter a welding mass (S) is extruded onto the heated profile surfaces (1a, 1b) in two streams along each edge of the profile surface (1a, 1b) and the welding mass coated hole profile portions are pressed together by means of a press roller (10). The invention is characterized in that the welding is performed with a welding head (3) coupled to an extruder and provided with a welding keel (4), which from the outside is inserted between two profile surfaces (1a, 1b) to be welded together. Hot air (L.sub.1, L.sub.

Abstract: A method for joining spirally wound thermoplastic pipes is disclosed. The method includes providing a first spirally wound thermoplastic pipe and a second spirally wound thermoplastic pipe, wherein each thermoplastic pipe includes a spirally wound hollow profile. The method further includes placing the end of the first thermoplastic pipe against the end of the second thermoplastic pipe such that a gap having a step is formed between the end surfaces, applying a stainless steel band over the gap and heating the steel band, positioning an extruder and a slide and smoothing organ inside the thermoplastic pipes, heating the end surface of the first thermoplastic pipe and the end surface of the second thermoplastic pipe with a heating means, and extruding melted thermoplastic from the extruder and into the gap between the end surfaces and applying pressure to the melted thermoplastic with the slide and smoothing organ.

Abstract: A method for manufacturing a joint pipe from a spirally wound thermoplastic profile is described in which the pipe end to be furnished with a joint pipe is pushed onto a rotatably driven, slightly conical mandrel, after which a melt profile of thermoplast is extruded and spirally wound in overlapping wraps around the mandrel and the pipe end in a direction extending from a point furthest from the pipe end, followed by cooling of the joint pipe, cutting of its end surface, and removal of the pipe end from the mandrel.

Abstract: A spiral-wound tube formed of a hollow section 1 is provided wherein the hollow section is joined together by extruder welding or gluing. The hollow section is coextruded and comprises an outer layer (2) of pastic with a homogenous surface and good weldability. An intermediate layer 3 is provided of a modified polymer and an inner layer (4) is also provided. The interior space defined by the tubular layers (2, 3, 4) is preferably rectangular in cross-section.