Abstract: A method for renovation of pipelines, comprising introduction of lining layers into the existing pipeline, the lining layers corresponding in length to the length of the pipeline to be renovated. The lining layers consist of fusible polymers and are presurized and fused together by the introduction of a heat source into the inside of the innermost lining layer.

Abstract: A continuous method of extruding an oriented plastic article of improved strength. A chemically reactive polymer, monomer or other compound is included in the matrix material(s) and a (multilayer) parison is extruded or melt formed having built-in thermoplastic orientation caused by shear or caused by elongational flow. A reaction can be activated in the molten state thereof by additional heat resulting in a cross-linked structure or at least the mobility of the molecules being reduced, resulting in a longer relaxation time which makes the freezing of permanent orientation possible. The soft matrix can be stretched while still hot in the hoop and/or axial direction. Then, the product thus obtain is calibrated and cooled in an oriented state.

Abstract: The invention relates to a material wherein the main constituent is PVC for manufacturing pipes to be used for relining underground pipelines by the pipe in a folded condition being drawn into the pipeline and being engaged with the inside surface of the pipeline by temperature increase. By the addition of polymer thermoplastic elastomers which can be mixed with PVC the material has a glass transition temperature ranging from 45.degree. to 75.degree. C. and a ratio (Emod, T=20.degree. C.)/(Emod, T=75.degree. C.)>20. The invention also relates to a method for restoring underground pipes by relining such pipes with a pipe which has been folded after the extrusion.

Abstract: The invention relates to a method and apparatus for manufacturing ribbed piping, wherein a formable mass in a plastic state is extruded into a substantially cylindrical forming space of a corrugator, the forming space being delimited by forming molds movable in the production direction of the apparatus and having grooves on the inner surface thereof for forming rib flanges. A stationary kernel portion of a mandrel cools the interior surface of the piping and extends beyond the forming space constituted by the forming molds of the corrugator.

Abstract: Method in manufacturing a heat insulated tube includes a tube (17) for conducting fluid and a sheath (12) enclosing said tube, a heat insulating material (15) being disposed between the fluid tube and the sheath. The sheath is being extruded in an angle extruder die (10) while the fluid tube and the heat insulating material enclosing said tube are being fed axially through the angle extruder die as the sheath is being extruded around the heat insulating material. Then the sheath (12) extruded from the angle extruder die is kept spaced from the heat insulating material (15) enclosing the fluid tube (17), over an initial length of the axial movement thereof up to chains of chill molds (13) for imparting to the sheath a corrugated shape by forming the sheath against the chains of chill molds under the influence of negative pressure. The invention also relates to a device in extruders having an angle extruder die (10) for the manufacture of the heat insulated tube.