Abstract: An electroweldable socket comprising a conducting wire or gauze near the inner wall of the socket, the socket being manufactured by feeding conducting metal wire or gauze to a transverse extrusion head of an extruder and cutting the pipe extruded from the extruder to a socket length.Conducting wire may be fed to the extrusion head after having been wound to a helical spiral, the helical spiral may also be formed in the extrusion head or supplied accommodated in an outer groove of a thin walled tube having a helically extending outer groove. The wire may also be supplied as a hose assembled from said wires.Gauze is supplied in a pipe form obtained from a strip.The wire may comprise sections of helical spirals of mutally different pitch.Windings or groups of windings may be short-circuited.The socket is provided with connections for connecting to an electrical source if a conducting wire is present.

Abstract: A sealing body for a pipe connection bonded chemically and/or mechanically to a fixation part being attachable to an end portion of a socket pipe. The fixation part consists of plastic material or of reticulated elastomer.

Abstract: In a non-destructive method the state of ageing of plastic products is determined by means of infrared radiation, which is passed through the product.The invention is based upon the discovery that there is a clear relationship between certain physical and/or chemical changes occurring during the course of time in the interior of plastic materials, detectable by infrared analysis, and the mechanical properties of the product. On the basis of this relationship, the method may be used to decide whether products can be safely used or whether they must be disqualified and removed.The method is particularly well suited with crates which are to contain bottles; the radiation is then passed through a crate wall.Apparatus for performing the method may be arranged in a line such as a conveyor belt bottling line.

Abstract: Tube of thermoplastic material, comprising longitudinal channels of rounded cross section and having such wall stresses that, after axially cutting the tube, the edge parts beside the cut edges overlap each other for less than 5% of the outer circumference of the tube.

Abstract: Plastic pipes comprising an inner and outer wall being interconnected by lengthwise extending connecting partitions, forming channels, the ends of the channels being each separately sealed by sealingly pressing the end walls of a channel to each other after these walls have been heated to a temperature surpassing the plasticizing temperature.

Abstract: Pipe with socket end provided with an annular groove chamber containing a sealing ring supported by a support ring, which support ring compresses the sealing ring less than the final inserted spigot end. The support ring closes the groove and the sealing ring or the closed space is provided with lubricant.

Abstract: Plastic pipes comprising an inner and outer wall being interconnected by lengthwise extending connecting partitions, forming channels, the ends of the channels being each separately sealed by sealingly pressing the end walls of a channel to each other after these walls have been heated to a temperature surpassing the plasticizing temperature.

Abstract: An apparatus for forming a plastic pipe having a circular cross-section and elongated longitudinal channels in the pipe wall is disclosed. A mass of synthetic plastic material is pressed through an annular space defined by inner and outer annular supports, the annular space having a plurality of spaced pin supports concentrically disposed therein and regulating the quantity of material flow through the annular space, depending on the shape of the pin supports, by selectively moving the walls of the annular supports closer to each other. In a particularly advantageous embodiment, either the wall of the inner annular support or the wall of the outer annular support, or both, are moved closer to each other in the area between adjacent pin supports.

Abstract: This invention relates to a method of making a tube of thermoplastic material, comprising longitudinal channels of circular cross-section and having such wall stresses that, after axially cutting the tube, the edge parts along the cut edge overlap each other for less than 8% of the outer circumference of the tube.

Abstract: Plastics pipes comprising an inner and outer wall being interconnected by lengthwise extending connecting partitions, forming channels, the ends of the channels being each separately sealed by sealingly pressing the end walls of a channel to each other after these walls have been heated to a temperature surpassing the plasticizing temperature.