Fluid is directed against an article of indefinite length to support the article as it is moved along a passline. The fluid may be used to modify the temperature of the article. The method and apparatus disclosed are particularly applicable to supporting a telecommunications cable while cooling extruded jacketing material on the outer surface of the cable.

The cooling device consists of a plurality of cooling elements which are arranged in such a manner that they surround the tubular sheeting without interspace. Cooling elements with plane inner surface alternate with cooling elements with curved inner surface, the plane surfaces and the projections of the curved surfaces each have the shape of a regular trapezoid. The cooling elements can be adjusted to the diameter of the tubular sheeting in transverse as well as in oblique direction with respect to the axis of the hollow space formed by the cooling elements.

In the dual extrusion manufacture of an insulated coaxial cable having one or more spiral spacing ribs 2a wrapped around an inner conductor 1 and surrounded by a tubular sheath 2b, the longitudinal contraction of the sheath during cooling and the attendant warp curvature of the rib is avoided by providing a sizing device 7 having a central die portion 12 with vacuum exhaust holes 14 therein. Water from a cooling pool 8 is drawn in through the clearance space between the sheath and the die portion as the cable passes therethrough to pre-cool and lubricate it, and one or more dies 15 are provided in the cooling pool to prevent the longitudinal contraction of the sheath and thereby avoid any appreciable rib inclination or curvature.

A vulcanizing device in which a member is enclosed in an extruder device and the enclosed member is vulcanized at a predetermined pressure in a vulcanizing tube connected to the extruder device, wherein the vulcanizing tube is placed at a distance from the extrusion device, a sealing device is positioned directly before and coaxially to the vulcanizing tube, the length of the sealing device being less than the said distance, the sealing device contains a sealing housing, whose interior has spaced radial guiding elements which have coaxial openings for the passage of the enclosed member and divide the interior of the sealing housing into individual chambers lying axially behind each other, the sealing housing has an inlet opening between the ends, which is connected as a locking medium to a source, of which the pressure is arranged to be somewhat higher than the pressure in the vulcanizing tube, and the chambers are connected to outlet openings in the sealing housing, which are connected to throttled discharge conduits.

An improved ram extruder for the production of plastic pipe, especially plastic pipe of high molecular weight low pressure polyethylene, which comprises an extrusion die, heating means for heating polymer to be extruded, a ram which is reciprocated in the extrusion die, means for reciprocating said extrusion die and a mandrel which determines the inside diameter of plastic pipe to be extruded, the mandrel being rigidly connected with the ram. Also disclosed is a process for ram extruding plastic pipe by the use of such a ram extruder, especially a process for the formation of plastic pipe of high molecular weight low pressure polyethylene of molecular weight of more than 500,000. A pipe or tube of high molecular weight low pressure polyethylene of molecular weight more than 500,000 is also disclosed together with its use as a liner for a steel pipe.