Abstract: Plastics coated metal tube produced by folding a strip of metal into a tubular form, seaming the tube and immediately extruding layers of plastics material onto the inner and outer surfaces of the metal tube, and cooling the plastics layers by passing the tube through a water bath, contains air injected under pressure to assist adhering the extruded plastics coating onto the inner surface of the metal tube and to test the integrity of the tube. The invention provides apparatus comprising jaws which clamp the tube within the water bath in order to seal the tube while the inner coating is still plastic so that when the tube is cut into lengths at the seals the internal pressure is retained until the tube is eventually used.

Abstract: Apparatus for forming a plastics coated metal tube comprising means for forming a continuous strip of metal into a U-shape and a forming sleeve for folding the strip into an overlapping tube. A mandrel is also provided which extends through the forming sleeve and through a locating sleeve. The locating sleeve centralizes the tube as it passes over the mandrel and welding means are provided for welding the overlapping tube as it passes through the locating sleeve. Both the forming sleeve and the locating sleeve are mounted on the mandrel so as to float with the mandrel.

Abstract: A metal connector for the end of an internally and externally plastics coated metal tube maintains the metal of the tube, for example aluminium, out of contact with the metal of the connector, for example brass, and thereby avoids problems of anodic corrosion. This is achieved by forming the male portion of the connector with a tapered shank over which the tube end is forced for connection, and a shoulder to act as a stop for the tube end, the shoulder being of such relatively shallow radial depth that it abuts the internal plastics coating but not the metal of the tube. In another aspect of the invention, a second shoulder radially outward of the inner shoulder abuts the outer plastics coating and the two shoulders are radially separated by a radial groove that thereby prevents contact between the end of the metal tube and the metal connector.