Abstract: A method is disclosed for the manufacture of an electrofusion coupler, for connecting adjoining lengths of thermoplastics pipes, and which coupler takes the form of a sleeve of thermoplastics material, to receive adjoining ends of adjoining pipes, the sleeve having an electrical resistance heater embedded therein and extended around the sleeve. In the method, a plastics preform is wound with a resistance heating wire, while heating the wire, to melt the surface of the preform, or applying molten plastics to the preform in the vicinity where the wire runs onto the preform, in order to ensure that the heating wire is fully embedded in the preform. A pressing roller may be run over the preform surface before the molten plastics has solidified, in order to smooth over the molten plastics. The preform 10 is subsequently placed in an injection mould and an outer encapsulating jacket is injection moulded around the preform.

Abstract: A method is disclosed for the manufacture of an electrofusion coupler, for connecting adjoining lengths of thermoplastics pipes, and which coupler takes the form of a sleeve of thermoplastics material, to receive adjoining ends of adjoining pipes, the sleeve having an electrical resistance heater embedded therein and extended around the sleeve. In the method, a plastics preform is wound with a resistance heating wire, while heating the wire, to melt the surface of the preform, or applying molten plastics to the preform in the vicinity where the wire runs onto the preform, in order to ensure that the heating wire is fully embedded in the preform. A pressing roller may be run over the preform surface before the molten plastics has solidified, in order to smooth over the molten plastics. The preform 10 is subsequently placed in an injection mould and an outer encapsulating jacket is injection moulded around the preform.

Abstract: A method and apparatus for moulding an assembly of a thermoplastics member with a fusion pad 2b such as a pipe tapping tee saddle or a pipe coupling. The fusion pad 2b has an element which is to be electrically heated to weld the assembly to a compatible thermoplastics material and this pad is mounted in the cavity 105, 106 of an injection moulding tool 100 by which the thermoplastics member is to be moulded over the fusion pad 2b. During this latter moulding a control system 111 electrically heats the element to assist in bonding the thermoplastics envelope of the fusion pad to the thermoplastics of the member which is being moulded. A wall part 103 of the moulding tool 100 on which the fusion pad 2b is mounted may be temperature controlled 122 to maintain the surface of the fusion pad in contact therewith substantially solid.

Abstract: A clamp assembly for temporarily clamping a tapping tee saddle 1 to a pipe 9 has a platform 2 and a pressure member 32 which is connected to the platform by a rod 24 slidable in a screw shaft 16, the shaft 16 being screw adjustable relative to the platform 2. A compression spring 40 is provided between the pressure member 32 and the shaft 16. Flexible straps 54 are connected to the platform 2 to extend around the pipe 9 for clamping the assembly to hold the saddle on the pipe. Clamping pressure is provided by screw adjustment of the shaft 16 in the platform 2 to compress the spring 40 between the member 32 and shaft 16 and a consequent reaction against the straps 54. During adjustment of the shaft 16, the rod 24 is displaced relative thereto and its position in the shaft 16 provides an indication of the clamping pressure which is exerted on the saddle 1.

Abstract: A plug valve comprises a plug rotatable in a body of plastics. The plug fits closely within a thin walled metal can. The valve body is formed by moulding around the can and plug, the can thereafter remaining fixed within the valve body, while the plug is rotatable in the can. Seals which are also embedded in the valve body during moulding project through the fluid passage openings in the can to engage the surface of the plug. The provision of the can prevents damage to the plug during moulding of the valve body and prevents the plug from being bonded to the valve body, or the valve body shrinking onto the plug.

Abstract: A fusion pad is produced by forming a spiral groove 22 in the pad upper surface. A wire 16 is fed from a reel 18 through a hole in the pad and secured to a terminal on the pad under surface. The pad is rotated causing the wire 16 progressively to enter the groove 22. The groove side walls have a height greater than the diameter of the wire 16 to ensure that the groove walls project above the wire 16 in the groove 22. An electrical heating tool 26 is applied to each part of the groove 22 as soon as the wire 16 is located in that groove part to cause the adjacent groove walls 24 to melt at their upper regions. These molten upper regions collapse inwardly onto the wire 16 therebetween and solidify to retain the wire 16 in the groove 22.