A coupling piece for an outer end of a multilayered conduit, includes a coupling pipe which is provided on the outer side with a radially upright wall, wherein the wall is widened in an axial direction at a radial distance from the outer side of the body. The outer side of the coupling pipe, the upright wall and the widened portion enclose an annular insertion space into which the outer end of the conduit can be directly inserted, wherein the inner wall of the coupling pipe is reinforced with an adjacent reinforcing layer which has a greater strength than the material of the coupling pipe. The reinforcing layer is provided with axial engaging elements, while the inner wall is provided with axial connecting elements which correspond with and connect to the engaging elements.

An electrofusion joint includes a main body and a heating wire. The main body is configured to be connected to a resin pipe containing a thermoplastic resin. The heating wire is in the main body. The heating wire includes a conducting wire and an insulating cover film that is around the conducting wire. The insulating cover film has a melting point of at least 230 degrees.

A method of joining polymer-lined pipe sections end-to-end comprises friction welding a polymer liner bridge fitting to parent liners of the pipe sections and welding metallic outer pipes of the pipe sections to each other before, during or after the friction welding operation. The fitting may be engaged telescopically with the pipe sections in socket formations formed by the parent liners. Friction welding is effected by relative rotational movement between the fitting and the pipe sections about a common longitudinal axis. A spinning tool is advanced longitudinally within at least one of the pipe sections, inserted into the fitting, anchored within at least one of the pipe sections, engaged with the fitting and rotated to effect the relative rotational movement. This friction-welds the fitting to the parent liners simultaneously at interfaces located at respective ends of the fitting.

To connect two plastic pipes 3 together, an induction connection sleeve 1 is used, which is provided with annular recesses 5 into which the pipes 3 with the ends 3A are pushed. Subsequently, induction heating elements 9 present in the induction connecting sleeve are heated with induction hand pliers 21 and the induction connecting sleeve is pressed against the end 3A of one of the tubes 3. The induction connection sleeve fuses to the tube. Because the induction hand pliers 21 are provided with ribs 27, grooves 19 are pressed into the pipe wall 3B in order to check whether sufficient heating and pressing has taken place over the entire circumference to obtain a gastight connection.