An electrofusion fitting includes a tubular length of thermoplastic material, of an outer diameter commensurate with the inner diameter of the ends of a compatible thermoplastic material lining of adjacent lengths of metal pipe, there being at each end of the fitting at least two heater coils on or in close proximity to the outer surface of the fitting, electrical leads from the heater coils extending through the fitting to emerge at the inner surface of the tubular length, for connection to a source of electrical power.