GB892884A - Improvements in and relating to joints and repairs for electric cables - Google Patents

Abstract

A method of moulding a thermo-plastic covering, e.g. polythene, over a joint between thermoplastic insulated electrical conductors or for repairing the insulation of a single conductor, which conductors or conductor have strands with interstices filled with a material, e.g. butyl rubber compound or polyisobutylene compounds, whose metling point is at or below the moulding temperature of the thermoplastic covering comprises the steps of enclosing the conductor(s) in a mould whose temperature is below that of the melting temperature of the strand filling material, injecting the covering material at its moulding temperature until the mould is filled, applying heat to the mould until its temperature is at least equal to the moulding temperature whilst simultaneously maintaining the injection pressure, maintaining the mould pressure and temperature to enable the covering material to unite by fusion with the thermoplastic insulation and then allowing the temperature of the mould to drop but maintaining the injection pressure. The mould may be pre-heated prior to the insertion of the conductor or conductors, and may be subsequently cooled by a water jacket or by blowing air over its external surface.