Abstract: The invention relates to the welding of components made of heat-fusing plastic, using an electrical heating resistor arranged in the thickness of a connection component.According to the invention, the resistor is a thin electrically conductive layer advantageously formed on a supporting film made of heat-fusing plastic and capable of causing the tearing of the layer at a specific temperature corresponding to the welding temperature of the components.The invention is used particularly for the thermal welding of polyethylene pipes used in the gas industry.