Sealing face surfacing method of nuclear power station pressure releasing valve

The invention discloses a sealing face surfacing method of a nuclear power station pressure releasing valve. The method comprises the steps that firstly, a heating belt is wound on the to-be-surfaced surface of a component of the pressure releasing valve, the heating belt is connected with a thermal treatment temperature control device, and the component is wrapped by insulation cotton; secondly, the heating belt is heated by starting the thermal treatment temperature control device till the to-be-surfaced sealing face of the component is preheated to the preset temperature; thirdly, surfacing is carried out on the to-be-surfaced sealing face of the component wrapped by the insulation cotton through a welding device; and fourthly, after welding, the thermal treatment temperature control device is stopped, and the component wrapped by the insulation cotton is naturally cooled. By means of the thermal treatment temperature control device, preheating and surfacing are carried out on the whole component through winding of the heating belt and wrapping of the insulation cotton, natural cooling is carried out still through the insulation cotton wrapping manner after welding, and therefore during preheating, the temperature evenly reaches the preset temperature to the greatest extent, the temperature can be kept to the greatest extent during surfacing, and during cooling, the cooling speed can be effectively lowered.