After the hot pressing plate is removed, the rust particles are removed with a steel brush, and then the rust spots are removed with dilute hydrochloric acid (concentration of 15% - 20%) to expose the metal color of the pressing plate.
The 422 welding rod with a diameter of 5mm is used for surfacing in the corrosion zone. Because single side surfacing will cause bending of pressing plate, double-sided surfacing should be adopted to offset the welding stack stress.
The overlaid pressing plate is planed on both sides on the gantry planer, and the planing amount is 0.5mm.
If the welding seam of the plug is cracked due to planing, it needs to be patched. That is, after double-sided planing, steam pressure test shall be carried out for each pressing plate one by one. If water drops are found, mark them. After the test steam is turned off, the long groove or round groove is ground out at the welding seam of the water ball with the angle grinder, and then the welding seam is overlaid, and then the grinding machine is used to smooth it.