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According to the valve damage, the replacement of the valve stem and threaded rod door sleeve, the valve seat and the valve sealing surface grinding repair, the sealing surface to find the upper contact position on the boiler side actually 1.2mm gap, the steam turbine There are also 0.6mm side of the gap, that is to say the seat and the valve plate taper has been seriously inconsistent, affecting the tightness of the valve, resulting in valve leakage. In order to solve this defect, only consider the site to repair the valve, as the main steam electric main steam valve is a single valve wedge gate valve, then to solve the problem only to repair the valve flap with the same seat taper. To make repairs, you must accurately measure the taper. How to measure the taper? The use of measuring instruments Because of the deep inside the valve, the human hand is difficult to reach the bottom of the seat, so you can not accurately measure the valve seat high and low, and the measured point of the distance, it can not accurately measure the valve seat Taper, after careful consideration, in order to repair the valve work developed a construction program. Step 1: In order to solve the problem of the taper of the valve seat and the valve disc, firstly, two shutter molds slightly larger than the valve disc are manufactured and then suspended on the contact surface of the valve seat. Four small iron bars are used to hold the shutter mold It is completely in contact with the valve seat, the welding will be four small iron bars with two models uniform welding firm, to be taken out after cooling, measured with a protractor gate model taper. Step 2: the valve flap according to the taper of the valve plate model turning, the carved good valve flap into the seat for repair, repairing the method can be used Hongdan contact; when the taper is basically the same, within the valve flap Concave surface of the car is also the same taper surface, used as the sealing surface after welding turning datum. Step 3: The valve sealing surface surfacing. Welding electrodes can be used according to the temperature of the valve to be selected, welding electrodes for welding are semi-ferritic high-chromium steel and nickel-chromium molybdenum silicon two categories, mainly for the working temperature is lower than 600 ℃ high-pressure valve Sealing surface surfacing; or using cobalt-based hard sealing surfacing electrode: D802, D812. In the welding process of sub-welding, to prevent excessive welding temperature caused by disc deformation. Surfacing work and working conditions are very complex, surfacing must be based on the different requirements of the appropriate selection of electrodes. Different workpieces and welding electrodes to use a different surfacing process, in order to obtain satisfactory surfacing effect.