Brief introduction to the repair method of high-pressure main steam regulating valve for clamp type fluorine lined butterfly valve manufacturer

clamp-on Fluorine-lined Butterfly Valve Manufacturer's description of repair method for high-pressure main steam regulating valve

1.1 Working mechanism of valve disc guide shoulder. Unit 2 is a (N300-16.7/537/537-3 type) steam turbine manufactured by Dongfang Turbine Co., Ltd. Its high-pressure main steam regulating valve consists of one main steam valve and two regulating valves. The high-pressure regulating valve is used to regulate the inlet steam flow of the high-pressure cylinder. check valve When the unit is running, the hydraulic servo motor serves as a mechanical lifting device, causing the valve disc guide shoulder to move up and down along the guide groove, controlling the opening of the regulating valve disc. Fluorine lined DC globe valve During the operation of the unit, the high-temperature steam of the regulating valve is 16.7 MPa, 537 ℃, and the guiding shoulder mainly bears thermal stress and certain circumferential shear stress. The diameter of the valve disc and seat of the No.1 high-pressure regulating valve is 170 mm. The structure of the valve disc is shown in Figure 1, and the size of the guide shoulder is 55 mm × 30 mm × 10 mm (height × width × thickness). The valve disc material is made of 20Cr3MoWVA alloy steel. In order to improve the cavitation resistance of the valve disc, its surface is treated with high-temperature nitriding.

1.2 The selection of welding materials and welding equipment depends on the working conditions of the regulating valve, PTFE lined valve The valve disc guide shoulder should ensure sufficient high-temperature strength and meet certain wear resistance. Due to the emergency repair of the unit, it is not possible to purchase better matching materials. Referring to the selection principles of welding materials and the analysis of the mechanical properties of each welding material, TIG-R34 (12Cr2MoWVTIB, Φ 2.5 mm) welding wire similar to the base material material is selected. The welding equipment adopts Lincoln V300-1 and argon arc welding matching tools; The temperature monitoring uses an American MX2 infrared thermometer.

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