The fluorine-coated valve flange cover must not be opened at will. Unless it is ready to be connected to the pipeline, otherwise the PTFE flange surface may be damaged by temperature differences, foreign objects, impacts or distortions, which will affect the sealing. If the cover needs to be moved for inspection purposes, it must be reset immediately after the inspection to protect the PTFE flange surface. 

2. It is strictly prohibited to perform any high-temperature welding operations on the fluorine-coated butterfly valve, as this could cause permanent damage to the lining layer. 

3. After repair, the fluorine-coated valves must pass the relevant standards tests before they can be installed. 

4. When operating the fluorine-coated valves manually, it is strictly prohibited to use any other levers to apply force and forcefully open or close the valves. 

5. When connecting the fluorine-coated butterfly valve to the pipeline, usually no additional gaskets are used separately. However, when connecting to flanges of different materials (such as metal surfaces), appropriate gaskets should be employed to protect the PTFE flange surface. 

6. In the event of leakage of the fluorine-coated valve during system operation, if the temperature is high, the system should be cooled to room temperature first, and then the cause should be identified and repairs carried out. 

Pre-sampling before painting 

The medium used for fluorine-coated valves should not contain hard particles, crystals, impurities, etc., as this could cause the valve core, valve seat, or fluorine-coated gasket to be worn out during the opening and closing operation. If the medium contains hard particles, crystals, or impurities, the valve core and valve seat can be replaced with Hastelloy alloy. 

2. Operating temperature of fluorine-coated valves: The fluorine plastics used in our various fluorine-coated valves are F46 (FEP). The operating temperature of the medium cannot exceed 150℃ (the medium temperature can reach 150℃ for a short period of time, but the long-term operating temperature should be controlled within 120℃). Otherwise, the components coated with F46 will easily soften and deform, causing the valve to fail to close properly and resulting in excessive leakage. If the medium temperature is below 180℃ for a short period or below 150℃ for a long period, another fluorine plastic - PFA can be selected. However, the price of the fluorine plastic coated with PFA is slightly higher than that of the fluorine plastic coated with F46. 

3. The pressure and pressure difference should be controlled within the allowable range. Especially for the fluorine-coated regulating valves and fluorine-coated stop valves with bellows seals. Since the bellows is made of tetrafluoroethylene material, it is prone to rupture under high pressure and pressure difference. For the fluorine-coated regulating valves with bellows seals and high pressure and pressure difference conditions, tetrafluoroethylene packing seals can be adopted instead. 

4. For fluorine-lined valves, the diameter of the valve should be selected based on the required flow rate (Cv value). When choosing the valve, the diameter that should be selected for the fluorine-lined valve and the opening degree of the valve should be calculated according to the required flow rate (Cv value) and other technical parameters. If the diameter of the valve is too large, it will inevitably cause the valve to operate with a relatively small opening degree for a long time. Coupled with the pressure of the medium, this may easily cause the valve core and the rod to be impacted by the medium, resulting in valve vibration. If the valve core and the rod are subjected to the impact of the medium for a long time, they may even cause the valve stem to break. When users select various types of fluorine-lined valves, they should try to understand and master the usage technical conditions in order to select and use them properly and increase the service life of the valves. When encountering situations beyond the usage technical conditions, it is necessary to raise the issue to the manufacturer, negotiate together, and take corresponding countermeasures to solve the problem. 

5. Avoid negative pressure. The fluorine-coated valves should be used in pipes without negative pressure. If there is negative pressure, it is likely to cause the fluorine-coated layer inside the valve to be sucked out (pushed out) or peeled off, resulting in malfunction of the valve's opening and closing. 

Ten reasons for valve leakage: 

The sealing surface was not ground properly. 

2. The sealing ring does not fit tightly with the valve seat and the valve disc. 

3. The valve disc is not securely connected to the valve stem. 

4. The valve stem is bent and twisted, causing the upper and lower closing elements to not be aligned. 

5. The closing process was too rapid, resulting in poor contact between the sealing surfaces or the surfaces having already been damaged. 

6. The material was improperly selected and was unable to withstand the corrosion of the medium. 

7. Using stop valves and gate valves as regulating valves. The sealing surfaces cannot withstand the erosion caused by the high-speed flowing medium. 

8. For certain media, after the valve is closed, they gradually cool down, causing fine cracks on the sealing surface and resulting in erosion. 

9. For some sealing surfaces, they are connected to the valve seat and valve disc by threads. This can lead to the formation of an oxygen concentration difference cell, causing corrosion and loosening. 

10. Due to the presence of impurities such as welding slag, rust, and dust, or because mechanical parts from the production system have fallen and blocked the valve core, the valve fails to close tightly.