Detailed Introduction Of Fluorine-lined Valves

Lined Valve, also known as fluoroplastic lined valve, is a valve made by placing polytetrafluoroethylene resin (or processed profile) on the inner wall of steel or iron valve pressure-bearing parts or the outer surface of valve internal parts by molding (or inlaying) method, and using its unique performance in resisting strong corrosive media to make valves. Fluorine-lined valves are suitable for various concentrations of sulfuric acid, hydrochloric acid, hydrofluoric acid, aqua regia and various organic acids, strong acids, strong oxidants and other corrosive media, but fluorine-lined valves are relatively limited by temperature (only suitable for media between -50℃ and 150℃). Valves that can be made of fluoroplastic lined include: fluorine-lined butterfly valves, fluorine-lined ball valves, fluorine-lined stop valves, fluorine-lined diaphragm valves, fluorine-lined gate valves, fluorine-lined plug valves, etc.

With the rapid development of modern industry, fluorine-lined valves and their various pipeline accessories have been rapidly applied and promoted in various fields such as petroleum, printing and dyeing, chemical industry, and electricity, showing strong vitality. As the preferred project in the project, it has attracted great attention and favor from various engineering design units and construction units. It is a promising product with great market potential.

Fluorine-lined valves have the dual functions of switching and flow regulation. They can conveniently open and close the gas line without affecting the flow, ensuring the repeatability of the flow. It opens slowly, reducing the impact of instantaneous pipeline pressure on the instrument. It is equivalent to adding a damper, which greatly increases the service life of the needle valve. Fluorine-lined valves are specially used to control corrosive or highly corrosive media. The inner surface of the valve body is covered with various fluoroplastics that can be selected. It is suitable for different working temperatures and fluid pipelines, and has the characteristics of high strength and good corrosion resistance.

Fluorine-lined valves are relatively expensive, and the working environment they are in is harsh. They are either toxic and harmful chemicals, or highly corrosive acids, alkalis or organic solvents. Improper use will result in significant economic losses and serious consequences. Correct use and maintenance of valves can extend the service life of fluorine-lined valves, prevent all kinds of accidents, and ensure the normal operation of pipelines. Therefore, the following points must be noted during use:

1. Please read the product manual carefully before use.

2. Use within the range of pressure, temperature, and medium specified on the nameplate or manual.

3. Prevent fluorine-lined valves from generating excessive pipeline stress due to temperature changes during use, minimize temperature changes, and add U-shaped expansion joints before and after the valve.

4. It is forbidden to use levers to open and close fluorine-lined valves. Pay attention to the opening and closing indication position and limit device of fluorine-lined valves. After opening and closing, do not force closing to avoid premature damage to the fluorine plastic sealing surface.

5. For some unstable and easily decomposed media (such as the decomposition of some media will cause volume expansion and cause abnormal increase in working pressure), which will cause valve damage or leakage, measures should be taken to eliminate or limit the factors that cause the decomposition of unstable media. When selecting valves, the changes in working conditions that may be caused by unstable and easy decomposition of the medium should be considered and fluorine-lined valves with automatic pressure relief devices should be selected.

6. For fluorine-lined valves on pipelines with toxic, flammable, explosive, and highly corrosive media, it is strictly forbidden to replace the packing under pressure. Although fluorine-lined valves are designed with sealing functions, it is not recommended to replace the packing under pressure.

7. For pipelines with self-ignitable media, measures should be taken to ensure that the ambient temperature and operating temperature do not exceed the self-ignition point of the medium to prevent dangers caused by sunlight or external fire.

8. For severe and long-term vibration of the pipeline, measures should be taken to eliminate it to avoid damage to the fluorine plastic lined valve.

9. During the use of fluorine-lined valves, the fluorine plastic sealing surface is often damaged by crystallization and solid particles of the medium due to its soft texture, resulting in sealing leakage. After discovery, repair or replace the seal in time.

10. Some fluorine-lined valves are partially opened during use to adjust the flow rate. High-speed media causes premature damage to the sealing surface. In this case, replace the seal in time.

11. Gaskets are generally not added to the flange of fluorine-lined valves. If leakage occurs at the middle flange, tighten the middle flange nut evenly to eliminate leakage. If the sealing surface of the middle flange is damaged, repair the sealing surface and add a middle flange gasket to solve the problem.

12. If the handle or handwheel is not flexible or cannot open and close the fluorine-lined valve, loosen the gland nut appropriately. The rotation is still not flexible. The gland may be skewed and the gland should be adjusted. If the fluorine-lined valve cannot be opened and closed flexibly after adjustment and loosening the gland, it should be disassembled for inspection, dirt should be removed, and faults should be eliminated. When disassembling this type of fluorine-lined valve, pay attention to what medium is in the fluorine-lined valve pipeline, whether it is used or newly installed. If the medium used is toxic, flammable, or explosive, the staff should wear protective masks and rubber gloves, wear protective clothing, and operate in accordance with the operating procedures. Avoid accidents during disassembly and prevent accidents.

Installation of fluorine-lined valves:

1. During installation, check whether the valve markings (such as valve type, nominal diameter, pressure level, material, etc.) are consistent with the use requirements, and whether the flow direction markings on the shell are consistent with the flow direction of the pipeline.

2. During installation, try to install it horizontally with the valve stem facing upward. Prevent the valve from tilting and install the valve in a natural state. Prevent the valve from generating large installation stress due to pipelines, supports, etc. The hand wheel should not be used for valve lifting during installation.

3. During installation, if the pipe flange sealing surface connected to the fluorine plastic lining sealing surface at both ends of the valve is metal, fluorine plastic sealing gaskets must be added. The flange sealing surface connected to it should be in the structure of Figure A, and the structure of Figure B should not be used, otherwise it will cause premature damage and leakage of the valve sealing surface.

4. If the pipeline has sufficient strength to bear the weight and operating torque of the valve, no support is required for this valve. Otherwise, a special support point should be set for the fluorine-lined valve.

5. After installation, the valve must be in the fully open position when the system or pipeline is pressure tested.