A fluorine-lined valve is a type of valve that has a fluorine plastic (e.g., PTFE) lining to improve the corrosion resistance of the valve. The main components of a fluorine-lined valve include the valve body, valve stem, valve cover, and bushing. The bushing is a liner made of fluoroplastic that provides a surface inside the valve in contact with the fluid. Fluorine-lined valves are commonly used to handle corrosive liquids and gases such as acids, alkalis, and chlorine. With good corrosion resistance, wear resistance, high temperature resistance, and good sealing properties, fluorine lined valves are widely used in the chemical, petroleum, pharmaceutical, and food industries.
Fluorine-lined valves have the following characteristics:
1. Good corrosion resistance:
Fluorine lined valves are internally lined with fluorine plastic, which has good corrosion resistance and can handle various corrosive media.
2. Good sealing:
Fluorine lined valve adopts a bushing sealing structure, which performs well and effectively prevents medium leakage.
3. Good abrasion resistance:
The fluorine lined valve is lined with fluorine plastic, which has good abrasion resistance and can adapt to the flow of high speed fluid.
4. Good high temperature resistance:
Fluorine plastic has good high temperature resistance, and fluorine lined valves can adapt to high temperature media processing.
5. Long service life:
The fluorine plastic lining inside the fluorine lined valve has good corrosion and wear resistance, which can prolong the valve’s service life.
6. Convenient maintenance:
The fluorine plastic lining inside the fluorine lined valve is easy to clean and maintain, which can reduce the maintenance cost and workload.
With the continuous application of new chemical materials and the improvement of lining technology, fluorine-lined valves are favored by manufacturers and users for their safety, reliability and high cost performance. They are increasingly widely used in strong corrosive process media in petroleum, chemical, pharmaceutical, and other industries. However, fluorine-lined valves are not able to adapt to all corrosive working conditions. Like other valves, it is very important to choose and use fluorine-lined valves well.
1. The temperature of the fluorine-lined valve should be about 30% lower than the upper limit
The temperature used for fluorine-lined valves: currently commonly used valve lining materials include synthetic rubber (-10-120°C), polytetrafluoroethylene PTEF (-200-180°C), soluble polytetrafluoroethylene PFA (-196-260°C) , FEP F46 (-85-150°C). The actual temperature of the medium used varies according to the material and pressure.
The long-term use temperature should usually be lower than the upper limit by about 30%, otherwise, the lining of each part of the valve is easily deformed, resulting in large leakage or failure of the valve to switch normally.
2. Fluorine-lined valves are not suitable for high pressure and high pressure difference occasions
Especially for the fluorine-lined bellows sealing regulating valve (because the bellows are mostly made of polytetrafluoroethylene, the bellows will easily break when the pressure and pressure difference are too large), most of the manufacturer’s selection samples indicate that the nominal pressure is PN≤2.5MPa , this is for insurance purposes.
3. The medium should not have hard particles, crystals, impurities, etc
Requirements for the medium of fluorine-lined valves: the medium used for fluorine-lined valves should not have hard particles, crystals, impurities, etc., so as to avoid the wear of the fluorine-lined plastic layer or bellows during the opening and closing of the valve.
If the medium has hard particles, crystals, and impurities, corrosion-resistant precious metal materials can be selected according to the characteristics of the process medium, such as hard-sealed valves such as Hastelloy alloy, nickel-based alloy, and alloy steel.
4. The diameter of the fluorine-lined (plastic) valve should be 30~85%
The fluorine-lined regulating valve is usually made of a fluorine-lined bellows sealing structure, which has the advantages of good corrosion resistance and no leakage. When selecting, the diameter of the valve should be calculated according to the process parameters, and the normal opening should be within the range of 30-85%.
If the valve diameter is too large, it will cause long-term operation with a small opening degree, and the valve adjustment performance will deteriorate. Especially in the case of small opening, not only the erosion will be intensified, but also the valve core and stem will vibrate due to the impact of the medium, and even the valve stem will be broken and the bellows will be deformed.