Advantages and disadvantages of fluoropolymer-lined valves
Fluoroplastic-lined valves, also known as fluoroplastic-lined corrosion-resistant valves, are made by molding (or embedding) polytetrafluoroethylene resin (or processed profiles) into the inner wall of steel or iron valve pressure-bearing components (the same method applies to the lining of various pressure vessels and pipeline accessories) or the outer surface of valve internals. This utilizes its unique resistance to highly corrosive media to create various valves and pressure vessels.
Advantages and Disadvantages of Fluoroplastic-Lined Valves:
1. Fluoroplastic-lined valves are more reliable in terms of corrosion resistance than valves like 316L. The main disadvantage is that they are primarily used at normal temperatures and pressures. Due to the low temperature of the medium, condensation may form on the valve shell, causing rust on the carbon steel shell, especially at the valve, packing gland, and bolts. This can lead to leakage from the valve stem and packing, damaging the valve.
2. The main advantage of PTFE-lined valves is their corrosion resistance; they can withstand strong acids and alkalis. The limitation is that the temperature cannot be too high. Leaks, drips, or spills are due to the valve’s material or quality issues.
3. Made of corrosion-resistant and aging-resistant perfluoropolymer (F46), fluoropolymer-lined valves offer reliable corrosion resistance and sealing performance. They are widely used in chemical, petroleum, metallurgisch, and pharmaceutical industries for regulating, switching on, or cutting off highly corrosive media such as acids and alkalis during production processes. Their effectiveness is most pronounced in water treatment process control.
4. A major advantage of fluoropolymer-lined valves is their ability to withstand strong acids and alkalis. Jedoch, they also have disadvantages: they cannot seal perfectly, even under high vacuum; temperature control is severely limited; if the reactor temperature is high, the plastic will soften, and fluoroplastics are not wear-resistant, preventing the flow of particulate media and damaging the seal.
5. Domestically produced fluoropolymer-lined valves are prone to internal leakage, making their sealing performance inferior to ordinary valves. Therefore, it is difficult to solve the dripping problem with fluoropolymer-lined valves, which are mainly used for corrosion resistance.
6. They are much cheaper than corrosion-resistant metal materials. Fluoropolymer-lined valves generally have limitations regarding temperature, the absence of particulate media, and the inability to flow under vacuum. They are more expensive than carbon steel valves but cheaper than stainless steel valves!
