Fluorine-lined Ball Valve Manufacturers Share How To Select And Use Fluorine-lined Valves

In the chemical industry, there are many materials that are highly corrosive. Under these special conditions, the selection of equipment, pipelines and valves is of great significance to ensure the stable operation of the device. Most corrosive media are usually highly corrosive to metals. General metal valves such as carbon steel and stainless steel will corrode quickly; even special alloys such as Hastelloy and Monel may be corroded. Moreover, special alloy valves are expensive, have a long processing cycle, and may cause casualties after corrosion.

With the continuous application of new chemical materials and the improvement of lining technology, fluorine (plastic) regulating valves and cutting valves are safe and reliable, cost-effective, and are favored by manufacturers and users. They are widely used in highly corrosive process media in the petroleum, chemical, pharmaceutical and other industries. However, fluorine (plastic) valves cannot adapt to all corrosive conditions. Like other valves, how to select and use fluorine (plastic) valves is a professional job.

Lined Valve The temperature should be about 30% lower than the upper limit

Using temperature of fluorine-lined (plastic) valves: Currently, the commonly used valve lining materials are synthetic rubber (-10-120℃), polytetrafluoroethylene PTEF (-200-180℃), soluble polytetrafluoroethylene PFA (-196-260℃), and polytetrafluoroethylene propylene F46 (-85-150℃). The above is the extreme tolerance temperature of each material. The actual medium temperature used varies according to the material and pressure. The long-term use temperature should generally be about 30% lower than the upper limit. Otherwise, the linings of the valve components are prone to deformation, resulting in large leakage or abnormal valve switching.

Fluorine-lined (plastic) valves are not suitable for high pressure and high pressure difference occasions

Using pressure (difference) of fluorine-lined (plastic) valves: Fluorine-lined (plastic) valves are generally not used in high vacuum conditions. When it is really necessary to use them in high vacuum conditions, corresponding measures should be taken (such as opening a dovetail groove in the inner cavity of the metal valve body, punching the valve plate, etc.). ), to prevent the inner cavity of the valve from being lined with fluorine, the lining plastic layer being pulled out (bulging), and the lining plastic layer being separated from the metal layer, causing the valve to fail to open and close normally.

Similarly, fluorine (plastic) valves are not suitable for high pressure and high pressure difference occasions. Especially for fluorine bellows sealed control valves (because the bellows are mainly made of polytetrafluoroethylene, excessive pressure and pressure difference can easily cause the bellows to rupture), most manufacturers choose samples to indicate that the nominal pressure is PN≤2.5MPa, which is for insurance. But sometimes due to special working conditions, solutions need to be found.

The medium should not have hard particles, crystals, impurities, etc.

Requirements for the medium of fluorine (plastic) lined valves: The medium used in fluorine (plastic) lined valves should not have hard particles, crystals, impurities, etc., so as to avoid wearing the fluorine lined plastic layer or bellows when opening and closing the valve. If there are hard particles, crystals and impurities in the medium, corrosion-resistant precious metal materials such as Hastelloy, nickel-based alloys, alloy steel and other hard sealing valves can be selected according to the characteristics of the process medium.

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 valve diameter 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 when the opening degree is small, and the valve adjustment performance will be poor. Especially when the opening degree is small, not only will the scouring be aggravated, but the valve core and valve stem will also be vibrated by the impact of the medium, and even the valve stem will break and the bellows will deform.