Precautions For Use Of Fluoroplastic Lined Anti-corrosion Valves

Reasonable selection and application of Lined Valve is a concern for everyone in engineering. Based on the experience of many users in field applications for many years, we put forward the following precautions for your reference.

Fluorine-lined plastic anti-corrosion valves have been widely used in devices that are exposed to strong corrosive media such as acids and alkalis in the petroleum, chemical, pharmaceutical, metallurgical, and electric power industries. However, how to select and use fluorine-lined plastic valves well, based on the experience of many users in field applications for many years, the following precautions are put forward for the use of medium temperature, pressure, pressure difference and other conditions when selecting fluorine-lined plastic anti-corrosion valves:

1. Medium temperature used by fluorine-lined plastic valves: All kinds of fluorine-lined plastic valves of our company use fluorine plastic F46 (FEP), and the medium temperature used cannot exceed 150℃ (the medium temperature can reach 150℃ for a short time, and the long-term use temperature should be controlled within 120℃). Otherwise, the F46 lining of each component of the valve is easy to soften and deform, resulting in the valve not being able to close and large leakage.

If the medium temperature is below 180℃ for a short time and below 150℃ for a long time, another fluoroplastic-PFA can be selected, but the PFA fluoroplastic is more expensive than the F46 lining.

2. Do not have negative pressure. Fluoroplastic-lined valves should avoid negative pressure in the pipeline. If there is negative pressure, it is easy to cause the fluoroplastic lining layer in the inner cavity of the valve to be sucked out (bulged) and peeled off, resulting in failure of the valve to open or close.

3. Pressure and pressure difference should be controlled within the allowable range. Especially for bellows-sealed fluoroplastic-lined regulating valves and stop valves. Because the bellows is made of PTFE material, the pressure and pressure difference are large, which can easily cause the bellows to rupture.

For bellows-sealed fluoroplastic-lined regulating valves, if the pressure and pressure difference are large under the use conditions, they can be replaced with PTFE packing seals.

4. The medium used in fluoroplastic valves should not contain hard particles, crystals, impurities, etc., so as to avoid the valve from wearing out the fluoroplastic layer or PTFE bellows of the valve core and valve seat during opening and closing. For the medium with hard particles, crystals, and impurities, the valve core and valve seat can be replaced with Hastelloy when selecting.

5. The diameter of the fluoroplastic regulating valve should be correctly selected according to the required flow rate (Cv value). When selecting, the diameter and 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, the valve will inevitably operate at a small opening degree for a long time. In addition to the pressure of the medium, it is easy for the valve core and stem of the valve to be impacted by the medium and cause the valve to vibrate. The valve core stem may even break under the impact of the medium for a long time.

When selecting various types of fluoroplastic valves, users should try their best to understand and master the technical conditions for use so as to select and use them well and increase the service life of the valve. When encountering situations that exceed the scope of technical conditions for use, this should be raised with the manufacturer for joint consultation and appropriate countermeasures to be taken to resolve the issue.