Fluorine-lined Plastic Anti-corrosion Valve Installation Instructions And Precautions

Lined Valve Installation Instructions and Precautions

The reasonable selection and application of fluoroplastic anti-corrosion valves 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.

Fluoroplastic 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 fluoroplastic 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 fluoroplastic anti-corrosion valves in the selection of medium temperature, pressure, pressure difference and other conditions:

1. Medium temperature used by fluoroplastic valves.

All kinds of fluoroplastic valves in our company use fluoroplastic 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 the valve components 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 fluoroplastic.

2. No 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 valve opening and closing failure.

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 changed to PTFE packing seals.

4. Medium conditions for fluoroplastic lined valves

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

5. Fluoroplastic lined regulating valves should correctly select the valve diameter size according to the required flow rate (Cv value).

When selecting, the valve diameter and valve opening degree should be calculated according to the required flow rate (Cv value) and other technical parameters. If the valve diameter 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 users select various types of fluorine-lined plastic valves, they 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 valves. When encountering situations that exceed the scope of the technical conditions for use, they should report to the manufacturer, negotiate together, and take appropriate countermeasures to solve them.