PVDF and chemicals: what the material can withstand in acid

PVDF is used in the chemical industry thanks to its excellent chemical resistance. Here’s how these properties work in practice. The material is suitable for pipes, sheets and components exposed to aggressive media.

What is PVDF?

PVDF is a fluoroplastic with high chemical resistance and good mechanical strength. The material can withstand temperatures of up to approximately 150 °C and is easier to machine than, for example, PTFE.

PVDF is used for pipes, hoses, sheets and components in the chemical industry, water treatment and the semiconductor industry. It is particularly well suited to applications where clean surfaces and resistance to aggressive media are required. The material is also resistant to UV light and is therefore suitable for outdoor use.

Unlike PTFE, PVDF can be thermally processed. This means it can be injection moulded and extruded into complex profiles. For large sheets and thick walls, pressed and sintered semi-finished products are often used.

Which chemicals is PVDF resistant to?

PVDF is resistant to most inorganic acids, including sulphuric acid and nitric acid, across a wide range of concentrations and temperatures. It is also resistant to many organic solvents, oxidising agents and aqueous salt solutions.

There are exceptions. Strong bases, certain amines and hydrogen fluoride adversely affect PVDF at higher temperatures. You should therefore always check the resistance to the specific medium and temperature applicable to your process.

For food and pharmaceutical applications, there are approved grades. These are accompanied by documentation demonstrating that the material meets the requirements for contact with food or medical fluids.

Common applications

PVDF is used for tanks and containers, pipework, valves and gaskets. In water and wastewater treatment, it is used for membrane holders and other components exposed to chemicals and moisture.

The material can be welded and thermoformed, making it possible to construct larger structures. Welding wire made of the same material is often used for welding. The welded joints offer good chemical resistance if carried out correctly.

In the electronics industry, PVDF is used for cables and conductors because the material has good dielectric properties and can withstand chemicals used in cleaning.

PVDF compared with other fluoroplastics

PTFE has even broader chemical resistance than PVDF, but is mechanically weaker and more difficult to process. PFA and FEP can withstand higher temperatures, but are more expensive and have lower mechanical strength.

PVDF therefore represents a compromise between chemical resistance, mechanical strength and machinability. For many applications in the chemical industry, PVDF is perfectly adequate, at a lower cost than the more expensive fluoroplastics.

Next steps

Do you need materials for a chemical process? Read more about chemical resistance, see PVDF in the materials guide or contact us for advice.

Welding and assembly

PVDF can be welded using hot-air or extrusion welding. The weld joint will have good chemical resistance if carried out correctly. For best results, the welder should be experienced in working with fluoroplastics and use the correct temperature and pressure.

PVDF sheets and pipes can also be thermoformed and drilled. When drilling, it is important to use sharp tools and adequate cooling to prevent the material from melting or cracking.

Environment and sustainability

PVDF is resistant to UV light and ages slowly when exposed to the elements. This makes the material suitable for outdoor applications such as solar panels, signage and pipework. Its service life depends on temperature, the chemical environment and mechanical stress.

At the end of its service life, PVDF can often be recycled as an engineering plastic. Always check local regulations regarding recycling and the management of industrial waste.

How to choose PVDF

PVDF is a material frequently used where both chemical resistance and mechanical strength are required. When selecting PVDF, you should check the chemical environment to which the component will be exposed, as well as the temperature and pressure it must withstand.

The material is available in several grades, including electrofused and extruded. Electrofused PVDF is suitable for complex components and pipes, whilst extruded semi-finished products are used for large sheets and thick-walled components. Food-grade grades are available for contact with food and pharmaceuticals.

Please ensure you have the correct machining equipment before placing your order. PVDF can be turned and milled, but requires sharp tools and appropriate cutting parameters to achieve a fine surface finish.

Summary

PVDF withstands most chemicals at high temperatures and is suitable for both the process industry and cleanrooms. The choice of grade and manufacturing method affects machining and performance.

Check the chemical environment, temperature and mechanical requirements before placing your order. Making the right choice ensures a long service life and fewer downtimes.

Frequently asked questions

Where is PVDF most commonly used? PVDF is used in chemical process equipment, piping systems, membranes and components for the semiconductor industry.

Is PVDF resistant to strong bases? PVDF is resistant to most acids, but strong bases and certain amines can affect the material at high temperatures.

Can PVDF be welded? Yes, PVDF can be welded using suitable equipment and methods, which is common practice in pipework installations.