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Many chemical processing and semi-conductor processing applications either occur in or produce extreme conditions including extreme heat and corrosive compounds that result in the degradation of many materials. Damage from corrosion and heat can go on to affect operations, leading to service interruptions, costly maintenance, and contamination of the chemical media.
One solution is to line surfaces with materials like Perfluoroalkoxy alkanes (PFA), a fluoropolymer with high melt strength, stability at high processing temperatures, excellent crack and stress resistance, and a low coefficient of friction. PFA linings are typically used in the construction of gas scrubbers, reactors, containment vessels, and piping. Both fabric-backed and plain PFA sheets can also be used to line heat exchangers to increase plant efficiency, or even be fastened to steel tanks for flue gas applications and desulphurization systems.
In this article, we will describe the benefits of PFA and explore why it is the preferred material in applications with extreme chemical loads and high temperatures, review several examples of how PFA can improved operational efficiency, and highlight a PFA supplier.
The PFA advantage
PFA is suitable for a broad range of applications thanks to its resistance to almost any medium and its ability to resist temperatures ranging from -190°C to +260°C (-310°F to 500°F). Using PFA linings to protect underlying structures against a variety of chemicals helps to reduce lifecycle costs and increase operational reliability. With the right choice of product, it is possible to significantly improve the service life of structures.
PFA linings can also be combined with a glass fabric backing system. These fabric-backed sheets enable a stronger bond between the sheet and the container.
Examples of PFA in action
One case study describes a ventilation system for an evaporator unit and how it experienced regular cracks and leaks leading to the shutdown of a production line every few months for repair and maintenance. The source of the problem was found to be the creation of nickel sulphate gas as well as an increase in sulfuric acid concentrations. The resulting corrosive acid vapor would then be funneled through the ventilation system where it would damage the vent. To solve the problem, lining was installed in the ventilation pipes using an adhesive specially designed for high-temperature environments. A one-year follow-up found that the PFA lining system had no trouble with the acidic vapor, requiring no maintenance for more than 12 months. The PFA lining allowed the facility to function without interruptions, improving plant productivity and increasing workplace safety while also delivering cost savings in repair and downtime.
PFA linings can also be used to protect chemical processing equipment from corrosion. As the industry continues to evolve, so has its demand for high-performance materials. In one example, a company with process equipment handling highly corrosive and toxic hydrofluoric acid (HF) had to find a way to increase the service life of their storage equipment. The solution implemented was to create specialized vessels capable of handling the containment of the acid. The vessels were constructed using the FRP dual-laminate method with a PFA glass-backed lining. The resulting product has demonstrated resistance to high temperatures and vacuum conditions.