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Kaylie: Hi, welcome, and thank you for joining us in today’s AGRU America podcast. In this podcast, we will explore our recent blog titled: “Using PFA Linings in Chemical-Processing Applications.” Joining me in today’s discussion is Cody Miles, marketing director here at AGRU. Together, we’ll review PFA linings and two modern applications of PFA liners. Welcome again, Cody.
Cody: Thank you, Kaylie, I’m always happy to join.
Kaylie: Let’s start by talking about PFA. What is it exactly and why is it useful?
Cody: PFA is short for Perfluoroalkoxy alkanes (PFA), which is a fluoropolymer with excellent chemical resistance to acids, bases, and solvents across a wide variety of temperatures.
Kaylie: Isn’t Teflon also a fluoropolymer?
Cody: Yeah, “Teflon” is a fluoropolymer. It is the most well-known “Brand Name” for fluoropolymers, and encompasses several polymers produced by one specific resin manufacturer. The first fully fluorinated polymer produced was PTFE, later similar polymers like FEP and PFA were produced by the same manufacturer and were included in the brand name. In some applications ETFE, a partially fluorinated polymer is also called “Teflon.”
Kaylie: That’s very interesting. Going back to PFA’s qualities, could you explain what you meant by its high temperature resistance—exactly how high are we talking?
Cody: PFA is capable of maintaining its integrity at temperatures of up to 500°F, though its actual service temperature is application dependent. Overall, its properties make it very useful as a specialized industrial liner for the construction of things like gas scrubbers, reactors, containment vessels, and piping.
Kaylie: Very impressive. I also noticed a lot of emphasis was placed on the material’s chemical stability, could you tell me more about that?
Cody: Many industrial processes rely on the use of corrosive or volatile chemicals. Over time, the equipment that house or transport these chemicals will deteriorate, forcing maintenance. PFA liners can be used to protect the equipment, providing a protective layer that is highly resistant to corrosion and extreme temperatures.
Kaylie: Yeah, I remember reading about the two case studies in the blog. The first described a ventilation system for nickel sulphate gas produced from an attached evaporator unit. In this situation, the original vents were not equipped to deal with the high concentration of these corrosive gases, right?
Cody: Right. The evaporation process was being used to reclaim precious metals from the waste solution left behind after copper refining. The waste solution was a mixture of nickel sulphate, sulfuric acid, and other byproducts. By raising the temperature of the vat to about 300°F, the facility could remove the valuable nickel sulphate from the solution.
Kaylie: And this is where the problems started?
Cody: Exactly. The more nickel sulphate they removed from the solution under these high temperature conditions, the higher the concentration of sulfuric acid. I believe the concentration rose from 15% to about 70%. Eventually, the sulfuric acid became highly corrosive vapor that required ventilation.
Kaylie: From what I saw, it looks like the original lining in the ventilation pipe was not able to withstand the highly corrosive gas, temperature fluctuations, or even the vacuum pressure. It shouldn’t be a surprise that the exposure led to cracks and leaks.
Cody: That’s true. And keep in mind that in this kind of situation, leaks can be very costly. They had to shut down one of two production lines every two to three months just to repair the lining. The disruptions to production was undoubtedly costing them a ton.
Kaylie: So, PFA to the rescue?
Cody: Pretty much. They collaborated with a company called Electro Chemical to design a solution using fluoropolymer linings. A PFA liners, made from AGRU PFA sheets, was installed in the ventilation pipes. After installing the new lining, they haven’t had to perform maintenance on the lining, which means almost no production downtime for more than a year.
Kaylie: Wow. That’s a significant improvement and quite validating to know that the economics of such an upgrade was worth it.
Cody: For sure. In the case study, one engineer was even quoted as saying that the PFA lining more than paid for itself after one year of operation thanks to saved maintenance costs and less downtime.
Kaylie: So, this case study demonstrates a use case of a PFA lining in large-scale industrial processes. The scale of these operations offer an economic incentive for an upgrade to this high-quality material. What are some uses on the other end of the spectrum? Are there cases where it makes sense to use PFA in a smaller scale operation?
Cody: That’s a great question and from what I’ve seen PFA liners and parts have use cases just about everywhere—from large-scale industry down to single-use products. In smaller scale applications, you will typically see PFA linings used in chemical processing and storage equipment.
Kaylie: Why is PFA lining important here?
Cody: Industries are constantly evolving and so has the demand for highly specialized and corrosive compounds like hydrofluoric acid.
Kaylie: Hydrofluoric acid has many uses in industry and research, right?
Cody: Yeah. It is the starting or intermediate material for processes in industrial chemistry, mining, refining, glass finishing, and silicon chip manufacturing.
Kaylie: OK, so we have a demand for a highly corrosive acid. How does PFA come into the picture?
Cody: Again, it comes down to economics. You have the option of using expensive metal alloys like titanium to manufacture what is essentially a container, or you could use a less expensive material and line it with PFA.
Kaylie: So, the solution was to line the inside of existing containers with PFA?
Cody: Not quite. While the PFA lining definitely checks off all the temperature and chemical resistance requirements, how do you keep it attached? The internal conditions of these containers are such that there is virtually no adhesive that can be used to keep the lining attached.
Kaylie: How about the other case study? They were able to line the vents with the PFA liner, right?
Cody: Yeah, but even in that situation the installers had to use a newly developed, specialized adhesive that was perfect for that situation and under those conditions. For chemical processing applications, a different approach has to be taken.
Kaylie: I remember reading that the solution involved creating new containers using the FRP dual-laminate method. How is the PFA lining attached with this method?
Cody: FRP stands for fiber-reinforced plastic, which is used as the structural layer. The inner layer is made with PFA that is integrated with a fabric backing on one side. With the dual-laminate method, the fabricator may thermoform and weld the PFA sheets into the intended shape before laminating the PFA to the FRP layer, yielding one composite structure. The fabric backing on the PFA is quite important here and is what is ultimately used to bond the two layers.
Kaylie: The fabric backing can be made with a variety of materials right? In the case study, I believe they used a glass fabric.
Cody: While polyester, synthetic, and glass backing materials are available—you would really only use a glass fabric backing for PFA as the others decompose during manufacturing.
Kaylie: OK, so that explains why they went with PFA glass-backed lining. Has the resulting chemical processing equipment worked for them?
Cody: The new product by the fabricator has already demonstrated excellent resistance to the temperature, chemical, and vacuum conditions. While there are advantages and disadvantages to using alloys and dual laminates, dual-laminate products are a great option in a variety of applications.
Kaylie: In both of these case studies, AGRU sourced the PFA lining material. Where does PFA stand in AGRU’s product lineup?
Cody: PFA sheets are one of AGRU’s semi-finished products, which also includes polyethylene, polypropylene, PVDF, ECTFE, and FEP. We call them semi-finished, because these products are offered as sheets, bar stock, and rods in a variety of dimensions that can be taken and fabricated into a final product, as we saw with the chemical processing case study.
Kaylie: One last question: What does it mean to get AGRU PFA in HP quality?
Cody: AGRU also offers PFA products in HP, or high-purity, quality. HP-quality PFA can be used for applications in the semiconductor, pharmaceutical, and food industries that require high purity levels. Our case studies today didn’t cover this kind of use case, but I’m sure we could go into more detail in a future podcast!
Kaylie: Thank you Cody! And with that, our podcast has come to an end. To our listeners, thank you for tuning in. We hope you’ve enjoyed this podcast. For more information about AGRU PFA and other semi-finished products, please visit us on the web at AGRU America dot COM. As always, we hope you’ve enjoyed listening and we welcome your feedback.