ECTFE: Maximum safety and reliability for the transport of highly aggressive media
by Christian Schiefer, Senior Solution Manager at GF Piping Systems
When it comes to highly aggressive media, the thermoplastic material PFA and stainless-steel pipes with a chemically resistant inner lining have been popular choices. However, PFA is considered cost-intensive, while stainless steel pipes are limited by their durability due to corrosion as well as their increasing weight at high flow rates. Here, ECTFE has established itself as an economical and high-performance alternative.
Sectors such as the chemical process industry, water treatment, and microelectronics are faced with fast-growing innovations and changing requirements. As a result, there is a shared interest across industries to find solutions that meet the highest quality and safety standards, are versatile and easy to retrofit, and ensure a cost-effective operational lifetime.
The balancing act between safety and efficiency is especially important for the transport of extremely aggressive chemicals. Companies in process-driven industries that rely on a continuous production are not only focused on production safety and minimizing downtime, but also on the protection of employees, plants, products, and the environment. Therefore, the need for piping systems that are reliable and durable, can be easily retrofitted, and reduce maintenance costs, is growing.
For this reason, the high-performance material ethylene chlorotrifluoroethylene (ECTFE) is gaining popularity. ECTFE has excellent chemical resistance and is a real alternative to conventional plastics due to its superior material properties. For sectors such as the chemical process industry, water treatment and microelectronics, ECTFE offers great potential for the long-term optimization of their installed piping systems.
Piping systems for aggressive media – a comparison
Sulphuric acid (H2SO4), Hydrogen peroxide (H2O2) and sodium hypochlorite (NaClO) are among the most aggressive media used on a large scale in today’s industries. Sulfuric acid, for example, is one of the most important chemicals with a growing global production of more than 265 million tons (2022). The extremely corrosive and strongly oxidizing acid is used primarily for fertilizer production, but also for the production of numerous media like hydrochloric or phosphoric acid. However, when sulfuric acid is present in its highly concentrated form, this places extreme demands on the storage and transport of the chemical. In addition to corrosion resistance and reliability, a resistance against stress-cracking and permeation are the main considerations when selecting a piping material.
Due to these extreme requirements, only few materials are suitable for the transport of particularly aggressive chemicals. Pipes made of common thermoplastics such as polypropylene (PP), polyvinyl chloride (PVC) or polyvinylidene fluoride (PVDF) are only conditionally appropriate for the transport of concentrated acids and alkaline solutions, especially when combined with process parameters such as elevated temperatures and pressures. Consequently, these types of applications often utilize a number of high-end materials that have significant advantages but nevertheless have critical weak-points that need to be considered.
1. PFA & PTFE
Perfluoroalkoxy polymers, commonly known as PFA, have become widely accepted in many industrial applications. PFA is a fully fluorinated plastic material with excellent chemical and temperature resistance. Its application ranges from small hoses up to 2” stiff-tubes for industrial use cases, such as the conveyance and tool supply of highly concentrated chemicals. One of the disadvantages of PFA, on the other hand, is the material’s limited mechanical performance regarding e-modulus, which leads to a large wall-thickness and decreasing economic efficiency, especially in high-pressure specifications. Additionally, permeation from media like HCL or HF through the elastomer-like material requires double-containment solutions.
Another fully fluorinated material widely known and used for small hoses is Polytetrafluoroethylene (PTFE), widely known as Teflon. With similar advantages to PFA when it comes to chemical and temperature resistance, it also suffers from the same disadvantages regarding mechanical properties and permeation behavior.
2. Steel pipes
Metal piping made of carbon steel or even high alloy stainless steel (SSt) is another very popular option for transporting aggressive chemicals, especially for diameters of d63 (2”) and above. Until today, industries like mining, water treatment or pharmaceutical & life-science widely rely on metal piping, partly on the basis of the material’s low initial costs and broad availability. Looking at the alloy’s chemical resistance, many solutions like SS 316 or Hastelloy C276 are capable of handling harsh chemicals. However, the welded areas on installed pipes are a critical point of failure in this context, as hard soldering or orbital welding affects the metallurgy, leading to corrosion caused by leakages.
3. Plastic lined piping
Lined piping commonly takes advantage of the excellent properties of PFA or PTFE and combines them with a solid outer shell made from Stainless Steel (SSt) or fiber reinforced plastic (FRP). The polymer liner is added to the steel pipe as a chemically and corrosion-resistant surface that is capable of handling highly corrosive media. However, lined steel pipes are susceptible to corrosion under certain conditions, despite their coated inner surface. This is because the connections use flanges that can become a weak point under harsh conditions, causing substantial maintenance efforts. Other issues may arise as a result of media permeating the polymer layer and chemically attacking the outer steel pipe. Furthermore, this type of piping system weighs significantly more than an equivalent full-plastic solution which is particularly noticeable with larger dimensions. At the same time, this increased weight negatively affects the installation costs, the statics of the suspension system, as well as overall handling and transportation.
3. ECTFE
ECTFE, on the other hand, is a thermoplastic fluoropolymer that offers excellent chemical resistance against highly concentrated chemicals at elevated temperature and pressure levels. It is a well-known high-end industrial material that is implemented in challenging conditions across all kinds of applications such as chemical processes, water treatment, food and beverage, and many others. Major advantages over other piping solutions include superior mechanical properties as a full plastic, stand-alone solution thanks to a higher pressure rating compared to PFA tubing, better permeation behavior regarding critical media, as well as a fully controlled and reliable IR-welding process. Moreover, the material maximizes flow rates, facilitates a fast, lightweight, and compact installation, and reduces maintenance requirements. These advantages allow operators to improve their process efficiency and meet higher safety standards.
A fast installation thanks to the latest IR welding technology
An important factor for the mechanical resistance of pipelines is the quality and consistency of the welded joints. Thanks to the capability of the latest infrared (IR) welding technology, ECTFE offers an additional advantage as it can be installed in a time-saving and cost-effective manner. Compared to conventional butt welding, the IR jointing method is characterized by significantly shorter overall welding times and high reproducibility as the components are melted contact-free through infrared radiation. This process shortens the heating time by more than 30%, avoiding unwanted bead formation during the alignment process. In addition, automated IR welding machines assist installers with a machine-controlled process that ensures consistent variables such as temperatures, jointing times, and cooling periods. Modern welding machines are also capable of detecting any deviations from the predefined parameters, while a printer can provide labels for full traceability. The result is a series of identical welds that remove the risk of human error and ensure an independent quality control.
Implementing ECTFE – What needs to be considered?
The application possibilities for ECTFE are numerous, and an example from the field of water treatment demonstrates the performance level that the material can achieve. In water treatment plants, sodium hypochlorite solution is often used to disinfect water. In high concentrations, sodium hypochlorite is highly corrosive and reacts with acids and oxidizing agents, sometimes generating intense heat, and releasing chlorine gas. In this case, ECTFE combines all the necessary material properties to ensure a professional and safe handling of this important substance.
Nevertheless, ECTFE should not be seen as a replacement, but rather as a useful addition to the existing PP, PVC and PVDF systems for use with extremely aggressive media. As a high-end industrial solution, the material has proven to be particularly suitable for chemicals with a pH value below 2 and above 12. It is ideal for applications where other plastics reach their limits, especially in combination with elevated temperature and pressure conditions that lead to inefficient process design.
Merck implements SYGEF ECTFE by GF Piping Systems
Merck & Cie. is a subsidiary of the German group Merck KGaA and specializes in the healthcare and life science sectors. With several facilities across Switzerland, the company produces high-quality products for the global market. As part of the production process, Merck uses a dedicated plant to treat a selection of wastewater with hazardous chemicals, which are typically transported with metal or commodity plastic piping systems. After a trial run, Merck decided to install the SYGEF ECTFE System by GF Piping Systems with the goal of increasing process efficiency.
Due to tight installation spaces, the complex layout of the existing piping system had to be replicated by the company Hürner AG from Tagelswangen as precisely as possible. Thanks to automated IR welding machines supplied by GF Piping Systems, the new pipes could be installed quickly and reliably, despite a limited time frame. Due to the overall performance of SYGEF ECTFE, Merck now benefits from an extended operational lifetime of their wastewater plant while minimizing maintenance costs and downtime.
SYGEF ECTFE is an IR-welded plastic solution that is specially designed for the most challenging industrial applications where other piping solutions reach their limit. To ensure maximum system integrity, GF Piping Systems conducted long-term ISO testing to verify a reliable hydrostatic strength curve, and extensively release tested the system with various hazardous media under hot operational conditions.
Conclusion
Applications using extremely aggressive media are common across industries and all have their unique requirements. While there is a wide range of piping materials that are up to the task, many of them are only conditionally suitable, resulting in a reduced operational lifetime, high maintenance costs, or even increased risks for workers and the environment. ECTFE is a material that combines many unique characteristics, making it the ideal alternative for heavy-duty industrial use. At the same time, longevity and efficient fluid handling make ECTFE exceptionally cost-efficient compared to other materials. Finally, cutting-edge IR welding improves the safety and consistency of pipe joints, while also increasing the ease and speed of the installation.
Constanze Werdermann
Global PR Manager
+41 763 399 218
constanze.werdermann@georgfischer.com
About GF Piping Systems
GF Piping Systems creates connections for life as the superior water and flow solutions provider for industries and infrastructure, enabling the safe and sustainable transport of fluids.
The division focuses on industry-leading leak-free piping solutions and engineering services for numerous demanding end-market segments. Its global sales, engineering, and manufacturing footprint reflects its strong focus on customer-centricity and innovation, and its award-winning portfolio includes fittings, valves, pipes, vaults, chambers, automation, fabrication, and jointing technologies.
GF Piping Systems has its own sales companies in 33 countries and fabrication hubs in 15 countries, which means it is always by its customers' side. Production sites in 40 locations in the Americas, Europe, the Middle East, and Asia ensure sufficient availability and quick, reliable delivery. In 2023, GF Piping Systems generated sales of CHF 2'100 million and employed 8'798 people. GF Piping Systems is a division of Georg Fischer AG (GF), founded in 1802 and headquartered in Schaffhausen (Switzerland).
www.gfps.com
