ECTFE: Maximum safety and reliability for the transport of highly aggressive media

Christian Schiefer

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 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 enabling low 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 industries 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 global production of more than 150 million tons per year. The highly corrosive and strong oxidizing acid is used primarily for fertilizer production, but also for production of numerous medias such as 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 such 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, especially in combinations with other process parameters like elevated temperature and pressure.

For that reason, such applications are normally being applied by high-end materials as the following, offering a set of advantages, but still having critical weak-points for special attention.

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1. PFA & PTFE

Perfluoroalkoxy polymers known as PFA, have become widely accepted in many industrial applications. PFA is a fully fluorinated plastic material with excellent chemical and temperature resistance. It is used from small hoses up to 2” stiff-tubes for industrial applications, such as conveyance & tool supply of high 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 thick wall-thicknesses and decreasing economic efficiency, especially at increased pressure specification. Additionally, permeation from diffusing medias like HCL or HF through the elastomeric kind-of material needs to be separately tackled by double contained solutions.

Another fully fluorinated material widely known and used for small hoses is Polytetrafluoroethylene (PTFE), better known as Teflon, the brand name from company Chemours (spin-off from DuPont). With similar advantages like PFA on chemicals and temperatures, also same disadvantages on mechanical properties and permeation behavior exists.

2. Steel pipes

Metal piping from carbon steel or even high alloy stainless steel (SSt) are another very popular option for transporting aggressive chemicals, especially on 2” and above. Until today, industries like Mining, Water Treatment or Pharmaceutical & Life-Science (Ph & LS) widely trust in different “state-of-the-art” metal piping, not only because of their low initial costs and broad availability. Looking on the alloy’s chemical resistance, many solutions like SS 316 or Hastelloy C276 are doing fine on harsh chemicals. However, the critical point of failure for the use with chemicals is located at welded areas on installed pipes, as hard soldering or orbital welding is changing the metallurgy, enabling chemical attack by corrosion.

3. Plastic lined piping

The linking of excellent PFA or PTFE properties with a solid outer shell made from SSt or fiber reinforced plastic (FRP) are commonly used by lined piping. The polymer liner is adapted as chemically and corrosion-resistant surface to the steel pipe for use with highly corrosive medias. However, lined steel pipes are susceptible to corrosion under certain conditions, despite the coated inner surface. Connections are mainly done by flanges, which counts for most of the leakage points under harsh conditions and requesting huge maintenance effort. Dispatching polymer layers are also known as reason for process interruptions and refurbishments, occurring by chemical attack to the outer steel pipe through permeating medias. Furthermore, and especially with larger pipe dimensions, the system becomes significantly heavier than any full plastic piping system, which has adverse effects on the costs of the installation, the statics of the suspension and efforts in handling & transportation.

4. ECTFE

Finally, ECTFE is a thermoplastic fluoropolymer, that offers excellent chemical resistance against high concentrated chemicals at elevated temperature and pressure. ECTFE is a well-known industrial high-end material, used in all kinds of industrial applications (CPI, WT, ME, F&B, Ph & LS) under challenging environmental conditions and the use of harsh chemicals.

Major advantages over other piping solutions are the set of superior mechanical properties in combination with a full plastic & stand-alone solution, offering higher pressure rating compared to PFA tubing, better permeation on critical medias and fully controlled & reliable IR-welding. At the same time, maximized flow rate, fast-, light-weight- & compact- installation with reduced maintenance is achieved. These advantages allow operators to improve their process efficiency and meet higher safety standards.

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Fast installation thanks to 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. The welding process consists of non-contact melting the components 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.

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Implementing ECTFE – Example and 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 which leads to inefficient process design.

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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 by metal or commodity plastic piping systems. After a trial run, Merck decided to install the SYGEF ECTFE System by GF Piping Systems instead to increase process efficiency.

Due to tight installation spaces, the complex layout of the existing piping system had to be replicated by the company Hu?rner AG from Tagelswangen as precisely as possible. Thanks to automated IR welding machines supplied by GF Piping Systems, the new pipes could be installed fast and reliable, despite a limited time frame. The overall performance of SYGEF ECTFE now offers Merck an even 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 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, but also exceptionally release tested SYGEF ECTFE system with various hazardous media under hot operational conditions.

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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 reduced operational lifetime, high maintenance costs or even increasing harm for human and environment. ECTFE is a material that combines many unique characteristics, which makes it the ideal alternative for heavy-duty industrial use. At the same time, longevity and efficient fluid handling on system approach, makes SYGEF ECTFE exceptional 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.

Media contact:

Constanze Werdermann, Global PR Manager

[email protected]

+41 76 33 99 218

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GF Piping Systems

As the leading flow solutions provider for the safe and sustainable transport of fluids, GF Piping Systems creates connections for life. The division focuses on industry-leading leak-free piping solutions for numerous demanding end-market segments. Its strong focus on customer-centricity and innovation is reflected by its global sales, service, and manufacturing footprint and its award-winning portfolio, including fittings, valves, pipes, automation, fabrication, and jointing technologies.?

GF Piping Systems has its own sales companies in 31 countries, which means it is always by its customers' side.?Production?sites in 36 locations in America, Europe, and Asia ensure sufficient availability and quick, reliable delivery. In 2022, GF Piping Systems generated sales of CHF?2'160 million and employed?8'085?people. GF Piping Systems is a division of Georg Fischer AG, founded in 1802 and headquartered in Schaffhausen, Switzerland.?

www.gfps.com