Kalrez Spectrum 7275 is a perfluoroelastomer that provides long life sealing in an array of aggressive chemical environments that typically make sealing difficult: ethylene oxide, acrylic monomers, silanes and chlorosilanes, and strong oxidizers such as nitric acid, chlorine and chlorine dioxide.
It has demonstrated improved chemical and compression set resistance and mechanical property retention when compared to competitor’s elastomers.
Kalrez Spectrum 7275 is based on a proprietary cross-linking system, and is uniquely identified by its light brown shade.
Targeted applications include industries that depend on mechanical seals, pumps, valves, compressors, filtration columns and analytical equipment for their critical processes.
Success Story: Kalrez® Spectrum™ 7275 Double Seal Life in Chlorine Dioxide Service
Chlorine dioxide is a strong oxidizing gas that finds many uses as bleaching agent and disinfectant, being a more effective and safer biocide than other sources of chlorine. Most of the production of chlorine dioxide is used at paper mills for pulp bleaching.
A North American based paper mill had to perform frequent repairs in a pump handling chlorine dioxide in water. According to the reliability engineer, the incumbent non-black FFKM typically failed within 5 months of installation because of the extremely aggressive nature of the stream. With replacement of the seals by Kalrez® 7275, the pump seal life was extended to more than 12 months, removing the pump from the “bad actors” list and into a regular yearly maintenance.
Kalrez® Spectrum™ 7275, a specialty non-black perfluoroelastomer product, is made with a DuPont patented crosslinking system, and is suggested for seal applications where high resistance to oxidizing and reactive media is required.
The original article can be found on Dupont’s website here.
Gallagher Fluid Seals is a long-time partner of DuPont™, predominantly focusing on the Kalrez® line of products. For more information about Kalrez®, or a quote, contact Gallagher Fluid Seals today.
High Performance Seals for Polycrystalline Silicon Process Equipment
To meet growing demand in solar cells, the Siemens* process is used to produce highly purified polycrystalline silicon by thermally decomposing tri-chloro-silane (TCS). The reactors employed require three kinds of high-performance seals in the following locations: A) bell jar seals; B) electrode seals between the electrode and ceramic inlet; and C) a gasket for the view port seal (see schematic).
The process involves a very hot, dry environment with temperatures up to 1200°C (2100°F). Sealing components see up to 300°C (572°F). Process media include TCS and aggressive by-products of its decomposition, such as HCl gas. Superior compression set performance is needed for effective sealing and extended seal life. Very low outgassing is a key requirement for preventing contamination of the process environment.
The presence of harsh chemicals in high temperature conditions often require an upgrade from standard sealing materials to PTFE or fluoroelastomers (FKM) to improve thermal stability and chemical resistance. However, PTFE can deform and creep “hot flow” in the bell jar seal increasing the risk of product loss. FKM, with its high temperature rating of 200°C (392°F), also has deficiencies in this 300°C (572°F) environment.
The Solution and Key Advantages of Kalrez PV8070
Kalrez PV8070 perfluoroelastomer parts installed as washers and gaskets in reactors for the Siemens CVD process have demonstrated outstanding performance in this demanding application. Kalrez® PV8070 parts are effective seals that provide: Continue reading Kalrez PV8070 Parts in Reactors→
DuPont™ Kalrez® 1050LF perfluoroelastomer parts are a carbon black-filled general-purpose product for o-rings, seals, and other parts used in chemical process industries. It is a classic-grade and longtime favorite for premium performance and provides a more economical option than similar compounds such as 7375.
Kalrez 1050LF o-rings can maintain their recovery with elasticity following high-pressure applications, maintaining a tighter seal for longer periods of time compared to other compounds. With a pressure rating of 1,500 PSI, it can help extend seal life and integrity, ultimately lowering costs.
With above-average hot water and steam resistance, the maximum application temperature for 1050LF is approximately 550°F (up to 288°C). This compound is also known for its excellent amine resistance and compression set properties. It has a Shore A durometer of 82.
In addition, Kalrez 1050LF has excellent chemical resistance, with the ability to withstand contact of over 1,800 different chemicals, plasmas, and solvents.
In particular, this compound stands out for wet applications in semiconductor manufacturing – stripping and copper plating, which include:
Seals for chemical containers
Seals for filters/connectors
This reliable compound from DuPont is classified as a general usage product. It is not recommended for use in organic or inorganic acids as high temperatures and is not recommended for applications that require rapid temperature cycling properties.
Oil and gas production and chemical manufacturing industries present sealing technologies with some of the harshest and most demanding operating environments.
Harsh and Demanding Operating Environments Require Chemically Resistant and Thermally Stable Seals
“We screen Kalrez against some of the most aggressive corrosive fluids,” says Dr Christopher Bish, Technical Fellow. “And in addition to the fluid testing, we did some compression set testing and stress relaxation testing at high temperatures. We now have one of the most chemically resistant and thermally stable compounds possible.”
We screen Kalrez against some of the most aggressive corrosive fluids
What really makes Kalrez sealing technology superior and more durable than competitors?
One of the things that sets Dupont Kalrez apart is their quality control system, which gives them the ability to track materials as they flow through the plant. Scanning the barcode on the part bag can pull up the entire production history of that part, including raw materials and process conditions.
Is Every Kalrez Seal Inspected?
Dupont performs a 100% visual inspection. It’s one way to ensure the quality rate is high and the return rate is virtually non-existent.
Despite the foreseen images of clean rooms, manufacturing in the semiconductor industry can be a harsh environment and cost of o-ring and seal replacement is significant.
“Kalrez parts are used as sealing materials in semiconductor wafer processing equipment, where high temperatures, aggressive chemicals, and plasmas are used. The most important thing for Kalrez sealing prodcuts is that the materials are resisting those aggressive conditions and not degrading or contaminating the chambers,” says Dr. Shuhong Wang, Technical Fellow.
Chemical and Science That Makes Kalrez Better
The polymer chains are fully fluoronated, forming one of the most inert polymer structures possible. Other elastomers have weak points along the chain structure, which are vulnerable to chemical attack and thermal instability. This, in combination with the unique cross-link technologies, many of which are patented, provides optimum durability and protection.
Check out a tour of one of the Kalrez manufacturing plants and learn what makes it the best choice for your demanding applications.
Kalrez 7375 offers broad chemical and water/steam resistance
The newer compound from DuPont™, Kalrez 7375, is an innovative FFKM oil-seal product exhibiting broad chemical and water/steam resistance properties required at high temperatures in chemical process industry applications. Kalrez 7375 parts present excellent compression set resistance, exceptional physical property retention, and improved mechanical strength properties. Other Kalrez compounds have done the job over the years when faced with many of these sealing challenges, but how does it compare to this new compound?
Three ways that Kalrez 7375 would be a suitable upgrade or compatible compound for your application:
1. Kalrez® 1050LF is a classic grade and longtime favorite for premium performance. 1050LF end-users will likely see a performance boost if they switched to 7375, especially if used in steam or hot water applications.
2. If using Kalrez® 4079 or Kalrez® 7075 and broad chemical resistance is essential (including water/steam), 7375 could be a superior compatibility match resulting in enhanced longevity. 7075 offers the highest thermal capability but cannot support 7375’s chemical compatibility with steam. See table below:
3. If lifetime issues or seeking to extend time between repairs are concerns when using Kalrez® 6375, end-users would most likely see a significant impact with 7375. However, transitioning to 7375 is not necessary if 6375 is executing up to standards.
Kalrez 7375 Benefits
Superior thermal stability of 572 °F (300 °C)
Excellent broad chemical resistance
Outstanding steam and water resistance
Available in most O-ring sizes: AS568, Metric, JIS (custom shapes upon request)
Combination of Kalrez® quality and Gallagher Fluid Seals’ customer service
DuPont™ Kalrez 7375 perfluoroelastomer parts are an innovative FFKM product based on a patented crosslinking system for chemical process industry applications where broad chemical and water/steam resistance are needed at elevated temperatures. Kalrez 7375 parts exhibit excellent compression set resistance, outstanding physical property retention, and good mechanical strength properties. A maximum application temperature of 300 °C is suggested.
The original article was featured on Dichtomatik’s website and can be found here.
Gallagher Fluid Seals is an authorized distributor of Kalrez products. For information about selecting the correct compound for your specific application, contact our engineering department.
Original content can be found on Parker’s Websiteand was written by Nathaniel Reis, Applications Engineer for Parker O-Ring & Engineered Seals Division.
In our semiconductor entry from last month, we noted that lowering the cost of ownership is a multi-faceted goal. We discussed how one of the areas for potential improvement is mechanical design and how the Parker EZ-Lok seal is a major solution to mechanical seal failure. In this entry, we’ll investigate a notably different type of cost-reduction opportunity – material selection – and see how Parker’s innovative HiFluor compounds can reduce seal costs to as little as half.
When it comes to the seal industry, the semiconductor market is well known as one where the most premium, chemical-resistant compounds are a necessity. Microelectronic manufacturing processes involve chemistries that push the limits of what elastomeric compounds can withstand in terms of both chemical aggressiveness and variety. The perfluorinated materials (FFKM) capable of withstanding these environments require intricate manufacturing processes regulated by closely-guarded trade secrets and the significant investment of resources.
These factors drive the price of FFKM compounds to the point of being as much as 50 times the cost of any other variety. Cutting just a slice out of this cost can result in significant savings – a chance to take out a quarter or even half the pie would be advantageous to the overall bottom line. Fabricators should be continually on the lookout for more cost-effective compounds that show equal performance in their pertinent operations.
This is why Parker’s HiFluor compounds offer an opportunity for cost savings that shouldn’t go unnoticed. A unique hybrid of performance between FFKM and the simpler technology of fluorocarbon (FKM) elastomers, HiFluor offers the most superb chemical compatibility in the many semiconductor environments where the high temperature ratings of FFKM aren’t necessary – and at a fraction of the cost.
Not only can HiFluor be used where even FKM is lacking, but its performance in applications with aggressive plasma exposure is spectacular as well. This can be observed by its overall resistance to plasma-induced material degradation. However, Parker has also developed multiple formulations that display extremely low particle generation when most materials would be expected to suffer severe physical and chemical etch.
Solutions and Cost Savings
As an example: One major semiconductor fab had several factors (other than their seals) dictating the frequency of their preventative maintenance (PM) intervals. The fab wanted to replace their seals at these intervals as a precautionary measure to limit the chance of them becoming another PM-increasing factor. However, this caused these premium FFKM seals to be a source of inflated cost. Parker assisted with a process evaluation that resulted in over half the seals being replaced with cost-effective HiFluor O-rings, while the tool regions with more intense plasma exposure were reserved for the elite performance of Parker’s FF302.
Another major fab in the microelectronics industry switched from FKM to FFKM seals in their oxide etch process. The tool owner achieved the desired performance improvement, but soon began searching for less expensive options. The owner recognized the plasma resistance and low particulate generation of Parker’s HiFluor compound, HF355. After implementing this change, he retained the performance improvement, but at a fraction of the cost.
Semiconductor tool owners understand that their aggressive processes require the most robust, expensive FFKM seal materials. The price tag on these seals is greater than those from any other compound family. Fortunately, HiFluor is a proven sealing solution that can bridge the gap and provide the same kind of high performance at a much lower cost.
Strong oxidizers can damage metal, causing pitting or rust and treating possible safety concerns.
In chemistry, strong oxidizers are substances (like chromic acid) that can cause other substances (like seals and gaskets) to lose electrons. So, an oxidizer is a chemical species that undergoes a reaction that removes one or more electrons from another atom.
This causes a change in mass. Metals will turn into their respective heavier oxides, and the carbon in graphite will oxidize into carbon dioxide—which, although molecularly heavier, is a gas at room temperature.
This happens in pumps, valves, pipelines or any other equipment that have seals and gaskets carrying a strong oxidizer. It will cause pitting or rust and, depending on your choice of seal material, may require shorter service intervals. Ultimately, you may have to look for a more suitable material that can handle strong oxidizers.
More importantly, an oxidizing agent can cause or contribute to the combustion of another material.
The U.S. Department of Transportation defines oxidizing agents specifically. DOT’s Division 5.1(a)1 means that a material may enhance combustion or quickly raise pressure causing a rapid chemical reaction. A fire may start or, even worse, create or facilitate an explosion.
There have been instances of fires or explosions in mining, chemical process and even fertilizer factories where strong oxidizers were used.
A West Texas fertilizer company storage and distribution facility caught fire on April 17, 2013. As firefighters attempted to extinguish the blaze, the plant exploded with the force of 10 tons of TNT, killing 15 people and injuring 200. It destroyed 60 nearby homes and left a 93-foot-wide crater where the plant once stood.
All said, it is important to choose the right sealing material for strong oxidizers. There are multiple products on the market for the chemical processing, oil and gas, mining and aerospace industries.
A fluoropolymer, such as polytetrafluoroethylene (PTFE), can handle most strong oxidizers, as long as the temperature is below 260 C (500 F). This is also true with a modified PTFE because they are chemically inert and stable.
Strong oxidizers will weaken most other material to various degrees. Much of a material’s capability to withstand a strong oxidizer depends on the used concentration, the service temperature and the service pressure. Therefore, consult with the sealing material manufacturer to ensure compatibility.
How Graphite Handles Strong Oxidizing Environments
Graphite starts as natural mineral flake and is mined in various parts of the world. The flakes form a layered structure of completely crystalline graphite, which is essentially elemental carbon. In this form, it is used for products like powdered lubricant and lead in pencils. It has excellent lubricity in this form.
Expanded graphite is produced with the use of strong oxidizing agents such as sulfuric and nitric acids. The acids weaken the bonds between the graphite layers, the flakes are then rinsed, dried and exposed to high heat.
The heat causes the layers to separate and expand dramatically to form expanded worm-like macro structures. The structures can then be recompressed into flexible graphite forms.
Flexible graphite is a soft material that is resistant to many strong chemicals and high heat. It has a low coefficient of friction and is proven to be advantageous over braided carbon or graphite fiber packings mainly as it is a better conductor of heat—a plus on moving shafts.
Flexible graphite is also naturally lubricious, conformable and resilient. It has good corrosion resistance and is compressible, allowing it to conform to most mating surfaces or valve cavities.
The chemical compatibility of flexible graphite can be enhanced with a blocking agent like PTFE. However, flexible graphite’s temperature limit will be restricted by PTFE’s limit of 260 C (500 F). If high temperature is an issue, this configuration will not work.
Flexible graphite, in combination with PTFE, is an extremely effective material in sealing fugitive emissions or volatile organic compounds (VOCs). VOCs have been targeted by several government agencies as a source of air pollution. Although, flexible graphite alone has a long way to go in stopping all fugitive emissions, it is a trusted sealing material for valves, flanges and stems in the chemical process, power generation, and oil and gas industries.
Flexible Graphite Pitfalls
Flexible graphite may be susceptible to chemical attack in the presence of strong oxidizing fluids, including air at extremely high temperatures. These include liquids such as 20 percent concentration of nitric acid or a 98 percent concentration sulfuric acid, the same chemicals that are used to break down mined graphite into expanded graphite flake.
Some flexible graphite compositions include oxidation inhibitors or are physically structured to extend temperature capability when exposed to these extra strong oxidizers.
The class of organic chemicals that should not be used are those that are highly oxidizing like nitrates, persulfates, perbenzoates and peroxides. Unacceptable compatibility for inorganic chemicals includes molten sodium, potassium hydroxide and chlorine dioxide.
However, many of the chemicals depend on the concentration, and some engineering groups can create an inhibitor that is right for a specific oxidizer. For instance, a 704 stainless steel cladding provides the user with protection against strong oxidizers while still providing the benefits of flexible graphite.
When in doubt, do a test loop using a pump to pressurize the strong oxidizer exposing it to flexible graphite. The pressure, temperature and concentration of the oxidizer must be exact as used in service, as to provide some idea of how the material will react to a given chemical.
It is easier to list the chemicals that are not compatible with flexible graphite (about 50) than those that are (more than 600 tested). A list of incompatible materials are listed below:
Below is the third and final section of the white paper, which will discuss the importance of proper seal and groove design.
Proper Seal & Groove Design
Proper seal design is a necessity for elastomer seals to perform reliably over the long term. Many of the instrument applications mentioned above use o-ring seals. The suggested compression for an elastomer o-ring seal to perform properly is typically a minimum of 16%, and a maximum of 30%. However, this range must also take into account the thermal expansion of an elastomer at elevated temperatures as well as any swell due to chemical exposure. Many of the elastomer seals used in instruments are small o-rings, which can create design issues. This is especially true for perfluoroelastomer parts which have a relatively high coefficient of thermal expansion (CTE). Fluoroelastomers have a lower CTE, making seal design easier at elevated temperatures.
Below is the second section of the white paper, diving into applications where the measurement is made in analytical laboratories which employ numerous solvents in a wide range of analyses and test equipment.
The final set of instrumentation is laboratory test equipment. As opposed to the laboratories in chemical plants, which often perform the same routine analyses on plant process streams, general analytical labs employ numerous solvents in a wide range of analyses and test equipment. As such, the ability of seals to resist a breadth of chemicals without degradation or leaching contaminants into a sample is of great importance. Although instrument seals are easily replaced in a laboratory environment, this operation still takes a technician time. It is always easier if the system can be flushed with a cleaning solvent and then be ready to run the next sample versus having to change out an elastomer seal due to incompatibility with a solvent.
FFKMs, also known as perfluoroelastomers, were first developed in the 1960s for applications involving high temperatures and/or aggressive chemicals. Perfluoroelastomers exhibit many properties similar to PTFE (polytetrafluoroethlyene, or Teflon®), and are considered inert in almost all solvents. However, PTFE is a plastic, and when compressed, it will not recover to its original shape. On the other hand, elastomers contain crosslinks, which act as springs to give the material resiliency and the ability to recover after a part has been compressed – this resistance to permanent compression gives the material the ability to maintain a seal over time. (To learn more about perfluoroelastomers, download our Introduction to Perfluoroelastomers White Paper).
The article below was recently published on FlowControlNetwork.com, and discusses how FFKMs are being used in oil & gas exploration, as production companies are increasingly operating in high-pressure, high-temperature (HPHT) downhole conditions.
HOW FFKMS PROTECT COMPONENTS IN ENHANCED OIL RECOVERY OPERATIONS
Companies are increasingly operating in high-pressure, high-temperature downhole conditions.
Improving technologies and methods to increase the recovery of oil from existing reservoirs is a global challenge. In the U.S., oil production at reservoirs can include three phases: primary, secondary and tertiary (or enhanced) recovery. The U.S. Department of Energy (DOE) estimates that primary recovery methods — which rely on the natural pressure of the reservoir or gravity to drive oil into the wellbore, combined with pumps to bring the oil to the surface — typically tap only 10 percent of a reservoir’s oil. Furthermore, secondary efforts to extend a field’s productive life — generally by injecting water or gas to displace oil and drive it to a production wellbore — still only push recovery totals to between 20 and 40 percent of the original oil in place. Clearly, much untapped oil and gas remains in existing wells.