Advanced Seals Enhance Safety and Reliability

Premium solutions prevent seal failure caused by extreme chemical process conditions

Seals and gaskets are mission-critical components in the chemical process industries (CPI), where seal failure can have catastrophic consequences. While the corrosive and aggressive media and extreme operating conditions typically found in chemical processes pushed the limits of traditional seals, recent material and design innovations have resulted in premium sealing solutions that offer higher levels of safety and reliability in demanding chemical processes.

Sealing challenges

“Chemical processors are navigating incredibly harsh operating environments, including aggressive chemicals and extreme temperatures and pressures,” says Greg Gedney, business development manager, industrial operations, with Greene Tweede (Lansdale, Pa.; www.gtweed.com). “Highly corrosive and aggressive media can degrade seal and gasket materials over time, leading to a loss of sealing integrity. And, with extreme temperatures and pressures, the operational window for these components is often pushed to the limits. High temperatures can cause materials to soften and lose their sealing force, while high pressures can lead to extrusion or physical damage.

“Today’s sealing solutions must be designed to maintain their properties and structural integrity across wide temperature and pressure ranges, preventing deformation and failure,” continues Gedney.

Additional challenges include unintentional leaks of hazardous vapors or gases. “Fugitive emissions pose risks to workers and the environment and can lead to significant regulatory fines. Reliability in seals is about uptime, but it’s also about safety,” says Gedney. “Chemical processors require technologies that provide a dependable seal that minimizes these risks and helps them meet strict standards.”

New materials for reliability

“Recent advancements in seals and gaskets center around material innovation,” says Zach Adamcyzk, product manager, Chemraz, with Greene Tweed. “Next-generation elastomers and thermoplastics such as advanced FFKMs (perfluoroelastomers), cross-linked polyether ether ketone (PEEK) and engineered composites, deliver superior chemical resistance and thermal stability, ensuring reliability in aggressive environments.

“We combine these material advances with engineering expertise and enhanced seal designs with features like optimized geometries and anti-extrusion features to help maintain sealing force under extreme pressures and temperatures, reducing failure risk and extending service life,” Adamcyzk says.

Greene Tweed’s Chemraz 541 is an example of a product that combines advanced materials with innovative engineering (Figure 1). As a universal, high-strength FFKM compound, Chemraz 541 was specifically designed to meet the rigorous demands of the chemical process industries.

“Chemraz 541 addresses the critical challenges in demanding industrial and chemical processes,” says Adamczyk. “Its formulation offers superior chemical resistance, making it highly effective in environments with aggressive media. For example, in third-party testing with aggressive amines used in carbon capture technologies, Chemraz 541 exhibited a volume change of less than 10% and no visual degradation after extended exposure at 150°C,” he continues.

“In addition to its chemical resistance, Chemraz 541 provides reliable sealing at continuous operating temperatures of up to 230°C. It also delivers impressive mechanical integrity with high tensile strength and excellent compression set resistance. These properties make it particularly well suited for demanding applications, such as pump, valve and mechanical seals, where both physical durability and chemical resistance are essential.”

Other material trends include the use of thinner materials and composite materials, says Tom Rimel, president of Stockwell Elastomerics (Philadelphia, Pa.; www.stockwell.com). “Composite materials that combine multiple layers of dissimilar materials, such as rubber, films, mesh, metal and adhesives, are being used to achieve custom gasket development (Figure 2). Additionally, there are constant developments for properties, such as compression set (CS), compression force deflection (CFD), density and color.

“There are also some new approaches to achieve various levels of electrical or thermal conductivity,” he says. “Stockwell is currently working on the development of a new electrically conductive adhesive for electromagnetic interference (EMI)-shielding applications where a conductive adhesive completes the shielding effectiveness of a multilayer gasket.”

EMI gaskets that are made of electrically conductive elastomers, such as silicone or fluorosilicone, provide environment sealing, thermal insulation and shielding against EMI. They support a variety of fabrication methods, are available in materials that meet tough standards and can be supplied with conductive adhesive backings for ease of installation. There are many types of EMI-shielding materials, but electrically conductive silicones provide gasket designers with performance and versatility.

Stockwell’s EMI gaskets seal the gap between two mating surfaces. Like other types of environmental gaskets, they seal out the external environment or seal-in to prevent leakage. What makes EMI gaskets different is that they also seal against conducted or radiated EMI that can disrupt circuits. When this electromagnetic interference “noise” reaches the EMI gasket, the signals are negated and the resulting electrical current is sent to ground. Silicone is normally an electrical insulator, rather than an electrical conductor, but the addition of metal or metal-coated particles imparts the necessary electrical conductivity.

And, material innovation is especially crucial today as per- and polyfluoroalkyl substances (PFAS) may be coming under regulatory scrutiny. “As many legislative and regulatory bodies have begun to enact or are considering enacting PFAS-related regulations, it could potentially impact all sealing device manufacturers and, subsequently, the chemical process industry at large,” explains Alan Evans, global director, product line management for the mechanical seal business with A.W. Chesterton (Groveland, Mass.; www.chesterton.com).

“The challenge with regulating PFAS has to do with the generic definition often used to define them,” explains Evans. “While some non-polymeric PFAS are a concern given their potential impact on human health and the environment, not all PFAS materials are hazardous. Specifically, one class of these chemicals, known as polymeric PFAS (that is, fluoropolymers), have been shown to be inert, non-toxic and non-mobile materials and they are critical materials in a wide range of applications due to their unique properties, which include resistance to chemical attack, thermal stability and very low friction capabilities.

“In many cases, these fluoropolymers have no known equivalent substitute,” notes Evans. “There will be a significant impact on the sealing device industry and for sealing device users globally if the wrong decisions are made,” warns Evans.

Performance and cost

“When developing seal technologies, the goal is to ensure process fluid containment, minimize fugitive emissions and reduce total lifecycle cost, while maintaining uptime and safe operations for plant operators,” says Jesse Fordyce, market manager with John Crane (Slough, UK; www.johncrane.com).

“For seals in the chemical processing industry, common challenges include managing hazardous and corrosive base chemicals, and toxic, carcinogenic, crystallizing, polymerizing and abrasive fluids. Mechanical seals need to operate reliably in transient conditions, such as pressure spikes, reverse pressure and fluid phase changes,” he says.

John Crane, Fordyce says, continues to develop mechanical seals that are tailored to handle the extreme conditions experienced in process industries. Recent innovations include non-contacting and low-emission seal technologies, such as gas-lubricated and dry-running designs. “These technologies limit heat generation, reduce energy requirements and can lower lifecycle costs,” he says.

One such tailored solution is John Crane’s Type 8628VL, which is designed for ethane and ethylene pipeline operators because these materials can change phase in the pipeline (Figure 3). Unlike other mechanical seals, Type 8628VL’s multiphase seal-face lubrication design results in a fully non-contacting seal.

“Test results indicate that this can extend mean time between repair to up to 48 months and even longer,” he says. “Compared to conventional mechanical seals used in ethane and ethylene pipeline applications, 8628VL can reduce the total cost of ownership by delivering more efficient and reliable operations and improving uptime.”

And, as chemical processors must be especially diligent to prevent potentially explosive gases from entering cabinets and equipment in ATEX-classified areas, advanced cable-transit solutions are also being developed.

“One of the most important developments in seals over the last few decades has been the adaptation of Roxtec’s HD transit solutions, says Leo Konradsson, global segment manager for process industries, with Roxtec (Karlskrona, Sweden; www.roxtec.com). “HD stands for ‘high density’ and refers to the high number of cables that can be safely routed through a minimum area of a cabinet. The migration from traditional cable glands has resulted in smaller and lighter cabinets, while also helping prevent gases from entering enclosures and minimizing ingress to reduce production disruptions and severe accidents.

“The seals also allow for late cable changes and on-site modifications without having to drill or weld on site. Users simply open the seal up, route the new cable through and then use the compression unit to seal the opening again.”

The Roxtec HD 72 is the latest addition to the Roxtec HD product range for cabinets, terminal boxes and smart junction boxes (Figure 4). It provides a larger package space for applications with a high density of larger cables, while limiting the weight and footprint of the enclosure. Up to 72 armored or non-armored cables can be sealed in one transit. It serves as a fit-for-purpose solution for advanced cabinets for electrical heat trace, input-output (I/O), programmable logic controller (PLC) systems and safety instrumented systems (SIS).

Roxtec’s Multidiameter brings additional flexibility to the field. “Cable sizes often change very late in the design. By using Roxtec’s cable transits with Multidiameter, users can simply peel away layers from the sealing modules to ensure a perfect fit. The extended range built in these modules can accommodate most changes without the need for onsite work, like drilling or punching and procuring new parts,” says Konradsson.

Installation and flexibility

Seal providers understand that seal failure is often related to human error during installation at the facility, so they are working to make designs that are more user-friendly. Modular, preset cartridge seals are one such solution, says John Crane’s Fordyce.

Cartridge seals operate by creating a reliable sealing environment within rotating mechanical equipment to prevent leakage. The cartridge seal design simplifies installation, while also ensuring effective sealing under various conditions. John Crane’s Universal Cartridge product family improves performance and reliability of mission-critical pumps across a range of process industries. The seal family accommodates fluids, including water, caustics, hydrocarbons and acids.

The cartridge seals come as a preassembled unit, with no need to set spring compression, simplifying installation and protecting the seal face to increase reliability, save time and reduce leakage.

Chesterton’s 1810 modular, single-cartridge seal also simplifies configuration and installation (Figure 5). The high-performance, scalable mechanical sealing solution provides a reliable and economical sealing solution for a variety of pumps. In addition to reducing installation errors, the 1810 offers selectable features around a common gland housing to provide flexibility. This allows processors to create the best possible sealing parameters for their equipment and for the application, thus maximizing single seal reliability.

Premium seal technologies

By addressing the root causes of seal failure, seal providers are beginning to create sealing devices that are more tolerant to process conditions, offering long-term reliability and significant reductions in the total cost of ownership of their pumps and equipment, notes Evans.

Greene Tweed’s Gedney agrees: “The most impactful benefit of implementing advanced sealing technologies is increased reliability and, therefore, less downtime. Today’s seals are designed to stand up to the most aggressive chemicals and extreme temperatures. That resilience extends the service life of critical equipment, creating longer mean time between repairs, reduced maintenance costs and increased plant uptime.

“Greene Tweed has done studies where these products have extended maintenance cycles from under a year to five years or more. That’s a significant gain in productivity,” he says.

Process optimization is important as well, he says. “When your seals can reliably handle higher temperatures and more aggressive chemicals, you have the confidence to push your production processes for greater efficiency and higher yields. Your sealing components are not a limiting factor,” explains Gedney.

Enhanced compliance with safety and environmental regulatations is another benefit of premium seals, because a more reliable seal will minimize the risk of fugitive emissions, which protects people from hazardous chemicals and helps chemical processors meet strict environmental regulations, explains Adamcyzk.

“At the end of the day, investing in a premium sealing solution is an investment in operational excellence,” he says. “It enables chemical processors to run their facilities more safely, reliably and profitably,” Adamcyzk says.

Joy LePree