by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Harsh Chemical Environments: Why Polymer Seals Outperform Metal

In industries where equipment is constantly exposed to harsh chemical environments, corrosion is a leading cause of premature seal failure, unplanned downtime, and costly maintenance. Even with protective coatings and careful material selection, metal is still vulnerable to pitting, stress corrosion cracking, and galvanic attack.

Certain engineering polymers are inherently resistant to the many forms that chemical degradation can take. They provide a proven and reliable solution to sealing even in some of the most corrosive environments. 

This article reviews the basics of corrosion, explains why corrosion is not a problem for polymers, and discusses the most common engineering polymers used in sealing solutions.

Metals Sealing Solutions and Corrosion

Metal seals used to be chosen for their strength and rigidity, but their metallic composition makes them susceptible to various forms of corrosion. For example, uniform corrosion can occur when the entire surface is exposed to a reactive chemical, causing the material to gradually thin. Another example is pitting corrosion, which is very common in chloride-rich or acidic environments. This type of corrosion generates localized damage that can quickly compromise sealing integrity.

Galvanic corrosion is another issue, especially when dissimilar metals come into contact in the presence of an electrolyte. In addition, stress corrosion cracking can occur when tensile stress and a corrosive atmosphere act together, leading to sudden and unexpected failure. Once corrosion begins, sealing forces diminish, leakage risk increases, and imminent failure awaits if the seal is not replaced proactively.

Why Polymers Excel in Harsh Chemical Environments

Polymers do not experience galvanic corrosion because they are non-conductive. In addition, some high-performance polymers (e.g., PTFE) are chemically inert, meaning they will not react with acids, bases, or solvents. This level of chemical stability allows them to maintain their dimensions and mechanical properties even after years of exposure to aggressive media. When used with compatible chemicals, several engineering polymers do not experience pitting or stress corrosion cracking. 

In addition to corrosion resistance, polymers offer low friction and reduced wear rates, which can extend the service life of both the seal and the mating surface. Some, like PTFE and UHMW-PE, provide self-lubricating properties that enable dry running. Their lighter weight can also benefit marine and transportation applications where every pound matters.

Polymer Beads

Commonly Used Materials for Seals in Harsh Chemical Environments

PTFE (Polytetrafluoroethylene)

PTFE (commonly known as Teflon) is one of the most widely used polymers for seals due to its exceptional chemical resistance, extremely low friction, and broad operating temperature range from -200°C to +260°C. It remains stable in the presence of almost all industrial chemicals, making it ideal for O-rings, gaskets, and dynamic seals used in even the most aggressive environments.

PEEK (Polyetheretherketone)

PEEK is a go-to choice for sealing applications that demand both chemical resistance and mechanical strength under high temperature and pressure. It maintains integrity in aerospace, oil and gas, and chemical processing environments where seals are subjected to extreme loads and aggressive media.

Hytrel (Thermoplastic Polyester Elastomer)

Hytrel has an unusual combination of flexibility with chemical resistance, making Hytrel sealing solutions exhibit reliable performance across a wide temperature range. It is commonly used in automotive, hydraulic, and pneumatic seals where both elasticity and resistance to fuels, oils, and industrial fluids are critical.

Kynar (Polyvinylidene Fluoride, PVDF)

Kynar, sometimes referred to as PVDF, provides excellent resistance to acids, bases, and organic solvents. Its stability under long-term chemical exposure makes it a reliable material for seals and gaskets in chemical processing equipment, including pumps, valves, and pipelines.

PPS (Polyphenylene Sulfide)

PPS offers high-temperature capability and chemical resistance, making it a strong candidate for sealing in automotive and industrial applications where both thermal cycling and aggressive fluids are present. It retains dimensional stability and mechanical performance under prolonged exposure to harsh conditions.

Performance Benefits in Harsh Chemical Environments

Polymer sealing solutions can avoid the problematic degradation mechanisms plaguing traditional metal seals. Corrosion immunity combined with other key seal properties allows them to maintain sealing pressure and integrity over more extended periods, reducing the frequency of replacements. Also, lower maintenance requirements translate into both cost savings and less downtime.

Materials with dry-running capability, such as PTFE or filled PEEK, allow operation without lubrication. This can be critical in environments where lubricants could be washed away or contaminated. In aerospace systems, the weight savings from polymer components alone can improve energy efficiency and handling.

Conclusion

When corrosion is a constant threat, polymer seals offer a long-lasting, low-maintenance alternative to traditional metal designs. The chemical resistance, dimensional stability, and low-friction properties of engineering polymers make them ideal as sealing solutions for harsh chemical environments. By specifying polymer seals early in the design phase, engineers can improve system reliability, reduce downtime, and lower lifetime costs.

Contact Advanced EMC or request a quote to discuss polymer sealing solutions engineered for your specific operating conditions and chemical challenges.

by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Labyrinth Seals for High-Speed Rotating Equipment: Non-Contact Protection for Wind Turbines

Labyrinth seals for high-speed rotating equipment are essential to the reliability of today’s wind turbines. These systems face extreme conditions, including high rotational speeds and fluctuating loads, as well as airborne contaminants, which can quickly compromise traditional contact seals.

In critical interfaces, such as gearboxes and generator shafts, seal failure often results in lubricant loss, contamination, and costly downtime. Labyrinth seals address these issues with a non-contact design that forms a tortuous path to block ingress and retain lubrication without generating friction, heat, or wear.

For wind energy applications, where uptime and longevity are non-negotiable, polymer labyrinth seals offer additional advantages, including corrosion resistance and lightweight design. In this blog post we discuss how labyrinth seals meet the demanding requirements of high-speed rotating systems in modern wind turbines.

Sealing Demands in Wind Turbines

Wind turbines are unique machines. They operate in harsh environments from salty offshore platforms to dust-laden plains and must run continuously for years with limited access to maintenance. At the heart of these systems lie high-speed rotating components, including the gearbox output shaft, the generator interface, and, in some direct-drive designs, high-speed rotor hubs.

These components rotate at thousands of revolutions per minute. They are subjected to wide-ranging temperatures, frequent load reversals, and axial or radial misalignment caused by structural flexing. Worse, they must do all this while preventing the ingress of moisture, dirt, and particles that degrade internal components.

Traditional contact seals struggle here. Frictional heat accelerates wear. Surfaces degrade. And eventually, lubricant escapes, or contaminants enter, leading to bearing failure or gearbox damage. The cost of even one unplanned maintenance event can be staggering. Sealing solutions must offer more than just barrier performance: they need to support longevity, stability, and efficiency under continuous high-speed operation.

Spring Energized PTFE Seal

How Labyrinth Seals Work in High-Speed Wind Energy Applications

The power of a labyrinth seal lies in its geometry. Instead of using contact pressure to form a barrier, it creates a complex, narrow passage through which air, oil, or particles must travel. Each directional change or constriction in the path dissipates pressure and reduces the flow’s momentum. By the time the fluid or gas reaches the other end—if it ever does—its energy is largely lost.

This design is ideal for high-speed rotating equipment. No physical contact means no friction. No friction means no heat generation or surface wear. The result is a sealing system that performs reliably over extended periods, particularly in dynamic, high-load environments such as wind turbines.

Modern labyrinth seals may include straight-through paths, stepped grooves, or interlocking designs. Some systems incorporate shallow grooves on the shaft and mating grooves on the stationary housing, creating a highly restricted channel without touching components.

In wind turbines, materials also matter. Polymer labyrinth seals offer significant advantages over metal or elastomeric solutions for wind energy applications. Polymers such as PTFE, PEEK, and UHMW-PE resist corrosion, weigh less, and are less abrasive to surrounding components. These qualities make polymer labyrinth seals well-suited for outdoor and marine turbine installations, where exposure to salt spray, moisture, and UV radiation can cause degradation of metal components over time.

Spring Loaded Seal

Technical Advantages of Labyrinth Seals for Wind Energy Equipment

For design engineers and maintenance professionals, the benefits of labyrinth seals in high-speed wind turbine equipment go beyond just sealing. Here’s how they add real-world value:

1. Wear-Free Operation

Since labyrinth seals rely on flow dynamics and not frictional contact, they do not degrade from continuous rotation. This eliminates a primary failure mode in conventional seals—surface wear—and extends operational life.

2. Superior Thermal Behavior

High-speed shafts generate heat, particularly during periods of high power output. Traditional seals may harden, melt, or lose tension when exposed to heat. Labyrinth seals are immune to these issues. Their non-contact nature means virtually no temperature rise due to sealing friction.

3. Resistance to Misalignment

Wind turbines experience tower sway, yaw misalignment, and thermal expansion. Labyrinth seals are more tolerant of these shifts than rigid-contact seals. The sealing gap may vary slightly, but performance remains largely unaffected.

4. Low Torque Drag

Especially at startup or low-speed conditions, reducing system resistance is key. Labyrinth seals exert no drag torque, allowing for more efficient rotation and reduced energy loss. Over time, this contributes to better system efficiency and lower mechanical loading.

5. Contaminant Rejection

Particles, moisture, and even insects are a constant threat to wind turbine internals. Labyrinth seals, with their tortuous flow path, effectively reject solid contaminants, particularly when paired with centrifugal motion or positive internal pressure.

6. Maintenance Reduction

Perhaps the most significant benefit: reduced service frequency. For remote or offshore turbines, extending service intervals by even a few months can translate into substantial savings in crew time, transportation, and lost production.

Conclusion & Engineering Recommendations

Labyrinth seals for high-speed rotating equipment have proven themselves in gas turbines, aircraft engines, and now increasingly in wind turbines, where high-speed rotation and long-term reliability are essential. Their non-contact geometry makes them uniquely suited for systems that must endure thousands of hours of continuous operation with minimal maintenance.

In wind energy, where environmental exposure, mechanical stress, and economic pressure converge, polymer labyrinth seals offer a compelling balance of performance, durability, and design flexibility. They protect critical systems without the drawbacks of traditional friction-based seals.

For engineers seeking to extend component life, improve drivetrain reliability, or reduce long-term maintenance costs, labyrinth seals—especially those built from advanced polymers—deserve serious consideration. Whether you’re designing next-generation turbines or retrofitting legacy systems, Advanced EMC can help develop custom labyrinth sealing solutions that meet your exact performance requirements.