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  • The Role of Temperature and Pressure in Seal Performance

    The importance of sealing systems is often overlooked in industrial applications, from hydraulic systems and automotive engines to aerospace components and food processing machinery. While seals may appear to be simple components, their performance is significantly influenced by environmental factors. Among the most critical of these are temperature and pressure. Understanding how these variables affect seal performance is essential for maximising efficiency, safety, and product lifespan.

     

    Why Temperature and Pressure Matter

    Both temperature and pressure directly impact the physical properties and longevity of sealing materials. When improperly matched to application conditions, seals can degrade, fail prematurely or compromise system integrity.

     

    Temperature Effects on Seals

    Temperature extremes, both high and low, can significantly alter the characteristics of seal materials:

    High Temperatures
    Excessive heat can significantly impact seal performance by altering the physical and chemical properties of the sealing material. High temperatures may cause rubber seals to soften and swell, reducing their ability to maintain a tight seal and increasing the risk of extrusion. Elastomers such as NBR (nitrile rubber) can lose elasticity under heat stress, leading to deformation and leakage. Prolonged exposure can also break down the material’s chemical structure, resulting in shrinkage, cracking, or permanent set – where the seal fails to return to its original shape after compression, ultimately compromising sealing integrity.

    Low Temperatures
    At lower temperatures, some elastomers become brittle or lose flexibility, making them prone to cracking or breaking under stress. Cold temperatures can cause some seal materials to contract, leading to gaps and leaks and therefore compromising their ability to maintain a tight seal. A material that performs well at ambient temperatures may fail entirely in cryogenic applications unless specifically engineered for such conditions.

     

    Pressure Effects on Seals

    Pressure, especially in high-performance systems, can place immense stress on seals:

    Static Pressure
    In static sealing applications, the main concern is material extrusion or compression set. Over time, a constant high pressure can deform the seal, leading to leakage or loss of sealing force.

    Dynamic Pressure
    In systems with moving parts, such as pistons or rotating shafts, high pressure combined with motion can cause abrasion, extrusion or rapid wear. The choice of seal geometry and material must account for both pressure levels and dynamic conditions.

    Pressure Spikes
    Sudden pressure increases, common in hydraulic systems, can challenge seal integrity. Without proper design (e.g. back-up rings or high-durometer materials), seals may fail catastrophically under such transient loads.

     

    Finding the Right Balance

    Selecting the appropriate seal for a given temperature and pressure environment is not just about the material; it's also about design, tolerances and system compatibility. Key considerations include:

    Material Selection
    Fluorocarbon (FKM), PTFE, silicone, and other advanced polymers offer superior resistance to extreme temperatures and pressures, but other considerations such as chemical compatibility and mechanical requirements must also be considered.

    Seal Design
    Profiles such as O-rings, lip seals and gaskets each behave differently under thermal and pressure stress. A consultation with a sealing expert is recommended to discuss the best seal type and design based on the specific demands of the application.

    Testing and Validation
    Proper testing under simulated operating conditions ensures the seal can withstand real-world pressures and temperatures over time.

     

    Asking Seal Experts

    Technical expert with years of experience in engineering and supplying sealing solutions are best placed to offer advice on seal performance in any application, even for the most demanding environments.

    We work closely with customers to assess temperature and pressure conditions, along with other considerations, in order to recommend optimal materials and designs, and ensure long-term sealing performance.

    Contact us today to speak with a sealing expert and explore the best sealing solution for you.