The Difference Between a Gasket and a Seal

July 22, 2025

In industrial applications, the terms “gasket” and “seal” are often used interchangeably. However, they serve distinct functions. Both are designed to prevent leaks and maintain pressure, yet their materials, roles, and applications vary significantly. This article explains the differences between gaskets and seals, how each component works, and when to use one over the other.

What Is a Gasket?

A gasket is a mechanical component placed between two stationary surfaces to create a seal and prevent leakage. Gaskets are typically made from flexible materials such as rubber, graphite, or metal and are primarily used in static applications. Their main function is to fill irregularities between mating surfaces, creating a tight seal that prevents fluid or gas leaks.
When compressed, a gasket conforms to surface imperfections and creates a barrier that blocks the escape of media. This makes gaskets essential in industries like automotive, manufacturing, and HVAC. Their effectiveness depends on the material composition, thickness, and the amount of compression applied.

Common applications include:

  • Engine cylinder heads
  • Pipe flanges
  • Heat exchangers
  • Industrial enclosures

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    For high-temperature or chemically aggressive environments, Durlon® flexible graphite sheet gaskets provide reliable sealing in critical static applications. They conform to flange surfaces and maintain integrity across wide temperature ranges, making them ideal for demanding conditions.

    What Is a Seal?

    A seal prevents the leakage of fluids or gases in dynamic systems, where parts are in relative motion. Seals are typically found in applications such as pumps, valves, compressors, and rotating shafts. These components are made from durable materials including rubber, elastomers, PTFE, or metal alloys, selected based on the application’s temperature, pressure, and chemical compatibility requirements.

    Unlike gaskets, seals are designed to endure continuous movement and fluctuating operating conditions. For example, in an automotive crankshaft or hydraulic cylinder, a seal prevents oil or hydraulic fluid from escaping under pressure while components are in motion.

    Typical seal applications include:

  • Rotary shafts
  • Hydraulic and pneumatic systems
  • Mechanical pumps
  • Gearboxes

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    Key Differences Between Gaskets and Seals

    While both components are used to prevent leaks, their operating environments and functions differ.

    1. Application Type

  • Gaskets are used in static applications, where there is no movement between the joined surfaces.
  • Seals are used in dynamic applications involving motion between components.

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    2. Material Composition

  • Gaskets are generally made from softer, compressible materials like rubber, graphite, or non-asbestos fibers.
  • Seals are constructed from more durable materials such as elastomers or metal to handle dynamic stress.

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    3. Pressure and Temperature Tolerance

  • Seals are engineered to withstand higher pressures and temperature variations in dynamic systems.
  • Gaskets are effective under moderate pressure and temperature in static environments.

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    4. Design and Complexity

  • Gaskets are often flat and simple in shape, designed to match the flange or joint geometry.
  • Seals can be more complex, incorporating springs or lip designs to maintain contact during movement.

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    When to Use a Gasket or a Seal

    The choice between a gasket and a seal depends on the application’s requirements:

    • Use a gasket when sealing stationary components where the primary goal is to prevent leaks in fixed joints.
      Examples include flange connections, pressure vessels, and engine covers.
    • Use a seal in applications where parts move relative to one another and where maintaining a barrier under motion is critical.
      Common examples include rotary pumps, shaft assemblies, and gear systems.

     
    Proper selection ensures long-term reliability and prevents premature equipment failure. Inaccurate selection may lead to leaks, equipment downtime, and safety hazards.

    Find the Right Gasket Solution

    Understanding the difference between gaskets and seals is essential for selecting the right sealing solution for your equipment. Gaskets are optimal for static applications requiring a tight seal between stationary components. Seals, on the other hand, are engineered for dynamic environments where parts are in motion and exposed to variable pressure and temperature.

    Contact us today for expert guidance on sealing solutions or to learn more about our high-performance flexible graphite sheet gaskets. We’ll help you select the right product to enhance the efficiency and safety of your system.