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A gasket in the form of a ring with a circular cross section, used to seal connections in pipes and tubes.

PTL Boffins - Job Role

O-rings are a common and critical type of sealing component used in various industries to prevent the leakage of fluids or gases between two mating surfaces. They are named for their shape, which resembles the letter “O.” They are typically made from elastomeric materials, such as rubber or synthetic polymers, and they come in various sizes and materials to suit different applications.

Key features of O-rings

Here are some key points about O-rings:

Sealing Function

O-rings are primarily used to create a reliable and tight seal between two stationary or moving parts, preventing the escape of liquids or gases. They are often found in hydraulic systems, pneumatic systems, pumps, engines, and various industrial equipment.

Material Varieties

O-rings can be made from a wide range of materials, including but not limited to:

Nitrile (NBR)

Resistant to oil, fuel, and water, NBR O-rings are commonly used in automotive and industrial applications.

Viton (FKM)

Suitable for high-temperature and chemical-resistant applications, such as in the aerospace and chemical industries.

Silicone (VMQ)

Known for its flexibility and resistance to extreme temperatures, making it ideal for medical and food-grade applications.

EPDM (Ethylene Propylene Diene Monomer)

Offers excellent resistance to weathering, ozone, and UV radiation, often used in outdoor applications.

Sizes and Dimensions

O-rings come in various sizes and standard dimensions, which are defined by international standards such as AS568 (in the United States) or DIN ISO 3601 (in Europe). These standards ensure compatibility and interchangeability of O-rings in different systems.


They are typically placed in a groove or recess in one of the mating parts. When the two parts are joined, the O-ring is compressed between them, creating a seal. Proper installation and lubrication are crucial for the O-ring’s effectiveness and longevity.

Temperature and Pressure Range

The choice of material must consider the operating conditions, including temperature and pressure. Different materials have varying temperature and pressure tolerances.

Maintenance and Replacement

O-rings may wear out or degrade over time, especially in demanding environments. Regular inspection and maintenance are essential to ensure their continued effectiveness. When they become damaged or deteriorated, they should be replaced promptly to prevent leaks or system failures.


In some cases, custom-designs may be required to meet specific sealing needs. These can be tailored in terms of material, size, and shape to fit unique applications.

The role of O-rings in industry

Overall, O-rings are fundamental components in a wide range of industries and applications, contributing to the reliability and safety of various systems by preventing fluid or gas leakage. Proper selection, installation, and maintenance of O-rings are essential to ensure their effective sealing performance.

Check out Pure Transfer’s range of standard gaskets.

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