O-ring

An O-ring is a loop of elastomer with a round (o-shaped) cross-section used as a mechanical seal. They are designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.

Theory and design

Successful o-ring joint design requires a rigid mechanical mounting that applies a predictable deformation to the o-ring. This introduces a calculated mechanical stress at the o-ring contacting surfaces. As long as the pressure of the fluid being contained does not exceed the contact stress of the o-ring, leaking cannot occur.

Related Topics:
Stress - Pressure - Fluid

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The seal is designed to have a point contact between the o-ring and sealing faces. This allows a high local stress, able to contain high pressure, without exceeding the yield stress of the o-ring body. The flexible nature of o-ring materials accommodates imperfections in the mounting parts.

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O-rings are available in a large number of standard sizes and materials. Manufacturers or reference books supply application and machining data for the mounting.

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O-rings are one of the most common and important elements of machine design.

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