Which provides a better seal, an O-ring or a gasket?

O-rings and gaskets are widely used in industry and daily life, but we may wonder which one offers better sealing. Let's look at their similarities and differences.

Similarities between O-rings and gaskets: Both meet this implicit condition: when the sealing contact pressure is greater than the pressure of the sealed medium, the seal is maintained; when the sealing contact pressure is less than the pressure of the sealed medium, the gasket or O-ring is forced open, resulting in significant leakage.

Differences between O-rings and gaskets: Flat gasket seals consist of a gasket, flange, and bolts, forming a complex statically indeterminate system; the sealing contact pressure is provided by the deformation of the bolts. The contact pressure distribution of a flat gasket is uniform during operation; when the medium pressure fluctuates and exceeds the contact pressure, leakage may occur.

In comparison: For constant pressure conditions, both can be matched; however, for variable pressure conditions, when the pressure rises, it may exceed the gasket's contact pressure range, causing the medium to force open the seal gap and leak. O-rings completely outperform gaskets. In application, gaskets are only used for static sealing, while O-rings can be used for both static and dynamic sealing in reciprocating linear motion. In design, traditional methods for gasket sealing are not rigorous enough, and new flange gasket design specifications are currently under experimental research; O-ring design can be easily found in this design manual, which is simple, reliable, and convenient.

In fact, whether it's an O-ring or a gasket, the most important thing is suitability, allowing it to better perform its sealing function.