Rubber Seals Designs

The basic reason for using rubber seals is to prevent leakage of liquid between two joined surfaces. This is basically a mechanical seal used in static and dynamic sealing applications. Rubber seals, made of natural rubber or synthetic rubber, are used in various industries such as automotive, aerospace, construction etc. This seal is widely adopted in various applications due to features such as resistance to aging, fire retardation capabilities etc.

Rubber Seals Designs

There are different varieties of such seals available in the market on the basis of their designs, materials, usage and applications. There are three popular designs of these seals and each design has its distinct cross section. Let us discuss these designs below:


As the name suggests, these are round shaped, in the shape of O or a doughnut. It has the ability to do a sealing action by deforming to take the shape of the cavity and can easily fit into it. It can be a static or a dynamic seal. In static sealing, there is no or little motion between the mating surfaces. In dynamic cases, a relative motion is seen between the mating surface. O ring has simple mounting requirements.


This design is in the shape of the letter-X and hence referred as X-rings. At times, it is also known as Q-rings. Considered to be a better alternative to O-rings. Used mainly in rotary seal applications. X rings provide double-closing action. They have a four-lobed configuration which prevent the seal from being twisted. With two areas to be sealed, they require less deformation to offer an effective sealing.

Square Rings

These are seals with square cross sections. Made of natural or synthetic rubber, these are used mainly in high pressure gasketing functions. Square rings are used in place of similar sized O-rings or other molded seals. They are ideal for static applications but not for dynamic applications. Some basic advantages of square rings are controlled surface smoothness, better elasticity, correctly formed edges, and accurate hardness.

U-cup Seals

Another popular design of rubber seals is the U-cup seal. They are mainly used to join stems or rams. With small glandular spaces, they become more perfect. With a U-shaped cross section, sealing itself is possible for inner and outer diameters. There are three varieties of such seals.