What Is the Difference between O Ring and Gasket Seals?

10 December 2019
If you need to replace a seal, it is critical to know if you need a gasket or an O ring. While both are seals, they are very different. Yes, they both keep liquids or gasses from exiting or entering a joining in a piece of machinery. But the two seals have significant differences and cannot be used interchangeably. Understanding the specific qualities of each will help you choose the right type of seal. So exactly what is the difference between an O ring and a gasket?

An O ring is a seal in a circular ring shape. It can be made with a variety of materials, and it is most commonly made by either moulding or extrusion. Generally, this seal has some give and can withstand pressure and vibration. Conventionally, an O ring is fitted into a groove where two faces come together. It can be used in either static or dynamic applications. O rings are the optimum choice in high-pressure applications.

Gaskets are flat seals that can be made in any shape required. They can be made of a range of materials including polymers and metal, and are often made with layers of different materials. Gaskets can be used in high or low temperatures. They are fitted between two flat-surfaced flanges and typically use a bolted joint. Because gaskets can be designed in so many different shapes and made of so many different materials, it helps to think of ‘gasket’ as an umbrella term covering many different seals.

Choosing between O Ring and Gasket Seals

When designing equipment, it is important to consider the various functions a seal must accomplish before deciding if an O ring or a gasket is better for this application. Both perform the same basic function of stopping liquids or gasses from ingressing or egressing.

The shape of the seal is one key criteria where the difference between an O ring and a gasket becomes very clear. In some applications, only a gasket will work because the shape of the joint makes it difficult or impossible to design a good seal using an O ring, which requires a groove to sit in.

The other key factors are temperature and pressure. The material used to make the seal is a critical factor with regards to operating temperature. While both O rings and gaskets can perform well in a wide temperature range, gaskets have the edge in extreme temperatures. O rings, however, are the superior choice in applications with extreme pressure. Under pressure, an O ring’s performance will improve while a gasket’s effectiveness will decrease.

Understanding the difference between O rings and gaskets is critical to making the choice that will function best and longest in the application in question. At Abbey Seals, we invest in state-of-art technology to create custom materials to meet your needs. Our recommendation is always to review the total application from the customer and, with all the information in hand, we can offer the most appropriate seal for whichever application. Contact our experts today, and we will happy to answer any questions you might have about