Gasket vs. O-Ring: What are the Differences?

Some folks use the term gasket and O-ring interchangeably. Although both are categorized as seals, they're actually very different in terms of application as well as their appearance. In engineering, most sealing products are interchangeable. But these two components have distinctive uses.

So can you readily identify situations where each seal is most suitable? Let’s look at the two.

What are Gaskets?

So, what is a gasket? It is a material used to seal two flat-surfaced components or flanges to prevent leaking. Gaskets are made of different substances such as silicone, nitrile, Viton, neoprene, etc. When the seal is in place, it prevents liquid, air or both from leaking out or in an area.

You can cut gaskets in different sizes and shapes – they could be rounded and circular, triangular, half-circle, square, rectangular (basically, any form you can think of). Similarly, gaskets can be layered with a different coating to help out with their application and end-use. Such layers include pressure-sensitive adhesives, various coatings and can even be laminated.

Gaskets are used in various applications. In commercial kitchens, they're commonly used to seal refrigerator and freezer door. 

What are O-Rings?

What comes to your mind when you hear the word O-rings? A rubber ring? Well, you’re absolutely right! These seal products are made of flexible materials such as neoprene, polyurethane or rubber.

As the name suggests, the seals are circular but come in different sizes and materials. These seals products are used when containing or separating machines fluids from various environments. The ring will sit between two cylindrical parts (in a groove) – when the two parts compress, a liquid-tight or an air-tight seal is created.

O-rings are ideal for creating a seal at extremely high pressures. Some O-rings can withstand pressures of up to 5,000 per square inch. They will maintain their integrity even when exposed to high pressure and prevent gas or air from escaping. Given their shape, they're ideal for both dynamic and static applications.

Gaskets vs. O-Rings: The Key Differences

• Gaskets are mechanical seals made up of a flat piece of material. By definition, you can say that an O-rings is a gasket, but not every gasket is an O-ring.
• Gaskets are made from any material, while O-rings are made of elastomer materials that can stretch and revert to their initial size and shape without breaking.
• O-rings are all circular. On the other hand, gaskets come in different shapes. Moreover, gaskets can be customized to fit different complex mating surfaces.
• When it comes to the shape of a seal, the difference between a gasket and an O-ring is noticeable. An O-ring requires a groove to sit in, while a gasket is ideal for flat surfaces.

• The operating temperature and pressure should also come in as a factor. Both gaskets and O-rings can work in a wide range of temperatures, but gaskets will always have the upper hand in extreme temperatures. On the other hand, extreme pressures favor O-rings – they are more efficient than gaskets under high-pressure conditions.