Gasket vs. Seal: What is the difference?

This article takes a look at what the differences are between a gasket and a seal. Although often confused for one another, their construction and uses are different.

Gaskets

Gaskets are used when two flat surfaces of a component or flange are put together. The gasket is placed between the two and is there to prevent leakage. Basically, the gasket makes a static seal between two non-moving items. Whenever a piece of equipment is taken apart, a new gasket should be fitted.

Gaskets are manufactured from a variety of materials including Neoprene, Rubber, Nitrile, Viton, Graphite, Cork, EPDM and SBR. Cork and Graphite are used when the gasket is to be put under high rates of compression.

Gaskets are commonly used in the oil, gas, paper, automotive and electrical industries.

Seals

Seals are used to prevent leakages between two moving parts such as pumps, engine parts and shafts. A seal is generally round and flat, whereas a gasket will often be cut into a specific shape to fit the component it is to be fitted to.

Most seals are constructed of a metal outer ring with an inner rubber surface. This inner surface is tilted to create a lip, creating a second barrier against any drops of liquid that pass the first edge. A seal is often used to seal hydraulic lines and to prevent leakage from the end of a shaft.