Gaskets are a type of mechanical seal that inhibits leakage by filling the gap between static mating surfaces. As the gasket is deformed by a compressive force, it conforms to the profile of the surface and fills the gaps between its peaks and troughs.
Depending on the type of material used and construction, gaskets can be divided into three main categories: non-metallic, semi-metallic, and metallic gaskets.
Non-metallic gaskets are either made of homogeneous materials such as flexible graphite sheet and virgin PTFE, or a composite of fibers and granules embedded in an elastomer resin. These types of gaskets are suited for low to medium pressure applications.
Sem-metallic gaskets are composites of metallic and non-metallic materials. The metallic component provides structural strength and increased toughness, while the non-metallic part offers enhanced sealing.
Metallic gaskets are used for extremely high pressure and temperature applications.
In selecting a gasket, it is important to evaluate the process fluid‘s pressure, temperature, and chemistry. For non-metallic gaskets, take note of the thickness. Thinner gaskets with the same ratings have better sealing performance.
Improper compression, overheating, gasket reuse, and chemical attack are the most common reasons why gaskets fail.