What is a Gasket
What is a gasket? A gasket is a seal that acts between two mating surfaces with the primary purpose to prevent leakage and fluid ingress.
Gaskets provide seals in high-cost and safety applications, therefore the correct material must be selected for the application due to the potential consequences of leaking gaskets.
Gasket Types and Uses
Gaskets are manufactured from a wide range of materials, including rubber, cork, paper, neoprene and more. A gasket can serve multiple functions such as anti-vibration and sound reduction, benefiting from its flexible material.
Gaskets have a wide range of application and are present in almost every industry. These sectors include oil and gas, food, rail, automotive and many more.
The application of the gasket will control the material used. For example, a head gasket in a car engine needs to operate in a high-temperature environment. For this reason, they consist of a combination of steel and elastomer.
In the chemical industry, sheet gaskets are used to seal pipes. The gaskets are made from synthetic rubber and manufactured by ‘punching’ them from a sheet of material. The synthetic rubber material used is perfect for the application as it is corrosive resistant and capable of working in the presence of steam.
What Is The Purpose Of A Gasket?
The nature of fitting a gasket means that it under compression during its application. The application of compression allows the gasket to serve its primary purpose as a seal. During the application of elastomeric/polymer gaskets, the compression results in the material displacing and filling in irregularities within the mating surfaces.
Therefore, when selecting a gasket to create a seal between surfaces that contain irregularities, it is best to use one of an elastomeric material. Building upon this, it is unwanted for a gasket to be made from a material with high yield stress as it will have a reduced ability to fill irregularities.
How Can a Gasket Fail
Uneven compression
Uneven compression can stem from a variety of factors. The first is human factors. Uneven application of bolt pre-load can lead to asymmetric compression. Asymmetric conditions will lead to a compression reduction increasing the likelihood of leakage.
Torque loss
Due to factors like vibration and temperature fluctuations, bolts will lose torque and pre-load over time, reducing compression and leading to leaks. Using bolts that are longer and have a smaller diameter are ways to reduce a loss of torque. On the other hand, using a thinner and smaller gasket will result in more torque loss
Surface not smooth
Although discussed above how a gasket fills irregularities, if a surface is extremely rough it will provide a path for leaks. The excessive roughness means that the gasket is not capable of filling in the large voids
Summary
Gaskets serve the primary purpose of producing seals between mating surfaces, aided by the compression force present on the joint. They are made from a wide range of materials, with the most common being an elastomeric material. Depending on the application, the material will change. For example, a head gasket on an engine consists of a combination of steel and elastomer.
Uneven compression and torque loss are the most common methods leading to gasket failure, which is prevented by applying torque tightening correctly and using a bolt tightening sequence.
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