Understanding Gasket Leakage and its Solutions

Apr 04, 2016 Flange Gaskets

Flange leakage in piping systems is an expensive affair. It results in the process plant being shut down, and using a lot of down time to repair the leak. Gaskets are among the crucial components of flanged joints of piping systems. The design of the gasket, and the choice of materials are extremely important to prevent flange leakage.

Understanding Gaskets

Gaskets comprise either a single, or a combination of materials that are placed in between a flanged mechanical joint. The gasket closes up imperfections of the flange surface, and creates a tight seal. This installation allows the gasket to create a static sealing around the joint. The rougher the mating surface, the tighter the seal.

Why do Flange Gaskets Leak?

There are a few basic reasons behind flange gasket leakage.

The inner diameter of the gasket has to be exact according to the specifications of the flanged joint. If the diameter is incorrect, the gasket may stick to the sealing surface, but leakages will still take place.
Many times, a thread lubricant called Never-Seez is applied onto the gasket for ease of installation. Some manufacturers believe that if the gasket does not have enough Never-Seez, it will lead to gasket leaks.
Most sticking gaskets are constructed from glue and fiber materials. When installed, the glue can get squeezed out and flow into the pores of the metal joint. This will hinder the gasket’s performance, leading to leakage.

What are the Solutions to Prevent Flange Gasket Leakage?

There are certain points that should be kept in mind when designing the gasket. Proper design will ensure that the gasket does not leak during operation.

There must be enough flange pressure to compress the gasket, thus ensuring a tight seal.

All aspects related to temperature, such as bolt elongation, creep relaxation, and thermal degradation must be considered. The reason is that all these temperature related issues can affect the flange pressure.

If the gasket is being used to seal a fluid, then it should be designed such that it not only seals the fluid, but is also unaffected by the fluid’s corrosive properties.

The surface finish of a gasket should not be too fine, neither too deep.

In terms of thickness, the gasket should be minimum four times thicker than the surface roughness of the flange faces. Also, the gasket should be thick enough to cover the shape of the flange faces, while being able to compress easily due to the flange load.

The width of the gasket should never be wider than necessary. While the width should be up to the required size, the outer diameter of the gasket should be as large as possible. This will ensure that the gasket can withstand high pressure levels.

Designing industrial gaskets is not an easy task. However, by keeping the above mentioned points in mind, you can design and manufacture a gasket that will meet application requirements, and customer expectations.