What is a Gasket it’s Types and Applications

A Gasket is a type of mechanical seal that is used to fill the space and take care irregularities between mating surfaces to prevent leakage (gas or fluid) in the joint in compression condition. 

In this article we will understand various types of gaskets, their material and applications in various industries. We suggest you also read this article on various types of check valves, their working and applications.

Applicable Standard

Types of Gaskets

Following types of gaskets are available in the market has different applications:

  • According to Manufacturing Process
    1. Die Cut gaskets
    2. Extruded Gasket
    3. Molded Gasket
    4. Form-in-Place and Cure-in-Place Gaskets
  • According to type of Material
    1. Non-Metallic Gasket
    2. Metallic Gasket
    3. Composite Material Gasket
  • According to Construction of the Gasket
    1. Round Gasket
    2. Spiral Wound Gasket
    3. Constant Seating Stress Gasket
    4. Fishbone gaskets
    5. Flange gaskets
    6. Kammprofile gaskets
    7. Double-jacketed gaskets
Types of Gaskets according to Manufacturing Process

Gaskets can be primarily classified into four types according to the type of manufacturing process used.

1. Die Cut Gasket
this image shows a type of Die Cut Gasket

Die cut gaskets are uniform thickness flat gaskets that can be cut in various sizes and shapes from flat sheets. When required double sided tapes are also used with gaskets to stick them with mating surfaces.

2. Extruded Gasket
This image shows various types of Extruded Gaskets

Silicon and rubber gaskets in various shapes and designs are available in the market. To use the gasket, it is cut at the required length. When used in standard design extruded gaskets, cost is very low.

3. Molded Gasket
this image shows a type of molded gasket

Customized Molded gaskets has advantages of using in complex 3D shapes and size. But they require special tool development. They are used in application where mating parts have complex 3D surfaces that can not be covered by flat round or extruded gaskets.

4. Form-in-Place and Cure-in-Place Gaskets
this image shows a Liquid Gasket Dispensing Machine

Form-in-place and cure in place gaskets utilizes a liquid.  material that is dispensed manually or machines on to the mating surface. Afterwards dispensed material is cured using uv rays, air or heat. In this way a good bond between mating surface and gasket material is created and manually gasket assembly operation can be avoided.

Gaskets according to Material Type
1. Non-Metallic

A non-metallic or soft gasket is the most commonly used type of gasket that has a very good compression ratio. They are manufactured in materials such as Rubber (silicone, Nitrile, neoprene, Butyl, Hypalon, EPDM and SBR), Teflon and PTFE etc.

2. Metallic

Metallic gaskets are also known as ring or RTJ gaskets are manufactured with soft metals such as stainless steel, monel, inconel and soft iron etc. They are used in applications where high clamping force between mating parts is used.

3. Composite Material Gasket

Composite Material gaskets are manufactured with the combination of metallic and non-metallic materials. Spiral-wound, Metal-Jacketed, and Kamprofile are the example of composite material gaskets.

Types of Gaskets according to their Construction
1. Spiral-Wound Gasket
This image shows Spiral Wound type of Gasket

Spiral Wound Gaskets are a type of composite material gaskets consisting of inner & outer ring, filler material (graphite or PTFE) and winding material (stainless steel) that is a thin sheet of metal. Inner ring is used to provide support to the winding material.

3. Constant Seating Stress Gasket

The constant seating stress gaskets are used to achieve uniform sealing stress and avoid uneven loading problems. They are used in high pressure applications where thermal loading can be a concern. Constant seating stress gaskets consist of a solid incompressible carrier ring (usually steel) with channels on both sides. These channels are filled with compressible sealing material such as PTFE or expanded graphite.

4. Fishbond Gasket

The Fishbone gaskets are a type of metallic gaskets. They are the good replacement of kamm-profile Spiral-Wound gaskets with lowest leak rate. The bones in fishbone gasket remain ductile even in compressed conditions and this helps during thermal cycling.

5. Flange Gasket
this image shows a type of Die Cut Gasket

Flange gaskets are the simplest type of gaskets that are designed to be used in between flanges of the mating surfaces. We suggest you also read this article on various types of flanges in piping.

6. Kammprofile gaskets

Kammprofile gaskets have metal cores (stainless steel) with concentric grooves surrounded by non-metal filler materials such as graphite or PTFE. They are used in heat exchangers, oil and gas industries.

7. Jacketed Gaskets

Jacketed gaskets have a soft non-metallic interior with a metallic coating. They can be single-jackets or double-jackets. 

Single jackets gaskets consist of soft filler material completely enclosed in a single jacket. Whereas double jacketed gaskets consist of soft filler material encapsulated by a metal jacket and insert and they are used in high temperature and pressure applications.

Selection of a Gaskets

Following points shall be considered during the selection of a gasket for an application.

  • Gasket Material
    1. Compatibility of Gasket Material with Fluid
    2. Stress Relaxation or Creep resistance for gasket Material
    3. Molded Gasket
    4. Porousness in gasket Material
  • Construction and Type of Gasket
    1. Compression Ratio
    2. Structure of mating surfaces
  • Fluid Internal Pressure and Temperature
  • Life of the Gasket

We will keep adding more information on various types of gaskets available in the market. Please add your suggestions, comments or questions on What is a gasket and their types in the comment box. We suggest you also read this article on various types of mechanical couplings.

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