What is a Gasket and the Types Used in Pipes?
What is a gasket? There’s key information to know. Learn everything you need to know below.
Are you about to undertake a piping project? If you are, you must know how essential it is to use only high-quality materials. This is even more important if you need to use a flange. Flanges help connect pipes, valves, pumps, as well as other equipment that essentially complete an entire piping project.
Flange leaks usually result in a significant loss of energy and products. A handful of such occurrences even have highly disastrous consequences as it leaks hazardous or toxic material that can harm humans and the environment.
This is why you need high-quality gaskets, as they provide the seal required to prevent leaks from flange joints.
This post covers what a gasket is as well as the types of gaskets used extensively in pipes.
What is a Gasket?
A gasket is an essential element for flanged joints within a piping system of operating plants. It is a soft sealing material – or a combination of different materials – creatively clamped between 2 divisible mechanical members of a flanged joint – or mechanical joint – producing the weakest link of the joint.
In other words, gaskets are mechanical seals that fill the space between 2 or more mating surfaces. They are designed to prevent leakages into or from the joined objects under severe compression.
But in piping systems, gaskets work as static seals, efficiently maintaining the leak-proof sealing in every operating condition.
Applications and Usage of Gaskets
The types of gaskets are determined by their overall function and usage. Gaskets are created from soft materials – like rubber, etc. Gaskets are primarily used for sealing pipes in order to prevent the leakage of fluid. Some gaskets also have typical applications such as mounting, ant-vibration, etc.
For instance, manway gaskets are an industry-standard as they are used in a wide range of applications such as large tank boilers as well as other types of closed vessels. They are used extensively in the dairy, beverage, and pharmaceutical industries. Depending on its application or use within a specific industry, manway gaskets can also be vulcanized to any desired dimension.
Another type of gasket is commonly used in electrical transformers, especially the type that is water-cooled and oil-filled. The gaskets work as weather seals in order to boost the ingress protection (IP) rating of the compartments within a transformer. They can also work by sealing the oil and water against leakage while ensuring transformer enclosures remain accessible.
Several different gaskets are used in the chemical, petrochemical, oil, and gas industries. The application of gaskets depends on their use within a particular industry.
Types of Materials Used in Making Gaskets
Before highlighting the types of gaskets available today, let’s look at the types of materials used to make them.
Here they are in no particular order:
- Metallic Gasket
Metal is the material of choice for ring-type joints within high-pressure applications, such as the ever-popular oil and gas supply production. Metal ring type joint gaskets are used on pipework and valves, assemblies in refineries, etc.
This type of gasket seals initial contact lines or wedging action as compressive forces are applied. They are available in octagonal and oval cross-sections.
- Non-metallic Gasket
They are usually made from graphite, rubber, compressed non-asbestos fiber (CNAF), Teflon, and PTFE. They are designed to compress quickly with low tension bolting and are often used for low temperature/low-pressure applications.
Graphite gaskets can be used in environments with incredibly high temperatures as high as 460 degrees Celsius. Elastomer and rubber gaskets are generally not used for pipelines transporting hydrocarbons.
- Composite Gasket
This type of gasket combines metal and non-metal materials, usually based on service requirements. Spiral wound, kammprofile, and metal jacketed gaskets are in this category. They are used extensively in a wide range of temperature and pressure services.
They are highly cost-effective though careful handling is required. They are used on male-female, raised, tongue-and-groove flanges.
Types of Gaskets
Several standards in gaskets for flanges of pipes exist today. They exist under the following categories:
1. Ring Gaskets
They are also known as RTJ – for TRJ flange faces – and are commonly utilized in oil and gas pipelines offshore. They are primarily designed to work exceptionally well under enormous high pressure.
Ring gaskets are solid rings of metal but with different cross-sections like octagonal, oval, round, etc. Some ring gaskets come with a hole in their center for pressure.
2. Sheet Gaskets
A sheet gasket is punched out of a sheet of a particular material such as composite asbestos. Crude, inexpensive, and fast gaskets are usually created this way but serve the purpose for which they are made.
Sheet gaskets can also be made from matted graphite or other fibrous materials. They meet numerous chemical requirements, often based on the inactive status of the material employed. For instance, non-asbestos sheet gaskets are ideal for multiple materials since they are generally thick.
Sheet gaskets find excellent application in corrosive chemicals, acids, mild caustics, or steam environments.
3. Spiral Wound Gaskets
This type of gasket is created using filler material and metal. Gaskets in this category are carbon-rich or fabricated from stainless steel. They are then wound outwards, taking up a circular spiral with the filler material, such as flexible graphite, though it is possible to take up other shapes. The latter is also wound in the same manner but from the opposite direction.
The result is an alternating layer of metal and filler. The latter acts as the sealing component, while the metal only provides structural support.
Spiral wound gaskets are highly reliable and often used in various applications.
4. Corrugated Metal Gaskets
This type of gasket is fabricated from thin corrugated metal or embossed concentric rings facing flexible graphite or other soft material.
Common types of gaskets include:
- Fishbone gaskets
- Kammprofile gaskets
- Flange gaskets
- Jacketed gaskets
Different gaskets exist and are employed based on their applications and usage. These are the major types of gaskets used in piping, and each one is suitable for its environment and application.
Since gaskets are made from a wide range of materials, you have several options to work with. Therefore, it is essential to fully understand the uses as well as applications of every gasket type in order to ensure you take full advantage of it.
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