Main Types of Flange Gaskets Used in Pipes
There is a reason for the creation of different types of flange gaskets. They each provide a different use, depending on the application and environment. Below is a breakdown of the main ones to know.
The main types of flange gaskets used in pipes (in the oil and gas industry) help to prevent leakage from these pipes. As such, gaskets reduce the potential for product and energy to leak from flanges joints.
It’s worth noting that leakages can release harmful substances that impact on human health and the environment. On the other hand, we’ve outlined flange gasket types, their functionality, and generally, all you need to know about gaskets used in pipes.
What is a Gasket?
A gasket is a mechanical seal that is placed between two or more surfaces in contact. The seal prevents leakage from or into the joint components during compression.
When it comes to piping, gaskets are the sealing material placed between flanges to create static seals. There is no leakage from the flanges joints irrespective of the operating conditions within these pipes.
Other Functions of Gaskets
Gaskets serve other purposes asides from preventing leakages in flanges. These materials have applications in anti vibration and mounting.
Gaskets are also used in fuel tank boilers and other closed vessels.
These materials have found application in electrical transformers where they are used to seal the oil and water tanks to prevent leakage. Some have found use cases as weather seals to increase the ingress protection (IP) rating of compartments.
Types of Flanges Gaskets Used in Pipes
The main types of flanges gaskets used in pipes are:
- Non-metallic gaskets
- Metallic gaskets
- Composite gaskets
It is important to choose the right gasket material for your application and the environment the gasket will be used.
Accordingly, here’s a breakdown of each gasket material.
1. Non-metallic Gaskets
These gaskets can be made from different materials including Compressed Non-asbestos Fibre (CNAF), PTFE Rubber, Graphite, or Teflon. What’s more, these gaskets can compress easily with low tension bolting.
A gasket like the Non-asbestos gaskets full and raised face are used for low-pressure, low-temperature, and non-critical applications.
However, graphite gasket makes an exception since it can be used for temperatures that are as high as 460 degrees centigrade. Further, rubber gaskets have not found a use case in pipelines employed in transporting hydrocarbons.
Here’s a more detailed outline of the Non-asbestos gaskets:
These are the simplest types of flanges gasket. They are produced by cutting organic or inorganic non asbestos sheets into the desired shape.
There are two main types of non-asbestos gaskets and these are the full face (FF) flanges and the flat ring type for raised face flanges (RF).
Materials used to make non-asbestos gaskets are not limited to:
- Aramid NBR binder
- Fluorocarbon (Viton)
- SBR (styrene-butadiene)
- CR-chloroprene (Neoprene)
- Carbon graphite reinforced
- EPDM gasket (ethylene propylene)
- Glass reinforced (steam service gasket)
- PTFE bi-axially oriented (silica filler)
2. Metallic Gaskets
Metal gaskets are used for ring type joints (RTJs) in high-pressure applications. RTJs are used on valves and pipework assemblies in several process industries including refineries. They tend to seal via initial line contact or a wedging action as compressive forces are applied.
Ring joint gaskets style R, RX, BX are used for RTJ flange faces.
Here’s a more detailed outline of Ring joint gaskets:
Ring Joint Gaskets R, RX, BX:
This type of gasket offers a strong and durable seal between two joined RTJ flanges. Here, the softer material of the ring joint gasket is squeezed into the flanges groves as the flanges are bolted.
Coupled with that, there are three styles of RTJ gaskets and these are R (oval, octagonal), RX, and BX.
Ring Joint Gaskets Materials Types:
These materials include:
- Soft Iron
- SS316L UREAD
3. Composite Gaskets
The gaskets are created from the combination of metal and non-metallic material based on service materials. They are a cost effective option to metal gaskets even though they have to be carefully handled.
The types of composite gaskets are Spiral wound, Kammprofile gasket, and Metal Jacketed gasket. These gaskets are used in several pressure and temperature services.
Spiral wound gaskets, for instance, are used in higher temperature and pressure oil and gas applications.
Let’s take a quick look at the gasket types in this class.
Spiral Wound Gaskets:
These gaskets are classified as semi metallic gaskets. This is because they have a metal sealing element filled with PTFE, graphite, ceramic fibers, and non-asbestos fibers (fillers). The metallic component of the spiral wound gasket gives the seal strength while the fillers improve the resilience and conformability of the gasket.
There are different types of spiral wound gaskets and they are classified depending on the number of rings and the materials of the gasket’s inner and outer ring.
Spiral Wound Gasket Types:
Spiral wound gaskets types include:
- Type 00: These are Spiral Wound Gaskets without rings. Often used for tongue and groove, male and female flanges.
- Type 01: These are Spiral Wound Gaskets with an inner ring. They are used for male and female or special flange types.
- Type 10: These are Spiral Wound Gaskets with an outer ring. They are used for raised face flanges.
- Type 101: These are Spiral Wound Gaskets with inner and outer rings. They are used for raised face flanges.
Spiral Wound Gasket Materials:
The winding materials include:
- SS 304L
- SS 316L
- SS 321
- Nickel alloys
Kammprofile gaskets are made through the application of a sealing layer in non-metallic or metallic materials on both sides of a metal core. The application of Kammprofile gaskets spans across industrial, power generation, petrochemical, and nuclear installations.
The gaskets are used to seal flanges, superheaters, heat exchangers, and other pressure equipment. These gaskets are also of two types, parallel root cores/convex root cores, and two designs.
The materials of a Kammprofile gasket are:
- Soft Iron
- Steel (LCS)
- Stainless Steel 309
- Stainless Steel 304
- Stainless Steel 304 L
- Stainless Steel 316 L(1)
- Stainless Steel 316 Ti
- Stainless Steel 321
- Stainless Steel 347
Metal Jacketed Gasket:
This gasket has an interior soft material core, as well as, an outer metallic shell. The filler within offers resilience to the gasket while the metal gasket shields the inner core of the gasket.
Some jacket materials include:
- Carbon Steel
These are the main types of flange gaskets used in piping. Each gasket material is best suited for its application and the environment it will be used. The wide range of these materials means you have several options to work with.
Therefore, understand the uses and applications of each gasket to make the most of it in your piping system.
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