Sealing Gasket Solution: How to Choose the Suitable Gaskets for Your Applications

PTFE envelope gasket

There are so many kinds of sealing gaskets, and how to choose the suitable gaskets for your applications?

With various types of sealing gaskets and different sealing materials, it is critical to choose the right material and right type of gaskets for our applications.

Here we analyze and compare six common materials for your reference.

Industrial Rubber

  • Natural rubber is suitable for the use in water, seawater, air, inert gases, alkali, saltwater solutions, and other media, but not resistant to mineral oil and non-polar solvents. It cannot be used for a long time in the environment of temperature over 90℃, but it’s an excellent material to be used at -60℃ due to its low-temperature performance.
  • NBR is suitable for petroleum industries such as petroleum, lubricating oil, fuel oil, etc. Its working temperature is 120℃ and can withstand low temperature to -10~20℃. However, when it’s used in hot oil, the max. working temperature can be 150℃.
  • Neoprene Rubber is good for seawater, weak acid and alkali, salt solution. It has perfect oxygen resistance and ozone aging performance and oil resistance.

The working temperature is from -30~90℃.

  • Viton rubber has good acid resistance, oxidation resistance, oil resistance, solvent resistance. It can be used in almost all acid media as well as some oils and solvents. The working temperature is ~120℃.

 

Gaskets made from rubber sheets are always used in pipes or manholes and handhole which is often removed and with pressure not exceed 1.568Mpa. Due to its softness, the rubber gaskets can provide a sealing function under a light load. But it’s easy to be a blowout when under internal pressure. Rubber gaskets are the best choice for the vacuum environment of low pressure (less than 0.6Mpa).

The rubber gaskets are easy to be swelling, weight-increased, softer and sticky when in some organic solvents like benzene, ketone, etc.

PTFE Material:

PTFE is easy to creep under pressure and high temperature, so it’s always used in applications of low pressure, medium temperature, strong corrosion.

The friction coefficient of PTFE is small (when the pressure is over 4Mpa, the friction coefficient 0.035~0.04), which results in the slip outward when preloading. To solve this problem, the gaskets are better to be used to raise the face flange. When used in a flat face flange, we should make the gaskets’ outer diameter contact with the bolt which can prevent the gaskets’ slipping outward.

Metal Jacketed Gasket:

The metal jacket provides a protect of the filler from outside media, in this way it improves the filler material’s sealing function to work a long time and can be used for a wider range of applications.

When the temperature is over 450℃, the filler material should be ceramic tape or carbon fiber tape, and graphite filler is also a common material for metal jacketed gaskets.

Metal jacketed gaskets can be manufactured to different shape and different dimensions used in heat exchangers, manhole flanges, etc

We can also stick a graphite layer on the metal jacketed gaskets’ both sides to provide a better sealability.

Spiral Wound Gasket:

With the metal’s heat resistance. resilience and strength together with non-metallic material’s softness, spiral wound gasket is a perfect sealing choice.

Graphite spiral wound gaskets can withstand the pressure of 14.7Mpa in air and 30Mpa in liquids and its working temperature is -190℃~+600℃.

PTFE Spiral wound gaskets are suitable for use in low-temperature environments and at the same time, it can used in corrosion applications. The working temperature is up to 200℃.

   When referring to medium pressure and temperature over 300℃, we should consider using spiral wound gaskets with inner rings and outer rings.

Metal Flat Gasket and Kammprofile Gasket:

Metal flat gaskets and kammprofile gaskets are used for valves and pipes and flanges of high pressure.

Ring Joint Gasket:

Ring Joint gasket is used in RJ flanges. Octagonal RTJ is a face seal gasket while oval RTJ is a line seal gasket.

Besides the above, we also provide RX, BX, SRX, SBX according to API standard.

The ring-type joints are precision machined from solid metal and designed for high pressure and high-temperature services. The gaskets material should be softer than the flange material in case of any damage to the flanges.

 

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