Industrial GaskGaskets Guide
Industrial GaskGaskets Guide
Industrial GaskGaskets Guide
28 Feb 2014
Is A Gasket The Same As A Seal? What’s The Difference?
Firstly a gasket does seal two parts and stops liquid or gases inside from leaking out, but it’s not the same thing as a seal. Gaskets are used where two fixed/stationary parts need to be fixed together and sealed. Seals on the other hand are used where one or both elements have moving parts. This article relates specifically to gaskets, but you can click the link to read our guide on industrial seals.
Why Is A Gasket Required?
No matter how finely two parts are smoothed and how well you bolt them together, at a microscopic level, there will be gaps through which liquids or gases can escape. Where the inner workings of the equipment create heat and/or pressure, the liquid/gas will become more viscous and simultaneously the pressure will force it out from any weak points. This can be catastrophic to a machine running under extreme forces and heat, which therefore requires constant lubrication and heat dissipation, or where the equipment is pumping liquid/gas in a production facility.
Placing a gasket between these parts using a different material effectively ‘fills’ these microscopic gaps and creates an effective barrier to keep the liquid or gases in.
What Are The Key Considerations When Buying Gaskets?
There are a number of very important things to consider when buying gaskets:
- Dimensions: This includes some basic elements, such as the number and size of bolts (requiring holes or indents) in the gasket and the dimensions of the gasket required (pipe size, inner diameter, outer diameter, bolt hole diameter, thickness, etc). Your engineering team should be able to provide all these to you and the gasket supplier/manufacturer will ask for any other relevant dimensions they need.Next comes the grade of the bolts required. This will identify the downward pressures exerted on the surface of the gasket and therefore the level of compression. In turn this will determine the type of materials required to form a durable seal.
- Application: There are many different applications for gaskets. Differing liquids, from water to oil and chemicals; gases, which might be toxic or indeed require protection from external contamination; or even to protect sensitive equipment from electromagnetic/radio frequency interference or leakage of same from equipment. Finally, does the application specifically require non-conductive materials to be used in the gasket?Whatever it is you are trying to stop getting in or out will have a direct impact on the materials and type of gasket used. Your gasket manufacturer will discuss this with you and determine whether an off-the-shelf industrial gasket will suffice or whether a custom gasket will need to be designed and manufactured for you.
- Lifespan: A gasket to be used in a part that is serviced regularly will be very different from a part that must remain sealed and fully operational for many years. Lifespan is therefore a very important factor.
- Pressure: The amount of pressure acting on the gasket will be critical to determining the material used. Already mentioned in the Dimensions section, the pressure downwards will determine how much the gasket needs to deform and the type of material used. However, more importantly is the amount of pressure from inside (or outside) the equipment/pipe.
- Temperature: Extreme temperatures, whether high or low, will have a direct bearing on the gasket material and type. Temperature fluctuations must also be determined, which will cause extra stresses through expansion and contraction of all materials.
- Compatibility: Often overlooked, some materials/compounds are not compatible with each other and so those combinations must be avoided. Additionally, where equipment is flushed, the liquids or gases used in this process must also be determined to ensure premature degradation of the gasket does not occur.
A note on pressure and temperature:
These two factors are closely related and impact on each other (as heat rises pressure does too and vice versa). Therefore ensure these factors are discussed with your gaskets supplier thoroughly to avoid excessive failure rates.
What Type Of Gaskets Are Most Common?
The most common gasket types are:
- High-Temperature Gaskets Used in high temperature, high pressure and corrosive environments. Most commonly made from metal, carbon and/or graphite.
- Metal Gaskets Metal gaskets can be used in many and varied applications from low-stress/pressure/temperature to very high stress/pressure/temperature. They can be flat metal, serrated or corrugated and can be made from very hard metal to softer metal. They may also have a soft filler material for specific applications.
- Rubber Gaskets Rubber gaskets are ideal in applications that require flexible seals and may have fluctuating temperatures. It also helps where noise/vibration dampening is a requirement. Made from a wide variety of materials, including PVC, Silicone, Polyethylene, Polyurethane, Neoprene or EPDM; rubber gaskets provide the best combination of flexibility, sealing qualities and durability.
- Soft-Cut Gaskets These gaskets are made to easily compress and therefore provide excellent seals in applications that have low bolt load. Typical materials include PTFE, Asbestos, Flexible Graphite, Soft Rubber and Metal.
- Sponge Gaskets Made from sponge and foam materials, these gaskets are ideal for moisture, dust, powder, air and gas retention. Used in relatively light bolt loads, they can be made in Open Cell and Closed Cell configurations, whereby open cell provides more compressibility and closed cell does not easily compress and so are ideal for water exclusion and sound/gas retention.
Abbey Seals International Limited is Ireland’s premier manufacturer of Gaskets and distributor of O Rings and Seals. Established in 1983, Abbey Seals has over 30 years of expertise in gasket and seal applications across virtually every sector and industry, both domestic and international.
Our unique approach means that we can have the product you require delivered to your door within hours of ordering.
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