It is often recommended that using a thinner gasket type/material will result in better sealing performance.
Why?
Because thinner gaskets tend to require much less gasket stress to provide applications with the perfect seal, they also have an excellent response to relaxation, which results in less surface pressure loss and less loss of thickness.
Thinner gaskets in flanges can also withstand higher bolt loads as well as be less exposed to the media.
However, there is no simple solution or quick answer when it comes to gasket thickness for particular applications. Quite often, it can be trial and error, that and speaking with a sealing specialist who knows a thing or two about gaskets and o ring materials!
The team at Specialist Sealing Products (www.specialistsealinproducts.co.uk) will typically always recommend using a thinner gasket wherever possible. However, we are aware that a thicker gasket is more suitable in some situations and indeed preferred.
Situations where a thicker style gasket is more appropriate include:
- Flanges that are thin in composition.
- Waterline flanges (AWWA), i.e., those with larger diameters.
- Worn or damaged flanges.
- Flanges suited for low internal pressure applications requiring limited bolting.
If there is limited bolting and low compression set on the gasket, thicker gaskets will be preferred as thin gasket materials can warp and twist when bolted. And with slight compression created, thin gaskets simply won’t be able to handle those flat flanges.
This situation mainly occurs in angle iron flanges where the flange is unable to stay flat; hence a suitable seal will not be achieved.
Thicker gaskets are also more suited to warped flanges due to the gaskets unique capability to fill any irregularities as it has the ability to compress across a larger distance. It is this additional compression that allows a thicker gasket to deep fill any low spots or scratches.
One of the main disadvantages of opting for a thicker gasket material, however, is that it can cause relaxation due to higher creep, so retorquing of fasteners to maintain the correct compressive load will be required.
This is compounded further as the gasket’s surface area is increased and exposed to internal pressures, creating a higher force pushing the gasket out of place considerably.
Thicker spiral wound gaskets can also create larger permeation meaning there is a greater risk of leaks.
When flanges are designed for high-pressure applications, they are often thicker and will typically remain flat when bolted. In these situations, thin gaskets are the preferred choice.
Offering:
- High level of resistance to blowouts.
- Less chance of leaks occurring.
- Because of the lower creep relaxation, there is better torque retention.
- A cheaper gasket altogether.
Of course, things aren’t as straightforward as thick or thin, and there are situations where specific thickness levels will be required.
In these circumstances, it is the final compressed thickness that must be considered.
Examples, where bespoke thickness gaskets may be required include:
Split case pumps. Finding the right level of thickness is critical for split pump applications because the clearance between the two halves will be dramatically affected. Most commonly found in these instances is the compressed non-asbestos gasket.
Piping systems. A thin spiral wound gasket may cause spacing issues in a long run of pipe, especially if there are numerous joints throughout the piping system, producing a gap at the end of the run.
Gaskets in grooves. Gaskets in grooved applications must be suitable to fill the space when the application is compressed and before the flanges hit. This means you must calculate the compressed thickness after loading.
With all applications calculating the compression and loading is vital to ensure the right gasket is chosen in order to prevent leaks and potential contamination to products.
You must also consider the type of gasket material as this will also determine the thickness required to seal certain joints.
It’s also important to note that gaskets that offer a higher compressibility value will not require the same level of thickness as harder gaskets that provide less compressibility. This
Is because a high compressible gasket will adapt to flange irregularities much more easily.
Correct installation is essential to support the style and thickness of gaskets.
To help support you further, at Specialist Sealing Products, we provide an extensive range of gaskets, spiral wound gaskets, and o rings in various materials and thickness levels to suit a range of applications across all industries.
To find out more about SSP, visit our website or call us on 01535 274 776.
