Compression Gaskets vs Formed-In-Place (FIP) Gaskets: A Comparison
Advantages of Compression Gaskets
Compression gaskets are pre-formed to a specific size, shape, and thickness. Formed-in-place (FIP) gaskets or liquid gaskets are liquids that cure after the parts are assembled. Both have their uses, and one may be more suitable than the other, depending on the application.
Compression gaskets are made from a variety of materials, including cork, rubber, and synthetic blends. Formed in Place or FIP gaskets are either anaerobic adhesives or room temperature vulcanizing silicone. Again, the choice between an anaerobic adhesive or an RTV silicone will depend on the application.
The use of pre-formed conventional compression gaskets is widespread and is normally the first port of call for a customer looking for an instant pressure seal.
Advantages of Formed-In-Place Liquid Gaskets
Formed-in-place liquid gaskets are increasingly used to reduce inventory of various size and shape gaskets and to increase seal strength.
The advantages of formed-in-place gaskets over compression gaskets include:
Improved reliability
If metal surfaces are damaged or scratched, the adhesive will flow into the gap and prevent leakage
No need to store gaskets in all shapes and sizes – reduced inventory
Can apply automatically, so ideal on a production line
Eliminate bolt retorquing – lower servicing costs
Easier Application
Single component – no mixing
Easy to automate
Rapid curing and certain products give instant low-pressure sealing before full cure
Easier service
Formed-in-place gaskets allow easier disassembly and clean-up than compression gaskets
One package for multiple flange size
Benefits of Anaerobic Gaskets
Benefits of anaerobic gaskets over traditional sealing systems include:
No gasket relaxation (so no need to retighten, therefore reducing servicing costs)
Non-shimming
Structural strength
Excess material remains liquid (so it easily flushes through the system)
The surface finish of metal components needn’t be “mirror finish,” scratches and imperfections are catered for
No cure before assembly
Reduced inventory costs
Chemical compatibility
Ideal for heavy-handed people that have problems handling pre-formed gaskets without damaging them!
Limitations of Anaerobic Gaskets
Anaerobic adhesives do not offer gasketing solutions for all applications. Limitations include use on applications that require temperature resistance above 200°C and gaps greater than 0.5mm. For applications requiring temperature resistance over 200°C or where gap fill requirements are greater than 0.5mm, consider silicone gaskets.
Benefits of Silicone Formed-In-Place Liquid Gaskets
Benefits of Silicone formed-in-place liquid gaskets include:
Ideal for sealing large gaps
Highly flexible, so they flex with flange movement
Can cope with scratched, damaged or pitted metal surfaces
Reduced inventory costs, again there is no requirement to have a large stock of various shapes and sizes of pre-formed gasket
Temperature range of between -70°C to 315°C for most; some achieve nearly 350°C!
Good adhesion to a wide variety of metals
Limitations of Silicone Formed-In-Place Liquid Gaskets
Limitation of Silicone “formed-in-place” liquid gaskets
Poor resistance to fuel and aromatic solvents
Not recommended for high-pressure applications due to their high elongation, low shear, and low tensile strength.
Relatively slow cure speed
Choosing the Best Gasketing Method for Your Application: Considerations
There is no single answer that is correct for all requirements or all applications. Understanding the limitations and benefits of each method allows the best selection for the application.
For further help and advice, please contact Permabond.
