We cannot stress enough how important gaskets and seals can be. Gaskets are vital for an application’s reliability and integrity, and trust us when we say, choosing the right gasket now can help you avoid costly issues in the future.
Taking a closer look at pipe flange gaskets
A flange is a way to connect a valve to pipework and other equipment. Ultimately, and in their simplest form, two flanges are joined together and have a gasket placed between them.
We specify a flange by type and facing, pipe size, pressure class, standard, material, and schedule, and these specifications will all be stamped onto the flanges themselves for identification processes.
Flange gasket material selection
When choosing the right gasket, it’s essential that you’re aware of:
Fluid type – the type of fluid the seal will be exposed to, and the pressure and temperature of said fluid are important factors to be aware of. This is because different gasket materials will be required to ensure the flanged joint continues to perform over time. Various pipeline gaskets will resist varying temperatures, pressures, and fluids.
Temperature and pressure rating – the pipe flange gasket you opt for must be able to withstand the highest temperatures and pressures your application will carry out and work with. This is to ensure flanged joints remain effective and prevent leaks. Ideally, your flange gasket should withstand the maximum pressure expected.
Fugitive emissions law – additional guidance and regulations will affect gasket choice and drive decisions about the flanges and gaskets you use.
Vibrations – your chosen gasket and seal must be able to withstand vibrations if this is a factor in the application.
Risk of fluid contamination – this area is vitally important in the pharmaceutical and food and beverage industry with specific applications and processes.
Flange corrosion – does the gasket need to be able to withstand stress corrosion?
Integrity – if you require a completely leak-proof seal that 100% prevents contamination, then a spiral wound gasket is the most obvious choice, providing a much tighter and stronger seal with all round.
Choosing the wrong gasket can have a huge financial impact and negatively affect the end-user, so you need to have all of the information regarding the process, the application and more ready to choose the ideal gasket material.
Factors affecting flange performance
- Gasket outer diameter
- Gasket width
- Fluid type
- Gasket thickness
- Gasket surface finish
- Stress relaxation
Come in two forms:
Flat face – sealing is achieved by compression of a flat non-metallic gasket between concentric grooved surfaces. Fitting over the entire face of the flange, you will typically use flat face flanges for low-pressure appliances.
Raised face – sealing is achieved when the non-metallic gasket fits within the bolts of the flange.
Note: The flange surface finish should always be checked for imperfections, as these can lead to difficulties when trying to achieve the perfect seal.
Types of flange face finishes include:
- Smooth – suitable for gaskets with metal facings.
- Concentric serrated – contains concentric grooves that are spaced evenly across the face.
- Spiral serrated – continuous spiral grooves generated using a 90-degree tool.
- Stock finish – a continuous spiral groove that is suitable for 99.9% of general service requirements.
Types of flange gaskets
Flange gaskets are used to create a static seal between two flange faces. Flange gaskets perform well under varying pressure, temperature, and operating conditions. Designed to prevent leaks, flange gasket materials include non-metallic, semi-metallic, and metallic, and gaskets must be installed correctly into the flange faces to ensure a leak-free connection.
Some of the most popular types of flange gaskets include:
Spiral wound gasket – have the ability to recover from the effects of pressure and temperature fluctuations, i.e., the temperature differences across the flange face matched with bolt stress, creep, and relaxation, requires a gasket with adequate flexibility to recover quickly, maintaining the sealing properties even under those varying conditions. Spiral wound gaskets are the precision-engineered solution. Spiral wound gaskets are great for fluctuating and low bolt loads.
Cam profile gaskets – great for use in industrial applications between flanges and in heat exchanger units. Most suitable where high temperatures and pressure are maintained, so bolt loads need to be controlled.
Metal jacket gaskets – manufactured with an outer metallic shell with either a metallic or non-metallic filer. The filler material provides the gasket with resilience and protection against pressure, temperature, and corrosion. Used for pumps, valves, and heat exchangers. Metal jacket gaskets require smooth flange surface finishes, high bolt loads, and flange flatness to offer good sealing properties.
The good news is Specialist Sealing Products manufacture flange gaskets to various sizes using the latest and the most sophisticated technology available.
Gaskets can be cut from sheet materials such as rubber, sponge, and compressed fibre, all to suit your pipe flange gaskets perfectly.
Reference video: ProjectMaterials.com