Rubber gaskets play an important and widespread role in everday life. These common items perform a sealing function, preventing the unintended escape or release of liquids, gases, and semi-solids. In industrial and automotive applications, gaskets are an integral part of equipment, machines, systems, and components, ensuring safe operation and reliable performance. In this blog, we provide tips that readers will find helpful for choosing the right rubber gasket for their particular application.
Every application is different, and there is no one gasket material that will successfully service all applications. Choosing the right material is critical for ensuring that a rubber gasket will not fail when placed into service and that it will continue to provide an effective seal over its expected life cycle.
General application factors that should be considered when choosing a rubber gasket include the risks to be managed, whether the gasket will need to support continuous versus intermittent operation, whether the application constitutes standard or severe service, the equipment or joint being sealed, (including the type, number and size of fastening bolts required), and the presence of any regulatory requirements (i.e., NSF/ANSI 61 for potable water applications, or Low-E for low emission requirements). Beyond these general requirements, more specific application-related requirements, such as temperature, pressure, media compatibility, as well as hardness and compression set, must also be considered. These are discussed below.
Reviewing the application requirements, especially temperature and pressure as discussed below, will be useful in highlighting the type of gasket that should be employed. For example, while gaskets made from elastomers or compressed non-asbestos sheet work well for many applications, there are some critical applications involving high temperatures and pressures that require the use of metallic or semi-metallic gaskets.
Some elastomers lose strength at higher temperatures. When considering the temperature that a rubber gasket will be exposed to within an application, it is important to consider time as a key factor. What is really important is the length of time that the gasket will be exposed to the maximum temperature likely to be encountered. For this reason, the continuous maximum service temperature is a more relevant and useful parameter than just knowing the maximum temperature alone. As a general rule, as an application’s temperature increases, the range of suitable gasket materials becomes more limited. More precisely, as an application’s temperature approaches the maximum continuous operating temperature recommended for a given material, it will be necessary to consider an alternative material.
Pressures within an application can vary widely. Because gasket materials vary in their ability to support the pressures that may exist within an application, the maximum pressure to be serviced by a gasket must be known. As with temperature, as application pressures increase, the range of suitable materials will likely narrow. In addition, pressures may not be continuous within an application and the gasket material may be subject to pressure changes that result from process cycling. A competent gasket supplier will be able to offer guidance on the best material to choose given the range of service pressures that may exist within an application.
Because temperature and pressure are closely related within an application, the product of the application’s maximum pressure and temperature (PxT value) can be helpful in material selection. If the gasket material you are considering has a PxT value that is close to your application’s PxT value, you may want to consider using a more robust material.
Gasket materials also have varying resistance to the different fluids and gases with which they can come into contact within an application. Some media are relatively benign, while others, for example, are highly corrosive and may break down a gasket whose material is not able to withstand the aggressive chemical attack. It is therefore important to know the characteristics and properties of the media being sealed and to choose a gasket material that is fully compatible. Once again, competent suppliers will be able to provide guidance on the gasket materials that will best service the media present in your application.
Durometer refers to how well a gasket material resists indentation. As a general rule, a rubber gasket should be soft enough to fill and seal the gap between two surfaces, but at the same time needs to be hard enough to resist loading forces and not be extruded out of the joint. Hardness of a gasket elastomer is typically measured by the Shore A scale. Gasket hardness is a relative term – what is hard enough for one application may be too soft for another, so care needs to be exercised in specifying the hardness desired.
Compression set refers to how well a gasket material returns to its original thickness after a load has been imposed. Over time, as a rubber gasket is compressed by a load, it loses resiliency and the ability to return to its original thickness. This loss of resiliency may reduce the gasket’s ability to maintain an effective seal. Because there are different methods of measuring and specifying compression set, it is best to seek advice from a competent gasket supplier on the preferred material for a given application.
Gaskets of different types and made from different materials naturally have different costs. However, the purchase cost of a gasket is only one component of the total costs incurred over the gasket’s life cycle. Other costs, beyond the purchase cost, should be considered as relevant costs – including costs for installation, inspection and maintenance, downtime, and disposal. Because the purchase price is only one element in the total life cycle costs for a gasket, a gasket which is initially cheaper to buy, but which needs more frequent replacement than another, may actually be more expensive in the long run. Therefore, total life cycle costs, and not just the purchase costs, should be considered when choosing gaskets.
Gasket fabrication requires experience, expertise, access to the best materials, and excellent manufacturing capabilities. Reputable suppliers have the knowledge and experience to help their customers choose the right gasket for their application. These suppliers fabricate their gaskets from quality materials, using proven manufacturing methods and techniques. They also carry a wide range of gasket materials, meaning that they can service most applications and ensure ready availability. Finally, for specialized applications, such as those where an oversized gasket may be needed, good suppliers will have the expert fabrication capabilities needed to produce these items.
For over 30 years, CRG has been supplying our customers in Canada and beyond with the finest rubber gaskets. We are a full-service provider that can support all aspects of your gasketing needs. Our experienced team can provide guidance on selecting the appropriate material for your application, and we use the latest CNC technology to produce high-quality gaskets made exactly to your specifications. We stock a wide range of gasketing materials, including elastomers, compressed non-asbestos sheet, and foams and sponges, allowing us to fabricate gaskets for almost any application. We can handle orders of any size and emergency service is available upon request. To find out more about how CRG can service your rubber gasket needs, contact our sales team directly at firstname.lastname@example.org.
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