What is a Rubber Gasket? What to Consider while Selecting Rubber Gaskets?

A gasket is a seal that is made of rubber, plastic, or other synthetic material. They are used to seal or protect openings in equipment such as boilers, air conditioners, furnaces, and water heaters. Gaskets are typically installed on the outside of the equipment, but they can also be installed on the inside.

Rubber gaskets are flexible components used to mechanically seal a microscopic gap between two mating surfaces or joints. Such surfaces are, for example, flanged surfaces of pipes and joints, connecting surfaces of the car cylinder head and engine block, tank edge and cover, door edges, door frames, etc. Rubber gaskets seal surfaces by flowing in and filling surface irregularities of rigid parts. The sealing effect is created by parts that apply compressive forces that make the sealing plastic. Natural or synthetic rubbers belong to a family of materials called elastomers. Elastomers are a class of highly elastic polymers created by linking long polymer chains into amorphous structures. The intermolecular forces between polymer chains are relatively weak. This allows them to reconfigure under stress. Thanks to this property, elastomeric seals easily adapt to the profile of surfaces and form a tight seal.

Here are the factors to consider to choose the right rubber gasket.

Application of Rubber Gasket

The application includes considering when selecting a rubber gasket include hazards, whether the gasket’s support is required continuously or intermittently, whether the application is standard or heavy maintenance, and whether the hardware or joint is sealed (including the type, number, and size of mounting, bolts required), and any regulations. The requirements of every specific application are different, and there is no single gasket material that will successfully serve all applications. Choosing the right material is critical to ensure that the gasket is not damaged during service and that it will function as an effective seal throughout its expected life.

Environmental Factors

A number of environmental factors can affect the longevity of the seal. In addition to the temperature, the following four factors are critical to the success or failure of a seal:

• UV radiation: Exposure to UV radiation can be damaging to the gasket.
• Moisture Resistance: Materials can degrade when exposed to moisture, causing failure.
• Chemical Resistance: Acidic, corrosive, toxic, or abrasive chemicals will affect the integrity of the gasket or seal.
• BSR and NVH damping: Vibration can damage sensitive parts, causing product failure and annoying noise.

Testing the chemical resistance of the gasket against the corrosive properties of the liquid it works with is essential. Some can withstand oil, but should not be used with oxygenating fluids. ePTFE is excellent for all applications in the pH range of 0-1, but cannot tolerate molten alkali metals or certain elements. When looking for a sealant, make sure you know what fluid you’re dealing with.

Temperature

Consider the temperature that the rubber seal will encounter in the application along with time as a key factor. The amount of time the gasket is exposed to the highest possible temperature is the key to its longevity. As the temperature of the application increases, the choice of appropriate sealing materials becomes more limited. Specifically, if the operating temperature approaches the maximum continuous operating temperature recommended for a given material,  an alternative material must be considered. Therefore, the continuous maximum operating temperature is a more important and useful parameter than simply knowing the maximum temperature.

Pressure

The ability of the gasket material to resist the pressures that can occur in an application is different, the maximum pressure of the gasket must be known. As with temperature, the selection of suitable materials narrows as the applied pressure increases. In addition, pressures within an application may not be constant, and seal material pressure may change due to process cycling. An expert gasket supplier can provide guidance on selecting the best material based on the operating pressures that may occur in the application. Since temperature and pressure are closely related in an application, the product of the application’s maximum pressure and temperature (PxT value) can be useful in material selection. If the PxT value of the sealing material you are considering is close to the PxT value of your application, you should consider using a more durable material.

Cost

The purchase price of the gasket is only one part of the total costs incurred during its life cycle. In addition to purchasing costs, other costs including installation, inspection and maintenance costs, downtime, and disposal should be considered as related costs. Since the purchase price is only one part of the total life cycle cost of the package, an initially cheaper but more frequently replaced package may be more expensive in the long run. Therefore, when choosing gaskets, the entire life cycle costs must be considered, not just the purchase costs.

Harkesh Rubber’s sealing solutions are precisely calibrated with high-quality material and torque-reducing designs. Our gaskets have a high-pressing action that results in excellent sealing all while operating with just the required amount of force. Get in touch with our industry experts to learn more.