Gaskets are usually inexpensive to purchase but play a crucial role in the devices they are present in. A gasket’s primary role is to provide a strong seal to a gas or liquid throughout the life cycle of a device. Efficient design of gasket is required since it covers up for any imperfections in the mating material.
Though gasket applications vary to a great deals, some commonalities between them should be analyzed to make sure the seal serves its purpose in the device.
The following key parameters need to be considered while selecting the material for gasket:
Temperature is one of the many key factors affecting material selection. Temperature can alter various properties of gasket material, for example stress level and maximum tolerance of the material to temperature. Internal and external temperature both should be considered while performing stress testing. Gaskets may also face large variations in temperature from very high temperatures to low freezing temperatures. Thus determining the range of temperature variation is also very essential in material selection.
If the pressure level exceeds and gasket is weak, it may completely break. Thus pressure and temperature both are considered as key parameters to judge suitability of a gasket material.
Media stands for the liquid or gaseous component that the gasket is sealing. Once a suitable material matching the temperature and pressure level is selected, we need to make sure that material doesn’t cause any adverse reaction with the media component. Various chemicals may impact both structural and functional properties of the material.
UV & Ozone:
UV and Ozone may cause degradation of rubber made gaskets. Ozone is found in atmosphere as well as electric set ups. Drying, cracking or hardening would be signs of degradation due to UV.
EMI & RFI requirements:
Gaskets in automotive and aeronautic devices may need to meet several EMI standards for their products. To restrict EMI emitted by wires, they need to be encapsulated in conductive materials Thus to fulfil this requirement gasket material should be conductive in nature.
In general, depending on the medium, the gasket material should have following properties :
Impermeable: Material must not allow any kind of leakage even when exposed to high pressure.
Resilience and Strength: Must adapt itself according to all irregularities on flange surfaces and provide sufficient tensile strength to resist blow-out under operating conditions.
Creepage: Must not spread under high bolt pressure or high contained fluid pressure – even at high temperatures.
Chemicals: Must not be weakened by a wide range of fluids even when exposed for extended periods at high temperatures.
Temperature: Must remain robust for long periods of time at low or high temperatures.