This is the first of a series of blog posts on the types of materials used to make industrial gaskets. Generally speaking, the types of gasket can best be described by the materials of construction and classified as non-metallic, semi-metallic and metallic.
We’ll begin with the broad Non-Metallic Category. Included in this category are the gaskets made from elastomers.
Elastomer gaskets are used generally in low to moderate pressure ranges, and in a wide ranges of chemical service including acids and alkalis up to moderate temperatures and miscellaneous low duty applications.
Elastomer gaskets are generally only used for relatively low pressure applications as at high seating stresses a rubber gasket may extrude from between the flanges. (Note that rubber in itself is incompressible and has to displace.) There is a vast range of elastomeric materials available. These include natural, nitrile, neoprene, butyl, ethylenepropylene, fluorocarbon and silicone to name but a few. Thus, a wide range of chemicals can be catered for. Some of the more common and popular types of elastomers used for gaskets are:
Hexafluoropropylene-Vinylidene Fluoride (FKM or FPM)
Most common trade names: DuPont VITON® and 3M FLUOREL®
- Resistant to aliphatic, aromatic and halogenated hydrocarbons, acids, animal and vegetable oils
- Attacked by ketones, low molecular weight esters and nitro-containing compounds
- Good weathering properties and resistance to elevated temperatures
- Available in several types and grades
- Temperature limit: 400ºF (205ºC)
Neoprene – Chloroprene (CR)
- Resistant to moderate chemicals, acids, oils, fats, grease, many solvents and ozone
- Attacked by strong oxidizing acids, esters, ketones, chlorinated, aromatic and nitro hydrocarbons
- Good weathering resistance
- Flame retarding
Nitrile or Buna-N – Acrylonitrile Butadiene (NBR)
- Generally resistant to fats, oils, greases and aliphatic hydrocarbons
- Not ozone resistant
- Attacked by ketones, esters, aldehydes, and aromatic chlorinated and nitro hydrocarbons
SBR or Buna-S – Styrene Butadiene (SBR)
- Fluid compatibility is similar to “Natural”
- Good physical properties
This list of materials is not intended to be comprehensive, but rather to represent some of the more common types of rubber used in rubber gasket production. As always, remember, selecting an elastomer for your particular application, depends on the operating criteria the gasket is expected to function in.