Sealing materials

versatile and tight

Male adaptors are mounted on other threads. Standards often define the type of sealing, e.g. by sealing edge form B according to DIN 3852-2 (metallic sealing), taper thread sealing form C according to DIN 3852-2 (sealing in thread) or profile sealing ring form E according to ISO 1179-2 (soft sealing). We offer sealing rings in various materials, depending on the application parameters.

FKM/FPM – Fluorocarbon rubber

Fluororubber figures among the most significant developments in materials technology of the 1950s. The difference between FPM and FKM is only the name: FPM (according to DIN/ISO) and FKM (according to ASTM). The initial material is FDA-compatible (CFR 21, §177.2600). It is also known under the trading name Viton®.

FKM features high temperature, weathering, ozone and chemical resistance. The temperature application range is from –20°C to +200°C, short term +250°C.

FKM is highly resistant to nearly all mineral-oil and synthetic-based hydraulic fluids, as well as to ozone, oxygen, fuels, aromatic compounds, many organic solvents and chemicals. There are however restrictions for use in hot water, steam and at low temperatures. Due to the diminished low-temperature flexibility and moderate hot water and steam resistance, special materials should be selected for these applications. FKM is also not resistant to polar solvents, such as acetone, glycol-based brake fluids, ammonia gas, alkalis and low molecular-weight organic acids (formic acid and acetic acid).

PEEK – Polyetheretherketone

PEEK is one of the most important representatives of the thermoplastic PTFE plastics which maintains its excellent properties up to temperatures of +260°C.

PEEK is very resistant to water vapour, hydrolysis, fuels, alcohols, greases, oils and alkalis. The material is used for example in guide rings, ball valve hubs etc. that have to meet the highest requirements. It is also well suited to low temperatures down to –100°C.

EPDM – Ethylene-Propylene-Diene-Rubber

EPDM elastomers are very resistant to ageing and weathering, even with UV exposure and ozone influence. They exhibit low water vapour permeability and extremely low brittleness temperature. Due to its high elasticity and good chemical resistance, EPDM is used for diverse seals, such as e.g. o-rings and flat gaskets. The working temperature ranges from –40°C to +160°C, short term up to +180°C.

EPDM possesses excellent resistance to hot water and steam and good resistance to polar liquids, such as acetone, methanol, etc. The material is not resistant to aliphatic and aromatic hydrocarbons (mineral oils, benzine, fuels) and greases.

FFKM/FFPM – Perfluoroelastomer

Chemically, FFKM is very similar to polytetrafluoroethylene (PTFE) and it combines the elasticity and sealing strength of a true elastomer with the chemical resistance of PTFE. Compared to pure PTFE seals, FFKM parts do not demonstrate creep behaviour or yield and little permanent deformation. FFKM perfluoroelastomer parts maintain their elastic properties in long-term operation at up to +315°C and in periodic operation up to +350°C, even when in contact with corrosive chemicals.

Because of its comparably high kilogram price, the applications are limited to those with contact to highly aggressive media, particularly in situations where there are high safety and purity specifications or where the costs in the event of failure would be very high. Such applications are found, for example, in the chemical, petroleum producing and processing industries, equipment manufacturing, power plant construction, semiconductor and food industries or in the aerospace industry.

FFKM parts are resistant to nearly all chemicals, such as ethers, solvents, ketones, esters, amines, fuels, acids and alkalis.  

PTFE – Polytetrafluoroethylene

Due to its outstanding chemical, physical, thermal and electrical properties, PTFE is an important material in a variety of industrial sectors. The material is non-toxic in its pure form and FDA-compatible (CFR 21, §177.1550). The working temperature is between –200°C and +260°C (short term up to +300°C). PTFE has an exceptionally low coefficient of friction, tends, however, to cold flow and only has low resistance to pressure and wear.

PTFE is resistant to nearly all organic and inorganic chemicals (except elementary fluorine under pressure or at high temperatures, fluorine-halogen compounds and alkali metal fusions). At room temperature, PTFE is physiologically stable; contact with aggressive media does not alter its material properties.

VMQ – Silicone-Elastomer

VMQ is particularly characterised by its broad range of thermal application. The very good cold flexibility, the good ozone resistance and the good dielectric properties are additional advantages. The gas permeability is not as favourable as with other elastomers. The working temperature range is between –60°C and +250°C.

NBR – Acrylonitrile-Butadiene-Elastomer

The abbreviation NBR stands for Nitrile Butadiene Rubber. NBR is the most frequently used material in sealing technology because of its good resistance to most mineral oils and greases. The thermal range of application is normally between –30°C and +100°C, short term up to +130°C; at higher temperatures the material hardens. Additionally, NBR exhibits favourable ageing characteristics and low surface abrasion.

NBR is resistant to hydraulic oils, water glycols and oils in aqueous emulsions, mineral oils and mineral-oil products, animal and vegetable oils, benzine, fuel oil, water up to ca. +70°C, butane, propane, methane, ethane. NBR swells greatly with aromatic hydrocarbons, e.g. benzene,  chlorinated hydrocarbons (e.g. trichloroethylene), esters, polar solvents, such as acetone, as well as in glycol ether-based brake fluids.


NBR-LT (Low Temperature) has the same resistance and properties as NBR with a thermal application range from -50°C to +100°C.