Stainless Steel

The term stainless steel is applied to a range of iron based alloys which rely on their chromium content for resistance to corrosion. The chrome thats containd in the alloying oxidized and generates a hard invisible surface protection layer that prevents further corrosion – until the surface gets damaged and the process repeated itself.

The steels used by Flexseal have 17%-18% Chromium content and 8% -11% Nickel content and are in full compliance with the manufacturing standards and has a life span up to 100 years.

In poorly drained gravel ground and the existence of industry and coal mining and in cases where the grounds and the ground water with a chloride concentration more than 1000 ppm the quality tend to pittng corrosion.

Because of this Flexseal offers two different steel grades. By standard all used steel pieces are out of autentic stainless steel according to DIN 1.4301 (V2A).

For the contaminated grounds mentioned above and also for special sealings we can equip our bushes with a steel quality according to DIN 1.4401 (V4A) if it is desired. An increased molybdenum addition in the alloying improves the corrosion-resistance of the steel by a multible.

Standard configuration:
authentic, stainless steel – DIN 1.4301 – AISI 304 – V2A

Special equipment:
authentic, stainless steel – DIN 1.4401 – AISI 316 – V4A


Our seals are  -depending on the DIN-specifications – produced with elastomeres according to DIN 681-1 and DIN 681-2.

Mainly the following elastomer-types are used :

EPDM Rubber (Ethylene Propylene Diene Monomer)

EPDM is a terpolymer elastomere and belongs to the copolymeres with sated polymerframe. Because of its excellent resistance to ozone, sunlight and severe weather conditions, EPDM is ideal for outdoor service. It has good resistance to alkalis, acids and oxygenated solvents and therefore it is an ideal sealing material.

NBR Rubber (Nitrile or Acrylonitrile Butadiene)

NBR Rubber can be offered as an alternative material for instances when the drainage effluent is contaminated by hydrocarbons, oils, fats and greases. It should be noted that the nitrile compound is classed as medium grade and is therefore only suitable for drainage applications.

ATTENTION: If you want to use our NBR-sealing for sewage foreign purposes, please contact our sales office. There you will be informed if the seal is suitable for your purpose.

SBR Rubber (Styrene Butadiene)

SBR Rubber as one of the most common synthetic caoutchouc comes with similar properties like NR (Natural Rubber), but loses its elastic requirement in evidence.

NR (Natural Rubber)

NR is mainly made out of polyisopren and gets extracted  from plants that grow in tropical areas, especially euphorb family.It has good elastic properties but ages quite fast.






Ozone Resistance


adequate adequate


Acid Resistance


adequate satisfactory


Liquor Resistance


adequate satisfactory


Electric Resistance


poor good


Impact Rebound


satisfactory satisfactory


Elongation at Break


good good




good adequate


Oil Resistance


good poor


Fuel Resistance


good unsatisfactory


Temperature Window

– 50° to +150°

– 30° to +100° – 40° to +80°

– 40° to +80°

Short-term Peak Temperature

+ 160°

+ 130° + 130°

+ 130°

For most of our seals we use high-quality EPDM caoutchouc. Essentially there are used nature rubber or synthetic caouchouc. Our EPDM -mixture contains diffrent additives which ensure the permanent sealing techniqe that is desired.

By heating the EPDM rubber it gets vulcanized. After this process the rubber is extremely elastic. It is possible to form the material at will without loosing its initial shape.

EPDM is resistant to most of the acids and chemical bases that appear in waste water (detailed inventory list is available). At the same time EPDM resists temperatures up to 160°C. As constant load the temperature is 130°C.