Chemical resistance table
|MEDIUM||MEMBRANE HOUSING||GASKETS MATERIAL AVAILABLE|
|AISI 316L / 1.4404||AISI 904L / 1.4539||SILICONE||EPDM||VITON (FKM)||Kalrez (FFKM)|
|Temperature||Up to 425°C||Up to 400°C||Up to +100°C||-40 ÷ +110 °C||-25 ÷ +80 °C||Up to +200°C|
|H2O2 / Peracids||5||4||3||4||5||5|
|brine / chlorides||4||5||5||5||5||5|
|Butter / lard||5||4||5||2||5||5|
|Hydrocarbons (lubricants and fuels)||4||5||3||1||5||5|
LEGEND: 5 - excellent resistance, 4 – good resistance, 3 - conditional use, 2 - use advised against, 1 - complete lack of resistance
SILICONE - is undoubtedly the most popular substance used for gaskets in the food and pharmaceutical industries because it is indifferent to processed raw materials, regardless of whether they have a fat base or not. It is a polymer in which the central atom of the chain is silicon, thanks to which it exhibits low resistance against silicone oils (therefore it is avoided in the cosmetics industry) and oxidants.
EPDM (ethylene propylene diene monomer) - it is distinguished by a great material memory, thanks to which it returns to its original shape after the mechanical stresses cease. Compared to silicone, it is more resistant to abrasion, while at the same time showing better chemical resistance. Its main disadvantage is very low resistance against fats and non-polar substances. Other trade names: Nordel, Polimieri, Buna EP, Keltan, Vistalon, Resitix
VITONTM - is the original name reserved by DuPoint for fluoro rubber. Other common trade names are FKM and FMP. The distinguishing feature of this polymer is its excellent resistance to petroleum products. Compared to silicone, it is more resistant to oxidants. It has the lowest resistance to steam sterilization of all available gaskets.
FFKM - also developed by DuPoint, perfluorine rubber under the trade name KarlezTM is considered to be the best polymer structure for chemical and petrochemical applications. It can be considered as VITONTM with increased chemical resistance. Its properties are similar to PTFE (TeflonTM), hence its excellent chemical resistance, but at the same time it is classified as an elastomer, so compared to PTFE it remains flexible
NOTE: all gaskets and steels in the indicated above do not accept fluorine compounds and therefore cannot be used.
AISI 316L / 1.4401- is an alloy enriched with molybdenum, thanks to which, compared to AISI 304, its resistance to chlorides has been increased almost three times - good resistance to intercrystallite and pitting corrosion, even at high temperatures. It has good enough properties for wide use in the food, pharmaceutical and biotechnology industries even in the presence of brines and sea water. Tensile strength 490 ÷ 690MPa, Hardness <215HB, Impact strength KV20°C: 60J, Elongation A:> 45%, Elasticity E = 215 Gpa
AISI 904L / 1.4539 / UB6 - compared to AISI 304, the alloy is enriched with nickel, chromium and molybdenum, thanks to which the passivation process is improved and long-lasting. In principle, the alloy is similar to DUPLEX steel with the ferritic-austenitic structure 1.4462 / X2CrNiMoN22-5-3 / UNS S31803 and S32205, however, compared to it, it has an admixture of copper, thanks to which it has better ductility and machinability. Very high resistance to both intercrystallite, pitting and stress corrosion; as well as increased resistance to contact and crevice corrosion. Used for the treatment of media with an extreme chloride content, mainly in the chemical, petrochemical and heavy industries. Tensile strength 530 ÷ 570MPa, Hardness <230 HB, Impact strength KV20°C: 90J