Best Gasket Types that are Compatible for Strong Chemicals

30 August 2017

Strong chemicals will eat into poorly selected gaskets, make no mistake about that. Sure, that joint seal has been designed to handle high temperatures and intense pressures, but the clock is ticking. The deteriorating material will fail. A chemically resistant gasket doesn’t suffer from such issues. It retains its toughened outlines and its sealing duties, no matter how corrosive the chemical attack. Still, not all corrosion-resistant gaskets are created equal.

Chemically Compatible Gaskets

The following elastomers and metals are robust substances, but that durability factor doesn’t necessarily mean much, not when the reactive properties associated with a particular chemical compound are known to target that particular material. With that fact in mind, the correctly selected gasket type uses a compatibility model to avoid corrosive action, as imposed on a pipe or fitting joint. Just to illustrate that point, most oils and fuels are seemingly harmless. If someone rubs an oil drop between two fingers, no harm is done. However, those same oils have a very different effect on rubber gaskets. Seal deterioration is likely, as is the likelihood of a nasty leak. Nitrile, EPDM, and Viton gaskets are designed to counteract that material deterioration effect.

Chemical Resistance Charts

Material deterioration effects progress differently, depending on the composition of the chemical medium. Fuels corrode certain elastomers, as do the oils we mentioned earlier. Even vegetable oils and vehicle lubricants can corrode non-compatible gasket rubbers. Hybrid materials, including elastomer-bonded cork seals, are one solution to this best gasket selection puzzle, but the preferred approach is to use data sheets and chemical resistance charts. Like a unique fingerprint, these substance resistivity documents provide details on which rubbers and metals work best with particular fluid stream types. From dust ingress protection to strong acid and alkali protection, the information assures seal compatibility.

A Chemical Compatibility Primer

If nitrile gaskets perform well when aggressive hydrocarbons are carried in-pipe, then EPDM is the next favoured member of this synthetic rubber group. Ethylene propylene diene monomer, is an excellent outdoor chemical seal, with its UV-resistant polymer base acting as a superior open-air pipe jointing product. Nitrile, on the other hand, is every bit as popular as EPDM, but its chemical resistance fingerprint makes the material a preferred gasketing solution in vehicles, in the car engines that carry corrosive hydrocarbons. Curiously, of all the singular materials on the market, few are rated to handle every conceivable chemical type, which is why special bindings and coatings are making headway into every engineering branch, even those that add high temperatures and pressures to the fluid mix. One example of this approach is a PTFE (Polytetrafluoroethylene) coating, a synthetic fluoropolymer that maintains chemical resistance while allowing the base gasket polymer to retain its mechanical traits.

A medium-grade flexible gasket compresses well and handles high temperatures, but it may not resist a certain acid or fuel type. Bonded with a PTFE coating, the hybrid product gains a newly augmented measure of chemical resistivity. Meanwhile, tried and true synthetic rubber gaskets, nitrile and EPDM among them, target nominated chemical compounds as long as the correct chemical resistance chart has been properly interpreted. Finally, tough Viton gaskets and spiral wound metal composites excel when pressure extremes drive those caustic fluid streams, although the latter product must use a ring alloy that doesn’t chemically react with the chemical medium.

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