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.
Gaskets divide into two discrete classes when they’re employed in automotive applications. There are the passive areas where the seals protect passengers and driver. They’re the door gaskets and window seals, products that are formed from extruded lengths of weatherized rubber. What about the active seals, though, the common gaskets that manage engine and exhaust fluids?
Extraneous System Seals
The coolant in a car lays dormant. When the ignition circuit sparks life into the engine, that fluid rapidly heats as it recirculates around the engine and absorbs mechanically-generated heat. It’s in here that water-glycol resistant seals withstand the heat without ageing prematurely. Meanwhile, the gruelling conditions throughout the oil distribution system generate a corrosive environment. Fortunately, cork and cured nitrile automotive gaskets resist the impact of aromatic hydrocarbons while creating a formidable barrier that blocks oil leaks.
Engine Gasket Solutions
Head gaskets are one example of the automobile engine seal, then there are intake manifold seals, exhaust manifold gaskets, seals for the engine block, the oil pan, and much more besides. Compressed by torque-heavy tools, the engine segments clamp tightly down on these parts so that the internal combustion chamber maintains its explosive cycle. If that measured air/fuel mix is to be compressed and combusted, this rugged seal family needs some heavy-duty sealing characteristics, just like the super-tough industrial pipe gaskets we’ve been describing in other articles. With that thought in mind, expect a head gasket and its associated engine seals to be manufactured from thin layers of heat-treated steel. More accurately, those bonded layers are likely fabricated as composite parts, as die cut inserts that are layered with an elastomeric coating.
All around a vehicle, common gasket types fill every conceivable application. They’re in the electronic control modules as cable protection inserts. Oil-bathed transmission systems use cork gaskets and compressed fibre seals. Whatever the application, the material exists to meet the need, be it a super-hot coolant stream or a channeled supply of engine oil. Down in the depths of the engine, geometrically shaped gaskets allow the passage of cylinder heads, so they’re die cut and manufactured from layers of composite material, from steel, copper, and from a wear-resistant rubberized coating. Of course, should a weatherized window seal crack, the extruded material simply leaks rainwater. However, if that engine head gasket fails, the combustion cycle is compromised, plus there’s a possibility of a nasty fluid contamination scenario, which is why even the most common vehicle gasket is built according to a stringent manufacturing methodology.