How does the term ‘High-Pressure Vessel’ impact gasket design? For openers, this is an engineering scenario that implies a substantial stress factor. The pressure, if it were to be released, would be dangerously high, perhaps even explosively destructive. If that pressurized fluid is to be reliably contained at each and every vessel seam, capable gasket materials must be employed then correctly installed. What exactly are the best materials for this job?

Choose Metallic Strength

Strong elastomers equipped with a fluoropolymer backbone compress and then hold their shape when the upper end of the medium pressure scale is realized. Equally resilient carbon seals and mineral fibre inserts provide adequate jointing properties when they’re moderately stressed, plus they retain their strength when the fluid temperature climbs high. For true high-pressure resistance, however, it’s metal that gets the recruitment call. Pure metal rings, alloy gaskets with graphite inserts, and even specially profiled ceramic-packed rings fill this gasketing family with metallurgically established durability. Let’s check out those solid metal gasket materials.

A Stronger Gasket: Alloys and Pure Metals

Picture metal seals as the ultimate high-pressure sealing solution. Sure, at least initially, the alloys seem too rigid and too unyielding, but all metals include a certain degree of elasticity. That slight amount of malleability acts just like the compression feature inside an elastomeric seal, except the feature is far more capable as a stress mitigation mechanism. Obviously, softer alloys have a strong presence here, with bronze and copper providing a fluid-resistant base, especially when the conveyed fluids have a corrosive ingredient. Higher up on the pressure spectrum, its aluminium and stainless steel that provide more strength, yet these alloys still have a slight amount of elasticity locked inside their structural form so that they perform superbly in their gasketing duties. Again, these strong yet slightly material-soft alloys are designed to handle intense fluid pressures and just as severe temperatures.

What could be better than solid steel as a gasket material when the fluid pressure is transferring massive quantities of stress? In place of that dense ring of metal, there are specially profiled metal gaskets, products that handle blow-out stress and transient pressure spikes, among other things. They use corrugated layers and grooves to manipulate the compressible characteristics of the seal. Jacketed variants push that principle in a different direction by adding special fillers, including graphite to the mix. Finally, consider spiral wound gaskets, a semi-metallic solution that uses one or more V-shaped inserts to centre the ring and add resilience to gasket materials for high-pressure vessels.

Synthetic fiber gaskets are imbued with specially tailored properties. A long list of man-made materials fills this category. They resist corrosive fluid attacks from specific acid strains, food types, or chemical compounds. Mechanically sound, the material structure of a calendered synthetic fiber is designed to withstand flange compression extremes and to handle large temperature fluctuations. With that being said, maybe we should take a closer look at this manufactured material.

What Are Synthetic Fibers?

Picture synthetic fibers as man-made materials, as the plastic and glass-based filaments that are built with a toughened molecular backbone. Fluoropolymer bonds and strong thermoplastic linkages create gasket sheets that deliver superior physical properties and custom-manufactured fluid handling traits. PTFE is a popular source for these synthetic strands, but there are many proprietary products, brand names that contain unique material characteristics. Cut by die cutting equipment, these synthetic filaments can be tailored to fit any conceivable sealing application.

Examining the Manufacturing Process

Special blends of rubber and aramid act as a structural framework for the exotic strands. They bind together to form long sheets, at which point they’re die stamped into synthetic fiber gaskets. Again, this process varies from one manufacturer to the next, but a binding agent is regarded a critical part of the manufacturing phase, for it bonds those toughened filaments in place. The sheets are loaded with a blend of graphite, glass, PTFE, and other synthetic filaments. The exact mix ratio is managed by the manufacturer so that the artificial material specifically accommodates a preordained fluid medium.

Synthetic Fiber Gaskets: Assorted Applications

If a data sheet filled with operational conditions impedes the adoption of a natural gasketing material, then synthetic fiber gaskets are on hand to take up the slack. Calendered and bonded to rubber or cork, these manufactured material seals serve the aerospace and automobile industry as fuel and lubricant-resistant seals. They exhibit excellent dimensional stability, even when the flange fastening pressure bears down with great compressive strength. A minor change in the formula, a substituted graphite base or man-made felt binding agent, is enough to alter a fluorocarbon stranded gasket group and its subgrouped product lineage so that the next iteration in the product inventory seals a solvent based fluid or a caustic chemical compound.

Every property assigned to a group of synthetic fiber gaskets is alterable. Controlled by the manufacturing process, the Teflon-strengthened bonds and their brand-determined siblings are endowed with a superior compressibility feature, plus a finitely adjustable filament base, one that can be intelligently adjusted to withstand any material type, pressure, or temperature variance. After the artificially manufactured strands are bonded to rubber or cork, the calendered sheets are readily cut up into ranks and rows of dimensionally stable gaskets.

Few mechanical breakdown events engender as much dread in a car owner’s heart as a blown head gasket. Located between the engine block and the cylinder head compartment, this mechanically-essential seal is responsible for containing the internal combustion process, plus all of those explosively rising and falling cylinder parts. It’s because of these stress factors that this gasket doesn’t leak, it blows. What are the causes of blown head gaskets?

What is A Head Gasket?

As we briefly explained a moment ago, this is the all-important engine seal that contains internal combustion stress. When the engine block is mated to the cylinder head, this geometrically complex gasket is fitted between the two core engine parts as a seal. If you were to look at it, you’d see a row of cylinder apertures, plus an accompanying series of smaller holes. The latter array of openings exists to deliver the engine lubricant and a coolant. If this primary seal were to be breached, what would happen? Well, engine compression ratios drop like the proverbial stone if the gasket leaks. Furthermore, the once isolated lubricants and coolants leak and mix. From here, the engine overheats, it spits out clouds of smoke, and there’s an increased risk of permanent engine damage.

The Causes of Blown Head Gaskets

If we know the causes, we can avoid them. For instance, those two engine halves are forged from strong alloys. Still, even the smallest manufacturing difference can alter the way one of those segments reacts to stress. If combustion cycles do produce heat, the thermal energy is making the metal expand and contract. Mechanical creep hits the head gasket hard, especially if it’s made from an overly rigid material. The result of this expansion effect is head gasket fatigue, which means a blown head gasket is imminent. Head bolt overtightening is the other culprit here, with the bolt pressure over compressing the head gasket material. Engine assembly expertise rectifies this latter problem by applying the correct torque to each bolt and installing each one in the right sequence.

Substandard head gasket materials don’t react well when placed under pressure. The segment marrying stress, perhaps done out of sequence, over compresses the seal and introduces a weak spot. Meanwhile, a poor lubrication fluid or low coolant level causes rapid expansion and contraction cycling, a repeating event that’s felt as a mechanical creep effect. Have the engine serviced by an expert, someone who will install a high-quality head gasket correctly. On top of that provision, avoid high-temperature cycling effects by using a superior lubricant and a properly topped coolant reservoir.

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.