Properties and Applications of Polyurethane Gaskets

04 November 2019

Polyurethane is a remarkable material. Used in gaskets, the infinitely adaptable polymer takes advantage of its resilient molecular structure to create a whole range of industry-leading products. Adhesive substrates and industry foams have drafted in many different urethane enhanced products. Similarly beguiled by the polymer’s application resistive properties, the gasketing sector hasn’t been slow in adopting a whole smorgasbord of polyurethane derived gasketing products.

Polyurethane Gaskets Exhibit Superior Mechanical Strength

Before talking about chemical resistance and heat indefatigability, let’s see if polyurethane gaskets have any physically relevant strong points. Mechanically tough, the flexible plastic deforms but doesn’t abrade easily. It’s a compressible substance, but gaskets made out of PU (PolyUrethane) have a gift for regaining their shape after flange loads are removed. Cut and nick resistant, crack and tear impervious, too, gaskets made out of this polymer are designed to be application robust. And yet, somehow, through the art of chemical reprocessing, the plastics and foams that PU can be formed into are highly adaptable. A gasket can be rigid and as durable as a comparable metal ring. Alternatively, the sealing product can be formulated so that it exhibits a high elasticity coefficient.

Illustrating Harsh Application Examples

So, polyurethane gaskets are physically tough. Even high tensile steel is tough, but it can corrode when attacked by oxidizing fluids. No worries, PU seals are chemically tough, too. They also retain their sealing properties when the temperature drops low or climbs high. A -60°C to 149°C span of nominal effectiveness is typically attached to a gasket made out of die-cut polyurethane. Chemically, the polymer functions unaffected when assailed by corrosive chemical streams, oils, hydraulic fluids, and solvents. Therefore, expect to see PU gaskets used heavily in chemical processing and oil refining facilities. However, these pressure and temperature-capable plastics do not do well against alcohols. If the gaskets are used on the crude oil side of a refinery, they wouldn’t then be employed as after-fractionalization gaskets, not in pipes and fittings that contained alcohol-like fractions.

To overcome application generalization issues, tailored polyurethane families have become available. All the same, a more focused study should be conducted before a series of polyurethane gaskets are installed. For example, PU seals are designed to handle most acidic bases and solvents, but that doesn’t mean the gasketing material will function as a universally acid proof plastic. At the end of the day, polyurethane gaskets slot into an industry opening, one that exists between flexible rubber gaskets and metal strengthened rings. They can be every bit as resilient as that metal, as pliable as the rubber, just by adding an additive or polymer-tailoring operation.

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