Types of Gasket Materials for Sealing Aggressive Chemicals18 September 2019
Aggressive chemicals can “burn” though ill-suited gasketing materials. Solvents, strong acids, caustic alkalis, all of these substances are capable of causing corrosive fallout. As an unsuitable seal material erodes, the corrosive chemicals then leak and pool. Depending on the nature of this caustic chemical leak, it could then vapourize and take flight. Clearly, on contemplating the terrible consequences of a corrosive gasket leak, engineers must always demand suitable gasket materials.
Chemically Suitable and Compatible Gasket Types
If high pressures stress a seal, then a mechanically capable seal is tightened by a ring of bolts that’ll handle a quoted load factor. With high or low temperatures, expandable seals cope with known thermal variances. Moving onto chemical fluid loads, design problems are compounded by strange material oxidizing and catalyzing energies. Chemistry, the study of atomically scaled material reactance, is a harder field to quantify. As such, specific gasket materials should match given compound formulas. Otherwise, perhaps if an acid-resisting gasket were to be used to contain an alkaline fluid, then it couldn’t be counted on to function. Even if the alkaline substance was diluted, the flange or fitting might fail because it’s protected by a mismatched gasket. Again, because this point deserves emphasis, specific chemical bases must be matched against particular seal material types.
Selecting The Right Gasket Material Type
For concentrated acids and alkalis, a high-quality EPDM (Ethylene Propylene Diene Monomer) will provide plenty of protection. Fluoroelastomers are also designed to handle such corrosive energies. After all, Nitric and Sulphuric acids are but two of a vast range of differently formulated acids on the market. Moving over to fluids that erode seals but are otherwise ordinarily non-corrosive, fuels and oily substances are held back by Buna-N, which is more commonly known as Nitrile Rubber. Other seal rubbers seem to collapse and age when attacked by fuels, but Nitrile gaskets hold firm. Finally, considering the vast number of corrosive compounds flowing around today’s chemical facilities, PTFE (PolyTetraFluoroEthylene) gaskets are generally used as all-round sealing products, for they’re often classed as broad-spectrum chemical resistance seals.
Chemical leaks are viewed as nightmare incidents by every gasketing engineer. They create their own leakage pathways, eat through that weakness path, then they pool innocuously on the ground. Worst case scenario, that leak could spread to a combustible fluid containment unit, or it could evaporate and become airborne. Respiratory damage becomes a real concern when this happens. One more time, to prevent such hazardous incidents from ever occurring, a specific gasket type and material family must be selected to suit a chosen compound base. Choose one of the above material families, but do remember that chemical reactions can further alter a compound’s formula, in which case yet another gasket material would be needed to compensate for the state change.
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