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Fastener Coatings for Outdoor & Offshore: Hot-Dip Galvanising vs PTFE/Xylan | LOKRON Technical Insights
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Fastener Coatings for Outdoor & Offshore: Hot-Dip Galvanising vs PTFE/Xylan 2026-02-28 · 9 min read
The Electrochemical Case for Surface Protection on Industrial Fasteners ASTM A193 B7 Cr-Mo alloy steel (4140/4142) delivers exceptional tensile strength — up to 860 MPa minimum at standard diameters — but it has essentially no inherent corrosion resistance. In the electrochemical potential series, plain carbon and low-alloy steels occupy a highly active position, meaning they corrode rapidly when exposed to moisture, chloride ions, and oxygen. In outdoor, marine splash zone, or chemical plant environments, an uncoated B7 stud bolt will show heavy surface rust within days and loss of dimensional integrity within weeks. The coating choice is therefore not cosmetic — it is a core engineering decision that determines service life, maintenance interval, and long-term joint integrity.
Hot-Dip Galvanising (HDG) — The Sacrificial Zinc Standard https://www.thelokron.com/en/insights/fastener-coatings-hot-dip-galvanising-vs-ptfe
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