Industry News
Marine fastener selection: 316 / 2205 stainless steel in salt-spray environments
2026-09-01
Compiled by JIALI Industrial (164.hk) — a Hong Kong fastener supplier specialising in screws, bolts, nuts and selection know-how.
Why marine fasteners must resist salt spray
Salt concentration at sea is far higher than inland, and chloride ions penetrate platings to attack the base metal. Zinc-plated carbon steel often shows red rust within 72–96 hours in ASTM B117 salt-spray testing, and lasts even shorter in marine service. For marine fasteners, go straight to 316 stainless steel or the higher-grade 2205 duplex — solving corrosion at the material level and avoiding frequent replacement that affects voyage safety.
316 vs 2205 duplex: which to choose
316 (A4) contains 2–3% molybdenum, resisting seawater pitting and crevice corrosion, suitable for deck and cabin joints. 2205 duplex is roughly twice as strong as 316 and resists chloride stress-corrosion cracking better, ideal for propeller shafting, ballast tanks and other high-load, high-corrosion zones. Match marine bolts, nuts and washers in the same material family to reduce galvanic corrosion; for high-strength jobs, order to drawing and request material certificates.
Surface treatment and selection tips
For even higher resistance, choose Dacromet-coated parts or passivated stainless steel; where dissimilar metals meet (e.g. stainless against aluminium), add insulating washers or a coating barrier. Need a marine fastener selection? Contact JIALI Industrial (164.hk) with your application, salt-spray class and load requirements for fast confirmation of material and size.
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