Metal for Marine & Offshore: Grade Selection Guide

Short answer: For marine and offshore duty choose metals that resist chloride pitting and crevice attack: copper-nickel and 90/10 for seawater piping, duplex and 316L stainless for structural and splash-zone parts, aluminium 5083 for hulls, and titanium where life-cycle cost justifies it. Pair the choice with the right coating and isolation to control galvanic risk.

At a Glance

The Marine Corrosion Problem

Seawater is a warm, aerated, chloride-rich electrolyte, so the failure modes are pitting, crevice corrosion and galvanic corrosion. Selection starts from our Seawater Corrosion Guide and the galvanic series, and is confirmed by pitting and corrosion-under-insulation guidance.

Piping and Heat Exchangers

Copper-nickel 90/10 and 70/30 dominate seawater cooling and condenser tubing because they resist biofouling andFilm velocity limits — stocked by our Copper-Nickel Supplier and Copper Pipe Supplier. Titanium tube is the long-life upgrade for aggressive duty.

Structural and Splash Zone

Duplex 2205 and super-duplex 2507 give high strength with chloride resistance for offshore structures and desalination; see our Duplex Stainless Supplier and Stainless Steel Pipe Supplier. 316L serves topside fittings and shafts where full immersion is avoided.

Hulls, Superstructure and Hardware

Aluminium 5083 and 5086 are the marine plate workhorses for hulls and superstructure (our Aluminium Sheet Supplier); titanium Grade 2/5 is reserved for critical long-life parts. Finishes and protection follow our Metal Surface Treatment Guide and Coating Thickness Guide.

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Frequently Asked Questions