Corrosion selection: evaluate the assembly and exposure

Begin with actual exposure

Aluminium’s protective surface oxide is useful, but it does not make every alloy suitable for every environment. Hydro’s bridge study discusses localized corrosion, contact with other metals and retained seawater. The Aluminum Association also distinguishes the corrosion behaviour of alloy families. Use these as prompts for evaluation, not as blanket approval for an unrelated component.

Inspect the interfaces

Document dissimilar metals, fasteners, electrical contact paths and locations that may remain wet. Ask the designer to review isolation, drainage and access for cleaning. Examine the whole installed joint rather than choosing an alloy from a catalogue and leaving interface details until assembly. Protection measures should be compatible with the mechanical and electrical functions they serve.

Connect material and fabrication

State alloy, temper, form, welds, finish and service conditions together. Ask whether the proposed fabrication route or repairs change the basis for acceptance. For a harsh or unusual exposure, request relevant application evidence or a project-specific assessment. Avoid extrapolating a successful atmospheric installation to immersion, chemical exposure or a different joined configuration.

Set an evidence threshold

Record what evidence supports the selection, which assumptions need confirmation and who approves the final design. Agree maintenance access and cleaning requirements where relevant. The cited corrosion report concerns a particular bridge concept; its optimistic project statements and numerical limits are not universal aluminium guarantees. This overview supplies assessment questions rather than corrosion rates, service-life predictions or structural design approval.

Sources and verification

Selected facts checked 14 October 2026. Source data is reference information, not certification of supplied material.

• Hydro • Langenuen aluminium girder study: corrosion and maintenance — Public project report excerpt, section 3.9; recommendations project-specific · checked 2026-10-14
• Aluminum Association • Alloy standards and strengthening overview — Live overview; September 2026 standards action text; linked paid standards not read · checked 2026-10-14

Review the electrically connected assembly

TWI explains galvanic attack through dissimilar metals, electrical connection and a conductive environment. European Aluminium highlights the fastener stack, while UACJ uses sacrificial layers in brazing sheet. Material selection should include joints, coating damage, isolation and electrolyte exposure. Coating just one member is not automatically a complete solution; the actual assembly needs review.

Source: www.twi-global.com, www.uacj.co.jp, european-aluminium.eu