The benefits of copper-nickel alloys in marine environments

Copper-nickel alloys are used for seawater systems, desalination units and to protect offshore structures.

Copper, the most noble of the metals in common use, has excellent resistance to corrosion in the atmosphere and in fresh water. In seawater, copper nickel alloy has superior corrosion resistance.

Copper cladding of wooden-hulled warships, introduced by the Royal Navy in the 18th century to prevent damage by wood-boring insects and worms such as the teredo, and reduce coverage of weed and molluscs. This meant that ships could stay at sea for long periods without cleaning. Nelson’s successful blockade tactics, and subsequent victory at Trafalgar, was partly due to the superior speed and manoeuvrability of his clean-hulled ships.

A brass replacement for copper was developed in the 19th century, composed of around 60% copper and 40% zinc. Called Muntz Metal, it was cheaper than copper and could be hot rolled into thin sheets. An early application was cladding of the wooden hull on the Cutty Sark.

The addition of nickel to copper improves its strength and durability, and also the resistance to corrosion and erosion in natural waters, including seawater, brackish and treated water. These copper alloys also show excellent mechanical properties, including resistance to stress-corrosion cracking and corrosion fatigue.

Copper alloy is an ideal material for use in marine and saltwater environments for commercial and naval shipping, desalination plants, heat exchangers and equipment, sea water and hydraulic pipelines, oil rigs and platforms, fish farming cages, seawater intake screens, offshore renewables, ship and boat hulls and more.

This website provides a detailed overview of copper-nickel with data to allow good practices in design, fabrication and application.

More information on copper alloys for use in aquaculture: the farming of fish and other marine organisms.