Copper, the most noble of the metals in common use, has excellent resistance to corrosion in the atmosphere and in fresh water. In seawater, the copper-nickel alloys have superior resistance to corrosion, coupled with excellent anti-fouling properties.
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, was discovered to prevent biofouling by 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 of his clean-hulled ships.
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. The alloys also show excellent resistance to stress-corrosion cracking and corrosion fatigue.
The added advantage of high resistance to macro-fouling provides a material ideal for use in marine and saltwater environments for commercial and naval shipping, desalination plants, heat exchange equipment, seawater and hydraulic pipelines, oil rigs and platforms, fish farming cages, seawater intake screens, offshore renewables, ship and boat hulls and more.
Copper Alloys for Marine Environments
Copper Alloys for Marine Environments is a CDA publication that provides engineers with an appreciation of copper alloys commonly used in marine applications. It gives an overview of the range of alloys and their properties, with references and sources for further information. Click here
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Copper Alloys in Seawater: Avoidance of Corrosion
Copper Alloys in Seawater: Avoidance of Corrosion is a CDA publication that gives practical guidance for engineers on the avoidance of corrosion in copper alloys for seawater applications.
Copper alloys have been widely used in seawater and related brines, such as in thermal desalination plants, for many years, generally with excellent results. They are commonly used for piping, valves, pumps and heat exchanger tubing, but have found many other applications.
Occasionally there are failures due to corrosion, and in many cases these could be avoided by following some simple design recommendations, by selecting an alternative copper alloy, or by using a simple preventative strategy. This publication covers the most common types of corrosion and shows simple methods to avoid them. If these are implemented at the design stage, it can save a large expenditure after a corrosion failure.
The guide has been written principally for marine, mechanical and other engineers who have to select materials of construction but do not have a corrosion background. Click here
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