Corrosion and Biofouling Resistance Evaluation of 90-10 Copper-Nickel
Carol Powell
Consultant to Copper Development Association, UK.
Square Covert, Caynham, Ludlow, Shropshire, UK. Tel 0044 (0)1584 872805,
Fax 0044 (0)1584 876632. carol.powell@btinternet.com
Abstract
Copper-nickel alloys for marine use were developed for naval applications in the early part of
the 20th century with a view to improving the corrosion resistance of condenser tubes and
seawater piping. They still enjoy widespread use today not only for many navies but also in
commercial shipping, floating production, storage and offloading vessels (FPSOs), and in
multistage flash desalination. The two popular alloys contain 90% or 70% copper and differ
in strength and maximum sea water velocity levels they can handle but it is the 90-10 copper-
nickel (CuNi10Fe1Mn) which is the more economic and extensively used. An additional
benefit of this alloy is its high resistance to biofouling: in recent years this has led to
sheathing developments particularly for structures and boat hulls.
This paper provides a review of the corrosion and biofouling resistance of 90-10 copper-
nickel based on laboratory test data and documented experience of the alloy in marine
environments. Particular attention is given to exposure trials over 8 years in Langstone
Harbour, UK, which have recently been completed by Portsmouth University on behalf of the
Nickel Institute. These examined four sheathing products; plate and foil as well as two
composite products with rubber backing. The latter involved copper-nickel granules and slit
sheet.
The trial results are consistent with the behaviour of the alloy in the overall review. There is
an inherent high resistance to marine biofouling when freely exposed. Prolonged exposure to
quiet conditions can result in some growth of marine organisms but this is loosely attached
and can readily be removed by wiping or a light scraping. The good corrosion resistance of
90-10 copper-nickel in sea water is also confirmed and associated with