Copper Nickel also known as Cupro nickel or CuNi, has proven to be very resistant to seawater, brine water, organic compounds, salts, diluted non-oxidizing acids, and more. Due to its complete resistance towards marine organisms such as barnacles, Copper Nickel tubing is commonly used in seawater piping systems.

Copper nickel alloys are of two types that include 70/30 and 90/10. The 70/30 copper nickel alloys have great resistance to sea water-related corrosion due to the presence of significant amounts of manganese and iron. Whereas, 90/10 has high strength corrosion resistance with high ductility and toughness, makes it a popular grade for marine, architectural and industrial applications.

CuNi 70/30:

70/30 is a 70% copper, 30% nickel alloy with additions of iron and manganese. These elemental additions make it somewhat more resistant to corrosion and erosion and with slightly improved strength level than 90/10, making it suitable for more demanding applications. In particular, its corrosion resistance is notably improved in high-velocity waters (up to 4.5m/s) and polluted seawater.

CuNi 90/10:

Carlson Alloy 90 10 Cu Ni is a copper-based alloy developed as a cost-effective substitute for 70 30 Cu Ni. An addition of approximately 1.4% iron was made to increase its resistance to general corrosion, erosion and impingement corrosion resulting form, the turbulent flow of water containing air bubbles and silt flowing at a high velocity. 90 10 Cu Ni has good strength at moderately elevated temperatures. It can be fabricated by both hot and cold-working procedures, and is readily weldable.


90 10 Cu Ni is widely used in marine service, offshore platform sea water piping, tidewater power plants, desalination plants, oil refineries, and in the chemical process industry.

Key Properties

Properties of copper nickel alloys vary with composition, however, some properties of copper nickel alloys are outlined below.

Outstanding resistance to corrosion
70/30 is stronger and has superior resistance to impingement corrosion
90/10 is slightly superior compared to the 70/30 alloy

Salient Features

  • Ductile
  • Can be hardened only by cold working
  • Good corrosion resistance
  • Good strength
  • Electrical resistance

Product applications include condenser tubes and plates, distiller tubes, tube sheets and baffles for condensers and heat exchangers, evaporator and heat exchanger tubes, salt water piping, water boxes, ship hulls and hot water tanks.

Sunflex Metal Industries is committed to achieving the goals set by our customers. We also maintain additional inventory of copper nickel in plate, bar, pipe, flanges and more. Contact our knowledgeable sales associates today to inquire as to how we can assist you in your copper nickel tubing needs!

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