Cu-Ni 70/30, or Copper-Nickel 70/30, is an alloy composed of 70% copper and 30% nickel, often with trace amounts of iron and manganese to enhance its strength and corrosion resistance. Known for excellent durability in marine environments, it resists seawater corrosion, biofouling, and stress cracking, making it ideal for applications such as seawater piping, heat exchangers, and condensers. Its high ductility and good thermal conductivity also allow for ease of fabrication and welding, further supporting its widespread use in shipbuilding, desalination plants, and offshore oil and gas operations.

Copper-Nickel (Cu-Ni) pipes are generally available in two main grades based on their composition, which offer distinct properties for various industrial applications. The primary grades are: Cu-Ni 90/10 (UNS C70600): Comprising 90% copper and 10% nickel, this grade includes small amounts of iron and manganese to improve corrosion resistance. It is particularly popular for seawater piping, heat exchangers, and desalination systems due to its moderate strength and excellent resistance to biofouling and seawater corrosion. Cu-Ni 70/30 (UNS C71500): With 70% copper and 30% nickel, this grade is stronger and offers superior corrosion resistance compared to 90/10. It also includes iron and manganese to enhance durability and withstand more aggressive environments, making it suitable for high-pressure systems, offshore platforms, and other critical marine applications. Each of these grades is further categorized by standards such as ASTM B466, B467, and B111, which specify dimensions, pressure ratings, and mechanical properties for various applications.