70/30 Copper Nickel is mainly preferred when the severity of service conditions (Cooling Water, Steam, Condensate, Temperature, etc.) is such as to virtually rule out all other copper metals. Due to its hardness and to the type of oxide whereby its surface is self-protected, 70/30 Copper Nickel has excellent resistance to impingement and erosion-corrosion by suspended solids in sea water flowing at up to 3-3.5 m/s (10-11.5 ft /s). Like all Copper-nickels, 70/30 Copper Nickel is virtually immune from stress-corrosion cracking. It can be very sensitive to deposit attack and is therefore not recommended for stagnant or slow-moving (under 1 – 1.2 m/s or 3.5-4 ft/s) water.

C715 copper alloy is also known as 70/30 copper-nickel, as it is comprised of 30% nickel. Copper nickel alloy 715 finds its greatest application in areas of high temperatures and pressures combined with high velocity and destructive turbulence. The small iron content, up to 0.5%, gives the C715 alloy an extraordinary resistance to general corrosion and stress corrosion cracking, making it very suitable and ideal for marine or industrial industries.