70/30 Copper Nickel

70/30 Copper Nickel is mainly preferred when the severity of service condition (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 surfaced 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. 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) water.

90/10 Copper Nickel

90/10 Copper Nickel is widely used in sea water. It has very good corrosion resistance to clean or moderately polluted marine or estuary water, even containing dissolved incondensible gases.

This alloy is virtually immune from stress-corrosion cracking. In clean sea water, velocities of up 2.2 – 2.5 m/s are accepted while 4 m/s is the upper limit for clean fresh or slightly saline solutions. To avoid the risk of deposit attack, it is generally recommended to never operate at water velocities below about 0.8 – 1 m/s. 90/10 Copper Nickel can also be used, with appropriately reduced flow velocity, in contact with water containing some sulphides or suspended solids. It is also often selected for its good mechanical properties. both at room and relatively elevated temperatures.

Aluminum Brass

Generally used with brackish or sea water. Through its arsenic inhibition, it is virtually immune from dezincification and when fully annealed, also practically free from stress-corrosion cracking. Aluminum Brass is resistant to pitting and even more so to impingement attack : in fresh water, a velocity of up to 3.5 m/s is admitted; it should be reduced to about 2.5 m/s when operating in sea water.