ASTM B151 C70600 2.0872 Cu-Ni Alloy Forged Weldneck Flange RF B16.5

ASTM B151 C70600 2.0872 Cu-Ni Alloy Forged Weldneck Flange RF B16.5

What is UNS C70600?

UNS C70600 is one type of copper-nickel alloys, which has excellent corrosion resistance even in marine environments. This alloy possesses average high strength and good creep resistance at high temperatures, and costs more in comparison to copper-aluminum alloys and other alloys with similar mechanical properties.

C70600 Copper Nickel 10% Alloy is used in applications where resistance to corrosion and stress cracking is important. C70600 Copper Nickel 10% Alloy is known for its moderate strength, weldability and formability.

C70600 copper-nickel is an alloy of copper, further classified as a copper-nickel (cupronickel). CW352H is the EN numeric designation for this material.

Corrosion resistance of Copper-Nickel Alloys

The corrosion resistance of CuNi alloys is due to the presence of protective surface film of copper nickel oxide which is firmly bonded to the metal and which is almost insoluble in water. This oxide film protects the piping from further attack. The protective oxide film takes about three months to stabilize. Hence it is recommended not to expose newly fabricated copper-nickel piping to aggressive environments. The corrosion rate in static seawater is approximately 0.1 mm/year. Once the protective film is formed the rate of corrosion is reduced to 0.01 mm/year. The corrosion rate dramatically increases in presence of sour environment such as H2S due to breaking of protective oxide film by sulphide ions.

In systems which are in continuous service, too high fluid velocities can break the protective film due to erosion. The copper oxide film can get destroyed by erosion at fluid velocities of about 3.5 m/s. To limit the erosional velocities, copper-nickel piping systems could have larger diameters than equivalent steel piping systems.

The following two alloys of copper-nickel are most commonly used in the industry.
90-10 Alloy (UNS C70600) containing 10% nickel also called Alloy 706
70-30 Alloy (UNS C71000) containing 30% nickel also called Alloy 710

Chemical Composition of C70600

Physical Properties

The following table shows the physical properties of UNS C70600 copper nickel alloys.

Mechanical Properties

The mechanical properties of UNS C70600 copper nickel alloys are displayed in the following table.

B151 C70600 Flange Application

-Fire protection systems
-Deluge systems
-Sanitary plumbing services
-Process cooling lines
-Seawater piping
-Splash zone sheathing