C72200 Copper Nickel Chromium

Cupronickel or copper-nickel is an alloy of copper that contains nickel and strengthening elements,such as iron and manganese. cupronickel is highly resistant to corrosion in seawater, because its electrode potential is adjusted to be neutral with regard to seawater. Because of this, it is used for piping, heat exchangers and condensers in seawater systems, as well as marine hardware, and sometimes for the propellers, crankshafts and hulls of premium tugboats, fishing boats and other working boats.

Condenser tubes of this alloy are giving long and dependable service at sea. It is also highly satisfactory for tubes in evaporators, inter-after condensers, air ejectors of steam condensers and in boiler feedwater heaters. This alloy is particularly desirable where high temperatures are encountered. It has the property of forming protective films of corrosion products, making it particularly desirable for service when erosion resistance is needed.

Developed by the International Nickel Company, C72200, a chromium modified copper nickel alloy, has exhibited significantly superior resistance to inlet end erosion and blockage erosion as compared to C70600 90/10 Copper Nickel. This alloy can serve as a lower cost substitute for titanium and C71640 (a modified C71500 70/30 copper nickel) to avoid erosion-corrosion problems. Available under the ASTM B111 / ASME SB111 specification, Ameritube has experience provided very thin wall, hard drawn and annealed C72200 for heat transfer applications. Where higher flow velocities cause faster corrosion of copper alloys, particularly in marine and saltwater applications, higher nickel content is required, C72200 avoids the higher cost of C71500 and titanium by limiting nickel content with the introduction of chromium. While all copper nickel alloys are famed for their heat transfer allowing for less use of chlorine due to their natural biofouling resistance, C72200 has a higher heat transfer than titanium, C71500 and C71640, making it a superior choice. Being a cost effective alternative to C71640 and offering a lower cost to titanium where its level of performance is not required, C72200 is an interesting alloy that should achieve larger acceptance among various applications including steam surface condensers in the air removal section and the main body as well as desalination plants.

 

Ameritube has been providing C72200 Copper Nickel Chromium according to the following standards:

  • ASME SB-111
  • ASTM B-111

To learn more about this alloy, click here for its data sheet.

To review a study conducted on this alloy in power plant applications, click here.

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