Copper Nickel Pipes & Tubes

Copper-nickel alloys (often referred to as cupro-nickels) offer moderate to high strength and excellent resistance to various waters, including seawater and form a protective surface film in such conditions. In addition they provide good anti-fouling properties and weldability.

The precipitation hardenable copper nickels (DEF STAN 02-835 and ULTIBRON™-NB) possess high strength and are used as an alternative to the 90/10 and 70/30 alloys and other copper alloys such as nickel aluminium bronze in marine applications. Other useful attributes include low magnetic permeability, imperviousness to hydrogen embrittlement, no loss of impact strength down to minus 196°C and good jet impingement resistance.

Applications for 90/10 and 70/30 alloys mainly involve tubes and tube plates in heat exchangers, including desalination and seawater piping systems. 70/30 alloy is also used for hose couplings, mechanical seals and pump shafts. Applications for the high strength cupro-nickels are varied and cover subsea bolting in Oil & Gas to hydraulic connectors and valve stems.

Usage in Naval vessels is widespread, for example, for bolting, propeller shafts, sonar components and weapons handling equipment. Copper-nickel alloys are also finding new applications replacing beryllium-copper alloys due to environmental difficulties in their manufacture.

 

The addition of nickel to copper improves strength and corrosion resistance but good ductility is retained. Copper-nickel alloys have excellent resistance to marine corrosion and biofouling.

The two main alloys are 90/10 and 70/30. The 70/30 is stronger and has greater resistance to sea water flow; but the 90/10 will provide good service for most applications and being less expensive tends to be more widely used. Both alloys contain small but important additions of iron and manganese which have been chosen to provide the best combination of resistance to flowing sea water and to overall corrosion.

Copper-nickel alloys are widely used for marine applications due to their excellent resistance to seawater corrosion, high inherent resistance to biofouling and good fabricability. They have provided reliable service for several decades whilst offering effective solutions to todays technological challenges.

 

Applications

  • Sea water pipework
  • Offshore fire water systems
  • Heat exchangers and condensers
  • Sheathing of legs and risers on offshore platforms and boat hulls
  • Hydraulic lines
  • Fish cages for aquaculture
  • Desalination units.

NS Standard Composition of Wrought Alloys (in at%). Maximum or range.

Alloy UNS No
Common Name
European Spec.
Ni
Fe
Mn
Cu
C70600 90-10 CuNi10Fe 9-11 1-1.8 1 Rem
C71500 70-30 CuNi30Fe 29-33 0.4-1.0 1 Rem
C71640 66-30-2-2   29-32 1.7-2.3 1.5-2.5 Rem

 

Subtle differences in corrosion resistance and strength determine which alloy is selected. Descending the table, the maximum allowable flow rate in piping increases, as does the tensile strength.

 

Properties of some Cu-Ni Alloys.

Alloy
Density g/cm3
Thermal Conductivity
W/(m-k)
TEC µm/(m·K)
Electrical modulus µOhm·cm
Elastic modulus GPa
Yield Strength MPa
Tensile Strength MPa
90-10
8.9
50
17
19
135
105
275
70-30
8.95
29
16
34
152
125
360
66-30-2-2
8.86
25
15.5
50
156
170
435

 

Copper Nickel Pipes - European Standards

Main Std NFA GAM BS EEMUA NES DIN EN ASTM
Seamless Pipes
CuNi10 Fe1 Mn
51102 MM 11 2871 CN 102 144 UNS 7060X 779 part 3 86019 2.1972 17664/17996 2.0872 12449 CW352 H B466 C70600
Seamwelded Pipes CuNi10 Fe1 Mn 2875 CN 102 144 UNS 7060X 86018 2.1972 17664/17996 2.0872 B467 C70600
Bars
CuNi10 Fe1 Mn
MM 11 MM 13 2872 CN 102
2874 CN 102
779 part 2 17664 2.0872 17672 2.0872.10 B151 C70600
B249
Plates
CuNi10 Fe1 Mn
2870 CN 102
2875 CN 102
B171 C70600
B402
Seamless Pipes
CuNi30 Fe1 Mn
51102 MM 11 2871 CN 107   780 part 3 17664 2.0882
17671/1755
12449 CW352 H B466 C71500
Seamwelded Pipes CuNi30 Fe1 Mn 2875 CN 107   17664 2.0882
17670 2.0882/86018
B467 C71500
Bars
CuNi30 Fe1 Mn
  2872 CN 107
2874 CN 107
  17664 2.0872 17672 2.0872.10 B151 C71500
B249
Plates
CuNi30 Fe1 Mn
2875 CN 107 B171 C71500
B402