Cupro-Nickel is an alloy designation which consists mainly copper element and contains nickel additionally. Also they consist some other elements like ferrous and manganese which increase the mechanical strength. Copper rate can change between 60%-90%.
Copper-Nickel alloys have high strength against salt water. That's why they are used in piping systems, condensers or heat exchangers which are directly contacted with sea water. Also cupro-nickel alloys are used in petrochemical, energy, defence and chemical sectors.
Most common grades of copper-nickel alloys are 90/10 Cupro Nickel and 70/30 Cupro Nickel grades. These numbers indicates copper and nickel element percentages in alloy. However these alloys contain mainly copper, nickel consistence makes their colour silver.
Application and Usage Area
Ship Building and Maintenance: Body of boats and ships, cooling systems for seawaters, fire fighting, hydraulic and pneumatic cooling systems.
Desalination plants and open sea systems: Condensers and heat exchanger tubes, tube sheets, high pressure fitting and pumps.
Offshore oil&gas platforms and FPSO vessels.
Power generation: Steam turbine condensers, cooling systems, high pressure heating systems.
Cryogenic applications: Cupro-nickel alloys perform good at low temperatures because of its good thermal conductivity and ductility properties.
C71500 vs C70600 – Which One to Choose?
| Consideration | C71500 (70/30) | C70600 (90/10) |
|---|---|---|
| Nickel content | 29-33% | 9-11% |
| Tensile strength | 360 MPa | 275 MPa |
| Yield strength | 125 MPa | 105 MPa |
| Thermal conductivity | 29 W/(m·K) | 40 W/(m·K) |
| Seawater velocity limit | Higher (turbulent flow) | Moderate (up to 3.5 m/s) |
| Weldability | Better (higher nickel content) | Good |
| Cost | Higher | Lower |
Selection guidance: Choose C71500 for high-velocity or turbulent seawater, offshore platforms, power generation, and applications requiring higher strength and better weldability. Choose C70600 for moderate seawater conditions where thermal conductivity is a priority and cost is a constraint.
Fabrication & Welding
Weldability: Copper-nickel alloys have good weldability and can be welded with traditional welding technics except oxyacetylene welding. 70-30 (C71500) and C71640 alloys have better weldability compared to 90-10 Cupronickel due to higher nickel content.
Welding to steel: Cupronickel alloys can be welded to steel material with electrodes which have similar chemical/mechanical properties to cupronickel.
Corrosion protection: Both grades show good crevice corrosion and stress corrosion crack (SCC) resistance in sea water because of a thin film on surface which forms after exposure to sea water within a few weeks.
Cryogenic performance: Cupro-nickel alloys perform well at low temperatures due to good thermal conductivity and ductility properties.
Common Cupro-Nickel Grades
| UNS Designation | Alloy | Thermal Conductivity (W/(m·K)) | Yield Strength (MPa) | Tensile Strength (MPa) | |
|---|---|---|---|---|---|
| C70600 | CuNi10Fe1Mn | 90-10 | 40 | 105 | 275 |
| C71500 | CuNi30Mn1Fe | 70-30 | 29 | 125 | 360 |
| UNS Designation | Alloy | Cu (%) | Ni (%) | Fe (%) | Mn (%) |
|---|---|---|---|---|---|
| C70600 | CuNi10Fe1Mn | 90-10 | Rest | 9-11 | 1-1.8 |
| C71500 | CuNi30Mn1Fe | 70-30 | Rest | 29-33 | 0.4-1 |
Both of above grades show good crevice corrosion, stress corrosion crack (SCC) resistance in sea water because of its thin film on surface which is formed after exposure to sea water within a few weeks. Copper-nickel alloys have good weldability and can be welded with traditional welding technics except oxyacetylene welding. 70-30 (C71500) and also C71640 alloys have better weldability comparing with 90-10 Cupronickel due to they have more Nickel content. Cupronickel alloys can be also welded to steel material with electrodes which is similar chemical/mechanical properties with cupronickel.
Quality Control for C71500 Copper Pipe
Chemical verification: Composition tested per EN 12451. C71500 requires Ni 29-33%, Fe 0.4-1.0%, Mn 1% max, Cu balance.
Mechanical testing: Tensile strength 360 MPa min, yield strength 125 MPa min per grade table.
Corrosion testing: Verification of crevice corrosion and stress corrosion crack (SCC) resistance in seawater.
Weldability testing: For traditional welding technics except oxyacetylene welding.
Dimensional inspection: Per EN 12451 for tubes and pipes.
Traceability: Test reports available.
Packaging for C71500 Copper Pipe
Bundling: Pipes formed into bundles with steel straps, plywood separators between layers.
End protection: Plastic caps on both ends.
Labels: Alloy (C71500 70/30), heat number, size, length, quantity.
Export packaging: Per customer requirements.
Factory Equipment for C71500 Copper Pipe
| Equipment | Purpose |
|---|---|
| Melting furnaces | Precise control of Ni 29-33%, Fe 0.4-1.0%, Cu balance |
| Continuous caster | Produces billet for pipe/tube extrusion |
| Extrusion press | Forms hollow pipe/tube shells |
| Cold pilger mills | Reduces OD and wall thickness |
| Draw benches | Final sizing, straightening |
| Annealing furnaces | Produces annealed temper, restores ductility |
| Tube straighteners | Corrects bending |
| Eddy current tester | Non-destructive testing for defects |
| Hydrostatic tester | Leak testing |
| Finning machine | Produces finned tubes per EN 12452 |
