Copper Nickel Products
Engineering Polymers
Precision Shims
Flange GuardsCu-Ni 90/10 vs 70/30 (C70600 vs C71500): Differences and Uses
Short answer: Cu-Ni 90/10 (C70600) is the standard, more economical choice for seawater piping, fire mains and ship systems, with excellent resistance to biofouling. Cu-Ni 70/30 (C71500) contains three times more nickel, so it is stronger and tolerates higher flow velocities and more aggressive conditions. It is used for condensers, heat exchangers and high-velocity or polluted seawater, at a higher price.
Side-by-side comparison
| Property | Cu-Ni 90/10 (C70600 / CW352H) | Cu-Ni 70/30 (C71500 / CW354H) |
|---|---|---|
| Nickel | 9–11% | 29–33% |
| Iron | 1.0–1.8% | 0.4–1.0% |
| Manganese | up to 1% | up to 1% |
| Copper | Balance (about 88%) | Balance (about 67%) |
| Typical min. tensile (annealed) | about 275–300 MPa | about 360 MPa |
| Typical design seawater velocity in pipe | up to about 3.5 m/s | up to about 4.5 m/s |
| Biofouling resistance | Excellent | Good |
| Common standards | ASTM B111, B122, B466, EEMUA 144/145/146 | ASTM B111, B122, B466 |
| Relative cost | Lower | Higher |
Where 90/10 is used
- Seawater cooling and service lines, fire-fighting mains
- Ship hull piping, ballast systems and sea chests
- Desalination plant brine and seawater intake lines
Where 70/30 is used
- Condenser and heat-exchanger tubes, especially in power and desalination plants
- High-velocity seawater, or water polluted with sulphides
- Naval and offshore applications that need higher strength and erosion resistance
How to choose
If the flow velocity is moderate and the water is clean seawater, 90/10 gives the best value and the strongest anti-fouling performance. If the system runs at higher velocity, sees turbulence or entrained sand, or the specification calls for C71500, choose 70/30.
Values are typical figures from published material standards and supplier data, for guidance only. Always check the mill test certificate and your design code for the exact grade you buy.
Need a price or stock check? Send the grade, size and quantity to sales@saifexindustries.com, WhatsApp +971 58 535 2330, or request a formal quote. See our Cu-Ni 90/10 (C70600).
Or see Cu-Ni 70/30 (C71500).
Frequently asked questions
What is the main difference between Cu-Ni 90/10 and 70/30?
Nickel content: 90/10 has about 10% nickel and 70/30 about 30%. The extra nickel makes 70/30 stronger and more resistant to erosion at higher flow velocities, while 90/10 is cheaper and resists biofouling better.
Is C70600 the same as Cu-Ni 90/10?
Yes. C70600 is the UNS number for 90/10 copper-nickel; the European equivalent is CW352H. C71500 (CW354H) is 70/30.
Which copper-nickel is best for seawater piping?
For most seawater piping, 90/10 (C70600) is the standard choice. 70/30 is preferred for heat-exchanger tubes and high-velocity or polluted water.
Can copper-nickel be welded?
Yes. Both grades are readily welded, normally with 70/30 copper-nickel filler metal for both alloys.