chenk222222
1557 posts
Aug 23, 2025
3:42 AM
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Copper Nickel 70/30 (CuNi 70/30) is a high-performance alloy made of 70% copper and 30% nickel, with small additions of iron and manganese that enhance its resistance to corrosion and erosion. Known for its exceptional durability in seawater and polluted marine environments, this alloy is widely used in industries that demand strength, longevity, and resistance to aggressive conditions.
Composition of Copper Nickel 70/30
Copper (Cu): ~70%
Nickel (Ni): ~30%
Iron (Fe) & copper nickel 70/30(Mn): Trace amounts for improved mechanical and corrosion resistance
This specific combination gives CuNi 70/30 its outstanding performance compared to other copper alloys.
Key Properties of Copper Nickel 70/30
Superior Seawater Corrosion Resistance: Performs reliably in aggressive, high-salinity, and polluted seawater.
High Strength: Stronger than CuNi 90/10, making it suitable for heavy-duty applications.
Resistance to Erosion & Stress Cracking: Withstands impingement attack, erosion, and stress corrosion cracking.
Thermal Conductivity: Efficient in heat transfer, making it ideal for heat exchangers and condensers.
Weldability & Fabrication: Easy to weld, fabricate, and bend without losing performance.
Long Service Life: Designed for decades of use with minimal maintenance.
Applications of Copper Nickel 70/30
Thanks to its mechanical and corrosion-resistant properties, CuNi 70/30 is used in critical systems across various industries:
Marine Industry: Seawater piping systems, condensers, seawater cooling, and shipbuilding.
Power Generation: Heat exchanger and condenser tubes in nuclear and coastal power plants.
Oil & Gas: Offshore firewater systems, subsea pipelines, and platform equipment.
Desalination Plants: Evaporators, condensers, and brine heaters for seawater processing.
Chemical Industry: Handling acidic and corrosive fluids in process equipment.
Standards & Availability
Copper Nickel 70/30 is produced according to international standards such as ASTM B466, B467, ASME SB466, EN, and DIN. It is available in multiple product forms, including:
Tubes & Pipes
Sheets & Plates
Rods & Bars
Flanges & Fittings
Manufacturers perform strict testing such as hydrostatic testing, eddy current inspection, ultrasonic testing, and NDT (non-destructive testing) to ensure reliability.
Advantages Over Other Alloys
Compared to CuNi 90/10: CuNi 70/30 offers higher strength and better corrosion resistance in harsh seawater.
Compared to Brass & Aluminum Brass: Provides superior resistance to impingement and biofouling.
Compared to Stainless Steel: Avoids seawater-induced stress corrosion cracking, a common issue in stainless grades.
Conclusion
Copper Nickel 70/30 (CuNi 70/30) is one of the most reliable alloys for marine engineering, offshore oil & gas, power generation, and desalination plants. Its unmatched resistance to seawater, combined with high strength and thermal efficiency, ensures long-lasting and low-maintenance performance in the most demanding environments.
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