Key points
Selecting copper alloys (CuNi 90/10, 70/30), nickel-based alloys, finned tubes, and tube sheets requires careful attention to ASTM/ASME standards, service environment (marine, chemical, HVAC), fin configuration (L/G/embedded), and machining tolerances.
This guide covers the essential technical criteria, applications, common mistakes, and a practical checklist to help you request a professional technical quote.
Why copper-nickel and nickel alloys are preferred for heat exchangers
Copper-nickel (CuNi) alloys and several nickel-based grades have become the industry benchmark for heat exchangers, condensers, desalination units, oil & gas plants, and chemical processing equipment. Their success is driven by the combination of corrosion resistance, thermal stability, conductivity, and durability in harsh operating environments such as seawater, brackish water, aggressive fluids, and cyclic temperature conditions.
In particular, CuNi 90/10 (UNS C70600) and CuNi 70/30 (UNS C71500) are widely used in marine and industrial systems. Nickel-based alloys (e.g., UNS N04400, N08800) are selected for high-temperature applications requiring oxidation resistance and strong mechanical integrity.
Bottom line: longer tube bundle life, fewer shutdowns, and a lower total cost of ownership.
How to define a complete technical specification
A clear, well-structured specification speeds up procurement and minimizes non-compliance risks. Key elements include:
Standards and compositions
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Reference norms: ASTM/ASME (e.g., ASTM B111 for seamless CuNi; ASTM B466/B467 for other combinations) and any EN/DIN equivalents required in the project specifications.
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Alloy composition: specify the family (CuNi 90/10, 70/30; nickel-copper; Fe-Ni-Cr, etc.) and UNS codes when applicable (C70600, C71500, N04400, N08800).
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Supply condition: drawn, annealed, welded/seamless, U-bend, SRL/DRL or custom lengths.
Dimensions and tolerances
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OD/WT and tolerances according to ASTM or client specifications.
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Straightness and ovality tolerances to ensure clean insertion into tube sheets.
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Internal surface roughness when relevant for heat transfer and pressure-drop requirements.
Testing and certification
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Mechanical and NDT requirements: Eddy Current, Hydrostatic, PMI, etc.
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Certifications: EN 10204 3.1/3.2 when required, heat/lot traceability, and full marking.
Finned tubes: when to use them and how to select the right type
Finned tubes increase the external surface area to improve the efficiency of condensers, coolers, HVAC units, and heat-recovery systems.
Common fin types
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L-fin (wrapped L-shaped fin): cost-effective, good adhesion for standard duty.
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G-fin (embedded): superior mechanical and thermal integrity for severe conditions.
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Embedded/knurled: fin mechanically “locked” into the tube for excellent thermal contact.
Parameters to specify
Fin material (aluminum, copper, copper-nickel), fin height and FPI (fins per inch), fin pitch, finned length, surface treatments, and temperature/environment limits.
Tube sheets: materials, machining, and tube-to-tubesheet joints
The tube sheet is the structural core of any bundle, it ensures alignment, sealing, and mechanical integrity.
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Materials: Choose materials compatible with the fluid and environment: CuNi, nickel alloys, or alloy steels.
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Machining: CNC drilling, countersinking/beveling, grooving, hole layout (triangular, square), and strict tolerances on pitch and parallelism.
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Tube-to-tubesheet jointing: Expansion, rolling, or TIG/laser welding according to the project specification; plus deformation control and leak testing.
Need a technical quotation?
Work with a manufacturer experienced in copper and copper-nickel alloys, finned tubes, and precision-machined tube sheets for industrial heat exchangers.
Send your drawing or specifications today to receive a free technical assessment with the optimal material selection and production timeline.
Industries and applications: how to select the right alloy
Marine and desalination
CuNi 90/10 is ideal for resistance to biofouling and brackish water; CuNi 70/30 is recommended for more aggressive conditions or higher seawater velocities.
Common mistake: underestimating erosion/cavitation issues at inlets and U-bend areas.
Oil & gas and chemical processing
In the presence of H₂S, chlorides, or elevated temperatures, consider nickel-based grades such as N04400 or N08800 for enhanced corrosion and oxidation resistance.
HVAC and refrigeration
Copper or CuNi tubes with optimized finning profiles to maximize heat transfer while minimizing weight and footprint; verify condensate management and corrosion-resistant coatings on fins.