Seamless Copper Nickel 70/30 Pipe
What is a Seamless Copper Nickel 70/30 Pipe?
Seamless Copper Nickel 70/30 Pipe (UNS C71500, approximately 70 % copper and 30 % nickel with controlled iron and manganese) is the highest-alloyed standard copper-nickel pipe, produced from a solid billet without a welded seam.
With nearly three times the nickel of 90/10, C71500 delivers substantially higher strength, better erosion-corrosion tolerance and superior performance in polluted harbors and high-velocity seawater. Its corrosion rate in moving seawater is among the lowest of any practical piping alloy.
Produced to ASTM B466/B467 and ASTM B111 for condenser duty, 70/30 copper-nickel seamless pipe serves demanding naval, offshore and desalination systems where 90/10 would be marginal.
Copper Nickel 70/30 vs 90/10 vs Titanium: High-Duty Seawater Systems
When seawater systems face higher velocities, pressures or temperatures than 90/10 is rated for, the 70/30 alloy is the conventional next step.
| Grade | Key Chemistry / Condition | Where It Fits |
|---|---|---|
| CuNi 70/30 (C71500) | 30 % Ni, 0.6 % Fe | Velocity capability to about 3 m/s, higher strength and better erosion-corrosion margin |
| CuNi 90/10 (C70600) | 10 % Ni, 1.4 % Fe | Economic standard for moderate duty |
| C71640 (66/30/2/2) | Plus 2 % Fe, 2 % Mn | Extended-duty variant for naval high-velocity systems |
| Titanium Gr.2 | CP titanium | Unlimited velocity but higher cost and no antifouling behaviour |
Product Specifications
Specification data for Seamless Copper Nickel 70/30 Pipe is compiled from the governing ASTM/ASME/EN standards and our routine production records; typical values are shown where a standard leaves a limit open.
| Category | Standard / Designation |
|---|---|
| Seamless Pipe & Tube | ASTM B466 / ASME SB466 |
| Welded Pipe | ASTM B467 / ASME SB467 |
| Condenser & Heat-Exchanger Tube | ASTM B111 / B552 |
| UNS Designation | C71500 |
| Werkstoff Number | 2.0882 (CuNi30Mn1Fe) |
Size and Weight Chart
| OD (mm) | Typical Wall (mm) | Weight (kg/m) |
|---|---|---|
| 15.9 | 1.0 | 0.42 |
| 19.05 | 1.2 | 0.6 |
| 25.4 | 1.5 | 1.01 |
| 31.8 | 1.5 | 1.28 |
| 38.1 | 2.0 | 2.03 |
| 50.8 | 2.5 | 3.39 |
| 63.5 | 3.0 | 5.1 |
| 76.2 | 3.0 | 6.17 |
| 101.6 | 4.0 | 10.96 |
| 152.4 | 5.0 | 20.7 |
| 219.1 | 6.0 | 35.91 |
The table lists typical production sizes with a common wall for each diameter; the full dimensional programme of the governing standard is available, and intermediate diameters, walls and lengths are cut to order.
Chemical Composition
| Element | Min (%) | Max (%) |
|---|---|---|
| Copper (Cu) | Balance | — |
| Nickel (Ni) | 29.0 | 33.0 |
| Iron (Fe) | 0.4 | 1.0 |
| Manganese (Mn) | — | 1.0 |
| Zinc (Zn) | — | 1.0 (max, residual) |
| Lead (Pb) | — | 0.05 (max, residual) |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength (typical, annealed) | 400 MPa (58 ksi) |
| Yield Strength (0.2 % offset, typical) | 170 MPa (24.6 ksi) |
| Elongation in 2 in. / 50 mm (typical) | 35 % |
| Hardness (typical, annealed) | ≤ 130 HBW |
| Condition | Annealed; half-hard temper available for higher pressure ratings |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.94 g/cm³ |
| Melting Range | 1237 – 1300 °C |
| Elastic Modulus | 150 GPa |
| Coefficient of Thermal Expansion (20–100 °C) | 16.2 µm/m·°C |
| Thermal Conductivity (at 20 °C) | 29.0 W/m·K |
| Specific Heat Capacity | 377 J/kg·K |
| Electrical Resistivity | 375 nΩ·m |
Equivalent Grades
| Standard System | Designation |
|---|---|
| UNS | C71500 |
| Werkstoff Nr. | 2.0882 |
| EN | CuNi30Mn1Fe / CW354H |
| ASTM | B466 / B111 / B467 |
Why 70/30 Handles the Toughest Seawater Circuits
Tripling the nickel content raises the alloy's general corrosion allowance and, above all, its resistance to erosion-corrosion at high flow: 70/30 tolerates design velocities around 3 m/s and short excursions beyond, where 90/10 would need velocity limiters. This makes C71500 the default for offshore fire mains, high-pressure seawater lift and injection lines, naval propulsion cooling and desalination brine circuits.
Strength rises with nickel as well — roughly 350 MPa tensile in the annealed state — supporting higher design pressures with the same wall, and the alloy retains its antifouling character and strong heat-transfer performance. We supply C71500 seamless tube to ASTM B466/B111 in the annealed condition with iron controlled to specification for a fully self-repairing film.
Manufacturing Process
Our seamless production route for Seamless Copper Nickel 70/30 Pipe follows these documented stages:
- Melting & Casting: Electrolytic copper, nickel and iron are melted and cast into sound cylindrical billets with tight control of Fe and Mn micro-alloying.
- Hot Extrusion / Piercing: Billets are hot-extruded or cross-pierced into seamless tubes, giving a dense, inclusion-free wall.
- Cold Drawing: Cold-drawing passes achieve final OD and wall with smooth bore and OD surfaces.
- Intermediate & Final Annealing: Annealing at about 650-750 °C between passes and after the final pass restores softness and stabilizes the single-phase structure.
- Pickling & Cleaning: Tubes are acid-pickled and rinsed to a clean, bright copper-nickel surface ready for shipboard installation.
- Testing: Hydrostatic testing, eddy-current examination and tensile verification are completed on every batch before release.
Surface Finish Options
- Pickled & Clean: Standard shipboard supply condition.
- Bright Annealed: For instrumentation and small-bore hydraulic lines.
- Polished OD: Where surface appearance or cleanliness classes are specified.
Dimensional Tolerances
Delivered dimensions are verified against the tolerances below; tighter tolerances can be negotiated for instrumentation and precision applications.
| Dimension | Tolerance |
|---|---|
| OD, tube ≤ 25.4 mm (cold worked) | ± 0.10 mm |
| OD, tube 25.4 – 38.1 mm | ± 0.15 mm |
| OD, tube 38.1 – 50.8 mm | ± 0.20 mm |
| OD, hot-finished pipe ≥ 50.8 mm | ± 1 % of OD |
| Wall thickness | - 12.5 % under-tolerance (min-wall basis) |
| Straightness | ≤ 1 mm per metre |
| Cut length | + 10 / - 0 mm (fixed lengths) |
Common Industrial Applications
Because of its characteristic property profile, Seamless Copper Nickel 70/30 Pipe is specified in the following industries and services:
- Naval & High-Speed Vessels: High-velocity seawater systems, fire mains and combatant-ship cooling circuits.
- Offshore Platforms & FPSOs: Seawater injection lines, firewater systems and produced-water service.
- Multi-Stage Flash (MSF) Desalination: Brine heater and evaporator tubing handling hot, high-salinity brine.
- Coastal Power Stations: Condenser tubing in plants with polluted intake water.
- High-Pressure Hydraulic Lines: Marine hydraulic piping benefiting from higher strength than 90/10.
- Petrochemical Cooling Circuits: Heat-exchanger bundles in aggressive saline cooling water.
Quality Assurance, Testing and Documentation
Every length of Seamless Copper Nickel 70/30 Pipe passes through a documented quality-control chain before dispatch:
- Material Certification: EN 10204 3.1 mill test certificates are issued for every heat; 3.2 certification with third-party witness (TUV, SGS, BV) is available on request.
- Chemical & Mechanical Testing: Heat-level chemical analysis plus tensile, hardness and, where applicable, flattening, flaring and reverse-flattening tests per the governing standard.
- Non-Destructive Examination: 100 % eddy-current or ultrasonic testing and hydrostatic or pneumatic pressure testing in line with the standard's supplementary requirements.
- Dimensional & Visual Inspection: Full OD, wall thickness, ovality and length verification with visual surface inspection after pickling or finishing.
- Traceability & Marking: Heat numbers stenciled or banded on every length, maintaining complete melt-to-pipe traceability.
Export and Packaging
Pipes are bundled with steel strapping and fitted with plastic or steel end caps, then packed in seaworthy wooden cases or crates and secured in containers for long-distance ocean freight. Standard export documentation — commercial invoice, packing list, certificate of origin, mill test certificates and, where required, third-party inspection reports — accompanies every shipment. Container-load and bulk project orders receive priority production slots and consolidated shipping documentation.
Frequently Asked Questions
Q1. When must 70/30 be used instead of 90/10?
A: Choose C71500 where seawater velocities are high, water is sulfide-polluted, or system pressure demands higher strength. For average shipboard service below 3 m/s, 90/10 is usually sufficient and more economical.
Q2. What flow velocity can 70/30 tolerate in seawater?
A: Design velocities up to about 3.6 m/s are common for general piping; specific velocity limits for condenser tube bundles follow standard heat-exchanger practice charts.
Q3. Is C71500 suitable for hot brine in desalination plants?
A: Yes — 70/30 is a reference material for MSF brine-heater tubing, handling oxygen-poor brine at temperatures up to about 120 °C with controlled chemistry.
Q4. Which filler metal is used for welding 70/30 pipe?
A: Matching 70/30 or the more common ERCuNi (65/35-type) fillers are both used; joint design follows ASTM B466 appendices and classification-society rules.
Ready to Request a Quotation?
Send us your size range, wall thickness/schedule, standard and quantity for Seamless Copper Nickel 70/30 Pipe, and our engineering team will respond with a detailed technical and commercial offer within 24 hours. Custom sizes, third-party inspection and full export documentation are part of our standard service.
