Copper Nickel Pipe Buying Guide: C70600 (90-10) & C71500 (70-30) for Seawater, Marine, and Desalination Service
Copper-nickel pipe — alloys C70600 (90-10) and C71500 (70-30) — carries seawater in ships, offshore platforms, power plants, and desalination units because it resists biofouling and chloride pitting where stainless struggles. Specify the wrong alloy, temper, or wall schedule and the pipe erodes at bends, the welds crack in service, or you pay 70-30 money for a 90-10 duty.
This guide compares the two alloys, the pipe specs buyers quote, welding and fitting notes, and an RFQ checklist.
90-10 vs 70-30
| Alloy | Cu-Ni | Strength | Seawater Duty | Cost |
|---|---|---|---|---|
| C70600 (90-10) | 90-10 + Fe/Mn | Moderate | General seawater, condensers | Lower |
| C71500 (70-30) | 70-30 + Fe/Mn | Higher | High velocity, polluted, hot | Higher |
Default to 90-10 for ordinary seawater piping; step up to 70-30 for high flow velocity, warm polluted water, or pressure-critical lines.
Pipe Standards and Sizes
- ASTM B466 / B467: seamless and welded copper-nickel pipe.
- ASTM B111: condenser and heat-exchanger tube.
- EEMUA 144 / 234: marine piping practice and working pressures.
- Sizes: 15–600 mm OD; walls to schedule / EEMUA tables.
Temper and Condition
- Annealed (O): soft, best for bending and forming.
- Half-hard / hard-drawn: higher strength for straight runs.
- State temper so bends don’t crack and flaring stays tight.
Welding and Fittings
- Filler: ERCuNi (70-30 wire for both alloys is common).
- Gas: pure argon backing; keep interpass temperature low.
- Fittings: Cu-Ni elbows, tees, reducers, and Cu-Ni/stub flanges.
- Avoid carbon-steel contamination — dedicated brushes and clean benches.
Common Applications
- Ship seawater cooling and fire mains.
- Offshore platform utility piping.
- Desalination intake and brine lines.
- Power-plant condensers and heat exchangers.
RFQ Checklist
- Alloy: C70600 or C71500
- Standard: ASTM B466 / B467 / B111, EEMUA if marine
- OD × wall and lengths
- Temper: annealed / half-hard
- Fittings and flanges needed
- Quantity, test certs, destination / Incoterm
FAQ
90-10 or 70-30 for my ship? 90-10 for normal cooling lines; 70-30 where velocity, temperature, or pollution is high.
Seamless or welded? Seamless for small sizes and high pressure; welded (B467) is economical for large diameters.
Can I braze it? Yes with suitable silver filler, but TIG with ERCuNi is standard for pressure lines.
Why Source Cu-Ni from Yihang Metal
Yihang Metal supplies C70600 and C71500 pipe and tube to ASTM B466/B467/B111 in annealed and half-hard tempers, with matching elbows, tees, and flanges, mill test certificates, and third-party inspection. Standard sizes typically ship in 25–35 days.
Ready to specify your copper-nickel pipe? Send us the alloy, standard, sizes, temper, and fittings, and we will confirm mill availability and lead time with a fixed-price quote and MTC. Email [email protected] or use the quote form on this page — our team replies within one business day.