In marine vessels and offshore equipment, the selection of piping materials for water systems directly affects navigation safety, maintenance costs, and equipment service life. One material, proven by more than half a century of real shipboard experience, has become a widely recognized standard solution among global shipyards and marine designers: 90/10 copper nickel seamless tube, also known as UNS C70600.

So, why is 90/10 copper nickel seamless tube suitable for marine water systems? What advantages does it offer compared with stainless steel, carbon steel, and ordinary copper tube? What should be considered during material selection and application?

This article provides a systematic explanation.

What Is 90/10 Copper Nickel Seamless Tube?

90/10 copper nickel seamless tube is a copper alloy tube mainly composed of approximately 90% copper and 10% nickel, with small additions of iron and manganese to further improve seawater corrosion resistance.

The term seamless tube means that the tube is not formed by welding, but manufactured through processes such as extrusion, cold rolling, and cold drawing. Since there is no weld seam, seamless tube offers clear advantages in pressure resistance, structural uniformity, and reliability.

This makes it especially suitable for ship piping systems with high safety requirements.

On marine design drawings, C70600 or CuNi10Fe1Mn usually refers to this material. C70600 copper nickel seamless tubes produced by HAOMEI comply with standards such as ASTM B111, ASME SB111, EN, and DIN. Certificates from classification societies such as DNV, ABS, LR, and CCS can also be provided according to customer requirements.

Why Choose 90/10 Copper Nickel Seamless Tube?

1. Excellent Seawater Corrosion Resistance

The most outstanding characteristic of copper nickel alloy in seawater is its ability to form a dense and strongly adherent oxide film.

This protective film can effectively block chloride ion penetration and has a self-healing ability, significantly reducing the corrosion rate.

2. Good Resistance to Impingement Corrosion

The iron content of C70600 copper nickel alloy is controlled at 1.0%–1.8%, which effectively suppresses impingement corrosion.

It can withstand seawater flow velocities of up to 3–4 m/s without significant damage. This feature makes it especially suitable for high-flow areas such as main cooling water pipelines and seawater mains.

3. Natural Anti-Biofouling Performance

Compared with ordinary carbon steel, copper nickel alloy slowly releases copper ions from its surface, which can repel and inhibit the growth of marine organisms such as barnacles, algae, and shellfish.

This means that the inside of the pipeline is less likely to be blocked by marine biofouling, allowing it to maintain good flow capacity over the long term and greatly reducing shutdowns for cleaning and maintenance.

4. Excellent Forming and Welding Performance

90/10 copper nickel seamless tube has good hot and cold workability and can be easily processed by bending, expanding, flaring, and flanging.

Its weldability is also excellent. It can be welded by various methods, including:

GTAW/TIG welding;

GMAW/MIG welding;

Submerged arc welding.

No special heat treatment is generally required. With properly matched filler metals, such as ERNiCu-7 or RNCu-10, the weld strength can reach more than 90% of the base metal strength.

5. Long-Term Stability and Low Maintenance Cost

Copper nickel tubes generally do not require additional coating protection or sacrificial anode maintenance during their design service life.

Although the initial purchase cost is higher than that of carbon steel or galvanized pipe, its proven service life of 30–40 years or more in shipboard applications makes the annualized maintenance cost extremely low.

6. Good Thermal Conductivity

Although the thermal conductivity of 90/10 copper nickel is lower than that of pure copper, it still offers good heat transfer performance and is significantly better than many stainless steel materials.

Therefore, it is highly suitable for seawater cooling systems, heat exchanger connection pipelines, and condenser systems.

Typical Technical Parameters of C70600 Copper Nickel Seamless Tube

Main Applications in Marine Vessels and Shipyards

90/10 copper nickel seamless tube is widely used in various types of ships and offshore equipment, including the following systems.

• Seawater Cooling Systems: Used for cooling pipelines of main engines, auxiliary engines, generators, and heat exchangers, ensuring long-term and stable equipment operation.

• Fire Water Systems: Used to transport seawater as the fire extinguishing medium over long periods. These systems require excellent corrosion resistance and reliable sealing performance.

• Ballast Water Systems: Used in ship ballast water transfer and treatment systems, suitable for complex marine environments.

• Desalination Units: Maintains excellent corrosion resistance during seawater intake, evaporation, and condensation processes.

• Air Conditioning and Refrigeration Systems: Used in seawater condensers and heat exchangers to improve heat exchange efficiency and extend equipment service life.

• Ship Domestic Water Supply and Auxiliary Systems: Suitable for cooling water, process water, and other auxiliary pipelines, providing reliable support for daily ship operation.

Advantages of 90/10 Copper Nickel Seamless Tube Compared with Other Materials

1. Compared with Carbon Steel Pipe

Carbon steel pipe has a lower purchase price, but it corrodes rapidly in seawater environments and usually requires coatings, cathodic protection, or frequent maintenance.

Once the coating is damaged, corrosion can develop quickly.

Although C70600 copper nickel seamless tube has a higher initial cost, it offers stronger corrosion resistance, longer maintenance intervals, and better long-term overall cost performance.

2. Compared with Stainless Steel Pipe

Stainless steel performs well in freshwater and ordinary atmospheric environments, but in chloride-containing seawater, it may suffer from pitting corrosion, crevice corrosion, and stress corrosion.

The risk is especially high in low-flow areas, sediment accumulation zones, and welded regions.

90/10 copper nickel alloy forms a stable protective film in flowing seawater, making its seawater corrosion resistance more suitable for marine water piping environments.

3. Compared with Ordinary Copper Tube

Ordinary copper tube has good thermal conductivity, but its corrosion resistance under high-velocity seawater scouring is inferior to that of copper nickel alloy.

By adding nickel, iron, and manganese, 90/10 copper nickel significantly improves seawater corrosion resistance and impingement corrosion resistance, making it more suitable for shipboard seawater systems.

4. Compared with 70/30 Copper Nickel

70/30 copper nickel has a higher nickel content and generally offers stronger corrosion resistance and impingement corrosion resistance, making it suitable for more severe operating conditions.

However, 90/10 copper nickel is already reliable enough for many conventional seawater pipelines and has a relatively lower cost.

Therefore, 90/10 copper nickel tube is often regarded as a balanced choice between performance and economy for marine seawater systems.

Why Do Shipyards Prefer 90/10 Copper Nickel Seamless Tube?

As the international maritime industry continues to raise requirements for vessel reliability and environmental performance, more and more shipbuilders are using 90/10 copper nickel seamless tube as a standard configuration.

The main reasons include:

1. Excellent seawater corrosion resistance;

2. Natural resistance to marine biofouling;

3. Good welding and installation performance;

4. High-strength seamless structure;

5. Long service life;

6. Low maintenance cost;

7. Clear life-cycle cost advantage;

8. Compliance with international classification society requirements.

As a result, it has become an important piping material for merchant ships, oil tankers, LNG carriers, naval vessels, offshore platforms, and marine engineering equipment.