Key points
Aluminum brass, also known as C68700, is a copper-zinc alloy enhanced with aluminum for improved strength and corrosion resistance. Known for its performance in harsh environments, aluminum brass is widely used in heat exchangers, condenser tubes, and marine systems due to its ability to resist saltwater corrosion, high fluid velocity, and biofouling.
What is aluminum brass?
Aluminum brass is a type of high-performance brass alloy composed primarily of copper and zinc, with small additions of aluminum and arsenic. The aluminum content significantly improves corrosion resistance by forming a thin, protective oxide film, while arsenic inhibits dezincification in aggressive environments.
This alloy is ideal for applications exposed to seawater, industrial chemicals, or high temperatures.
Composition of aluminum brass (C68700)
| Element | Content (%) |
|---|---|
| Copper (Cu) | 76.0 – 79.0 |
| Zinc (Zn) | Balance (~20–22) |
| Aluminum (Al) | 1.8 – 2.5 |
| Arsenic (As) | 0.02 – 0.06 |
| Others (Fe, Mn) | ≤ 1.0 combined |
This precise formulation allows C68700 to maintain strength and resist erosion and stress-corrosion cracking in turbulent, high-velocity systems.
Properties of aluminum brass
| Property | Performance |
|---|---|
| Corrosion resistance | Excellent in seawater and brine |
| Mechanical strength | Higher than naval or admiralty brass |
| Thermal conductivity | Moderate to high |
| Oxidation resistance | Self-forming, stable oxide layer |
| Biofouling resistance | Good, due to protective surface film |
| Formability & weldability | Excellent; suitable for cold-working and brazing |
Applications of aluminum brass
Aluminum brass is used where durability, heat transfer, and resistance to harsh fluids are essential:
1. Heat exchangers
C68700 tubes are commonly used in heat exchangers in desalination plants, refineries, and power stations due to their resistance to impingement and erosion.
2. Condenser tubes
In thermal and nuclear plants, aluminum brass offers long service life and reliable thermal performance.
3. Marine systems
Ideal for shipboard cooling systems, bilge pipes, and ballast systems where saltwater flow is continuous and aggressive.
4. Industrial cooling equipment
Effective in petrochemical and process industries that operate under extreme conditions.
Advantages over other copper alloys
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More corrosion-resistant than admiralty brass
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Stronger than standard brass alloys
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Performs under high fluid velocity (>2.5 m/s)
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Longer lifespan in aggressive or polluted waters
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Good biofouling resistance without coatings
What is the difference between aluminum brass and admiralty brass?
The main difference lies in their alloying elements and resulting performance. Aluminum brass (e.g. C68700) contains approximately 2% aluminum, which enhances its strength and forms a protective oxide layer that significantly improves resistance to corrosion and erosion, especially in high-velocity seawater and polluted environments.
In contrast, admiralty brass (e.g. C44300) includes a small percentage of tin (around 1%) instead of aluminum. While admiralty brass offers good corrosion resistance, it is generally better suited for moderate flow rates and less aggressive conditions. It may be more susceptible to impingement attack in turbulent fluids compared to aluminum brass.
In summary:
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Aluminum brass is preferred for harsh marine conditions and high-velocity fluid systems.
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Admiralty brass is more economical and sufficient for less demanding applications, such as fresh water or low-flow environments.
Sourcing C68700 aluminum brass tubes
At Admiralty Industries, we manufacture and supply high-performance aluminum brass tubes and components that meet ASTM B111 and international standards.
Our aluminum brass is available in:
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Seamless tubes for heat exchangers
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Custom-cut lengths and diameters
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Precision-engineered tubing for OEM applications
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Marine-grade and industrial-grade stock