C68700 aluminum brass is a copper-zinc alloy with additions of aluminum and a corrosion inhibitor, designed to provide excellent resistance to high-velocity seawater and brackish water service. The alloy offers improved strength, good thermal conductivity, and strong resistance to impingement attack and erosion-corrosion in demanding cooling environments.
Inhibited aluminum brass tubes (C68700) are widely used in condenser and heat exchanger systems, particularly in marine, power generation, and desalination applications where high water velocity and saline conditions can reduce the service life of conventional copper alloys.
Inhibited aluminum brass tubes (C68700) are widely used in condenser and heat exchanger systems, particularly in marine applications:
| Item | Specification |
| UNS No. | C68700 – BSI No. CZ110 – ISO Name CuZn22Al2 |
| Chemical Composition (%) | Cu: 76 – 79Al: 1.8 – 2.5Pb: ≤ 0.07Fe: ≤ 0.06As: 0.02 – 0.06Zn: Balance |
| ASTM Specification | B111, B395 |
| ASME Specification | SB111, SB395 |
| Temper | O61 (Annealed) |
Properties and Metrics:
| Property | Metric | English |
| Density | 8.33 g/cm³ | 0.301 lb/in³ |
| Tensile Strength | 345 MPa | 50 ksi |
| Yield Strength | 125 MPa | 18 ksi |
| CTE, Linear | 18.5 × 10⁻⁶/°C @ 20–300°C | 10.3 × 10⁻⁶/°F @ 70–570°F |
| Specific Heat Capacity | 0.09 cal/g-°C @ 20°C | 0.09 BTU/lb-°F @ 70°F |
| Thermal Conductivity | 100.4 W/m·K @ 20°C | 58 BTU/ft²/ft/h/°F @ 70°F |
| Melting Point | 932 – 971°C | 1710 – 1780°F |
* The values shown are typical reference data only and should not be used for exact design or engineering purposes.
1. What is C68700 aluminum brass?
C68700 aluminum brass is a copper-zinc alloy containing approximately 2% aluminum with small additions of arsenic as a corrosion inhibitor. It is specifically developed for condenser and heat exchanger tubing operating in seawater and brackish water, offering strong resistance to impingement, erosion, and corrosion.
2. What is aluminum brass used for?
C68700 aluminum brass tubes are commonly used in power plant condensers, marine cooling systems, desalination plants, offshore platforms, and industrial heat exchangers. They are particularly suitable for applications involving high-velocity seawater or contaminated cooling water.
3. Why is C68700 suitable for high-velocity seawater?
The aluminum addition forms a protective oxide film on the tube surface, which improves resistance to erosion and impingement attack. This protective layer helps prevent metal loss and ensures long-term reliability in turbulent and high-flow seawater systems.
4. What is the difference between aluminum brass and admiralty brass?
Aluminum brass (C68700) contains aluminum for improved erosion resistance and is better suited for high-velocity seawater. Admiralty brass (C44300) contains tin and is typically used in moderate flow and less aggressive cooling water conditions. Aluminum brass generally provides longer service life in demanding marine environments.
5. Is C68700 resistant to dezincification?
Yes. C68700 aluminum brass includes inhibitors such as arsenic that help prevent dezincification. This ensures the alloy maintains its strength and corrosion resistance when exposed to saline or polluted water.
6. Can C68700 aluminum brass tubes be expanded and bent?
Yes. C68700 tubes offer good fabrication properties and can be expanded into tube sheets, bent into U-tubes, and welded or brazed. This makes them suitable for various condenser and heat exchanger designs.
7. What industries use C68700 aluminum brass tubes?
Typical industries include power generation, desalination, shipbuilding, offshore oil & gas, petrochemical processing, and marine engineering. These sectors rely on aluminum brass tubes for durability in seawater cooling systems.
8. What standards apply to C68700 tubes?
C68700 aluminum brass tubes are commonly manufactured according to ASTM B111, ASTM B395, and ASME SB111 specifications for condenser, heat exchanger, and cooling system applications.
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