UNS C44300 Admiralty Brass Tube PDF
Certified Composition Ranges (Weight %)
| Element | SB111 C44300 (Admiralty Brass) | SB111 C70600 (90-10 Cupronickel) | Primary Function |
|---|---|---|---|
| Copper (Cu) | 70.0 - 73.0 | 86.5 minimum | Base metal, provides inherent corrosion resistance and conductivity. |
| Zinc (Zn) | Remainder (≈27-30%) | 1.0 max (impurity) | In C44300: Major alloying element for cost and strength. Corrosion vulnerability. |
| Tin (Sn) | 0.9 - 1.2 | - | In C44300: Improves general corrosion and erosion resistance in seawater. |
| Nickel (Ni) | - | 9.0 - 11.0 | In C70600: Primary alloyant. Enhances corrosion resistance, strength, and stabilizes the protective oxide film. |
| Iron (Fe) | 0.06 max (impurity) | 1.0 - 1.8 | In C70600: Critical. Dramatically improves resistance to impingement attack and stabilizes the oxide layer. |
| Manganese (Mn) | - | 0.30 - 1.0 | In C70600: Deoxidizer, improves hot workability and soundness. |
| Arsenic (As) | 0.02 - 0.10 | - | In C44300: Critical Inhibitor. Prevents dezincification by "poisoning" the selective leaching reaction. |
| Lead (Pb) | 0.07 max | 0.05 max | Impurity, controlled for weldability/fabrication. |
| Other Elements | 0.15 max (each) | 0.10 max (each) | - |
Metallurgical System & Phase Structure
C44300: A single-phase (alpha) brass. The arsenic is in solid solution, not a separate phase. The high zinc content places it in the alpha region of the Cu-Zn phase diagram, ensuring good cold workability.
C70600: A single-phase (alpha) solid solution copper-nickel alloy. The iron and manganese are in complete solid solution with the copper-nickel matrix, creating a homogeneous, tough structure.
Physical Properties at 20°C (68°F)
| Property | SB111 C44300 | SB111 C70600 | Implication for Design |
|---|---|---|---|
| Density | 8.53 g/cm³ (0.308 lb/in³) | 8.94 g/cm³ (0.323 lb/in³) | C70600 is ~5% heavier. Impacts weight calculations for large tube bundles. |
| Melting Range | 900 - 940 °C (1650 - 1725 °F) | 1100 - 1140 °C (2010 - 2085 °F) | C70600 requires higher energy for welding/brazing. Indicates higher service temperature capability. |
| Mean Coefficient of Thermal Expansion (20-300°C) | 20.2 x 10⁻⁶ /K | 17.1 x 10⁻⁶ /K | C44300 expands ~18% more than C70600 for the same ΔT. Critical for thermal stress management in fixed-tube-sheet designs. Must be matched to tube sheet material. |
| Thermal Conductivity (Annealed) | 109 W/m·K | 50 W/m·K | Most significant difference. C44300 transfers heat over twice as effectively. For equal duty, C70600 requires ~2.2x the surface area. |
| Specific Heat Capacity | 0.38 kJ/kg·K | 0.38 kJ/kg·K | Similar. |
| Electrical Conductivity (Annealed) | 26% IACS | 11% IACS | Consistent with thermal conductivity trend. C44300 is more conductive. |
Mechanical Properties
| Property (ASTM Test Method) | SB111 C44300 | SB111 C70600 | Engineering Significance |
|---|---|---|---|
| Tensile Strength, min | 330 MPa (48,000 psi) | 290 MPa (42,000 psi) | C44300 has a higher minimum tensile strength in the annealed condition. |
| Yield Strength (0.5% Ext. Under Load), min | 125 MPa (18,000 psi) | 125 MPa (18,000 psi) | Similar minimum yield strength. |
| Typical Yield Strength (0.2% Offset) | 130 MPa (19 ksi) | 140-165 MPa (20-24 ksi) | C70600 typically exhibits a higher actual yield strength. |
| Elongation in 2 inches (50 mm), min | 45% | 35% | C44300 is significantly more ductile, which can facilitate tube expansion and bending. |
| Modulus of Elasticity (Young's Modulus) | 105 GPa (15.2 x 10⁶ psi) | 135 GPa (19.6 x 10⁶ psi) | C70600 is ~30% stiffer. Better resistance to flow-induced vibration and sagging over long spans. |
| Shear Modulus | 39 GPa (5.7 x 10⁶ psi) | 52 GPa (7.5 x 10⁶ psi) | Consistent with higher stiffness of C70600. |
| Poisson's Ratio | 0.35 | 0.33 | Similar. |
| Hardness (Rockwell F) | 55-65 HRF | 45-55 HRF | C44300 is typically softer in the annealed state. |
| Fatigue Strength (Rotating Beam, 10⁸ cycles) | ~120 MPa (17 ksi) | ~160 MPa (23 ksi) | C70600 generally offers superior high-cycle fatigue resistance, crucial for turbulent flow conditions. |
| Creep Strength | Lower | Higher | C70600 is more resistant to slow deformation under stress at elevated temperatures (<300°C). |
Fabrication & Performance Properties
| Property | SB111 C44300 | SB111 C70600 | Notes |
|---|---|---|---|
| Machinability (% of Free-Cutting Brass) | 30% | 20% | Both are considered to have fair machinability. Require sharp tools, positive rake. |
| Cold Workability | Excellent (Alpha phase) | Good | Both can be readily cold drawn into tube. C44300 is more ductile. |
| Hot Workability | Good (800-900°C) | Excellent (875-1000°C) | - |
| Weldability / Brazeability | Fair. Requires care due to zinc fuming. Arsenic can cause weld pool toxicity. | Excellent. Readily welded by GTAW, GMAW, and brazed. No toxic fumes. | Major fabrication advantage for C70600. |
| Solderability | Excellent | Good | - |
Corrosion & Environmental Limits
| Condition | SB111 C44300 | SB111 C70600 | Rationale |
|---|---|---|---|
| Max. Recommended Water Velocity (Clean Seawater) | 2.1 - 2.4 m/s (7-8 ft/s) | 3.6 - 4.6 m/s (12-15 ft/s) | C70600's tough, adherent oxide film resists mechanical stripping by high shear forces. |
| Resistance to Dezincification | Excellent (with Arsenic inhibitor) | Immune | C70600 contains no zinc to leach out. |
| Resistance to Impingement Attack | Poor | Excellent | Directly related to velocity limit and Fe content in C70600. |
| Tolerance to Sulfide Pollution | Very Poor. Film breaks down, leading to rapid corrosion. | Good. Film is more stable, though not immune. Performance degrades with [H₂S]. | Critical for polluted harbor or biogenic sulfide conditions. |
| Ammonia Stress Corrosion Cracking (SCC) Resistance | Poor. Highly susceptible. | Good. Resistant in most marine concentrations. | Important for refinery or chemical plant coolers. |
| Galvanic Position in Seawater | More Active (Anodic). Potential ≈ -0.30 to -0.35 V vs. SCE. | More Noble (Cathodic). Potential ≈ -0.25 to -0.30 V vs. SCE. | Do NOT mix in the same unit. C44300 will corrode preferentially if coupled. |
| Marine Biofouling Resistance | Moderate. Copper ions provide some deterrence. | Superior. The Ni/Fe-stabilized oxide layer is less hospitable to organisms. |
How should I choose between C44300 and C70600?
Choose SB111 C44300 when:
Cooling water is fresh, clean brackish, or consistently clean seawater with low velocity (<2.1 m/s).
Initial capital cost is the primary constraint.
Maximum heat transfer efficiency is required from a given surface area.
Re-tubing an existing system historically successful with Admiralty.
Choose SB111 C70600 when:
Cooling medium is full seawater, estuarine, or variable-quality water.
System design involves high water velocity or risk of turbulence.
Water contains suspended solids (sand/silt) or risk of sulfide/ammonia contamination.
Long-term reliability, reduced maintenance, and life-cycle cost are prioritized over first cost.
For naval, offshore, or critical industrial applications.
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Founded in 2008, we are a leading professional exporter specializing in a comprehensive range of high-quality copper products for global markets. Our core product portfolio encompasses various forms and specifications to meet diverse industrial needs.
Copper Tubes & Pipes:
We supply both Copper Seamless Tubes (ASTM B68, B75) and Copper Welded Tubes, including Pure Copper Tubes (C11000, C12200), Brass Tubes (C23000, C26000, C28000), and specialized Admiralty Brass Tubes (C44300) for superior corrosion resistance in heat exchanger applications. Our offerings comply with key ASTM standards such as ASTM B88 for seamless water tube and ASTM B111 for condenser tubes.
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Our range covers from thin-gauge Thin Copper Sheet (ASTM B152) to heavy-duty Thick Copper Plate, available in alloys like Pure Copper (C11000), Brass Sheet (C26000), Phosphor Bronze Sheet (C51000, C52100), and corrosion-resistant Admiralty Brass Sheet/Plate (C44300).
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We provide Copper Round Rod, Copper Square Bar, Copper Hexagon Bar, and Copper Flat Bar in various tempers. Products include Free-Cutting Brass Rod (C36000 per ASTM B16), Oxygen-Free Copper Rod (C10100/C10200, ASTM B187), Beryllium Copper Bar (C17200, ASTM B196), and Admiralty Brass Rod (C44300).
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Our Copper Wire products include Bare Copper Wire (ASTM B1/B2/B3), Enamelled Copper Wire, and Brass Wire. We also supply precision Copper Strip (C11000, C26800), Brass Strip, and Admiralty Brass Strip (C44300) for electrical, marine, and fabrication applications.
