What Is The Precise Chemical Composition Of C71500?

SB 111 C71500 is a premium-grade, seamless pipe and tube material made from a specific copper-nickel alloy. The "C71500" refers to the chemical composition of the alloy itself, which is approximately 70% Copper and 30% Nickel, known commercially as 70/30 Cupro-Nickel. The "SB 111" is the ASME (American Society of Mechanical Engineers) code designation that specifies the manufacturing requirements, dimensions, and testing for the seamless pipe and tube product form. Essentially, it's a high-performance corrosion-resistant piping material designed for critical applications.

The most common name is 70/30 Cupro-Nickel. It is also frequently referred to as Copper Nickel 30 or Cu-Ni 30%. These names directly reflect its primary alloying composition.

The composition is tightly controlled. Key elements include:

Copper (Cu): 65.0% min (remainder) - The base metal.

Nickel (Ni): 29.0% - 33.0% - Provides solid solution strengthening and excellent corrosion resistance.

Iron (Fe): 0.40% - 1.0% - Crucial for erosion-corrosion resistance.

Manganese (Mn): 1.0% max - Acts as a deoxidizer and improves workability.

Impurities: Elements like Lead (Pb), Zinc (Zn), and Carbon (C) are restricted to very low levels (e.g., 0.05% max) to prevent detrimental effects on weldability and hot workability.

Iron is not an impurity; it is an intentional and vital alloying element. In seawater service, it forms a protective, adherent, and complex surface oxide film. This film is highly resistant to breakdown from high fluid velocities. Without sufficient iron, the alloy would be much more susceptible to "impingement attack," a form of erosion-corrosion that occurs in turbulent or high-flow conditions, such as at pipe bends or in condenser inlets.

Its key properties form a unique combination:

Superior Corrosion Resistance: Excellent resistance to seawater, brackish water, and many chemicals, including resistance to stress-corrosion cracking.

Excellent Biofouling Resistance: The slow release of copper ions from the surface inhibits the attachment and growth of marine organisms like barnacles and mussels.

High Erosion-Corrosion Resistance: Primarily due to the iron content, making it suitable for high-velocity applications.

Good Mechanical Strength: Significantly stronger than pure copper and brasses, allowing for thinner wall tubes.

Excellent Thermal Conductivity: Makes it an ideal choice for heat exchangers and condensers.

Good Fabricability: It can be bent, formed, and welded with standard techniques.

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Common Alloys & International Standards:

We master a wide array of materials compliant with ASTM, EN, JIS, and GB standards:

Pure Copper: C11000 (ETP Copper), C10200 (Oxygen-Free Copper), C12000 (DLP)

Brass Alloys: C26000 (Cartridge Brass), C27200 (Brass), C28000 (Muntz Metal)

Copper-Nickel: C70600 (CuNi90/10), C71500 (CuNi70/30)

Phosphor Bronze: C51900, C52100, C54400

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