Mechanical Properties of Copper-Nickel Pipe at a Glance

In This Guide

Why Mechanical Properties Matter
Mechanical Properties — CuNi 90/10 (UNS C70600)
Mechanical Properties — CuNi 70/30 (UNS C71500)
Side-by-Side Comparison
Effect of Temper (Annealed vs Drawn)
Effect of Temperature
Testing Requirements per ASTM B466
Comparison with Other Piping Materials
Frequently Asked Questions

1. Why Mechanical Properties Matter

For any pressure-piping application, mechanical properties — tensile strength, yield strength, elongation and hardness — directly determine the allowable design stress, the minimum required wall thickness for a given pressure rating, and the alloy's tolerance for forming, bending and field installation. Understanding these values for Copper Nickel Pipes is essential before specifying pipe schedule, fitting types or support spacing in any marine, offshore, desalination or industrial piping system.

2. Mechanical Properties — CuNi 90/10 (UNS C70600)

Property	Annealed (Soft)	As-Drawn / Light Drawn
Tensile Strength	275 – 345 MPa min	310 – 415 MPa min
Yield Strength (0.5% EL)	105 MPa min	205 MPa min
Elongation	30% min	10 – 20% min
Hardness (HRB)	≤ 65	65 – 85

3. Mechanical Properties — CuNi 70/30 (UNS C71500)

Property	Annealed (Soft)	As-Drawn / Light Drawn
Tensile Strength	365 – 415 MPa min	415 – 515 MPa min
Yield Strength (0.5% EL)	140 MPa min	275 MPa min
Elongation	30% min	15 – 20% min
Hardness (HRB)	≤ 70	75 – 90

4. Side-by-Side Comparison

Property (Annealed)	CuNi 90/10	CuNi 70/30	Difference
Tensile Strength	275 – 345 MPa	365 – 415 MPa	~20–30% higher in 70/30
Yield Strength	105 MPa min	140 MPa min	~33% higher in 70/30
Density	8.94 g/cm³	8.94 g/cm³	Identical
Melting Point	~1100°C	~1170°C	70/30 higher

5. Effect of Temper (Annealed vs Drawn)

Both alloys gain considerable tensile and yield strength when cold-drawn rather than fully annealed, at the cost of reduced elongation and ductility. Annealed (soft) temper is typically specified where maximum ductility for bending, flaring or forming is required — for example Copper Nickel Round Pipes that will be field-bent. As-drawn / light-drawn temper is specified where higher strength is the priority and the pipe will not require significant cold forming after delivery, such as straight-run Copper Nickel High Pressure Pipes.

6. Effect of Temperature

Like most copper alloys, Copper-Nickel pipe gradually loses tensile and yield strength as service temperature rises above ambient, while retaining good ductility. Copper-Nickel piping is commonly used up to moderate elevated temperatures in heat exchanger, condenser and boiler-adjacent piping applications, but allowable design stress at elevated temperature should always be confirmed against the applicable piping code (e.g., ASME B31.3) rather than assumed from room-temperature values alone.

7. Testing Requirements per ASTM B466

Chemical composition analysis (spectrometric)
Tensile test — tensile strength, yield strength, elongation
Hydrostatic pressure test, or eddy-current test as an approved alternative
Flattening test and/or flaring test, as applicable by pipe size
Dimensional and visual inspection

8. Comparison with Other Piping Materials

Material	Typical Tensile Strength	Seawater Corrosion Life
Carbon Steel (A106)	415 MPa min	Poor without coating
Copper-Nickel 90/10	275 – 345 MPa	Excellent (20–30+ years)
Copper-Nickel 70/30	365 – 415 MPa	Excellent, higher velocity tolerance
304 Stainless Steel	515 MPa min	Moderate — pitting risk in seawater

Engineering takeaway

Copper-Nickel pipe has lower raw tensile strength than carbon steel or stainless steel, but its vastly superior corrosion resistance in seawater service means a properly sized Copper-Nickel system will frequently outlast steel piping that requires periodic wall-thickness allowance or coating maintenance — making it the more reliable long-term choice despite the strength numbers alone.

9. Frequently Asked Questions

What is the tensile strength of Copper-Nickel 90/10 pipe?

Annealed Copper-Nickel 90/10 (UNS C70600) pipe per ASTM B466 has a minimum tensile strength of approximately 275–345 MPa, while as-drawn tempers achieve 310–415 MPa.

Is Copper-Nickel 70/30 stronger than 90/10?

Yes. Copper-Nickel 70/30 (UNS C71500) has higher minimum tensile and yield strength than 90/10 (UNS C70600) in the same temper, typically 15–20% stronger, due to its higher nickel content.

What tests does ASTM B466 require for Copper-Nickel pipe?

ASTM B466 requires chemical composition analysis, tensile testing (tensile strength, yield strength, elongation), hydrostatic or eddy-current testing, and applicable flattening/flaring tests depending on pipe size.