SB 111 C71500 Copper-Nickel Tube | 70/30 Cu-Ni Seamless Condenser Tube | UNS C71500 | Annealed Temper | OD 6.35–54.0 mm | For Heat Exchangers, Condensers & Seawater Piping | Per ASME SB-111 / ASTM B111
Overview – SB 111 C71500 Seamless Copper-Nickel Tube
SB 111 C71500 is a seamless copper-nickel tube specification covering the 70/30 Cu-Ni alloy (UNS C71500), designed for surface condensers, heat exchangers, and seawater piping systems. The alloy contains approximately 30% nickel, which provides substantially higher resistance to flowing seawater and impingement attack compared to the 90/10 Cu-Ni grade (C70600).
This tube is manufactured and certified per ASME SB-111 / ASTM B111, with material conforming to ASME Boiler and Pressure Vessel Code Section II requirements. Typical delivery condition is annealed (O61) for subsequent expansion or welding into tubesheets.
Chemical Composition (UNS C71500)
| Element | Content (%) | Function |
|---|---|---|
| Copper (Cu) | Remainder | Base matrix; thermal conductivity and formability |
| Nickel (Ni) | 29.0 – 33.0 | Primary alloying element; strength and seawater corrosion resistance |
| Iron (Fe) | 0.40 – 1.00 | Enhances resistance to impingement and erosion-corrosion |
| Manganese (Mn) | ≤ 1.00 | Deoxidation and solid-solution strengthening |
| Zinc (Zn) | ≤ 0.50 | Impurity; controlled to maintain corrosion resistance |
| Lead (Pb) | ≤ 0.02 | Impurity; controlled to avoid hot-cracking |
| Carbon (C) | ≤ 0.05 | Impurity control |
| Sulfur (S) | ≤ 0.02 | Impurity; low levels required for hot working |
| Phosphorus (P) | ≤ 0.02 | Impurity control |
Mechanical Properties (Annealed Condition)
| Property | Typical Value |
|---|---|
| Tensile Strength | 372 – 414 MPa |
| Yield Strength (0.2% offset) | 172 MPa |
| Elongation | 45% |
| Hardness (Rockwell 30T) | 77 – 80 |
| Elastic Modulus | 150 GPa |
| Density | 8.94 g/cm³ |
Available Dimensions
| Parameter | Range |
|---|---|
| Outer Diameter (OD) | 6.35 mm – 54.0 mm |
| Wall Thickness | 0.5 mm – 3.0 mm (standard); consult for heavier walls |
| Length | Straight lengths up to 18 m, or U-bent per request |
| Delivery Form | Straight lengths (hard or annealed) or U-bent tubes |
Corrosion Resistance – Seawater Service Parameters
C71500 is selected for seawater and brackish water service where C70600 (90/10 Cu-Ni) may experience higher metal loss rates under turbulent flow.
| Parameter | C71500 Performance |
|---|---|
| Seawater velocity (continuous) | Up to 3.5 m/s for clean seawater; consult for sand-laden or high-turbulence conditions |
| Resistance to impingement attack | Superior to C70600; suitable for high-velocity condenser inlet zones |
| Resistance to stress corrosion cracking | Good; copper-nickel alloys are generally resistant to SCC in seawater |
| Biofouling resistance | Copper ion release provides some resistance to marine organism attachment |
| Chloride environment | Suitable for full seawater (approximately 19,000–20,000 ppm chloride) |
Typical Applications
Surface condensers in coastal power plants and marine vessels
Heat exchangers using seawater or brackish water as cooling medium
Desalination plant heat exchangers (multi-stage flash and multi-effect distillation)
Seawater piping systems and offshore platform utility lines
Chemical processing where chloride-bearing fluids are present
Manufacturing and Testing
| Test | Scope | Standard |
|---|---|---|
| Eddy Current Test | 100% of tubes | ASME SB-111 |
| Hydrostatic Test | 100% of tubes (or per purchase order) | ASME SB-111 |
| Chemical Analysis | Per heat/lot | ASTM E478 or equivalent |
| Tensile Test | Per lot | ASTM E8 |
| Flattening / Flaring Test | Per lot | ASME SB-111 |
| Surface Inspection | 100% visual | No cracks, seams, or harmful defects |
Tube-to-Tubesheet Joint Considerations
C71500 is typically expanded or welded into tubesheets.
For welded joints, use matching C71500 or nickel-base filler metal per qualified WPS.
Annealed (O61) temper is preferred for expansion to achieve consistent pull-out strength.
Avoid excessive expansion beyond manufacturer recommendations to prevent work-hardening and stress corrosion susceptibility.
Documentation Per Shipment
Material Test Certificate per EN 10204 3.1 or 3.2
Chemical composition report (heat/lot traceability)
Mechanical property test report
Eddy current test report
Hydrostatic test report (if specified)
Dimensional inspection report
ASME SB-111 compliance statement
Selection Checklist – SB 111 C71500 Tube
Tube OD and wall thickness required
Straight length or U-bend configuration (with bend radius if U-bent)
Temper: Annealed (O61) or hard-drawn
Quantity (meters or pieces)
Hydrostatic test required (yes/no)
Third-party inspection requirement (if any)
Tube-end preparation (plain, beveled, or expanded)
Applicable standard: ASME SB-111 / ASTM B111 (specify edition)
Design Limitation Statement
C71500 is not recommended for service temperatures above approximately 300°C in continuous operation; consult for elevated-temperature applications.
Ammonia and ammonia-bearing compounds can cause stress corrosion cracking in copper alloys; verify fluid compatibility before selection.
Flow velocity should be limited per industry guidelines (typically ≤ 3.5 m/s for clean seawater) to avoid erosion-corrosion.
Welding of C71500 requires qualified procedures and appropriate filler metals; unqualified welding may result in joint failure or corrosion susceptibility.
