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YUHONG Group, with over 35 years of industrial expertise and a global supply network serving 85 countries, specializes in high-performance non-ferrous alloy tubing solutions. Our ASTM B111 C71640 Copper-Nickel Seamless Tubes are manufactured to meet rigorous international standards for critical applications in marine condensers, heat exchangers, and evaporators. We ensure full traceability, stringent quality control, and reliable performance for demanding service conditions worldwide.
Chemical Composition - ASTM B111 C71640 (UNS C71640 / CW353H)
Element
Composition (%)
Copper (Cu) + Silver (Ag)
Remainder
Nickel (Ni) + Cobalt (Co)
29.0 - 32.0
Iron (Fe)
1.7 - 2.3
Manganese (Mn)
1.5 - 2.5
Carbon (C), max
0.06
Sulfur (S), max
0.03
Nominal composition: 66% Cu - 30% Ni - 2% Fe - 2% Mn
The elevated iron and manganese content—higher than standard C71500 (70/30 Cu-Ni)—reinforces the protective surface oxide film, providing superior resistance to impingement attack in flowing seawater.
All tubes are manufactured as seamless products through extrusion and cold-drawing processes, with dimensional range up to 3⅛ inches (80 mm) OD. The following mandatory tests are applied per ASTM B111:
Test Type
Requirement
Expansion Test
30% of outside diameter (per Table 4)
Hydrostatic Test
Maximum 1000 psi (7 MPa) unless otherwise specified
Eddy Current Test
100% mandatory for quality assurance (ASTM E243)
Grain Size (Annealed)
0.010 - 0.045 mm
Residual Stress Evaluation
Mercurous nitrate or ammonia vapor test
Eddy-current testing is now the primary NDT method in most mills, with hydrostatic testing performed when specified for subsea or nuclear service.
Critical manufacturing note: Surface finish and initial condition are decisive for service life. Research indicates that pickling and surface preparation directly influence the formation of the protective Fe/Mn-enriched oxide layer that provides erosion-corrosion resistance. We maintain strict control over surface condition through controlled pickling and annealing processes.
Complementary Fabrication Capabilities & Material Grades
Beyond bare tubes, Yuhong Group supplies complete heat exchanger component packages:
Component
Available Materials
Tube Sheets
ASME SB171 C71640, C71500, C70600
Baffle Plates
Carbon steel, stainless steel, or copper alloy per design
Channel Covers & Heads
ASME-compliant materials
U-Bend Tubes
C71640, C71500, C70600
Tube Bundles
Full assembly with C71640 tubing
We support customized dimensions, U-bending, finning (low-fin/high-fin), and complete bundle fabrication.
Application Scenarios
Surface condensers in marine and power generation service
Shell-and-tube heat exchangers in offshore platforms
Evaporators in desalination plants (MSF and MED)
Brine heaters and heat rejection sections
Cooling water systems with seawater or brackish water
High-velocity seawater piping where erosion resistance is critical
Technical Advantages & Customization
Erosion-Corrosion Resistance: The 2% Fe + 2% Mn composition enables C71640 to withstand higher flow velocities than standard C70600 (90/10) and C71500 (70/30) alloys. It delivers the best erosion and impingement resistance among copper-nickel grades while retaining the family's natural antifouling behavior.
Biofouling Resistance: Copper-nickel alloys naturally resist marine biofouling, reducing maintenance frequency and preserving heat transfer efficiency over extended service intervals.
Temperature Range: Maximum working temperature up to 300°C (572°F).
Customization Options:
Dimensions: Custom OD, wall thickness, and length
Tempers: O61 (annealed) or HR50 (drawn/stress-relieved)
Finishing: Bright annealed, pickled, or polished
Forms: Straight, U-bent, or coiled
End preparation: Plain, beveled, or threaded
Technical FAQ - Common Industry Questions
Q: What is the difference between C71640 and C71500 (70/30 Cu-Ni)?
C71640 is a modified 70/30 alloy with elevated Fe (1.7-2.3%) and Mn (1.5-2.5%) versus C71500 (Fe 0.4-1.0%, Mn 1.0% max). This provides higher strength and superior erosion-corrosion resistance in sand-laden seawater.
Q: Why is C71640 specified for MSF desalination plants?
Multi-stage flash desalination involves high-temperature brine with suspended solids at high velocities. C71640 was developed specifically for this duty and has been extremely successful in heat rejection and brine heater sections.
Q: What NDT methods are applied to ASTM B111 tubes?
Per ASTM B111, every tube undergoes either eddy-current testing (ASTM E243) or hydrostatic testing. Most mills now use 100% eddy-current testing as the primary method.
Yuhong Group is one of the large scale group company in China, more than 35 years experience in the international market, providing high-quality services to over 3000 customers, end user which like Aramco, Petrobras, Pemex, Petronas, Ecopetro, Petroecuador, …. till now Yuhong Grou...
Yuhong Group is one of the large scale group company in China, more than 35 years experience in the international market, providing high-quality services to over 3000 customers, end user which like Aramco, Petrobras, Pemex, Petronas, Ecopetro, Petroecuador, …. till now Yuhong Grou...
