In a groundbreaking development poised to redefine durability and performance standards in the global HVAC&R (Heating, Ventilation, Air Conditioning, and Refrigeration) industry, TOBO Materials has officially launched its latest innovation: the TOBO-43 series. This next-generation product line features ASTM B111-compliant 90/10 Copper-Nickel (CuNi 90/10, UNS C70600) welded tubes, engineered with a proprietary precision-polished internal surface specifically designed for superior performance in demanding air conditioning and refrigeration systems. This launch directly addresses a critical but often overlooked challenge in system longevity and efficiency: internal tube corrosion and micro-fouling in condenser and evaporator coils .
The Material Science Breakthrough: Why CuNi 90/10 (C70600)?
The TOBO-43 series moves decisively beyond standard copper or aluminum tubing by utilizing Copper-Nickel 90/10 alloy. This material, long trusted in marine and offshore engineering for seawater pipelines, brings a suite of transformative properties to HVAC&R applications .
Unrivaled Corrosion Resistance: C70600 exhibits exceptional resistance to a wide range of corrosive threats, including formicary corrosion ("ants' nest corrosion")—a pervasive failure mode in standard copper tubes caused by volatile organic compounds (VOCs) from insulation, adhesives, or atmospheric contaminants . It also offers superior resistance to stress-corrosion cracking and pitting, particularly in environments with chlorides, ammonia, or sulfides. The corrosion resistance of C70600 is adequate for most kinds of water (fresh and seawater) at moderate temperatures, with corrosion rates typically below 0.025 mm/year in seawater service.
Superior Anti-Microbial and Anti-Fouling Properties: The alloy's surface chemistry inherently inhibits the adhesion and growth of biofilm, algae, and mineral scale . This is a transformative advantage for maintaining consistent heat transfer efficiency over time, preventing the insulating layers that drastically reduce system Coefficient of Performance (COP) and SEER/EER ratings.
Enhanced Mechanical Strength and Fatigue Life: Compared to pure copper, C70600 offers higher tensile strength (typically 275-450 MPa depending on temper) and dramatically better resistance to vibration-induced fatigue . This is a critical factor for compressor discharge lines and components in large rooftop units or industrial chillers subject to constant operational stress, enhancing the structural integrity of coils and reducing the risk of failure.
Excellent Thermal Conductivity: While slightly lower than pure copper, its thermal conductivity remains excellent at approximately 40 W/m·K . This is more than compensated for by its long-term surface integrity, ensuring consistent heat transfer performance over a 20-30 year lifespan.
The Precision Edge: Welded Construction with a Proprietary Polished Bore
The TOBO-43 tubes are manufactured using advanced welded and drawn processes, ensuring excellent dimensional consistency, tight tolerances, and cost-effectiveness for volume applications . The key differentiator is the application of a proprietary internal polishing and finishing process, which creates an ultra-smooth, mirror-like finish on the inner tube surface.
This polished surface delivers decisive performance benefits:
Optimized Hydraulic Flow: The mirror-smooth interior drastically reduces fluid friction and turbulence, minimizing pressure drop across the coil or piping run . This allows for more efficient refrigerant circulation, reducing compressor workload and directly lowering energy consumption.
Maximized Heat Transfer: A polished surface minimizes the microscopic nucleation sites where fouling can initiate . This ensures the tube's inherent high thermal conductivity is fully utilized throughout its service life, maintaining the system's designed heat exchange efficiency.
Facilitated System Cleanliness and Maintenance: In applications requiring periodic flushing or in systems where oil return is critical, the non-stick, polished surface prevents debris and scale from adhering strongly, promoting cleaner, more effective maintenance procedures .
Preservation of Material Properties: The polishing process further enhances the natural passive oxide layer of the CuNi alloy, reinforcing its corrosion resistance from the very start of service.
Manufacturing Specifications
Type: Longitudinal welded (LF) seamless-drawn
Outer Diameter: 6 mm – 50 mm (custom sizes available)
Wall Thickness: 0.5 mm – 3 mm
Length: According to customer drawing (max 25,000 mm)
Standard: ASTM B111, ASTM B359, BS 2871, EN 12451, DIN 1785
Temper: Soft, half-hard,Hard, etc.
Quality Assurance and Testing
All TOBO-43 tubes undergo rigorous testing to ensure premium quality:
Microstructure Examination: Ensures uniform grain structure
Tensile Test: Guarantees mechanical integrity
Expansion Test: Verifies ductility
Flattening Test: Checks workability
Flange Test: Confirms end formability
Eddy-Current Test: 100% non-destructive testing for wall integrity
Gas Pressure / Water Pressure Test: Validates pressure ratings
Purity & Roughness Test: Ensures polished surface specifications
Certification and Compliance: The ASTM B111 Benchmark
All TOBO-43 tubes are produced in strict adherence to the rigorous ASTM B111/B111M standard for Copper-Nickel Alloy Seamless and Welded Tubes . This certification provides engineers and OEMs with guaranteed parameters for:
Chemical Composition: Ensuring the precise 90/10 CuNi ratio (Ni 9.0-11.0%, Fe 1.0-1.8%, Mn ≤1.0%) .
Mechanical Properties: Tensile strength ≥ 275 MPa, yield strength ≥ 105 MPa, elongation ≥ 30% .
Dimensional Tolerances: Ensuring consistent fit and performance.
Pressure Integrity: Guaranteeing material traceability and performance predictability.
Target Applications: Where Reliability is Non-Negotiable
The TOBO-43 series is engineered for premium and mission-critical applications where system failure carries significant operational or financial risk :
Marine & Coastal HVAC&R: Air conditioning systems on vessels, offshore platforms, and coastal facilities where salt-laden, highly corrosive air rapidly degrades standard materials .
High-Value Commercial Refrigeration: Supermarket display case coils, cold storage warehouse evaporators, and food processing chillers where hygiene, efficiency, and reliability are paramount .
Specialty and Industrial Process Chillers: For chemical processing, pharmaceutical manufacturing, and data center cooling, where process stability, purity, and 24/7 uptime are essential .
High-Value Residential & Commercial AC: For manufacturers and installers targeting extended warranties, superior lifecycle value, and applications in coastal regions with polluted or corrosive atmospheres.
Industry Validation and Market Outlook
"The introduction of a polished C70600 tube specifically for HVAC&R is a game-changer for system designers focusing on total cost of ownership," stated Dr. James Keller, a consultant in thermal systems engineering. "While the initial material cost is higher than standard copper, the long-term benefits—near-elimination of formicary corrosion, sustained high efficiency, and potentially double the service life—present a compelling economic and engineering argument for critical systems. TOBO-43 makes this advanced material solution commercially and technically accessible" .
This launch signals a strategic shift in the HVAC&R components sector, moving from a commodity-focused model to a performance- and longevity-driven value proposition . As global regulations push for higher energy efficiency and lower environmental impact from refrigerant leaks, materials that ensure long-term system integrity will see accelerated adoption.
Available Alloys and Formats
Beyond C70600, TOBO-43 tubes are also available in:
C12200 / SIF (DHP): Standard copper for general HVAC
C12000 / SFR (DLP): Deoxidized low phosphorus copper
C14200 (DPA): Arsenical copper for enhanced corrosion resistance
C71500 (CuNi 70/30): Premium grade for extreme environments
Formats include straight tubes (random or fixed) and capillary tubes, as well as pancake coils for easy field installation .
Conclusion: Redefining the Lifespan of Thermal Systems
The debut of the TOBO-43: ASTM B111 C70600 Polished Surface Welded Tube represents more than a new product; it signifies a fundamental advancement in the materials science applied to HVAC&R systems. By combining the proven, robust corrosion resistance of marine-grade copper-nickel alloy with a precision-engineered internal surface, TOBO has created a component that actively preserves system efficiency and extends operational lifespan .
This innovation empowers engineers to design more resilient systems and provides facility managers with a powerful tool to reduce lifecycle costs and unexpected downtime. In an industry increasingly focused on sustainability and reliability, the TOBO-43 series stands as a testament to how intelligent material selection and precision manufacturing can build a cooler, more efficient, and more durable future .
About TOBO Materials:
TOBO Materials is a specialized developer and supplier of high-performance non-ferrous alloy solutions for demanding engineering environments. With expertise in metallurgy, corrosion science, and precision manufacturing, TOBO serves the marine, energy, chemical processing, and advanced HVAC&R industries worldwide. The company is headquartered in Shanghai's Jiading District, with robust production capacity and a commitment to strict quality control and customer service.