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A Comprehensive Industry Whitepaper on Precision double-walled low-carbon steel tubes for refrigeration and HVAC systems.
A Bundy Tube is a specialized type of double-walled low-carbon steel tube manufactured by wrap-rolling a copper-coated steel strip through 720 degrees. The seam is then furnace-brazed in a reducing atmosphere to create a molecular bond. Originating from the Bundy Tubing Company in the early 20th century, this metallurgical process results in a component that combines the cost efficiency and structural strength of steel with the heat transfer efficiency and corrosion resistance of copper.
In modern HVAC and refrigeration assemblies, copper-coated steel Bundy tubes serve as the arterial networks of condenser units, cooling loops, evaporators, and automotive brake piping. Due to their exceptional resistance to high internal pressures and mechanical vibrations, they have become the industry standard for commercial compressors and refrigeration cycles.
Global procurement managers and OEMs look for high-grade Bundy tubes that comply with tight dimensional tolerances, inner surface cleanliness, and flawless plating properties. In environments utilizing ecological refrigerants like R290, R600a, or carbon dioxide systems, Bundy tubes must withstand high burst pressures and avoid chemical reactivity.
Key metrics demanded by global buyers include wall-thickness uniformity (typically ±0.02mm), high resistance to salt spray tests (meeting ASTM B117 standards for over 72 to 120 hours without corrosion), and strict internal contamination thresholds (less than 0.19 mg/dm² of internal surface area).
To assist HVAC engineers in their strategic sourcing, the following table details the mechanical properties and metallurgical ratings of our low-carbon steel Bundy tubes.
| Parameters | Standard Specifications | Taojun Enterprise Guarantee |
|---|---|---|
| Material Standard | SAE J527, ASTM A254, EN 10305-6 | Fully Compliant with IATF 16949 & ASTM A254 |
| Outside Diameter (OD) | 3.17mm - 12.00mm | ±0.05mm ultra-precise tolerance range |
| Wall Thickness | 0.50mm - 1.00mm | ±0.02mm structural variance control |
| Tensile Strength | ≥ 290 MPa | Average test rating: 310 - 340 MPa |
| Yield Strength | ≥ 180 MPa | Excellent bending ductility, zero micro-fracturing |
| Internal Cleanliness | ≤ 0.20 mg/dm² residue | Double-cleaned system yielding ≤ 0.15 mg/dm² |
| Surface Plating | Copper-coated (≥ 3μm thickness) | Electroplated zinc or copper options customized |
Ningbo Taojun Refrigeration Equipment Co., Ltd. is located in Xiangshan, Ningbo, a beautiful tourist city. Founded in 1988, its predecessor was Xiangshan Refrigeration Accessories Factory of Zhejiang University. The company's leading products include: filter driers, check valves, air conditioning valves, condensers, brass and copper accessories, air conditioning cable ties, and other refrigeration accessories series products.
After 30 years of hard work and rapid development, it has now become a comprehensive enterprise integrating the design and development, production and sales, and after-sales service of refrigeration accessories. In 2021, it became a national high-tech enterprise. Our company is committed to technological and process innovation, equipment improvement, and the introduction of advanced management concepts to produce first-class products. Customer satisfaction is our unwavering pursuit. With reasonable design, reliable quality, and perfect after-sales service, the "Lingshan" filter has become a well-known brand in the domestic refrigeration industry.
The company has successively passed ISO9001:2008 quality management system certification, EU ROHS environmental protection directive certification, and US UL certification. The company always takes customer needs as the basis and continuously innovates management concepts to ensure efficient and stable development.
In 2012, Ningbo Taojun Refrigeration Equipment Co., Ltd. was established, creating the brand "Taojun" condensers, "Taojun" stop valves and other series of products. Over the years, it has established partnerships with well-known domestic and foreign home appliance enterprises such as Haier, Xinfei, Midea, Gree, Whirlpool, Electrolux, and Huarui.
The product sales network covers major and medium-sized cities in China and is exported to Europe, America, South America, Southeast Asia, the Middle East, Africa, and other overseas markets. The company's goal is to support and cooperate with every sincere customer to achieve a win-win situation.
With leading research and development abilities in refrigeration parts, we consistently deliver top-tier system solutions that extend the operational life of commercial refrigeration equipment.
Taojun has specialized in refrigeration parts for 38 years. Our copper filter driers, condensers, and Bundy tubes are engineered to absorb moisture and acids, keeping your cooling cycles performing at peak efficiency.
✓ Shell: High purity copper pipe (rust resistant, high pressure resistant).
✓ Inner Core: 3A molecular sieve (water absorption ≥20%) + activated carbon layer.
✓ Sealing Process: Argon arc welding to ensure no leakage under high mechanical load.
✓ Prolong Equipment Life: Reduces water and acid corrosion inside compressors.
✓ Rapid Cooling: Minimizes system friction resistance, optimizing refrigerant cycle efficiency.
✓ Versatile Application: Broadly utilized in domestic refrigerators, cold stores, and automotive HVAC.
✓ Complete Refrigerator & Freezer repairs and aftermarket component supply.
✓ HVAC maintenance and eco-friendly gas conversion upgrades.
✓ Large industrial refrigeration systems and cold chain transportation protection.
Driving the evolution of sustainable thermal transfer and clean-flow HVAC systems globally.
As the global HVAC industry shifts towards eco-friendly refrigerants such as Carbon Dioxide (R744) and Propane (R290), structural integrity and operating pressures have increased significantly. Standard copper tubes are being replaced with copper-coated double-walled steel Bundy tubes in high-pressure loops due to their lower degradation risk and superior burst capabilities.
Taojun is currently leading research to reduce internal surface roughness and achieve absolute dry atmospheres inside our tubes. This research guarantees zero chemical reactions with new-generation synthetic and natural oils used in compressor technologies.
By utilizing our integrated MES workshop management, each batch of tubing undergoes rigorous quality mapping. We integrate automated CCD visual checking to spot anomalies in plating thickness and seam structural geometry down to ±0.01mm. This eliminates thermal bypass errors and ensures a near-zero leakage operational lifetime for end-users.
Combining academic heritage, imported production equipment, and strict testing stages to ensure first-class product distribution.
Our core production equipment is imported directly from Germany to ensure perfect rolling, plating, and structural precision.
Our research and development center features 15 dedicated engineers, collaborating with professors and doctors from the University of Science and Technology of China.
Completely customized sizes, tube shapes, and specialized plating packages are available upon request. We work directly with engineers to make custom concepts reality.
We source our core raw materials with meticulous attention to structural longevity. Our ITO films (exhibiting zero shrinkage and zero color difference) and liquid crystal spacers are sourced directly from Japan. Key binding glues are imported directly from leading chemical producers in Europe. The liquid crystal components perform consistently across a temperature range of up to 70°C, and our protective layers withstand high-temperature exposure up to 80-90°C.
We run all final components through a battery of environmental tests. These include high and low-temperature stress tests at 75°C and -35°C for 500 consecutive hours; thermal shock cycles running from 10°C to 90°C for 30 minutes; and damp heat testing for 500 hours. Active components undergo a 24-hour electrical aging sequence, and smart films are tested using 100V high voltage inputs to ensure absolute zero breakdown.
Precision-focused capabilities that differentiate our manufacturing from average local providers.
Over 35 years of R&D expertise with Zhejiang University collaboration, maintaining a strong database of refrigeration patents.
ISO 9001 and IATF 16949 certified; utilizing our verified 5D quality system to keep average defect rates below 0.05%.
Exporting to a network of over 50 countries, with established supplier partnerships with Haier, Midea, and Whirlpool.
Complete OEM/ODM assistance. Low MOQ options (500 units) and express 72-hour global delivery paths for standard components.
RoHS, REACH, and WEEE certified; utilizing 100% recyclable shipping and protective packing materials.
Equipped with our centralized MES system, automated CCD visual inspections, and helium leak-testing chambers.
98.6% customer satisfaction index (2023 survey) backed by a 24-hour complaint and technical query resolution guarantee.
±0.02mm raw material tolerances and rigorous 10-year operational life simulated tests.
Eco-friendly manufacturing processes designed to lower emissions and aid global carbon neutrality targets.
Established in 1988, Taojun started as Xiangshan Refrigeration Accessories Factory, cooperating with research teams at Zhejiang University. Through decades of expanding production, we built our state-of-the-art MES intelligent facility.
1998: Early Factory
2008: MES Upgrade
2024: High-Tech Plant
We believe that a world-class brand is built on a strong corporate culture. We focus on: Honesty, Innovation, Responsibility, and Cooperation.
By integrating advanced testing equipment with skilled engineers, we ensure our global partners receive consistent quality, reliable delivery schedules, and responsive customer support.
Providing critical components for diverse global cooling, industrial heating, and flow systems.
Ensuring smooth procurement journeys and full ISO 9001, RoHS, and UL certified compliance.
✓ Inquiry Support: Technical support from engineers with 15+ years of HVAC and pump experience.
✓ One-to-One service: Direct consultation with a sales engineer to map custom specifications.
✓ Rapid Response: 24-hour service hotline with queries answered within 8 hours.
✓ Training & Evaluation: In-depth guidance for equipment installation and troubleshooting.
✓ Standard Warranty: Full one-year warranty on all products and lifetime technical support.
✓ Feedback Loops: Regular follow-ups to gather product performance data and drive continuous updates.
Ningbo Taojun Refrigeration Equipment Co., Ltd. maintains ISO 9001:2015 certification (Registration No: 41325Q00065R0S). This certification validates our quality controls across our filter drier, condenser, and access valve production lines.
Main Certification
Scope Certificate
Get answers to common technical, material, and ordering questions about our Bundy tubes and HVAC components.
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