Engineered for extreme pressure resistance, corrosion protection, and optimal thermodynamic performance.
Founded in 1988, Ningbo Taojun Refrigeration Equipment Co., Ltd. (originally known as the Xiangshan Refrigeration Accessories Factory of Zhejiang University) has established itself as an authoritative leader in high-performance metallurgy and heat exchange components. Nestled in the coastal industrial hub of Ningbo, China, the company spans over 35 years of innovation in the fabrication of premium copper, brass, and Bundy tube solutions.
Our commitment to rigorous scientific principles led us to establish strategic academic joint-ventures with leading Chinese universities. By integrating industrial scaling with scholarly research, our products – including robust copper Bundy tubes, advanced filter driers, check valves, and condensers – fulfill the most demanding requirements of domestic and international white-goods manufacturers.
In 2021, the company was recognized as a national High-Tech Enterprise, emphasizing our dedication to automation, low-tolerance extrusion, and environment-compliant coatings (including RoHS, REACH, and UL certifications).
Unveiling the structural integrity and performance metrics of copper-coated and double-walled brazed steel tubes.
Bundy tubes, also known as double-walled low-carbon steel tubes, are manufactured by laterally wrapping a copper-plated steel strip (SPCC or equivalent) through a 720-degree roll-forming system, followed by high-temperature liquid-phase copper brazing in a reducing atmosphere. This creates a unified cross-section that boasts superior structural strength, hermetic sealing under high burst pressures, and remarkable flexibility for post-processing bends.
Our standard double-walled tubes provide unparalleled security against refrigerant leakage. They are the backbone of modern evaporators, condenser coils, and high-pressure fluid conduits in light commercial and domestic cooling appliances.
| Technical Parameter | Double-Walled Steel Tubing (Bundy) | Single-Walled Seamless Copper Tubing | Testing Protocol / Compliance |
|---|---|---|---|
| Base Material Chemical Composition | Low-Carbon Steel Strip (C ≤ 0.08%, Mn ≤ 0.45%, P ≤ 0.02%) | Deoxidized High-Phosphorus Copper (C12200, Cu ≥ 99.90%) | ASTM A254 / ASTM B280 Standards |
| Tensile Strength (MPa) | ≥ 290 MPa | ≥ 220 MPa | GB/T 3091 Tensile Testing |
| Yield Strength (MPa) | ≥ 180 MPa | ≥ 60 - 90 MPa | ASTM E8/E8M standard methods |
| Elongation at Break (%) | ≥ 25% | ≥ 40% | Universal Material Tester Analysis |
| Internal Cleanliness (Residue) | ≤ 0.19 g/m² (Soluble residue) | ≤ 0.038 g/m² | DIN 8964 / ISO 13085 Cleanliness |
| Anti-Corrosion Surface Coating | Electroplated Zinc (Zn-Al/PVF/Epoxy) > 25 microns | Natural copper oxide passivated | ASTM B117 Salt Spray Test ≥ 500h |
Our structured pathway toward smart materials, eco-friendly surface passivation, and low-GWP refrigerant integration.
Phasing out Hexavalent Chrome (Cr6+) coatings. Over 98% of our production lines now utilize trivalent chromium passivation (Cr3+), Zinc-Nickel alloys, and advanced thermosetting fluorocarbon resins (PVF) to exceed REACH requirements.
Natural refrigerants demand elevated burst-safety ratings. We have optimized our high-frequency induction brazing parameters to guarantee zero-leak connections up to operating pressures of 120 bar, assuring compliance with safety regulations.
Integrating trace elements of titanium and boron to decrease wall thickness while retaining high yield strength. Our new generation Bundy tubes decrease total product weight by 15% without sacrificing pressure-resistance profile.
Analyzing current global demand, commercial shifts, and international supply dynamics for Bundy tubes and copper connections.
The transition toward highly energy-efficient heat pumps, commercial cooling solutions, and automotive thermal management systems has driven massive demands for durable, bend-optimized metal tubing. Worldwide, industries are moving away from traditional thick-walled pipes toward high-precision micro-bore tubing options to optimize space and maximize coefficient of performance (COP).
Furthermore, global regulations prohibiting ozone-depleting substances have pushed chemical refrigerant pressures higher (e.g., in R410A and R744/CO2 applications). This transition requires tubing solutions that ensure seamless metallurgical joints, smooth internal walls for minimizing flow resistance, and complete chemical neutrality to avoid catalytic breakdown of modern synthetic oils.
How Taojun components are tailored for different geographic and industrial environments worldwide.
In sub-zero climates, residential heat pump evaporators are subject to massive structural stresses caused by ice formation and thermal contraction cycles. Our Bundy and high-purity copper assemblies undergo rigorous 500-hour thermal shock testing from -35°C to 75°C. This guarantees that brazed connections maintain molecular continuity without micro-fracturing, mitigating the risk of slow refrigerant leakage over years of operation.
For commercial beverage coolers deployed in coastal regions of Southeast Asia and Latin America, standard tubing corrodes rapidly due to ambient moisture and salt. Taojun provides customized PVF (Polyvinyl Fluoride) and multi-layered electrostatic epoxy coatings. This advanced treatment passes strict 1000-hour neutral salt spray tests, shielding the steel structure from galvanic rust and acidic moisture damage.
Automotive Bundy tubing must endure continuous mechanical vibration, high hydraulic pressures, and gravel impacts. Our double-walled tubing features a proprietary annealed state that combines high tensile strength with exceptional ductility, allowing cold-flaring, bending, and expansion on automated assembly lines without any wall thinning or cracking.
Supercritical CO2 refrigeration systems operate at working pressures exceeding 100 bar. Standard copper tubes are insufficient under these parameters. Our micro-alloyed, heavy-wall double-walled steel tubes are engineered to handle high pressures, offering a safe, cost-efficient, and easy-to-weld alternative for display cases and condenser arrays.
Why leading global corporations trust Ningbo Taojun to secure their critical component supply chains.
Situated in Ningbo, Zhejiang, our factory is only hours away from Ningbo-Zhoushan Port, the world's largest port by cargo throughput. This guarantees daily shipping lines, minimal inland transit costs, and rapid custom processing for our worldwide B2B partners.
Our manufacturing utilizes a modern MES (Manufacturing Execution System) workshop setup, integrated in 2008. From raw copper coils to automated cutting, bending, and final high-pressure helium leak checks, every step is traced through unique batch codes.
By establishing long-term futures contracts with national copper refineries and high-purity steel mills, we isolate our clients from seasonal metal price spikes and guarantee a reliable supply of raw materials even in tight market cycles.
Furthermore, our engineering teams maintain close relations with domestic and foreign home appliance enterprises including Haier, Xinfei, Midea, Gree, Whirlpool, Electrolux, and Huarui. We do not just act as an external supplier; we actively participate in co-developing new refrigeration loops, utilizing our thermal laboratory to simulate specific customer operating conditions and recommending optimized tube geometries.
Our 5D quality management system ensures that every single batch conforms to internal standards before leaving the facility. Our verification process features two main pillars:
1. Raw Material Verification: Our ITO film (no shrinkage, no color difference) and liquid crystal spacer (excellent uniformity) are imported directly from Japan; high-performance structural adhesives are sourced from Europe. Our internal temperature thresholds range up to 70°C, with specialized protective films capable of resisting temperatures up to 80-90°C.
2. Finished Product Testing: Finished tubes and filter driers are subjected to intensive high & low temperature testing at 75°C and -35°C for 500 hours. Additionally, we run thermal shock tests (10°C to 90°C, 30 min transition), damp heat chamber tests for 500 hours, and continuous high-voltage testing at 100V to ensure zero electrical or structural breakdowns in smart-film components.
Officially certified by Zhongci International (Registration No.: 41325Q00065R0S) for manufacturing filter driers, condensers, and access valves.
100% lead-free, hexavalent chromium-free chemical surface treatment processes, satisfying strict European import thresholds.
Certified safety for North American pressure vessels, high-pressure evaporators, and commercial refrigeration components.
Detailed answers to the most common technical questions asked by HVAC/R and automotive procurement engineers.
Explore our complete range of certified copper tubing, brass adapters, and refrigeration components.
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