Stainless Steel Fan Coil Tube for HVAC Hydronic Systems
Product Overview
The stainless steel fan coil tube (Coil Tube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular component designed for integration into Fan Coil Units (FCUs) and hydronic radiant heating systems. As a critical heat exchanger element, the coil tube facilitates efficient thermal transfer between a circulating fluid (typically water or glycol solution) and the surrounding air, enabling precise temperature regulation in residential, commercial, and industrial environments.
This product is specifically optimized for applications in temperate and subtropical climates, including the Yangtze River Basin region, where seasonal temperature variations demand reliable performance in both heating and cooling modes. The coil tube is manufactured to meet international standards for dimensional accuracy, corrosion resistance, and thermal conductivity, ensuring long-term operational integrity in demanding HVAC (Heating, Ventilation, and Air Conditioning) installations.
Material & Properties
Base Material
- Primary Alloy: Austenitic Stainless Steel (奥氏体不锈钢), conforming to AISI 304 (UNS S30400) or AISI 316 (UNS S31600) specifications
- Alternative Grades: AISI 321 (UNS S32100) for elevated-temperature applications; Custom 450 (UNS N08825) for enhanced chloride resistance
- Wall Thickness Range: 0.30 mm – 1.50 mm, depending on design pressure and fluid velocity requirements
Mechanical Properties (Typical Values for AISI 304)
- Tensile Strength (抗拉强度): ≥ 515 MPa (74,700 psi)
- Yield Strength (屈服强度): ≥ 205 MPa (29,700 psi)
- Elongation (延伸率): ≥ 40%
- Hardness (硬度): ≤ 92 HRB
- Density (密度): 8.00 g/cm³
Thermal & Corrosion Properties
- Thermal Conductivity (热导率): 16.3 W/(m·K) at 100°C
- Corrosion Resistance (耐腐蚀性): Excellent resistance to atmospheric, freshwater, and moderate chemical corrosion; passivated surface provides a protective chromium oxide layer (Cr₂O₃)
- Operating Temperature Range (工作温度范围): −196°C to +870°C (AISI 304); extended range available with AISI 316 or duplex grades
- Hygienic Surface Finish: Ra ≤ 0.4 μm available for potable water and food-grade applications
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Code | JX-CT-661 | Internal Catalog |
| Outer Diameter (OD) | 9.52 mm / 12.70 mm / 15.88 mm / 19.05 mm (3/8" / 1/2" / 5/8" / 3/4") | ASTM A213 / GB/T 12771 |
| Wall Thickness | 0.50 mm – 1.50 mm (customizable) | Manufacturer Specification |
| Coil Length | Up to 500 m per continuous coil | — |
| Fin Type (if finned) | Integral stainless steel fins or aluminum fins brazed | — |
| Fin Spacing | 2.0 mm – 3.5 mm (adjustable per heat exchange requirement) | — |
| Surface Treatment | Pickled & Passivated (P&P); optional electropolished finish | ASTM A967 |
| Design Pressure | Up to 1.6 MPa (16 bar) standard; 2.5 MPa available | EN 12828 / ASME B31.9 |
| Maximum Operating Pressure | 2.5 MPa (25 bar) | — |
| Fluid Compatibility | Water, glycol-water mixtures (up to 50% vol.), brine solutions | — |
| Heat Transfer Coefficient | 150 – 350 W/(m²·K) depending on configuration | — |
| Connection Method | Welded (TIG/Orbital), flanged, or compression fittings | ASME B31.9 |
| Dimensional Tolerance | OD: ±0.05 mm; Wall Thickness: ±0.02 mm | ASTM A213 |
Manufacturing Process
- Raw Material Preparation: High-purity stainless steel strip is sourced from certified mills with full chemical composition verification via Optical Emission Spectroscopy (OES) and X-Ray Fluorescence (XRF) analysis.
- Coil Forming (盘管成型): The flat strip is precision-formed into tubular geometry using a continuous roll-forming process with calibrated rollers, ensuring uniform wall thickness and consistent outer diameter throughout the coil length.
- Seam Welding: Longitudinal seams are closed using High-Frequency Induction Welding (HF-W) or TIG (Tungsten Inert Gas) welding under inert gas shielding (Argon or Helium), producing a weld bead with metallurgical homogeneity and minimal heat-affected zone (HAZ).
- Heat Treatment & Annealing: The welded tube undergoes solution annealing at 1040°C – 1150°C followed by rapid water quenching to dissolve carbides and restore full austenitic microstructure, ensuring optimal ductility and corrosion resistance.
- Pickling & Passivation: The tube surface is treated with nitric/hydrofluoric acid bath to remove mill scale and weld discoloration, followed by passivation to establish a uniform chromium oxide passive film (ASTM A967 compliance).
- Coiling & Sizing: The finished tube is coiled onto precision mandrels to achieve the required coil diameter and pitch, with controlled tension to prevent ovality or kinking.
- Quality Inspection: Each coil undergoes ultrasonic testing (UT) for wall thickness verification, leak testing (helium or pressure decay), visual inspection of weld seams, and dimensional measurement per ASTM A213 acceptance criteria.
- Packaging & Dispatch: Coils are wrapped in moisture-barrier protective film, secured on wooden pallets, and labeled with material traceability data (heat number, lot code, test certificate reference).
Applications
Primary Applications
- Fan Coil Units (FCU): The coil tube serves as the core heat exchanger in FCUs installed in residential apartments, office buildings, and hospitals, providing both space heating and cooling through hydronic circulation. Field performance testing in the Yangtze River Basin has demonstrated effective radiant heating when integrated with concrete floor systems, achieving uniform temperature distribution and low surface temperatures (<29°C) per EN 1264 standards.
- Radiant Floor Heating Systems (辐射地板供暖): Stainless steel coil tubes embedded in concrete slabs provide low-temperature hydronic radiant heating, particularly suited for temperate climates where seasonal heating demands are moderate but sustained.
- Commercial HVAC Systems: Large-diameter coil tubes are employed in air handling units (AHUs), rooftop units, and chilled beam systems for commercial and industrial facilities.
Secondary Applications
- Food and beverage processing equipment heat exchangers
- Pharmaceutical clean-room temperature control systems
- Marine HVAC systems requiring chloride-resistant components
- Geothermal heat pump systems for sustainable building energy management
- Industrial process cooling and heating circuits
Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System — ensures consistent production quality and traceability |
| ISO 14001:2015 | Environmental Management System — minimizes ecological impact during manufacturing |
| ISO 45001:2018 | Occupational Health & Safety Management System |
| CE Marking | European Conformity — compliance with EU directives for construction products |
| EN 10216-5 | European standard for seamless and welded stainless steel tubes |
| ASTM A213 / A269 | American standards for austenitic stainless steel tube specifications |
| GB/T 12771 | Chinese national standard for welded stainless steel tubes |
| EN 12828 | Heating systems in buildings — component requirements |
| EN 1264 | Water-based underfloor heating systems — design and installation |
| 3.1 / 3.2 Material Test Certificates | Full chemical and mechanical test documentation per EN 10204 |
Unique Selling Points
- Superior Corrosion Resistance: Austenitic stainless steel construction eliminates the risk of internal corrosion and scaling common in carbon steel alternatives, extending system service life beyond 25 years with minimal maintenance.
- High Thermal Efficiency: Field measurements confirm heat transfer coefficients of 150–350 W/(m²·K), with particularly effective radiant performance when integrated into concrete floor systems in temperate climates.
- Precision Dimensional Control: Tight manufacturing tolerances (±0.05 mm OD, ±0.02 mm wall thickness) ensure optimal fit within FCU housings and consistent flow distribution.
- Hygienic & Food-Safe: Passivated surface finish prevents bacterial colonization and meets potable water standards (NSF/ANSI 61 equivalent), suitable for food processing and pharmaceutical environments.
- Full Traceability: Every coil is accompanied by mill test certificates (MTC), chemical analysis reports, and dimensional inspection records, ensuring complete supply chain traceability.
- Climate-Optimized Design: Product configurations are validated for the specific heating and cooling load profiles of subtropical regions, including the Yangtze River Basin, where dual-mode operation is required.
- Customizable Configurations: Coil dimensions, fin spacing, and surface treatments are adaptable to specific project requirements, supporting OEM and ODM partnerships.
Technical Note: Performance data referenced in this specification is derived from field measurements conducted in residential buildings across the Yangtze River Basin, evaluating the thermal performance of concrete radiant floors integrated with fan coil heating systems. Results demonstrate stable indoor temperature maintenance within ±1.0°C of setpoint under design conditions, with energy consumption in line with Class A efficiency per EN 15316.