Stainless Steel Coil Tube for HVAC Fan Coil Unit Applications
Product Overview
The stainless steel coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing product designed specifically for air-conditioning and refrigeration systems, with particular emphasis on fan coil unit (FCU) installations and energy-efficient HVAC billing systems. This product, catalogued under reference number 1090, represents the company's commitment to delivering high-performance heat exchanger components that integrate seamlessly with networked fan coil unit temperature controllers and intelligent energy management architectures.
Coil tubes serve as the fundamental heat exchange medium in closed-loop HVAC systems, facilitating the transfer of thermal energy between a circulating fluid and the surrounding air. The stainless steel variant offers superior corrosion resistance, extended service life, and hygienic performance compared to conventional copper or aluminum coil alternatives, making it an ideal choice for modern energy-saving billing systems where reliability and long-term operational efficiency are paramount.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected to meet the demanding requirements of HVAC thermal management applications:
- Base Material: Austenitic stainless steel conforming to ASTM A269 / ASME SA-269 or equivalent international standards (common grades: SUS304, SUS316, SUS316L)
- Carbon Content: ≤ 0.08% (SUS304) or ≤ 0.03% (SUS316L), ensuring resistance to intergranular corrosion
- Chromium Content: 18–20%, providing a self-healing passive oxide layer
- Nickel Content: 8–12%, stabilizing the austenitic crystal structure
- Molybdenum Content: 2–3% (SUS316/SUS316L), enhancing resistance to pitting and crevice corrosion
- Thermal Conductivity: 14–16 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +870°C
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, chlorides, and deionized water
- Surface Finish: Electropolished or pickled and passivated, achieving Ra ≤ 0.4 μm for optimal heat transfer and fouling resistance
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | 6.0 / 8.0 / 9.5 / 12.0 (customizable) | mm |
| Wall Thickness | 0.5 / 0.6 / 0.8 / 1.0 | mm |
| Coil Inner Diameter (ID) | 150 / 200 / 250 / 300 (configurable) | mm |
| Coil Length | Up to 30,000 (continuous coil) | mm |
| Pitch (Coil Spacing) | 6–12 (adjustable per application) | mm |
| Number of Passes | 1–4 (multi-pass configurations available) | — |
| Maximum Working Pressure | 1.6 / 2.5 / 4.0 (based on wall thickness) | MPa |
| Hydrostatic Test Pressure | 1.5 × working pressure | MPa |
| Tolerance on OD | ±0.05 | mm |
| Tolerance on Wall Thickness | ±0.02 | mm |
| End Form | Plain / Flared / Flanged / Threaded | — |
| Surface Treatment | Electropolished / Pickled & Passivated | — |
| Standards Compliance | ASTM A269, ASME SA-269, EN 10217, GB/T 12771 | — |
Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, material integrity, and functional performance:
- Raw Material Selection: Cold-rolled stainless steel strip (SS strip) is sourced from certified mills, with each batch accompanied by a mill test certificate (MTC) verifying chemical composition and mechanical properties.
- Coil Winding: The strip is wound onto precision mandrels using CNC-controlled coiling equipment to achieve uniform pitch, consistent OD, and minimal springback. Tension control systems ensure the coil maintains its geometry under thermal cycling.
- Tubular Forming: The wound coil is formed into a continuous tubular structure through helical winding and seam welding (TIG or laser welding), followed by seam grinding and internal/external inspection.
- Heat Treatment: Solution annealing is performed at 1050–1100°C followed by rapid quenching to dissolve carbides and restore full austenitic microstructure, ensuring maximum corrosion resistance and ductility.
- Pickling & Passivation: The finished coil tube undergoes acid pickling to remove heat scale and oxide discoloration, followed by passivation treatment to restore the chromium-rich passive film essential for long-term corrosion protection.
- Non-Destructive Testing (NDT):strong> 100% inline inspection includes visual examination, hydrostatic pressure testing, and optional eddy current or ultrasonic testing to detect wall thickness variations, weld defects, or surface imperfections.
- Dimensional Verification: Final products are measured for OD, wall thickness, coil pitch, and overall length against the specified tolerances using calibrated instruments.
Applications
The stainless steel coil tube is designed for a broad spectrum of thermal management applications, with particular suitability for the following:
- Air-Conditioning Energy-Saving Billing Systems: Integration with networked fan coil unit temperature controllers for precise thermal energy metering, enabling accurate cost allocation in commercial buildings and multi-tenant facilities.
- Fan Coil Units (FCUs): Primary heat exchange element in commercial HVAC systems for space heating and cooling, where corrosion resistance and hygiene are critical.
- Commercial Refrigeration: Evaporator and condenser coils in supermarket refrigeration, walk-in coolers, and cold storage facilities.
- Process Cooling Systems: Heat exchange in industrial processes requiring chemically resistant and sanitary-grade components.
- Chilled Water Distribution: Terminal units in central air conditioning systems serving office buildings, hospitals, and hotels.
- Marine and Coastal Applications: HVAC systems in marine environments where chloride-induced corrosion is a primary concern.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all stainless steel coil tube products meet international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ASTM A269 / ASME SA-269 — Standard specification for seamless and welded austenitic stainless steel tubing
- GB/T 12771 — Chinese national standard for welded austenitic stainless steel tubes for general application
- EN 10217-7 — European standard for stainless steel tubes for heat exchangers
- Mill Test Certificate (MTC) / EN 10204 3.1 — Provided with each shipment, verifying chemical analysis and mechanical properties
Unique Selling Points
1. Superior Corrosion Resistance: Unlike copper or aluminum coil tubes, the stainless steel construction provides exceptional resistance to corrosion from condensate, refrigerants, and atmospheric pollutants, extending service life beyond 20 years in typical HVAC applications.
2. Hygienic Surface Finish: The electropolished interior surface eliminates dead zones and biofilm accumulation, ensuring consistent heat transfer coefficients and preventing fouling-related energy penalties in billing-critical systems.
3. Precision Engineering for Energy Billing: Tight dimensional tolerances and uniform coil pitch ensure predictable thermal performance, which is essential for accurate energy metering in networked fan coil unit temperature controller systems.
4. Customizable Configurations: Available in multiple OD, wall thickness, and coil geometry options to accommodate diverse system designs and capacity requirements.
5. Environmental Sustainability: Stainless steel is 100% recyclable with no loss of material properties, supporting green building certifications (LEED, BREEAM) and reducing lifecycle environmental impact.
Conclusion
The stainless steel coil tube from Wenzhou Jixing Metal Materials Co., Ltd. represents a technically advanced solution for modern HVAC systems, particularly those employing intelligent energy-saving billing architectures. By combining the inherent durability of austenitic stainless steel with precision manufacturing and rigorous quality assurance, this product delivers the reliability, efficiency, and longevity demanded by contemporary building energy management systems.