Stainless Steel Coil Tube for HVAC Fan Coil Unit Systems
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (序号 No. 345)
Product Category: Coil Tube (盘管) — HVAC Thermal Exchange Components
1. Product Overview
The Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product specifically designed for integration into fan coil unit (FCU) and fresh air supply systems. These coil tubes serve as the core heat exchange elements within air-conditioning and ventilation infrastructure, facilitating efficient thermal transfer between circulating refrigerant and ambient air. The product line adheres to the principles outlined in the research framework of Energy-Saving Measures for Fan Coil Unit Plus Fresh Air Systems, ensuring optimal thermal performance with minimal energy consumption.
The coil tubes are available in a variety of coil configurations — including serpentine, helical, and spiral-wound forms — tailored to meet specific system design requirements for both residential and commercial HVAC applications.
2. Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steel, selected for their superior corrosion resistance, mechanical durability, and thermal conductivity characteristics essential for long-term HVAC performance.
- Base Alloy: AISI 304 / 316L (UNS S30400 / S31603) austenitic stainless steel
- Corrosion Resistance: Excellent resistance to condensation-induced corrosion, dehumidification cycles, and humid tropical environments
- Thermal Conductivity: 14–16 W/(m·K) at 20°C, ensuring efficient heat exchange
- Operating Temperature Range: −40°C to +150°C
- Mechanical Properties: Tensile strength ≥ 520 MPa; elongation ≥ 40%
- Surface Finish: Polished or passivated interior/exterior surfaces for reduced flow resistance and enhanced hygiene
3. Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | 6.0 / 7.0 / 8.0 / 9.52 / 12.7 | mm |
| Wall Thickness | 0.5 / 0.6 / 0.8 / 1.0 / 1.2 | mm |
| Coil Pitch | 3.0 – 15.0 (customizable) | mm |
| Coil Diameter | 50 – 500 | mm |
| Tube Length (per coil) | 1.0 – 12.0 | m |
| Number of Rows | 1 / 2 / 3 / 4 (multi-row configurations) | — |
| Pressure Rating (working) | ≤ 1.6 | MPa |
| Hydrostatic Test Pressure | 2.4 | MPa |
| Surface Roughness (Ra) | ≤ 0.8 | μm |
| Standards Compliance | GB/T 12771, ASTM A213/A269, EN 10216-5 | — |
| Available Grades | 304, 304L, 316, 316L, 321, 310S | — |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing protocol:
- Material Selection & Inspection: Cold-rolled stainless steel strip is sourced from certified mills and subjected to spectrographic analysis (PMI) to verify alloy composition.
- Coil Winding & Forming: Precision CNC-controlled coil winding machines form the strip into seamless spiral tubes with consistent wall thickness and dimensional accuracy (±0.1 mm tolerance).
- Resistance Welding: High-frequency induction welding or TIG (Tungsten Inert Gas) welding is employed to create hermetic seam joints with full-penetration welds, ensuring leak-free integrity.
- Heat Treatment: Solution annealing at 1050–1150°C followed by rapid water quenching to achieve a fully austenitic microstructure free of carbide precipitation.
- Passivation & Cleaning: Acid pickling and passivation treatment removes oxide scale and forms a protective chromium oxide layer (Cr₂O₃), enhancing long-term corrosion resistance.
- Non-Destructive Testing (NDT):strong> 100% hydrostatic pressure testing, with supplementary eddy current or ultrasonic inspection for weld integrity verification.
- Final Dimensional Inspection: Coordinate measuring machine (CMM) and laser diameter gauging confirm compliance with specified tolerances.
5. Applications
The stainless steel coil tubes are engineered for deployment in a wide spectrum of HVAC and thermal management systems:
- Fan Coil Units (FCU): Primary heat exchange coils in commercial building air conditioning systems
- Fresh Air Handling Units (AHU): Cooling and heating coils in fresh air ventilation systems
- Chilled Water Systems: Secondary-loop heat exchangers in large-scale district cooling networks
- VRF/VRV Systems: Variable Refrigerant Flow terminal units for multi-zone climate control
- Food & Pharmaceutical Processing: Sanitary-grade heat exchangers requiring hygienic conditions and resistance to CIP (Clean-in-Place) chemicals
- Marine & Coastal Environments: HVAC systems in offshore platforms, cruise ships, and coastal facilities where chloride-induced corrosion is a concern (316L grade)
- Energy-Saving Retrofits: Replacement coils in existing systems to improve COP (Coefficient of Performance) and reduce operational energy consumption
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality assurance framework ensuring product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- CE Marking — European Conformity for HVAC components (EU Directive 2009/125/EC)
- GB/T 12771 — Chinese National Standard for seamless stainless steel tubes
- ASTM A269 / A213 — American Society for Testing and Materials standards for austenitic stainless steel tubes
- EN 10216-5 — European Standard for non-ferrous metal tubes and pipes
- NSF/ANSI 61 — Drinking water system components certification (for sanitary applications)
- Third-Party Testing: Material test certificates (MTC) conforming to EN 10204 Type 3.1 issued for every production batch
7. Unique Selling Points
Energy Efficiency Optimization: The coil geometry and surface finish are engineered in accordance with energy-saving research principles for fan coil plus fresh air systems, achieving up to 15–20% improvement in thermal efficiency over conventional copper coil alternatives through reduced flow resistance and enhanced heat transfer coefficients.
- Superior Corrosion Longevity: 2–3× the service life of copper tubing in dehumidification and high-humidity environments, significantly reducing lifecycle maintenance costs.
- Customizable Coil Configurations: Flexible design parameters (pitch, diameter, row count, grade selection) enable OEM partners to optimize coils for specific system thermal loads.
- Lead-Free & Environmentally Friendly: Eliminates copper leaching concerns in potable water systems; fully recyclable end-of-life material stream.
- Low Flow Resistance Design: Precision-formed internal geometry minimizes pressure drop, reducing fan energy consumption in FCU applications.
- Scalable Production Capacity: Capable of supplying both prototype quantities and high-volume production runs with consistent quality control.