Stainless Steel Coil Tube for Fan Coil Units (FCU)
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered heat exchange component designed primarily for Fan Coil Units (FCU) and hydronic HVAC (Heating, Ventilation, and Air Conditioning) systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd, this product features a helical coil geometry optimized for maximum thermal transfer efficiency within compact installation footprints. The coil tube serves as the core heat exchanger medium in FCU systems, facilitating the transfer of thermal energy between circulating water (or refrigerant) and ambient air drawn through the unit.
This product integrates advanced metallurgical processing with precision forming technology, delivering superior thermal conductivity, corrosion resistance, and mechanical durability. The comprehensive thermal performance expression — encompassing both cooling capacity and heating capacity — is governed by the heat transfer coefficient, surface area, and temperature differential across the coil tube walls, making this component critical to system-wide energy efficiency.
Material & Properties
The coil tube is fabricated from high-grade stainless steel, selected for its exceptional combination of thermal performance, corrosion resistance, and long-term structural integrity in demanding HVAC applications.
- Base Material: Austenitic stainless steel conforming to ASTM A269 / ASTM A312 standards
- Common Grades: SUS304 (18Cr-8Ni), SUS316L (18Cr-10.5Ni-2Mo, low carbon)
- Thermal Conductivity: 14.6–16.3 W/(m·K) at 20°C
- Operating Temperature Range: −40°C to +250°C
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, waterborne chlorides, and condensate attack; SUS316L grade provides enhanced resistance to pitting and crevice corrosion
- Mechanical Strength: Yield strength ≥ 205 MPa (SUS304); tensile strength ≥ 515 MPa
- Surface Finish: Electropolished or passivated, Ra ≤ 0.4 μm for optimal heat transfer and reduced fouling
- Hygienic Compliance: Suitable for potable water and food-grade applications where required
Technical Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | 9.52 / 12.70 / 15.88 / 19.05 | mm |
| Wall Thickness | 0.50 – 1.00 | mm |
| Coil Pitch (Center-to-Center) | 10 – 25 | mm |
| Coil Diameter (Mean) | 100 – 300 | mm |
| Effective Length per Coil | 300 – 3000 | mm |
| Number of Tubes per Circuit | 1 – 4 (configurable) | — |
| Fin Material | Aluminum (Al 1100 / Al 3003) or Stainless Steel | — |
| Fin Density | 10 – 16 FPI (Fins Per Inch) | — |
| Design Pressure | 1.0 – 1.6 | MPa |
| Test Pressure | 1.5 × Design Pressure | MPa |
| Cooling Capacity Range | 1.2 – 12.0 | kW |
| Heating Capacity Range | 1.5 – 15.0 | kW |
| Approach Temperature | ≤ 3.0 | °C |
| Maximum Flow Velocity | 2.5 | m/s |
Manufacturing Process
The production of stainless steel coil tubes follows a rigorous multi-stage process to ensure dimensional accuracy, thermal performance, and long-term reliability:
- Material Selection & Inspection: Raw stainless steel tube stock is procured from certified mills and subjected to spectroscopic analysis (OES), hydrostatic testing, and visual inspection to verify grade compliance and absence of surface defects.
- Pre-Forming Annealing: Tubes undergo controlled furnace annealing at 1050–1100°C followed by controlled cooling to relieve residual stresses and ensure uniform microstructure for subsequent cold-forming operations.
- Precision Coiling: Automated CNC coil forming machines bend the tube into the specified helical geometry with controlled pitch, diameter, and springback compensation. The forming process is monitored via real-time dimensional feedback systems.
- Fin Attachment (if applicable): Aluminum or stainless steel fins are mechanically bonded to the coil tube using roll-bonding or brazing techniques to maximize the effective heat transfer surface area while maintaining structural integrity at the fin-tube junction.
- Hydrostatic Pressure Testing: Each coil assembly is pressure-tested at 1.5 times the design pressure using deionized water to verify weld integrity and detect any micro-leaks.
- Surface Treatment: Electropolishing or chemical passivation is applied to remove scale, enhance corrosion resistance, and achieve the required surface roughness for optimal thermal performance and condensate drainage.
- Final Quality Control: Completed products undergo dimensional verification (CMM inspection), visual inspection, and performance sampling to ensure compliance with design specifications.
Applications
The Stainless Steel Coil Tube for Fan Coil Units finds extensive application across commercial, residential, and industrial HVAC systems:
- Commercial Buildings: Office towers, hotels, retail centers, and hospitals requiring precise temperature and humidity control
- Residential HVAC: High-end residential systems utilizing central chilled water or hot water distribution
- Industrial Processes: Process cooling, cleanroom environments, and pharmaceutical manufacturing facilities
- Data Centers: Precision cooling for server rooms and telecommunications equipment
- Food & Beverage Industry: Cold storage, refrigeration systems, and hygienic processing environments (SUS316L grade)
- Marine & Coastal Applications: Buildings in high-humidity, chloride-rich environments where enhanced corrosion resistance is required
Quality Certifications & Standards Compliance
- ISO 9001:2015 — Quality Management System certification for manufacturing processes
- ISO 14001:2015 — Environmental Management System compliance
- CE Marking — Conformity with European Union directives for HVAC components
- EN 12831 — European standard for heating and air-conditioning heat exchangers
- ASHRAE Standard 90.1 — Energy efficiency compliance for building HVAC systems
- ASTM A269 / A312 — Material specification compliance for stainless steel tubing
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- SGS Testing Reports — Independent third-party verification of material composition and performance
Unique Selling Points
The coil tube product from Wenzhou Jixing Metal Materials Co., Ltd distinguishes itself through several key competitive advantages:
- Superior Thermal Efficiency: Optimized coil geometry and high-density fin configuration achieve a comprehensive cooling/heating capacity expression that exceeds conventional copper-tube alternatives by 5–8% in equivalent configurations.
- Exceptional Corrosion Durability: Full stainless steel construction eliminates galvanic corrosion risks inherent in copper-aluminum fin-tube combinations, extending service life to 25+ years.
- Hygienic & Food-Safe Design: Electropolished surfaces with Ra ≤ 0.4 μm prevent microbial adhesion, making the product suitable for pharmaceutical and food-grade HVAC applications.
- Compact Footprint: The helical coil design maximizes heat transfer surface area within minimal installation dimensions, ideal for space-constrained commercial and residential installations.
- Energy Efficiency: Low approach temperatures (≤ 3.0°C) reduce pumping energy requirements and contribute to lower overall system EER (Energy Efficiency Ratio).
- Customization Capability: Flexible design parameters (OD, pitch, number of circuits, fin density) allow tailoring to specific system requirements and capacity targets.