Stainless Steel Coil Tube (Coiltube) — HVAC Fan Coil Unit Application
Product Overview
The Stainless Steel Coil Tube (Coiltube), manufactured by Wenzhou Jixing Metal Materials Co., Ltd, is a precision-engineered coiled stainless steel tube specifically designed for integration into horizontal and vertical fan coil units (FCU) used in commercial and residential HVAC (Heating, Ventilation, and Air Conditioning) systems. This product is engineered to deliver superior thermal performance, exceptional corrosion resistance, and long-term structural integrity within demanding hydronic heating and cooling applications.
Coil tubes serve as the primary heat exchange medium within fan coil units, where refrigerant or hot water circulates through the coiled piping structure to facilitate efficient heat transfer to or from the surrounding air stream. The coiltube geometry maximizes surface area within a compact footprint, making it an ideal solution for space-constrained installations while maintaining optimal thermal efficiency.
Material & Properties
Material Composition
The coil tube is fabricated from high-grade austenitic stainless steel, conforming to internationally recognized metallurgical standards. The primary alloy grades utilized include:
- SUS 304 / AISI 304 — The standard grade offering excellent general corrosion resistance, weldability, and formability, suitable for most HVAC applications.
- SUS 316L / AISI 316L — Enhanced grade with added molybdenum (Mo ≥ 2.0%) providing superior resistance to pitting and crevice corrosion in aggressive environments.
Key Material Properties
| Property | Specification |
|---|---|
| Alloy Grade | SUS 304 / SUS 316L |
| Chromium (Cr) Content | 18.0–20.0% |
| Nickel (Ni) Content | 8.0–10.5% | Carbon (C) Maximum | ≤ 0.08% (304) / ≤ 0.03% (316L) |
| Tensile Strength | ≥ 520 MPa |
| Yield Strength | ≥ 205 MPa |
| Elongation | ≥ 40% |
| Thermal Conductivity | 16.3 W/(m·K) at 20°C |
| Operating Temperature Range | −196°C to +870°C |
| Corrosion Resistance | Excellent resistance to atmospheric, aqueous, and chemical corrosion |
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd |
| Product Category | Coil Tube / Heat Exchanger Tube |
| Product Code | No. 1022 |
| Outer Diameter (OD) | 9.52 mm (3/8"), 12.70 mm (1/2"), 15.88 mm (5/8") |
| Wall Thickness | 0.5 mm – 1.0 mm |
| Coil Diameter | 150 mm – 600 mm (customizable) |
| Tube Length (per coil) | Up to 100 meters (continuous coil) |
| Surface Finish | Pickled and Passivated (2B finish) or Polished |
| Joint Type | Welded (TIG / orbital) or Seamless |
| Pressure Rating | Up to 1.6 MPa (16 bar) working pressure |
| Standards Compliance | ASTM A213, ASTM A269, GB/T 14976, JIS G3459 |
| Color | Stainless (natural metallic finish) |
| Packaging | Coiled on protective reel, wrapped in moisture-proof packaging |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, material integrity, and surface quality:
- Raw Material Selection: Premium-grade stainless steel strip or bar stock is procured from certified mills, undergoing incoming inspection for chemical composition (via XRF spectrometry) and mechanical properties.
- Forming / Drawing: Cold drawing or cold forming processes are employed to achieve precise outer diameter and wall thickness tolerances, ensuring uniformity throughout the tube length.
- Coiling: The formed tube is wound into the specified coil geometry using CNC-controlled coiling equipment to maintain consistent coil diameter, pitch, and layer alignment without introducing residual stress or deformation.
- Welding (if applicable):strong> Where continuous tube lengths are required, TIG (Tungsten Inert Gas) welding is performed under argon shielding to produce high-quality, leak-tight joints with minimal heat-affected zone.
- Pickling and Passivation: The finished coil tube undergoes acid pickling to remove scale and discoloration, followed by passivation treatment to restore and enhance the protective chromium oxide layer, ensuring optimal corrosion resistance.
- Pressure Testing: Each coil is subjected to hydrostatic pressure testing to verify structural integrity and confirm the absence of leaks or defects.
- Final Inspection: Comprehensive quality checks including dimensional measurement, visual inspection, and surface finish verification are conducted prior to packaging.
Applications
The stainless steel coil tube is primarily designed for use in HVAC fan coil unit systems but finds application across multiple industrial and commercial sectors:
- Commercial HVAC Systems: Horizontal and vertical fan coil units in office buildings, hotels, hospitals, and shopping centers, where reliable and quiet operation is critical for occupant comfort.
- Residential HVAC: Ducted and ductless mini-split systems providing zone-based heating and cooling.
- Industrial Process Cooling: Heat exchangers in chemical processing, food and beverage production, and pharmaceutical manufacturing where corrosion resistance is paramount.
- Refrigeration Systems: Evaporator and condenser coils in commercial refrigeration and cold storage facilities.
- Marine and Coastal Applications: HVAC systems in marine vessels and coastal facilities where high humidity and salt spray exposure demand superior corrosion resistance.
- Chiller and Boiler Systems: Internal heat exchange coils in packaged chiller units and industrial boilers.
Comfort-Oriented Design Considerations
When selecting coil tubes for horizontal fan coil units from a comfort perspective, the following factors are critical:
- Low-Vibration Performance: The stainless steel material and precision coiling process minimize vibration transmission, reducing operational noise levels and contributing to acoustic comfort.
- Uniform Air Distribution: Consistent tube diameter and coil geometry ensure even airflow across the heat exchanger, preventing localized hot or cold spots that compromise thermal comfort.
- Corrosion-Free Operation: Unlike carbon steel alternatives, stainless steel coil tubes do not corrode or accumulate mineral deposits over time, maintaining consistent airflow and thermal performance throughout the equipment's service life.
- Hygienic Surface: The smooth, passivated stainless steel surface resists bacterial growth and biofilm formation, supporting indoor air quality (IAQ) standards.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework with the following certifications and compliance standards:
- ISO 9001:2015 — Quality Management Systems certification ensuring consistent product quality and continuous improvement.
- ISO 14001 — Environmental Management Systems certification demonstrating commitment to environmentally responsible manufacturing practices.
- ASTM Compliance — Product materials and performance verified against ASTM A213 (seamless austenitic stainless steel tubing) and ASTM A269 (welded austenitic stainless steel tubing) specifications.
- GB/T Standards — Conformance with Chinese national standards GB/T 14976 (seamless stainless steel tubes) and GB/T 12771 (welded stainless steel tubes).
- Material Traceability: Full batch traceability from raw material mill certificates through final product delivery, with accompanying Mill Test Reports (MTR) and Certificate of Analysis (COA).
- Third-Party Testing: Products available for independent verification by accredited laboratories (SGS, Bureau Veritas, or equivalent) upon customer request.
Unique Selling Points
Why Choose Wenzhou Jixing Metal Materials Co., Ltd Stainless Steel Coil Tubes:
- Superior Corrosion Resistance: Austenitic stainless steel construction eliminates the risk of internal and external corrosion, extending service life to 25+ years without replacement — significantly outperforming carbon steel alternatives.
- Precision Engineering: CNC-controlled coiling ensures dimensional accuracy within ±0.1 mm tolerance, guaranteeing seamless integration with fan coil unit housings and end plates.
- Hygienic and Food-Safe: The passivated surface finish meets sanitary standards suitable for food processing and pharmaceutical HVAC applications.
- Customization Capability: Flexible manufacturing capacity to accommodate custom coil diameters, tube lengths, wall thicknesses, and alloy grades to meet specific project requirements.
- Full Documentation: Every shipment includes complete material documentation, pressure test reports, and dimensional inspection records for compliance verification.
- Cost-Effective Lifecycle: While the initial material cost is higher than carbon steel, the elimination of corrosion-related maintenance, reduced replacement frequency, and consistent thermal performance deliver superior total cost of ownership (TCO).
Conclusion
The Stainless Steel Coil Tube (Coiltube) from Wenzhou Jixing Metal Materials Co., Ltd represents a premium-grade heat exchange solution engineered for reliability, longevity, and comfort performance in HVAC fan coil unit applications. By combining high-quality austenitic stainless steel materials with precision manufacturing processes and rigorous quality control, this product delivers exceptional value for commercial, industrial, and residential building services projects worldwide.