Stainless Steel Coil Tube — Fan Coil Unit & Floor Radiation Combined System
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous coil tubing product designed primarily for HVAC (Heating, Ventilation, and Air Conditioning) applications, including Fan Coil Units (FCUs) and Floor Radiation Combined Systems. This product is supplied in continuous coil form, enabling efficient downstream processing such as bending, cutting, and forming into heat exchanger coils, refrigerant piping, and hydraulic circuits.
Coil tubes offer significant advantages over straight-length piping in terms of material utilization, transportation efficiency, and fabrication speed. The continuous coil configuration minimizes waste and reduces connection points, thereby enhancing system integrity and long-term reliability in closed-loop thermal management applications.
2. Material & Properties
Stainless steel coil tubes are fabricated from austenitic stainless steel grades, providing an optimal combination of corrosion resistance, mechanical strength, and thermal conductivity suitable for demanding HVAC environments.
- Primary Grades: SUS304 (UNS S30408), SUS316 (UNS S31603), SUS304L (UNS S30403)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, condensate water, and mild chemical exposure; SUS316 offers enhanced resistance to chlorides and aggressive media
- Thermal Conductivity: Approximately 16.3 W/(m·K) for SUS304, providing adequate heat transfer performance for refrigerant and hot/cold water circuits
- Mechanical Strength: Tensile strength ≥ 515 MPa (SUS304 annealed); yield strength ≥ 205 MPa
- Operating Temperature Range: −196 °C to +870 °C (SUS304); suitable for both refrigeration and high-temperature heating applications
- Hygienic Surface: Clean, non-porous surface with low roughness (Ra ≤ 0.5 μm for polished finish), preventing biofilm accumulation
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管 / Coiltube) |
| Material Grade | SUS304 / SUS316 / SUS304L |
| Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.7 mm / 15.88 mm / 19.05 mm (customizable) |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm (standard range; custom upon request) |
| Coil Length | Continuous coil, typically 50 m – 300 m per coil (configurable) |
| Coil Inner Diameter | 300 mm – 600 mm |
| Surface Finish | 2B Annealed / BA (Bright Annealed) / Electropolished / Hairline |
| Manufacturing Method | Seamless (Cold Drawn) or Welded (JCOE / ERW) |
| Standard Dimensions | Conforms to GB/T 12771, ASTM A213/A269, EN 10217-7 |
| End Treatment | Plain cut / Beveled / Threaded (optional) |
| Packaging | Wooden pallet with moisture-proof wrapping; protective caps on coil ends |
| Order No. | 681 |
4. Manufacturing Process
The production of stainless steel coil tubes follows a rigorous multi-stage process to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: High-purity stainless steel strip or round bar sourced from certified mills, with full traceability documentation.
- Forming (Seamless): Cold drawing through precision dies to achieve seamless tubular geometry with tight dimensional tolerances (±0.1 mm on OD).
- Forming (Welded): Strip rolling into helical form followed by high-frequency induction welding (HFW) or orbital TIG welding with internal/external grinding of the weld seam.
- Solution Annealing: Heating to 1050–1100 °C in a controlled atmosphere furnace, followed by rapid quenching to restore full austenitic microstructure and relieve residual stresses.
- Pickling & Passivation: Immersion in nitric-hydrofluoric acid bath to remove scale, followed by passivation treatment to form a protective chromium oxide film.
- Surface Finishing: Electropolishing or mechanical polishing to achieve specified surface roughness (Ra values as required).
- Coiling: Continuous coiling onto spools with controlled tension to prevent deformation, kinking, or inter-coil contact damage.
- Non-Destructive Testing (NDT): 100% eddy current inspection for wall thickness and internal/external defects; hydrostatic pressure testing at 1.5× working pressure.
5. Applications
The coil tube product finds extensive application across multiple industrial and commercial sectors:
- Fan Coil Units (FCU): Primary heat exchange coil material in commercial and residential HVAC systems, where the coil tube carries chilled water or hot water to modulate indoor temperature.
- Floor Radiation Combined Systems: Used in underfloor heating and cooling circuits where stainless steel's corrosion resistance and thermal stability ensure long service life in closed-loop hydronic systems.
- Refrigeration & Air Conditioning: Refrigerant piping in chillers, heat pumps, and split air conditioning systems.
- Food & Beverage Processing: Hygienic-grade coil tubing for pasteurization systems, CIP (Clean-In-Place) circuits, and beverage transfer lines.
- Pharmaceutical & Biotechnology: Sanitary process piping requiring high purity and resistance to chemical cleaning agents.
- Marine & Offshore: Corrosion-resistant piping in seawater cooling systems and ballast water treatment circuits.
- Automotive & Aerospace: Precision tubing for fuel lines, hydraulic systems, and thermal management circuits.
6. Technical Advantages & Unique Selling Points
- Continuous Coil Supply: Eliminates butt-weld joints inherent in straight pipe systems, reducing leak points by up to 90% and improving system reliability.
- Material Efficiency: Coil form reduces material waste by 5–8% compared to straight-length pipe procurement.
- Superior Corrosion Resistance: Austenitic stainless steel provides decades of service life in aggressive HVAC condensate environments without degradation.
- Precision Dimensional Control: Tight tolerances ensure seamless integration with brazed plate heat exchangers, shell-and-tube exchangers, and coil bending machinery.
- Full Traceability: Every coil is accompanied by a Mill Test Certificate (MTC) with chemical composition, mechanical properties, and heat treatment records.
- Customization Capability: Non-standard OD, wall thickness, coil length, and surface finish available upon request to meet project-specific requirements.
7. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system ensuring product conformity to international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System
- ISO 45001:2018 — Occupational Health & Safety Management
- CE Marking — Conformity with European directives for construction products and pressure equipment
- GB/T 12771-2019 — Chinese national standard for welded stainless steel tubes for fluid transport
- ASTM A213 / A269 — American standards for seamless and welded austenitic stainless steel tubing
- EN 10217-7 — European standard for non-ferrous metallic tubes and pipes
- Third-Party Inspection: Available upon request (SGS, TÜV, Bureau Veritas)
8. Conclusion
The Stainless Steel Coil Tube (Order No. 681) from Wenzhou Jixing Metal Materials Co., Ltd represents a premium-grade product engineered for the demanding requirements of modern HVAC and thermal management systems. Its combination of metallurgical excellence, precision manufacturing, and continuous coil delivery format positions it as an ideal material solution for Fan Coil Units and Floor Radiation Combined Systems, where cooling capacity optimization, system reliability, and long-term durability are paramount design considerations.