Stainless Steel Coil Tube (Coiltube) — Energy-Efficient Fan Coil Unit Series
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) series manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled piping product designed primarily for use in fan coil unit (FCU) systems, HVAC (Heating, Ventilation, and Air Conditioning) installations, and industrial heat exchange applications. This product represents an advanced solution integrating high-performance stainless steel materials with optimized coil geometry to achieve superior thermal efficiency and long-term operational reliability.
Built upon extensive research into energy-saving measures for fan coil units, this coil tube product addresses critical challenges in heat transfer efficiency, pressure drop minimization, and lifecycle cost reduction. The coil design maximizes surface area within a compact footprint, enabling efficient heat exchange between working fluids and ambient air in both heating and cooling modes.
2. Material & Properties
2.1 Material Grades
- Primary Grades: SUS304 (UNS S30400), SUS316L (UNS S31603), SUS321 (UNS S32100)
- Alternative Grades: SUS430 (UNS S43000) for cost-sensitive applications; Super austenitic alloys upon request
2.2 Key Material Properties
| Property | SUS304 | SUS316L | SUS321 |
|---|---|---|---|
| Tensile Strength (MPa) | ≥ 520 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% Proof, MPa) | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (%) | ≥ 40 | ≥ 40 | ≥ 40 |
| Thermal Conductivity at 20°C (W/m·K) | 16.3 | 14.6 | 16.3 |
| Corrosion Resistance | Excellent (general environments) | Superior (chloride-containing environments) | Excellent (high-temperature oxidation) |
| Maximum Service Temperature (°C) | 870 | 870 | 925 |
2.3 Surface Finish Options
- 2B Finish (Cold Rolled and Annealed)
- No. 4 Brushed Finish
- Mirror Finish (BA — Bright Annealed)
- Electropolished Interior (EP) for sanitary applications
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Tube Outer Diameter (OD) | 6 mm, 8 mm, 10 mm, 12 mm, 16 mm (custom sizes available) |
| Tube Wall Thickness | 0.5 mm – 1.5 mm |
| Coil Diameter | 200 mm – 1200 mm |
| Coil Height (Active Length) | 100 mm – 600 mm |
| Number of Rows | 1, 2, 3, 4 rows (configurable) |
| Fin Pitch | 2.0 mm – 3.5 mm |
| Fin Material | Aluminum (standard), Stainless Steel (optional) |
| Operating Pressure | Up to 1.6 MPa (PN16); up to 4.0 MPa on request |
| Operating Temperature Range | −40°C to +200°C |
| Heat Transfer Coefficient | ≥ 60 W/m²·K (air-to-water) |
| Pressure Drop (Water Side) | ≤ 0.05 MPa at rated flow |
| Connection Type | Flanged, threaded, brazed, or welded |
| Product Standard | GB/T 14976, ASTM A269, EN 10217 |
4. Manufacturing Process
4.1 Process Flow
- Material Inspection & Certification: Incoming stainless steel strip or seamless tube undergoes spectroscopic analysis (PMI — Positive Material Identification) and dimensional verification against mill test certificates.
- Coil Forming: Precision CNC coil forming equipment shapes the tube into the specified helical geometry with controlled pitch and diameter tolerances (±0.5 mm).
- Fin Application: Aluminum fins are mechanically bonded or mechanically expanded onto the tube surface to increase effective heat transfer area by a factor of 3–5×.
- Welding & Brazing: Header connections and tube-to-plate joints are produced using TIG (Tungsten Inert Gas) welding or vacuum brazing to ensure leak-tight integrity.
- Hydrostatic Pressure Testing: Each coil assembly is pressure-tested at 1.5× the maximum operating pressure for a minimum hold time of 30 minutes.
- Surface Treatment & Cleaning: Optional pickling and passivation treatment removes scale and forms a protective chromium oxide layer for enhanced corrosion resistance.
- Final Inspection & Packaging: Visual inspection, dimensional verification, and protective packaging prior to dispatch.
4.2 Energy-Saving Design Features
- Optimized Coil Geometry: Computational Fluid Dynamics (CFD) simulation-guided design minimizes flow maldistribution and pressure drop while maximizing heat transfer surface utilization.
- Variable Fin Density: Graded fin spacing along the coil length matches local heat flux distribution, reducing overall fan power consumption.
- Low-Fouling Surface Treatment: Hydrophilic coating options reduce air-side fouling resistance, maintaining efficiency over extended operating cycles.
- Compact Multi-Row Configuration: Multi-row coil arrangements enable staged operation, reducing part-load energy consumption by 20–35% compared to single-stage systems.
5. Applications
- HVAC Fan Coil Units: Chilled water and hot water coils for commercial and residential air conditioning systems.
- Industrial Heat Exchangers: Process cooling/heating in chemical, pharmaceutical, and food processing industries.
- Refrigeration Systems: Evaporator and condenser coils for commercial refrigeration and cold storage.
- Sanitary & Pharmaceutical: Electropolished coil assemblies for CIP (Clean-In-Place) compatible systems in biotech and dairy processing.
- Marine & Offshore: Corrosion-resistant coils for marine HVAC and platform cooling systems.
- Geothermal Heat Pumps: Coil assemblies for ground-source and water-source heat pump installations.
6. Quality Certifications & Standards
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent product quality and process control. |
| ISO 14001:2015 | Environmental Management System certification for sustainable manufacturing practices. |
| CE Marking | Conformance with European health, safety, and environmental protection standards. |
| GB/T 14976 | Chinese national standard for seamless stainless steel tubes. |
| ASTM A269 / A270 | American standard for austenitic stainless steel seamless and welded tubes. |
| EN 10217-7 | European standard for seamless heat exchanger tubes. |
| NSF/ANSI 61 | Drinking water system component certification (for potable water applications). |
| PED 2014/68/EU | Pressure Equipment Directive compliance for pressurized applications. |
7. Unique Selling Points
- Energy Efficiency Leadership: Designed with energy-saving measures as a core principle, achieving up to 35% energy reduction in fan coil unit applications through optimized aerodynamic and thermal design.
- Full Material Traceability: Each product batch is traceable to mill origin with complete chemical composition and mechanical property documentation.
- Custom Engineering Capability: Flexible design parameters allow tailoring to specific system requirements including non-standard dimensions, multi-row configurations, and special alloy grades.
- Extended Service Life: Superior corrosion resistance and mechanical durability deliver a design life exceeding 25 years in typical HVAC applications.
- Low Lifecycle Cost: Reduced maintenance frequency, minimal fouling, and sustained efficiency translate to significantly lower total cost of ownership (TCO).
Note: All specifications are subject to verification against the applicable standard revision at the time of manufacture. Custom specifications may require a minimum lead time of 4–8 weeks. Wenzhou Jixing Metal Materials Co., Ltd. reserves the right to modify product specifications with prior notification to customers.