Stainless Steel Coil Tube — HVAC Fan Coil Unit Application
1. Product Overview
The Stainless Steel Coil Tube (Product No. 675) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubular product designed primarily for integration into Fan Coil Units (FCUs) and related HVAC (Heating, Ventilation, and Air Conditioning) systems. This coil tube serves as a critical heat exchange component, facilitating efficient thermal transfer between circulating refrigerant or heating medium and ambient air within fan coil assemblies.
Rooted in advanced research on Comprehensive Energy Efficiency Evaluation Technology for Fan Coil Unit Products, this coil tube is engineered to maximize thermal performance while minimizing energy consumption, contributing to improved COP (Coefficient of Performance) and SCOP (Seasonal Coefficient of Performance) metrics in end-use applications.
2. Material & Properties
The coil tube is fabricated from high-grade Stainless Steel (AISI 304 / 316), selected for its superior corrosion resistance, mechanical strength, and long-term service durability in HVAC environments.
- Base Material: Austenitic Stainless Steel (UNS S30408 / S31603)
- Corrosion Resistance: Excellent resistance to condensation water, refrigerant oils, and atmospheric pollutants
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, ensuring efficient heat transfer
- Temperature Range: Operating from −196°C to +870°C, suitable for extreme HVAC conditions
- Surface Finish: Mirror-polished or satin-finished interior to reduce flow resistance and prevent fouling
- Hygienic Compliance: Smooth inner surface (Ra ≤ 0.4 μm) inhibits bacterial growth and condensate accumulation
3. Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Name | Coil Tube (盘管) | — |
| Product No. | 675 | — |
| Material Grade | SUS 304 / SUS 316 | ASTM A269 / ASTM A270 |
| Outer Diameter (OD) | 6.35 mm / 9.52 mm / 12.7 mm (standard series) | EN 10217-7 |
| Wall Thickness (WT) | 0.50 mm – 1.20 mm | ASTM A213 |
| Coil Diameter | 200 mm – 600 mm (configurable) | — |
| Tube Length | Up to 200 m per continuous coil | — |
| Coil Pitch | 10 mm – 25 mm (adjustable per application) | — |
| Surface Treatment | Pickled & Passivated (P&P) or Electropolished | ASTM A967 |
| Pressure Rating | Up to 1.6 MPa (test pressure 2.4 MPa) | EN 10217-7 |
| Connection Type | Threaded, Flanged, or Brazed ends | — |
| Fin Type (if applicable) | Integral or external aluminum fins | — |
| Working Fluid | Water, Glycol solution, Refrigerant (R-410A, R-32) | — |
4. Manufacturing Process
The coil tube is produced through a multi-stage precision manufacturing process ensuring dimensional accuracy, structural integrity, and surface quality:
- Material Selection & Inspection: Certified stainless steel strip or seamless tube stock is selected and inspected for chemical composition and mechanical properties in accordance with ASTM and EN standards.
- Cold Drawing / Forming: The base tube is cold-drawn to precise OD and WT tolerances (±0.05 mm), ensuring uniform wall thickness and smooth internal geometry.
- Coiling Operation: Using CNC-controlled coiling machinery, the formed tube is wound into precise spiral configurations with controlled pitch and diameter to match fan coil unit design requirements.
- Heat Treatment (if required): Solution annealing at 1050°C followed by rapid water quenching to restore full austenitic microstructure and eliminate residual stresses from cold forming.
- Pickling & Passivation: Acid pickling removes scale and oxidation, followed by passivation treatment to form a protective chromium oxide layer, enhancing long-term corrosion resistance.
- Fin Attachment (optional): External aluminum fins may be mechanically or laser-welded onto the tube surface to increase heat transfer area by up to 5–8×.
- Hydrostatic Testing: Each coil is pressure-tested at 1.5× working pressure for minimum 30 seconds to verify leak-tightness and structural soundness.
- Final Inspection & Packaging: Dimensional verification, surface quality assessment, and protective packaging to prevent mechanical damage during transit.
5. Applications
The Stainless Steel Coil Tube is engineered for demanding HVAC and thermal management applications:
- Fan Coil Units (FCUs): Primary heat exchange component in commercial and residential fan coil systems for heating and cooling.
- Air Handling Units (AHUs): Integrated as coil sections within central air handling systems for large-scale building climate control.
- VRF / VRV Systems: Variable Refrigerant Flow / Variable Refrigerant Volume systems requiring high-efficiency heat exchangers.
- Chilled Water Systems: Heat transfer coils in chilled water distribution networks for commercial facilities.
- Condenser & Evaporator Coils: Refrigeration and air conditioning condensers and evaporators requiring corrosion-resistant tubing.
- Process Cooling: Industrial applications involving glycol-water mixtures or other corrosive working fluids.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality assurance protocols ensuring full compliance with international standards:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing quality
- ISO 14001:2015 — Environmental Management System certification for sustainable production practices
- EN 10217-7 — Conformity with European standard for stainless steel heat exchanger tubes
- ASTM A213 / A269 / A270 — Compliance with American material and product standards for stainless steel tubes
- CE Marking — European Conformity for CE-marked HVAC component supply
- Mill Test Reports (MTR) — Full chemical and mechanical test documentation provided per batch
- Third-Party Inspection: Available upon request by SGS, BV, or TÜV for independent quality verification
7. Unique Selling Points
Energy Efficiency Integration: Designed and validated through comprehensive energy efficiency evaluation research (风机盘管产品综合能效评价技术研究), this coil tube is optimized to deliver superior thermal performance metrics including enhanced EER (Energy Efficiency Ratio) and reduced pressure drop across the coil assembly.
- Superior Corrosion Resistance: SUS 304/316 stainless steel construction provides exceptional longevity in humid, condensing, and chemically aggressive HVAC environments, significantly outperforming carbon steel alternatives.
- Hygienic Surface Quality: Electropolished inner surface (Ra ≤ 0.4 μm) prevents biofilm formation and condensate-related contamination, critical for indoor air quality (IAQ) compliance.
- Precision Dimensional Control: CNC-coiling ensures exact pitch, diameter, and geometry tolerances, enabling seamless integration into compact fan coil unit designs with minimal assembly waste.
- Extended Service Life: Resistant to pitting, crevice corrosion, and stress corrosion cracking, reducing lifecycle maintenance costs by an estimated 40–60% compared to conventional coil materials.
- Customization Capability: Full configurability of OD, WT, coil diameter, pitch, and fin arrangement to meet specific OEM design requirements and thermal load calculations.
- Thermal Performance Optimization: Smooth interior surface reduces fluid friction losses, improving overall system COP and reducing compressor energy consumption.
8. Technical Reference Standards
| Standard | Description |
|---|---|
| ASTM A213 | Standard Specification for Seamless Austenitic Stainless Steel Tubing for High-temperature Service |
| ASTM A269 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tube for Chemical and Similar Severe Service |
| EN 10217-7 | Heat Exchangers and Radiators — Stainless Steel Tubes for Heat Exchangers |
| ASTM A967 | Standard Practice for Chemical Cleaning and Passivation of Stainless Steel Parts |
| ASHRAE 34 | Refrigerants — Designation and Safety Classification |
9. Ordering & Technical Support
For detailed thermal performance data, custom coil configurations, or bulk procurement inquiries, Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical support including:
- Thermal load calculation and coil sizing assistance
- Custom drawing and engineering documentation
- Sample provision for performance validation and compatibility testing
- OEM/ODM manufacturing with private labeling available
- Technical consultation on energy efficiency optimization for fan coil unit integration