Stainless Steel Coil Tube (盘管) — Fan Coil Unit Heat Exchanger Series
Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a precision-engineered heat exchange component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (温州继兴金属材料有限公司). Designed primarily for integration into Fan Coil Units (FCU, 风机盘管机组), this product serves as the core thermal transfer element in modern HVAC (Heating, Ventilation, and Air Conditioning) systems. The coil tube is formed from high-grade stainless steel wire, wound into a continuous serpentine configuration to maximize surface area and thermal efficiency while maintaining structural integrity under cyclic thermal and hydraulic loading.
This product line has been further refined through systematic study and application research in the field of Fan Coil Unit Noise Measurement and Application (《风机盘管机组噪声测定和应用》), incorporating acoustic optimization principles directly into the coil geometry and flow channel design to minimize aerodynamic noise during operation.
Material & Properties
The coil tube is fabricated from austenitic stainless steel, selected for its superior corrosion resistance, mechanical strength, and thermal conductivity. The following table summarizes the key material properties:
- Primary Grades: SUS304 (ASTM 304 / EN 1.4301), SUS316 (ASTM 316 / EN 1.4401), and SUS316L (ASTM 316L / EN 1.4404) for enhanced low-carbon applications in aggressive environments.
- Corrosion Resistance: Excellent resistance to oxidation, pitting, and crevice corrosion in humid, chlorinated, and acidic atmospheres. The chromium (Cr) and molybdenum (Mo) content provide passive film stability.
- Mechanical Properties: Tensile strength ranging from 520–750 MPa depending on grade and cold-work condition; elongation ≥ 30% ensuring ductility during forming operations.
- Thermal Conductivity: Approximately 14–16 W/(m·K) for austenitic grades, providing adequate heat transfer performance for HVAC duty cycles.
- Operating Temperature Range: −196 °C to +870 °C, accommodating extreme thermal cycling without embrittlement or stress cracking.
- Hygienic Surface Finish: Available in 2B, BA (Bright Annealed), and No. 4 polished finishes with surface roughness Ra ≤ 0.8 μm, facilitating fluid flow and reducing fouling.
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管 / Coiltube) |
| Product Code / Serial No. | 1657 |
| Material Grades | SUS304, SUS316, SUS316L (custom grades available upon request) |
| Wire Diameter (Outer Diameter, OD) | 3.0 mm – 12.0 mm (standard range; custom dimensions available) |
| Tube Wall Thickness | 0.3 mm – 1.2 mm |
| Coil Pitch / Spacing | 6.0 mm – 25.0 mm (adjustable per thermal load requirements) |
| Coil Length | 0.5 m – 15.0 m (standard); up to 30.0 m for special orders |
| Number of Rows / Passes | 1 – 8 rows (configurable for capacity scaling) |
| Fin Type (if applicable) | Aluminum or copper fin attachment; fin density 10–24 FPI (Fins Per Inch) |
| Operating Pressure | Up to 1.6 MPa (standard); up to 2.5 MPa (reinforced) |
| Operating Temperature | −196 °C to +870 °C |
| Thermal Efficiency | ≥ 92% (based on Fan Coil Unit Noise Measurement and Application study) |
| Acoustic Performance | ≤ 45 dB(A) at 1 m distance (optimized coil geometry per noise study) |
| Surface Finish | 2B, BA, No. 4 polished (Ra ≤ 0.8 μm) |
| End Connection Type | Flared, threaded (G, NPT, BSP), brazed, or welding-ready |
| Standards Compliance | ASTM A270, EN 10217-7, GB/T 12771, ISO 9001:2015 |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical integrity, and acoustic performance:
- Raw Material Inspection: Incoming stainless steel wire or tube stock is verified for chemical composition (via spectroscopic analysis) and mechanical properties (tensile testing, hardness measurement) in accordance with ASTM and GB standards.
- Cold Drawing & Annealing: The raw wire or tube is cold-drawn to precise OD and wall thickness tolerances (±0.05 mm). Intermittent annealing at 1050–1100 °C in a controlled atmosphere restores ductility and relieves internal stresses.
- Coil Winding: The formed tube is wound into a serpentine or spiral configuration using CNC-controlled coiling equipment. Coil pitch, turn count, and alignment are programmatically controlled to match the thermal and acoustic design parameters derived from the Fan Coil Unit Noise Measurement and Application research.
- Hydroforming / Expanding (for tube-in-tube configurations): In multi-tube designs, inner tubes are hydro-expanded into outer tubes to achieve a metallurgical bond, ensuring maximum heat transfer contact and structural rigidity.
- Fin Attachment: Aluminum or copper fins are mechanically inserted or brazed onto the coil tube at specified fin density (FPI) to augment the heat transfer surface area. Fin-to-tube bonding is verified via shear testing.
- End Processing: Coil ends are cut, deburred, and prepared with the selected connection type (flared, threaded, or brazed). Dimensional verification is performed using coordinate measuring machines (CMM).
- Pressure Testing: Each coil assembly undergoes 100% hydrostatic pressure testing at 1.5× the maximum operating pressure (typically 2.4 MPa for standard units) to confirm leak-free integrity.
- Acoustic Verification: Per the methodology established in the Fan Coil Unit Noise Measurement and Application study, representative samples are tested in an anechoic chamber to verify that aerodynamic noise levels remain within specified limits (≤ 45 dB(A)).
- Final Inspection & Packaging: Finished products undergo visual, dimensional, and performance inspection. Each unit is serialized, documented with a Certificate of Conformity (CoC), and packaged for shipment.
Applications
The Stainless Steel Coil Tube is a versatile heat exchange component deployed across a wide spectrum of industrial and commercial applications:
- Fan Coil Units (FCU, 风机盘管机组): Primary application — the coil tube serves as the evaporator or condenser element within FCUs used in commercial buildings, hotels, hospitals, and residential HVAC systems. The noise-optimized design ensures occupant comfort in noise-sensitive environments such as hospitals, theaters, and recording studios.
- VRF/VRV Systems (Variable Refrigerant Flow/Volume): Integrated into variable-capacity air conditioning systems for zoned climate control in multi-story commercial buildings.
- Chilled Water Distribution Systems: Used in constant-volume and variable-volume hydronic systems for large-scale commercial and industrial cooling.
- Food & Beverage Processing: Employed in pasteurization, refrigeration, and CIP (Clean-In-Place) systems where hygienic-grade stainless steel (SUS316L) is mandatory.
- Pharmaceutical & Biotechnology: Applied in cleanroom HVAC systems, fermentation cooling, and process water temperature control where GMP (Good Manufacturing Practice) compliance is required.
- Marine & Offshore: Deployed in shipboard air conditioning and dehumidification systems where resistance to saltwater corrosion (SUS316) is critical.
- Automotive Thermal Management: Used in electric vehicle battery cooling systems and HVAC units where compact, corrosion-resistant heat exchangers are essential.
- Industrial Process Heating & Cooling: Applied in chemical processing, semiconductor manufacturing, and electronics cooling where precise temperature control is paramount.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that every Stainless Steel Coil Tube meets or exceeds international standards:
- ISO 9001:2015 — Quality Management Systems certification, covering all production processes from raw material procurement through final inspection.
- ISO 14001:2015 — Environmental Management Systems certification, ensuring environmentally responsible manufacturing practices.
- ISO 45001:2018 — Occupational Health and Safety Management Systems certification.
- CE Marking (EU Conformity): Compliant with European directives for pressure equipment and HVAC components.
- ASTM A270 / ASTM A778 — Standard specifications for wrought austenitic stainless steel tubing and pipe.
- EN 10217-7 — European standard for non-heat-treated seamless stainless steel tubes.
- GB/T 12771 — Chinese national standard for stainless steel welded tubes for general applications.
- GB/T 14976 — Chinese national standard for stainless steel seamless tubes for fluid transport.
- ASME B31.5 — Code for refrigeration piping and liquid pressure piping, applicable to the pressure-rated coil assemblies.
- UL / CSA Listing — Available upon request for North American market compliance.
Note: The acoustic performance specifications incorporated into this product line are derived from the systematic study documented in 《风机盘管机组噪声测定和应用》(Fan Coil Unit Noise Measurement and Application). This research established empirical correlations between coil geometry parameters — including tube diameter, coil pitch, and fin density — and the resulting aerodynamic noise characteristics, enabling the engineering of coil tubes that achieve optimal thermal efficiency with minimized acoustic impact.
Unique Selling Points
- Acoustically Optimized Design: Industry-leading noise performance (≤ 45 dB(A)) achieved through research-driven coil geometry optimization, distinguishing this product in noise-critical applications.
- Grade Flexibility: Full range from standard SUS304 to marine-grade SUS316L, accommodating the most demanding corrosion environments.
- Precision Manufacturing: CNC-controlled coiling with ±0.05 mm dimensional tolerance ensures consistent thermal and hydraulic performance across production batches.
- 100% Pressure Testing: Every unit undergoes hydrostatic pressure verification, eliminating the risk of field failures.
- Hygienic Surface Finish: Ra ≤ 0.8 μm surface roughness minimizes fouling and facilitates cleaning in food-grade and pharmaceutical applications.
- Custom Engineering: Full customization of coil dimensions, row count, fin density, and connection types to match specific thermal load and space constraints.
- Traceability: Each product is serialized with full material traceability documentation, enabling lifecycle quality management.