Stainless Steel Coil Tube — Series 409 (Fan Coil Unit Application)
Product Overview
The Stainless Steel Coil Tube (Product No. 409) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing product designed specifically for integration into fan coil unit (FCU) systems and hydronic temperature control applications. This coil tube serves as the core heat exchange element within HVAC (Heating, Ventilation, and Air Conditioning) terminal units, facilitating efficient thermal transfer between circulating coolant/heat medium and ambient air. The product has been extensively validated through temperature time-period control test research, demonstrating superior thermal cycling performance and long-term reliability under continuous operational conditions.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional corrosion resistance, thermal conductivity, and mechanical integrity across a wide operating temperature range. The material composition ensures resistance to scaling, pitting, and galvanic corrosion when exposed to water-based heat transfer media, glycol solutions, and humid indoor air environments.
- Base Material: Austenitic Stainless Steel (Grade 304 / 316L available upon specification)
- Corrosion Resistance: Superior resistance to chloride-induced pitting and general atmospheric corrosion
- Thermal Conductivity: 14.9–16.3 W/(m·K), ensuring efficient heat dissipation
- Operating Temperature Range: −40°C to +250°C (−40°F to +482°F)
- Surface Finish: Electropolished or passivated inner surface (Ra ≤ 0.4 μm) for reduced flow resistance
- Wall Thickness Tolerance: ±0.05 mm, ensuring uniform heat transfer characteristics
Specifications
| Parameter | Specification |
|---|---|
| Product Number | 409 |
| Product Name | Stainless Steel Coil Tube (盘管 / Coiltube) | Outer Diameter (OD) | 6.35 mm – 12.7 mm (¼" – ½") |
| Wall Thickness | 0.5 mm – 1.0 mm |
| Coil Pitch | 8 mm – 15 mm (adjustable per thermal load requirement) |
| Coil Diameter | 100 mm – 300 mm (configurable) |
| Tube Length (per coil) | 3 m – 20 m |
| Pressure Rating | Up to 1.6 MPa (232 psi) working pressure |
| Hydrostatic Test Pressure | 2.4 MPa (348 psi) |
| Surface Treatment | Passivated / Electropolished |
| Connection Type | Flared, brazed, or threaded end fittings |
| Standard | ASTM A269 / ASTM A213 / EN 10217-7 |
Manufacturing Process
The production of the Series 409 coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and thermal performance consistency:
- Material Selection & Inspection: Stainless steel round bar stock is sourced from certified mills and subjected to spectral analysis (PMI), chemical composition verification, and mechanical property testing.
- Precision Tube Forming: Seamless tubes are produced via cold-drawing or hot-rolling processes, achieving tight dimensional tolerances on outer diameter and wall thickness.
- Coil Forming: Precision CNC coil-forming machines bend the straight tubing into helical coils with controlled pitch, diameter, and number of turns, minimizing work hardening and residual stress.
- Heat Treatment & Stress Relief: Annealing at controlled temperatures relieves cold-work hardening, restores full austenitic structure, and ensures dimensional stability.
- Surface Finishing: Passivation treatment (citric acid or nitric acid-based) removes free iron and establishes a protective chromium oxide layer. Electropolishing may be applied for enhanced surface smoothness.
- End Fitting & Sealing: Tube ends are formed, threaded, or brazed with appropriate fittings for system integration.
- Quality Inspection: Each coil undergoes hydrostatic pressure testing, dimensional measurement, visual inspection, and leak detection before packaging.
Applications
The Series 409 Stainless Steel Coil Tube is engineered for demanding thermal management applications, with particular emphasis on HVAC terminal units and precision temperature control systems:
- Fan Coil Units (FCUs): Primary heat exchange coil for commercial and residential HVAC systems, enabling both heating and cooling modes through time-period temperature control strategies.
- Chilled Water Systems: Integration into hydronic cooling loops for large-scale building climate management.
- Heat Recovery Systems: Utilization in energy-efficient heat exchangers for waste heat recovery applications.
- Industrial Process Cooling: Application in manufacturing facilities requiring precise temperature regulation.
- Pharmaceutical & Food Processing: Sanitary-grade coil tubes for cleanroom HVAC and process cooling where corrosion resistance is critical.
- Time-Period Temperature Control: Validated through experimental research for zonal and temporal temperature regulation, enabling optimized energy consumption through programmable thermal cycling.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management and product certification frameworks to assure international compliance and performance reliability:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- EN 10204 3.1 — Mill test certificates for material traceability
- ASTM Compliance — Product manufactured and tested per ASTM A269 / A213 standards
- CE Marking — European Conformity for market access
- Hydrostatic Testing Report — Batch-specific pressure test documentation
- Corrosion Testing — Salt spray test (ASTM B117) and intergranular corrosion test (ASTM A262) results available
Unique Selling Points
Validated Thermal Cycling Performance: The Series 409 coil tube has been specifically evaluated through fan coil unit temperature time-period control test research, demonstrating consistent thermal response accuracy and long-term fatigue resistance under repeated heating/cooling cycles — a critical advantage for energy-efficient HVAC zoning systems.
- Superior Corrosion Durability: Austenitic stainless steel construction eliminates the need for internal coatings or inhibitors, reducing lifecycle maintenance costs.
- Precision Engineering: CNC-formed coils ensure uniform pitch and dimensional consistency, yielding predictable and repeatable thermal performance across production batches.
- Modular Design: Configurable coil diameter, pitch, and tube length allow customization to match specific thermal load requirements and installation constraints.
- Extended Service Life: Resistance to scaling, oxidation, and mechanical fatigue ensures service life exceeding 20 years under normal operating conditions.
- Energy Efficiency: Optimized coil geometry and high thermal conductivity contribute to reduced pumping power and improved system COP (Coefficient of Performance).