Stainless Steel Coil Tube — Fan Coil Heat Exchanger Tube (Model: 406)
Product Overview
The Stainless Steel Coil Tube (Model: 406) is a precision-engineered coiled tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd, specifically designed for integration into air conditioning system fan coil heat exchangers. This product represents a critical element in thermal management systems, where efficient heat transfer between refrigerant and ambient air is paramount. The coil tube is fabricated to maintain consistent geometry, dimensional accuracy, and metallurgical integrity throughout its coiled configuration, ensuring reliable performance in continuous-duty HVAC (Heating, Ventilation, and Air Conditioning) applications.
This product is developed in alignment with advanced heat exchange model correction methodologies, incorporating empirical thermal performance data to optimize coil geometry, fin spacing, and tube diameter ratios for maximum heat transfer efficiency under variable operating conditions.
Material & Properties
The coil tube is constructed from high-grade austenitic stainless steel, selected for its exceptional corrosion resistance, thermal conductivity, and mechanical durability in HVAC environments.
- Base Material: Austenitic Stainless Steel (Type 304 / SUS304 or Type 316 / SUS316L)
- Composition: Fe balance, Cr (18–20%), Ni (8–10.5%), Mn ≤ 2.0%, Si ≤ 0.75%, C ≤ 0.08%, S ≤ 0.03%
- Hardness: HRB 80–100 (annealed condition)
- Tensile Strength: ≥ 520 MPa
- Elongation: ≥ 40%
- Thermal Conductivity: 14.9 W/(m·K) at 20°C
- Corrosion Resistance: Excellent resistance to chloride-induced pitting and atmospheric corrosion
- Operating Temperature Range: −60°C to +350°C
- Surface Finish: Bright annealed, Ra ≤ 0.8 μm
Technical Specifications
| Parameter | Specification | Unit | Tolerance |
|---|---|---|---|
| Outer Diameter (OD) | 7.0 / 9.52 / 12.0 / 15.88 | mm | ±0.10 |
| Wall Thickness (WT) | 0.50 / 0.60 / 0.80 / 1.00 | mm | ±0.05 |
| Coil Diameter | 300 – 1200 | mm | ±10 |
| Tube Length (per coil) | 3 – 50 | m | ±0.5 |
| Bend Radius (minimum) | ≥ 2.5 × OD | — | — |
| Number of Passes | 2 / 4 / 6 / 8 | — | — |
| Fin Spacing (compatible) | 1.5 – 3.0 | mm | ±0.1 |
| Refrigerant Pressure Rating | ≤ 3.5 | MPa | — |
| Water-side Pressure Rating | ≤ 1.6 | MPa | — |
| Heat Transfer Efficiency (typical) | ≥ 92 | % | — |
| Weight (per coil, typical) | 2.5 – 18.0 | kg | — |
Manufacturing Process
The production of Model 406 stainless steel coil tubes follows a rigorous multi-stage manufacturing workflow designed to ensure dimensional precision, metallurgical homogeneity, and surface quality:
- Material Selection & Inspection: Cold-rolled stainless steel strip is sourced from certified suppliers and subjected to spectroscopic analysis to verify chemical composition compliance with ASTM A269 / ASME B423.7 standards.
- Slitting: The strip is precision-slitted to the required width using computer-controlled slitting lines with laser width measurement for real-time dimensional feedback.
- Forming (Tube Making): The slit strip is fed through a roll-forming die set to produce seamless tubing with controlled ovality (≤ 0.5%) and consistent wall thickness.
- Welding (where applicable): Longitudinal welds are produced using TIG (Tungsten Inert Gas) welding under argon shielding to achieve full-penetration welds with minimal heat-affected zone (HAZ).
- Coiling: The formed tube is coiled to the specified diameter using CNC-controlled coiling equipment with hydraulic tension control to prevent deformation or kinking.
- Bending & Shaping: Multi-pass bending operations are performed at controlled temperatures to achieve the required pass configuration (2-pass, 4-pass, etc.) without inducing work-hardening or micro-cracking.
- Heat Treatment: Solution annealing at 1050–1100°C followed by controlled cooling to restore full austenitic structure and relieve residual stresses.
- Surface Treatment: Acid pickling and passivation to remove oxidation scale and establish a protective chromium oxide layer.
- Final Inspection: Dimensional verification, pressure testing (hydrostatic at 1.5× working pressure), and visual/magnetic particle inspection for weld integrity.
Applications
The Model 406 stainless steel coil tube is engineered for demanding thermal exchange applications, with primary use cases including:
- Air Conditioning Fan Coils: Central air conditioning systems, split-unit heat exchangers, and rooftop unit condensers where the coil tube serves as the refrigerant flow channel.
- Commercial HVAC Systems: Large-scale commercial buildings, hotels, hospitals, and data centers requiring high-efficiency, low-maintenance heat exchangers.
- Industrial Process Cooling: Precision temperature control systems in manufacturing, electronics, and pharmaceutical facilities.
- Refrigeration Systems: Medium-to-low temperature refrigeration units where corrosion resistance and long service life are critical.
- Heat Pump Systems: Dual-function heating and cooling applications requiring tubes that withstand thermal cycling and condensation.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system ensuring that all Model 406 coil tube products meet or exceed international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- ASTM A269 / A269M — Standard specification for welded austenitic stainless steel tubes
- ASME B423.7 — Standard for welded austenitic stainless steel tubes for heat exchangers
- EN 10217-7 — European standard for heat exchanger tubes
- API 5L / ASME B36.19M — Dimensional compliance references
- RoHS & REACH Compliance — Environmental and hazardous substance regulations
Unique Selling Points
- Optimized Heat Exchange Performance: Coil geometry is engineered using corrected thermal models that account for real-world operating deviations, achieving ≥92% heat transfer efficiency and reduced energy consumption.
- Superior Corrosion Resistance: SUS304/316L stainless steel construction provides exceptional resistance to condensation-induced corrosion, extending service life beyond 20 years in typical HVAC environments.
- Precision Dimensional Control: CNC-controlled manufacturing ensures tight tolerances (±0.10 mm OD, ±0.05 mm WT), enabling seamless integration with fin-and-tube assemblies and brazed headers.
- Multi-Pass Configuration Flexibility: Available in 2, 4, 6, and 8-pass configurations to accommodate varying capacity requirements from residential to industrial applications.
- Full Traceability: Each production batch is traceable through material certification, process records, and final test reports, supporting OEM quality audits and warranty claims.
- Cost-Effective Lifecycle: Although initial material cost is higher than copper alternatives, the elimination of corrosion-related maintenance, extended service intervals, and reduced replacement frequency result in significantly lower total cost of ownership (TCO).
Technical Notes
Design Consideration: When integrating Model 406 coil tubes into fan coil assemblies, it is recommended to apply the heat exchange model correction methodology outlined in the referenced technical literature. This involves adjusting nominal heat transfer coefficients (U-values) based on measured air-side and refrigerant-side resistance data, accounting for fouling factors (typically 0.0001–0.0003 m²·K/W for clean HVAC service), and verifying pressure drop across the coil at design flow rates to ensure compatibility with system blower and compressor capabilities.
Storage & Handling: Coils should be stored indoors in a dry environment, protected from mechanical damage and contamination. Upon receipt, verify coil diameter, pass count, and end-conditioning (beaded ends, flared ends, or plain ends) prior to assembly. Avoid dragging or dropping coils to prevent permanent deformation of the tube geometry.