Stainless Steel Coil Tube (Fan Coil Tube) — Product No. 527
Product Overview
The Stainless Steel Coil Tube (Product No. 527) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular component designed primarily for use in fan coil units (FCUs), air handling systems, and hydronic heat exchange applications. This product is engineered to withstand varying water temperatures and thermal cycling conditions, ensuring optimal cooling and heating performance over extended service life. The coil tube serves as the core heat transfer medium within HVAC (Heating, Ventilation, and Air Conditioning) systems, where thermal efficiency, corrosion resistance, and dimensional accuracy are paramount.
Based on extensive research into the relationship between water temperature and fan coil cooling performance, this product has been optimized to maintain consistent thermal conductivity and structural integrity across a wide operating temperature range. The stainless steel construction eliminates concerns associated with carbon steel alternatives, including internal corrosion, scaling, and premature degradation in humid or chemically aggressive environments.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior combination of mechanical strength, corrosion resistance, and thermal stability.
- Primary Material Grade: SUS304 (ASTM A213 TP304) — 18% Chromium, 8% Nickel austenitic stainless steel
- Alternative Grade: SUS316L (ASTM A213 TP316L) — Low-carbon 316 grade with 2% Molybdenum for enhanced pitting and crevice corrosion resistance
- Surface Finish: Electropolished (Ra ≤ 0.4 μm) or commercial passivated finish
- Corrosion Resistance: Excellent resistance to deionized water, glycol solutions, and mildly acidic/alkaline environments
- Thermal Conductivity: Approximately 16.3 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +450°C
- Mechanical Properties: Tensile strength ≥ 520 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%
- Hygienic Compliance: Food-grade compatible (FDA 21 CFR compliant for potable water systems)
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm / 9.52 mm / 12.70 mm (¼" / ⅜" / ½") | ASME B36.19M |
| Wall Thickness | 0.50 mm / 0.71 mm / 1.00 mm | ASTM A269 / A213 |
| Coil Length (per roll) | 50 m / 100 m / 200 m (custom available) | — |
| Coil Diameter | 150 mm – 600 mm (as wound) | — |
| Dimensional Tolerance | ±0.05 mm (OD); ±0.03 mm (wall thickness) | ISO 1307 |
| Surface Roughness | ≤ 0.8 μm (commercial); ≤ 0.4 μm (electropolished) | ISO 4287 |
| Winding Pitch | 1.5× OD to 3.0× OD (configurable) | — |
| Maximum Working Pressure | 1.6 MPa (standard); 4.0 MPa (reinforced) | GB/T 14976 |
| Hydrostatic Test Pressure | 2.5× working pressure, held for 30 seconds | ASME B31.5 |
| Thermal Conductivity | 16.3 W/(m·K) at 20°C | ASTM E1225 |
| Service Life | ≥ 25 years (continuous operation, treated water) | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional precision, metallurgical soundness, and surface integrity:
- Raw Material Selection: Cold-rolled stainless steel strip is sourced from certified mill suppliers, with incoming inspection covering chemical composition (spectroscopic analysis), mechanical properties, and visual surface quality.
- Slitting & Annealing: The strip is slit to precise widths and subjected to controlled atmosphere annealing (atmosphere: 95% N₂ + 5% H₂) to relieve residual stresses and ensure uniform microstructure.
- Forming & Seaming: Precision roll-forming machines convert flat strip into round or oval tubes. The longitudinal seam is formed and welded using TIG (Tungsten Inert Gas) welding with argon shielding to produce a smooth, corrosion-resistant internal weld bead.
- Coil Winding: Formed tubes are wound onto precision-controlled coils at the specified pitch and diameter, ensuring uniform tension and no inter-turn interference.
- Heat Treatment (if required): Solution annealing at 1050–1100°C followed by rapid air cooling for grades requiring stress relief or grain uniformity.
- Surface Treatment: Passivation using citric acid or nitric acid solution to remove free iron and enhance the passive chromium oxide layer. Electropolishing available for hygienic applications.
- Quality Inspection: 100% dimensional verification, visual inspection, hydrostatic pressure testing, and sampling for mechanical testing and surface roughness measurement.
- Packaging & Dispatch: Coils are wrapped in moisture-proof film, secured with steel strapping, and labeled with mill test certificates (MTC) and traceability codes.
Applications
The stainless steel coil tube (Product No. 527) finds extensive application across multiple industries:
- HVAC Systems: Primary heat exchange medium in fan coil units (FCUs), chilled water coils, and air handling units (AHUs) for commercial buildings, hospitals, and data centers.
- Refrigeration & Cold Storage: Evaporator coils in walk-in coolers, freezers, and industrial refrigeration systems where corrosion resistance is critical.
- Food & Beverage Processing: Hygienic-grade heat exchangers for pasteurization, CIP (Clean-In-Place) systems, and beverage dispensing equipment.
- Pharmaceutical & Medical: Clean-room HVAC coils and process cooling loops requiring validated material integrity and low particulate release.
- Marine & Offshore: Seawater-cooled heat exchangers and bilge cooling systems where chloride-induced corrosion is a primary concern (SUS316L grade).
- Industrial Process Cooling: Heat recovery coils in chemical processing, power generation, and semiconductor manufacturing facilities.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework ensuring product conformity with international standards:
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| CE Marking (PED 2014/68/EU) | Pressure Equipment Directive compliance |
| EN 10204 3.1 | Material Test Certificate — Manufacturer's Test Report |
| GB/T 14976 | Chinese national standard for seamless stainless steel tubes |
| ASTM A213 / A269 | Material specification for austenitic stainless steel tube |
| 3-A Sanitary Standards | Food processing equipment compliance |
Unique Selling Points
- Thermal Performance Optimization: Engineered specifically with reference to water temperature–cooling performance correlations, ensuring peak COP (Coefficient of Performance) across the full operating range of fan coil units.
- Superior Corrosion Resistance: Stainless steel construction eliminates the risk of internal rust, scale buildup, and biofilm formation common in carbon steel alternatives, reducing maintenance frequency and extending service life by 3–5×.
- Precision Dimensional Control: Tight tolerances (±0.05 mm OD) ensure optimal fin-to-tube contact when integrated into heat exchanger assemblies, maximizing heat transfer efficiency.
- Hygienic Grade Available: Electropolished finish suitable for pharmaceutical, food, and medical applications without additional surface treatment.
- Full Traceability: Each coil batch is accompanied by a mill test certificate (MTC) with complete chemical and mechanical data, enabling full supply chain traceability.
- Customization Capability: Flexible configuration options for OD, wall thickness, coil length, winding pitch, and surface finish to meet project-specific requirements.
Technical Advisory Note
Design Consideration: Research published in HVAC engineering literature (e.g., "Effect of Water Temperature on Fan Coil Cooling Performance") demonstrates that the supply water temperature significantly influences the dew point behavior, latent heat ratio, and overall energy efficiency of fan coil systems. When selecting stainless steel coil tube specifications, engineers should consider the expected supply water temperature range (typically 6–12°C for cooling; 40–60°C for heating) and ensure the tube geometry, wall thickness, and fin spacing are optimized for the intended thermal duty cycle. Wenzhou Jixing Metal Materials Co., Ltd provides technical consultation services to assist system designers in matching coil tube specifications to application-specific thermal loads.