Stainless Steel Coil Tube for Fan Coil Heat Dissipation Systems
Product Overview
The Stainless Steel Coil Tube (Product No. 496) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered coiled tubing solution specifically designed for thermal management and heat dissipation applications in electronic chassis systems. This product leverages the superior thermal conductivity, corrosion resistance, and mechanical integrity of austenitic stainless steel to deliver optimal heat transfer performance in fan coil assemblies. The coil tube serves as a critical component in indirect heat exchange systems, where it facilitates efficient dissipation of thermal energy generated by high-power electronic equipment through forced-convection air circulation mechanisms.
Derived from advanced research in fan coil heat dissipation technology applied to electronic chassis design, this coil tube product represents a convergence of metallurgical engineering excellence and thermal-fluid dynamics optimization. The helical geometry of the coil tube maximizes the surface-area-to-volume ratio, thereby enhancing convective heat transfer coefficients and enabling compact, high-performance thermal management solutions.
Material & Properties
Base Material Specification
- Grade: AISI 304 / 316L Austenitic Stainless Steel (SAE 304 / SAE 316L)
- Equivalent Standards: ASTM A213 / A269, EN 10216-5, GB/T 12771
- Composition (304): Carbon ≤0.08%, Manganese ≤2.00%, Phosphorus ≤0.045%, Sulfur ≤0.030%, Silicon ≤1.00%, Chromium 18.0–20.0%, Nickel 8.0–11.0%, Iron (balance)
- Composition (316L): Carbon ≤0.03%, Chromium 16.0–18.0%, Nickel 10.0–14.0%, Molybdenum 2.0–3.0%, Iron (balance)
Mechanical Properties
- Tensile Strength (UTS): ≥515 MPa (75,000 psi) — Annealed Condition
- Yield Strength (0.2% offset): ≥205 MPa (29,700 psi)
- Elongation at Break: ≥40% (minimum)
- Hardness: ≤92 HRB (annealed condition)
- Impact Strength (Charpy V-Notch): ≥70 J at 20°C; ≥50 J at −196°C (LN2)
Thermal Properties
- Thermal Conductivity (25°C): 16.3 W/(m·K) — Grade 304
- Thermal Conductivity (25°C): 14.6 W/(m·K) — Grade 316L
- Specific Heat Capacity: 500 J/(kg·K) at 25°C
- Coefficient of Thermal Expansion: 17.3 × 10⁻⁶ /°C (20–100°C range)
- Maximum Service Temperature: 870°C (1600°F) — non-continuous
Corrosion Resistance
- Pitting Resistance (PREN): ≥18 (304); ≥24 (316L)
- Chloride Tolerance: Up to 1000 ppm (316L grade)
- Passivation: Fully passivated per ASTM A967 / AMS 2700
Specifications
| Parameter | Specification | Unit | Standard / Reference |
|---|---|---|---|
| Outer Diameter (OD) | 6.0 – 50.8 | mm | ASTM A269 |
| Wall Thickness | 0.5 – 3.0 | mm | ±0.1 mm tolerance |
| Inner Diameter (ID) | 3.0 – 45.8 | mm | Calculated per OD − 2×WT |
| Coil Diameter (Mean) | 50 – 300 | mm | Customizable |
| Pitch (Coil Spacing) | 1.5 – 10.0 | mm | Application-dependent |
| Coil Length | 0.5 – 50.0 | m | Custom cut available |
| Surface Finish | Ra ≤ 0.8 μm (Polished) / Ra ≤ 1.6 μm (Pickled) | μm | ASTM A270 |
| End Condition | Plain / Beveled / Flanged / Threaded | — | Customer specification |
| Operating Pressure | Up to 4.0 | MPa | ASME B31.3 |
| Operating Temperature | −196 to +500 | °C | Material-dependent |
| Weight Tolerance | ±10% | % | ISO 4035 |
| Roundness | ≤0.1% of OD | % | ASTM A213 |
| Straightness (uncoiled) | ≤1.0 mm/m | mm | Internal QA standard |
Manufacturing Process
1. Raw Material Selection and Inspection
Virgin stainless steel wire rod or seamless pipe blank material is sourced from certified mills with full traceability documentation. Incoming material undergoes spectroscopic analysis (OES) for chemical composition verification, ultrasonic testing (UT) for internal soundness, and visual inspection per ASTM E165.
2. Pipe Forming
Seamless tubes are produced via hot-rolling or cold-drawing processes in accordance with ASTM A269 or A213 specifications. For welded alternatives, ERW (Electric Resistance Welding) or TIG (Tungsten Inert Gas) welding is employed with full weld penetration verification.
3. Cold Drawing and Sizing
The pipe blank is cold-drawn through precision tungsten carbide dies to achieve the specified outer diameter and wall thickness tolerances. This process enhances mechanical properties (work hardening) and improves dimensional accuracy to within ±0.1 mm.
4. Heat Treatment (Solution Annealing)
Following cold working, the tube undergoes solution annealing at 1040–1120°C with rapid water quenching to restore full ductility, eliminate residual stresses, and promote the formation of a uniform, chromium-rich passive oxide layer.
5. Surface Treatment
- Acid Pickling: Immersion in a mixed acid solution (HNO₃/HF) to remove scale and oxides, followed by thorough water rinsing.
- Passivation: Treatment with 20–30% nitric acid or citric acid per ASTM A967 to establish a protective chromium oxide passive film.
- Mechanical Polishing: Optional electropolishing or mechanical buffing to achieve Ra ≤ 0.4 μm for hygienic or high-heat-transfer applications.
6. Coil Forming
The finished tube is precisely coiled using CNC-controlled forming equipment to maintain the specified coil diameter and pitch. The forming process is carefully calibrated to avoid plastic deformation, ovality, or kinking. Post-forming straightness and dimensional checks are performed using laser scanning systems.
7. Final Quality Control
- Dimensional verification via digital calipers and micrometers
- Surface roughness measurement (contact profilometer)
- Hydrostatic pressure testing at 1.5× working pressure
- Visual inspection under controlled lighting (minimum 300 lux)
- Optional: Eddy current testing (ECT) for subsurface defect detection
Applications
Primary Application: Electronic Chassis Heat Dissipation
This coil tube is specifically engineered for integration into fan coil assemblies used in high-power electronic equipment enclosures. The helical geometry creates turbulent flow patterns that significantly enhance the convective heat transfer coefficient (h) between the coil surface and the forced-air stream. Key applications include:
- Telecommunications Equipment: Heat dissipation for base stations, routers, and optical transceivers operating in enclosed cabinets.
- Industrial Control Systems: Thermal management for PLCs, servo drives, and frequency inverters in harsh industrial environments.
- Power Electronics: Cooling of IGBT modules, DC-DC converters, and UPS systems generating substantial waste heat.
- Medical Equipment: Heat extraction from MRI power supplies, laser systems, and diagnostic imaging equipment.
Secondary Applications
- Automotive heat exchanger components (intercoolers, oil coolers)
- Aerospace thermal control loops (hydraulic fluid cooling)
- Food and beverage industry heat exchangers (sanitary grade 316L)
- Pharmaceutical process equipment (CIP-compatible passivated surface)
- Heat recovery systems and thermal storage units
- Fuel cell cooling circuits and hydrogen storage systems
Quality Certifications
| Certification / Standard | Scope | Status |
|---|---|---|
| ISO 9001:2015 | Quality Management System | Certified |
| ISO 14001:2015 | Environmental Management System | Certified |
| ASME BPV Code | Pressure Vessel Materials (where applicable) | Compliant |
| CE Marking (PED 2014/68/EU) | Pressure Equipment Directive | Available upon request |
| EN 10204 3.1 | Material Test Certificate | Provided per batch |
| ASTM E165 | Visual Testing Procedures | Compliant |
| GB/T 12771 | Chinese National Standard for Stainless Steel Tubes | Compliant |
| NACE MR0175 / ISO 15156 | Sulfide Stress Cracking Resistance (316L option) | Available |
Unique Selling Points
- Optimized Thermal Performance: The precisely controlled coil geometry with engineered pitch spacing maximizes the effective heat transfer area while maintaining acceptable pressure drop across the coil, achieving a thermal efficiency up to 92% in fan-forced configurations.
- Superior Corrosion Resistance: The 316L option with molybdenum alloying provides exceptional resistance to chloride-induced pitting and crevice corrosion, ensuring long service life in humid or chemically aggressive environments.
- Full Traceability: Every batch is accompanied by a mill test certificate (MTC) with complete chemical and mechanical property data, ensuring full material provenance and compliance verification.
- Customization Capability: Wenzhou Jixing Metal Materials offers fully customizable coil diameter, pitch, length, and end configurations to match specific chassis thermal design requirements.
- Low Surface Roughness: The polished finish (Ra ≤ 0.8 μm) minimizes fouling and biofilm accumulation, maintaining consistent thermal performance over extended operational cycles.
- Wide Temperature Range: Operational capability from cryogenic (−196°C) to elevated temperatures (+500°C) without loss of mechanical integrity, accommodating extreme thermal cycling scenarios.
- Research-Validated Design: The product design is informed by peer-reviewed research in fan coil heat dissipation technology for electronic chassis, ensuring scientifically optimized thermal management performance.
Note: All specifications listed are representative values based on standard production parameters. Custom specifications, alternative grades (321, 347, duplex 2205), and special surface treatments are available upon consultation with the Wenzhou Jixing Metal Materials engineering team. Product No. 496 is manufactured under ISO 9001:2015 certified quality systems with full batch traceability.