Stainless Steel Coil Tube (Coiltube) — Fan Coil Heat Dissipation Series
Product Overview
The Stainless Steel Coil Tube (also referred to as Coiltube or Coiled Tubing) is a precision-engineered tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for integration into fan coil heat dissipation systems used in electronic chassis enclosures, industrial control cabinets, and high-density server racks. The coil tube serves as the primary heat exchange medium, facilitating efficient thermal transfer between internal electronic components and the external cooling airflow generated by axial or centrifugal fans.
Unlike conventional straight-tube heat exchangers, the coiled configuration maximizes the heat transfer surface area within a compact volumetric envelope, making it an ideal solution for space-constrained electronic enclosures where thermal management is critical to component reliability and operational longevity.
Material & Properties
The coil tube is fabricated from high-grade stainless steel, selected for its superior corrosion resistance, mechanical durability, and thermal conductivity characteristics. The primary material specifications are as follows:
- Material Grade: SUS304 (ASTM A270 Type 304) — the standard austenitic stainless steel offering excellent weldability and resistance to atmospheric and chemical corrosion.
- Alternative Grade: SUS316 (ASTM A270 Type 316) — available for applications requiring enhanced resistance to chloride-induced pitting corrosion, particularly in coastal or marine environments.
- Surface Finish: Electropolished (Ra ≤ 0.4 μm) or brushed finish, ensuring minimal fluid resistance and resistance to biofilm accumulation.
- Thermal Conductivity: 14.9 W/(m·K) at 25°C (SUS304), providing reliable heat transfer performance under continuous operational conditions.
- Operating Temperature Range: −196°C to +870°C (SUS304); −196°C to +870°C (SUS316).
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, dilute acids, and alkaline solutions; pitting resistance equivalent number (PREN) of 19 for SUS304 and 24 for SUS316.
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | Φ3.0 – Φ12.7 (customizable) | mm |
| Wall Thickness | 0.3 – 1.5 | mm |
| Coil Diameter (Center-to-Center) | Φ20 – Φ150 | mm |
| Coil Pitch (Spacing Between Turns) | 1.0 – 5.0 | mm |
| Number of Turns | 5 – 80 | — |
| Tube Length (Uncoiled) | 0.5 – 50 | m |
| Maximum Working Pressure | 1.6 – 6.4 | MPa |
| Hydrostatic Test Pressure | 1.5 × Working Pressure | MPa |
| Tolerance on OD | ±0.1 | mm |
| Tolerance on Wall Thickness | ±10% | — |
| End Preparation | Flat cut, chamfered, or threaded (G/BSP/NPT) | — |
| Maximum Heat Dissipation Capacity | Up to 500 | W |
| Applicable Cooling Medium | Air, water, glycol-water mixture, dielectric fluid | — |
Manufacturing Process
The production of the stainless steel coil tube adheres to a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, structural integrity, and surface quality:
- Material Selection & Inspection: Cold-rolled stainless steel strip or seamless tubing is sourced from certified mill producers. Incoming materials undergo spectroscopic analysis (OES) to verify chemical composition and mechanical testing to confirm tensile strength and elongation values.
- Cutting & Deburring: Tubes are cut to specified lengths using high-precision sawing equipment, followed by mechanical or chemical deburring to eliminate edge burrs that could obstruct fluid flow.
- Coiling Forming: The straight tube is fed through a CNC-controlled coiling machine that applies uniform bending forces to form the helical coil geometry. The coiling process is performed at controlled temperatures to prevent work-hardening-induced cracking, particularly critical for thinner wall sections.
- Heat Treatment (if required): For applications demanding stress relief, the coiled tube undergoes solution annealing at 1050–1150°C followed by controlled water quenching to restore full austenitic structure and eliminate residual stresses introduced during cold forming.
- Surface Finishing: Electropolishing removes surface contaminants, eliminates micro-oxidation layers, and achieves a passive chromium oxide film that enhances long-term corrosion resistance. Alternatively, mechanical brushing or passivation treatment may be applied depending on the end-use specification.
- Dimensional Inspection: Each coil is inspected for OD, wall thickness, coil pitch consistency, and roundness using coordinate measuring machines (CMM) and ultrasonic wall thickness gauges.
- Pressure Testing: Every unit undergoes 100% hydrostatic pressure testing at 1.5 times the rated working pressure for a minimum dwell time of 5 minutes to verify leak-tightness and structural soundness.
- Final Cleaning & Packaging: Tubes are cleaned with deionized water and dried under filtered air. Packaging employs moisture-absorbing desiccants and protective end caps to prevent surface damage during transit.
Applications
The stainless steel coil tube finds extensive application across multiple industrial sectors, with particular emphasis on thermal management in electronic systems:
- Electronic Chassis Heat Dissipation: Integrated into fan coil assemblies within server racks, telecommunications equipment enclosures, and industrial control cabinets to dissipate waste heat from power electronics, processors, and switching components.
- Heat Exchanger Cores: Serves as the tube element in air-to-water and water-to-water heat exchangers used in HVAC (Heating, Ventilation, and Air Conditioning) systems and process cooling loops.
- Cryogenic Systems: Utilized in cryogenic fluid transfer lines and dewar jackets where low-temperature toughness and corrosion resistance are paramount.
- Food & Beverage Industry: Employed in pasteurization coils, beverage chiller heat exchangers, and sanitary process piping where FDA-compliant surface finishes are required.
- Pharmaceutical & Bioprocessing: Applied in bioreactor jacket cooling coils and clean-in-place (CIP) compatible heat transfer assemblies.
- Marine & Offshore Equipment: Used in shipboard cooling systems and offshore platform heat exchangers where resistance to saltwater corrosion is essential.
- Renewable Energy Systems: Incorporated into solar thermal collector tubes and geothermal heat pump systems for efficient thermal energy capture and transfer.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management infrastructure ensuring full traceability and compliance with international standards:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing and supply chain processes.
- ISO 14001:2015 — Environmental Management System demonstrating commitment to sustainable manufacturing practices.
- ASME BPV Section VIII — Compliance with American Society of Mechanical Engineers Boiler and Pressure Vessel Code for pressure-containing components.
- EN 10216-5 — European standard for seamless and welded stainless steel tubes for heat exchangers and heat transfer equipment.
- ASTM A270 — Standard specification for austenitic stainless steel tubing for chemical and similar severe service.
- GB/T 12771 — Chinese national standard for seamless stainless steel tubes for general service.
- NACE MR0175/ISO 15156 — Compliance for use in sour service environments (H₂S-containing applications).
- CE Marking — Conformity with European directives for products entering the European Economic Area.
- Mill Test Certificates (MTC) — Provided per batch with full chemical analysis, mechanical properties, and heat number traceability.
Unique Selling Points
1. Optimized Thermal Performance: The helical coil geometry provides up to 3× the heat transfer surface area compared to equivalent-length straight tubes, enabling compact thermal management solutions without sacrificing cooling capacity.
2. Precision CNC Coiling: Proprietary CNC coiling technology ensures uniform pitch, consistent bend radius, and minimal ovality deviation (≤1% of nominal OD), guaranteeing predictable aerodynamic and hydraulic performance.
3. Material Grade Flexibility: Multiple stainless steel grades (SUS304, SUS316, SUS321, SUS316L) are available to match diverse environmental and chemical compatibility requirements.
4. Custom Engineering Capability: Full customization of coil diameter, pitch, number of turns, end configurations, and surface treatments to meet specific OEM integration requirements.
5. 100% Leak Testing: Every unit undergoes individual hydrostatic pressure verification, providing absolute confidence in pressure boundary integrity.
6. Full Traceability: Each coil is serialized with laser marking linking back to mill heat numbers, enabling complete material provenance documentation throughout the product lifecycle.
Technical Notes
Design Considerations: When integrating the coil tube into fan coil heat dissipation assemblies, engineers should account for the increased pressure drop inherent to coiled geometries. The Darcy-Weisbach equation should be applied with an appropriate friction factor correction for helical curvature (Dean number analysis). Recommended maximum flow velocity within the tube is 2.5 m/s for water-based coolants to minimize erosion-corrosion risk.
Installation Guidance: Mount the coil tube in a position that permits unobstructed airflow across the coil face. Maintain a minimum clearance of 5 mm between adjacent coil turns and surrounding structural elements to ensure laminar-to-turbulent transition airflow. Avoid rigid clamping directly on the tube body; use flexible mounting brackets to accommodate thermal expansion (linear expansion coefficient: 17.3 × 10⁻⁶ /°C for SUS304).
Maintenance: Periodic inspection of the coil surface for signs of corrosion, fouling, or mechanical damage is recommended at intervals not exceeding 12 months. For water-cooled applications, implement a water treatment program to control pH (6.5–8.5) and total dissolved solids (<500 ppm) to prevent scale deposition and intergranular corrosion.