Stainless Steel Coil Tube (Coiltube) — Ice Storage & Heat Exchange Application
1. Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product formed into a continuous helical or spiral coil configuration. This product is specifically designed for applications requiring efficient thermal transfer, including Ice Storage Systems (Ice Thermal Energy Storage), district heating/cooling networks, solar water heating collectors, and industrial heat exchangers.
Based on extensive simulation research comparing ice storage performance across various pipe geometries and materials, the Coiltube product line has been optimized to maximize heat transfer efficiency, minimize pressure drop, and ensure long-term structural integrity under cyclic thermal loading. The helical coil geometry provides a large surface-area-to-volume ratio, enabling superior thermal exchange performance compared to straight-tube configurations in equivalent footprint areas.
2. Material & Properties
2.1 Base Material Grades
- Austenitic Stainless Steel (奥氏体不锈钢): SUS304 / 304L, SUS316 / 316L, SUS321, SUS310S
- Superaustenitic / Duplex Stainless Steel (双相不锈钢): SUS316Ti, 2205 Duplex (for aggressive environments)
- Custom Alloy Compositions: Available upon request for specialized corrosion or temperature resistance
2.2 Key Physical & Chemical Properties
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C (typical for austenitic grades)
- Specific Heat Capacity: ~460–500 J/(kg·K)
- Thermal Expansion Coefficient: 16–18 × 10⁻⁶ /K
- Corrosion Resistance: Excellent resistance to pitting, crevice, and intergranular corrosion in water, brine, and chemical solutions
- Operating Temperature Range: −196°C to +870°C (grade-dependent)
- Non-magnetic (essentially): Suitable for MRI environments and magnetic-sensitive applications
2.3 Performance in Ice Storage Applications
Simulation studies on ice storage performance of different pipe types have demonstrated that stainless steel coil tubes exhibit favorable characteristics for thermal energy storage systems:
- Superior corrosion resistance under prolonged contact with water/brine solutions prevents degradation of heat transfer surfaces
- Smooth inner surface (low Ra value) minimizes frictional pressure drop during fluid circulation
- Good mechanical formability allows tight coil winding without work-hardening failure
- Long service life under cyclic freezing/thawing conditions (thermal fatigue resistance)
3. Technical Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | Φ6 mm – Φ50 mm (standard); custom up to Φ100 mm | ASTM A213 / GB/T 12771 |
| Wall Thickness | 0.5 mm – 3.0 mm (standard); custom available | ASTM A213 / EN 10216-5 |
| Coil Diameter (Mean) | 50 mm – 500 mm | Company Standard / Customer Specification |
| Coil Length (per spool) | 10 m – 500 m (adjustable) | — |
| Surface Finish | BA (Bright Annealed), Pickled, or Custom (Ra ≤ 0.8 μm available) | ASTM A473 / EN 10204 |
| Tolerance — OD | ±0.1 mm (standard); ±0.05 mm (precision) | ISO 2852-1 |
| Tolerance — Wall Thickness | ±10% of nominal | ASTM A213 |
| Winding Tolerance | ±2 mm on coil diameter | Company Standard |
| End Forming | Plain end, beveled end, or custom fitting compatible | Customer Requirement |
| Hydrostatic Test Pressure | 2.0 × working pressure (minimum) | ASTM A213 / GB/T 24511 |
| Maximum Working Pressure | Up to 1.6 MPa (standard); higher upon request | ASME B31.3 / EN 13480 |
4. Manufacturing Process
4.1 Production Flow
- Raw Material Procurement: Virgin stainless steel strip or seamless/ERW pipe blank sourced from certified mills, with full material traceability documentation.
- Heat Treatment: Solution annealing at 1050–1150°C followed by controlled cooling to achieve full austenitic microstructure and optimal corrosion resistance.
- Forming & Coiling: Continuous cold-forming on precision CNC coil winding machines with controlled bending radii to prevent ovality and surface damage. Multi-axis forming ensures uniform coil geometry.
- Surface Treatment: Bright annealing (BA) in controlled atmosphere furnace, or acid pickling and passivation to remove surface oxides and enhance corrosion resistance.
- Quality Inspection: Dimensional verification (OD, wall thickness, coil diameter), surface defect detection (visual + eddy current), and hydrostatic pressure testing.
- Packaging & Dispatch: Protective wrapping with moisture-absorbing desiccants, wooden crate or pallet packaging for international shipping.
4.2 Key Process Controls
- Coil winding angle and pitch controlled within ±1° to ensure uniform heat transfer performance
- In-line dimensional monitoring via laser measurement systems
- 100% hydrostatic testing before shipment
- Full material traceability from mill certificate to finished product
5. Applications
5.1 Ice Thermal Energy Storage (蓄冰蓄冷系统)
The primary application domain. Stainless steel coil tubes are immersed in ice storage tanks to absorb/release thermal energy during peak/off-peak load shifting. The coil geometry maximizes heat exchange area within a compact tank volume, and the corrosion-resistant material ensures decades of service life in aqueous environments.
5.2 Additional Applications
- District Heating & Cooling: Heat exchange coils for central heating systems
- Solar Water Heating: Immersion coils in solar thermal storage tanks
- Industrial Heat Exchangers: Shell-and-coil configurations for chemical, pharmaceutical, and food processing industries
- Refrigeration Systems: Evaporator and condenser coils in cold storage facilities
- Geothermal Systems: Heat exchanger coils for ground-source heat pump applications
- Automotive & HVAC: Compact heat exchanger components
6. Quality Certifications & Standards Compliance
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| EN 10204 3.1 | Material Test Certificate (Mill Test Report) |
| CE Marking | European Conformity for pressure equipment |
| ASTM A213 / A269 | Product specification compliance |
| GB/T 12771 | Chinese national standard for welded stainless steel tubes |
| PED 2014/68/EU | Pressure Equipment Directive (where applicable) |
7. Unique Selling Points
- Simulation-Validated Design: Product geometry and material selection informed by rigorous CFD (Computational Fluid Dynamics) and thermal simulation studies on ice storage performance, ensuring optimal heat transfer coefficients in real-world operating conditions.
- Custom Coil Geometry: Tailored coil diameter, pitch, and length configurations to match specific tank dimensions and thermal load requirements.
- Superior Corrosion Durability: Full austenitic stainless steel construction eliminates concerns about rust, scaling, or material degradation in water-based thermal storage systems — significantly reducing lifecycle maintenance costs.
- Precision Manufacturing: CNC-controlled coil winding ensures consistent geometry and repeatable thermal performance across production batches.
- Full Traceability: Complete material certification chain from raw steel mill through final product inspection, meeting the most stringent international quality documentation requirements.
- Scalable Production Capacity: Flexible manufacturing capability supporting both small-batch custom orders and large-scale project supply.
8. Technical Support & Customization
Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical support including:
- Thermal performance simulation and heat transfer calculations for specific application scenarios
- Custom material grade selection based on operating environment (temperature, pressure, fluid chemistry)
- Engineering drawings and dimensional verification reports upon request
- On-site technical consultation for system integration
Note: All specifications are subject to confirmation based on the final engineering design and applicable project standards. Customers are advised to consult with our technical team for project-specific requirements and compliance verification.