Stainless Steel Coil Tube (盘管) — Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a precision-engineered seamless or welded stainless steel tubing product, manufactured in continuous coil form for downstream processing, forming, and fabrication. Supplied by Wenzhou Jixing Metal Materials Co., Ltd., this product is designed for high-performance applications requiring corrosion resistance, thermal stability, and mechanical integrity. The coil configuration facilitates automated processing in downstream operations such as bending, heat exchanger manufacturing, and HVAC (Heating, Ventilation, and Air Conditioning) fan coil unit assembly.
This product is particularly suited for integration into DC Brushless Fan Coil Systems (直流无刷风机盘管), where the coil tube serves as the primary heat transfer medium within air handling units, delivering efficient thermal exchange in commercial and industrial HVAC installations.
2. Material & Properties
2.1 Material Grades
- 304 (UNS S30400 / 1.4301): General-purpose austenitic stainless steel with excellent corrosion resistance and formability.
- 316 (UNS S31600 / 1.4401): Enhanced pitting and crevice corrosion resistance due to 2–3% Molybdenum (Mo) content; suitable for aggressive chemical environments.
- 321 (UNS S32100 / 1.4541): Stabilized grade with Titanium (Ti) addition; resistant to intergranular corrosion at elevated temperatures.
- 316L (UNS S31603 / 1.4434): Low-carbon variant of 316 for improved weldability and post-weld corrosion performance.
2.2 Mechanical Properties (Typical, Annealed Condition)
| Property | 304 Grade | 316 Grade |
|---|---|---|
| Tensile Strength (UTS, Ultimate Tensile Strength) | ≥ 515 MPa | ≥ 515 MPa |
| Yield Strength (0.2% Proof Stress) | ≥ 205 MPa | ≥ 205 MPa |
| Elongation at Break | ≥ 40% | ≥ 40% |
| Hardness (HB, Brinell) | ≤ 217 | ≤ 217 |
| Density | 8.00 g/cm³ | 8.03 g/cm³ |
| Thermal Conductivity (20°C) | 16.3 W/(m·K) | 14.6 W/(m·K) |
| Maximum Service Temperature | 870°C | 870°C |
2.3 Surface Finish Options
- 2B Finish: Cold-rolled, annealed, and pickled; smooth matte surface suitable for general applications.
- No. 4 Brushed Finish: Linear brushed grain; aesthetically pleasing for visible installations.
- Mirror Polish (8K): High-gloss reflective surface for decorative or hygienic applications.
- Pickled & Passivated (P&P): Chemical cleaning to remove scale and form protective chromium oxide layer.
3. Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 108.0 mm (custom sizes available) |
| Wall Thickness (WT) | 0.3 mm – 6.0 mm |
| Coil Inner Diameter (ID) | 500 mm – 1,200 mm (adjustable per customer requirement) |
| Coil Length (Continuous) | Up to 500 m per coil (typical: 100–300 m) |
| Coil Weight | 200 kg – 2,000 kg per coil |
| OD Tolerance | ±0.05 mm – ±0.10 mm (per ISO 6508 / ASTM A269) |
| WT Tolerance | ±10% (standard); ±0.02 mm (precision grade) |
| Manufacturing Standard | ASTM A269 / A270, ASME SA-213 / SA-214, EN 10216-5, GB/T 14976 |
| Heat Treatment | Solution Annealing (1050–1150°C), Water Quench |
| End Treatment | Plain end, beveled end, or flared end (upon request) |
| Packaging | Export-grade wooden pallet with steel strapping, VCI (Vapor Corrosion Inhibitor) wrapping |
4. Manufacturing Process
- Raw Material Preparation: Selection of certified stainless steel strip or seamless tube blank from qualified suppliers (e.g., Outokumpu, POSCO, Tsingshan). Incoming material undergoes spectroscopic verification (PMI — Positive Material Identification) to confirm chemical composition.
- Coiling / Tube Forming: For welded coil tubes, cold-rolled strip is formed into tube shape via roll-forming dies and continuously welded using TIG (Tungsten Inert Gas) or laser welding under argon shielding. For seamless coil tubes, hot-rolled or cold-drawn seamless tubing is coiled on precision winder equipment.
- Heat Treatment (Solution Annealing): The formed tube is subjected to solution annealing at 1050–1150°C followed by rapid water quenching to achieve a fully austenitic microstructure, eliminate residual stresses, and restore full ductility.
- Pickling & Passivation: Immersion in mixed acid solution (HNO₃ + H₃PO₄) to remove welding scale and heat-treatment oxide. Subsequent passivation forms a chromium-rich oxide film (Cr₂O₃) for enhanced corrosion protection.
- Dimensional Inspection: Automated laser measurement of OD, WT, and roundness. Sample-based hydrostatic testing per ASTM A269 Section 8 to verify wall integrity.
- Final Coiling & Packaging: Tubes are wound onto coils at controlled tension to prevent deformation. Each coil is labeled with heat number, grade, dimensions, and traceability information.
5. Applications
5.1 HVAC & Fan Coil Systems
Stainless steel coil tubes are integral components in DC Brushless Fan Coil Units (直流无刷风机盘管电机), serving as heat exchanger tubing for both heating and cooling coils. The corrosion resistance of austenitic stainless steel ensures long service life in humid indoor environments, while the coil form factor enables compact serpentine tube configurations optimized for airflow heat exchange efficiency.
5.2 Additional Applications
- Food & Beverage Industry: Hygienic-grade tubing for beverage processing lines, CIP (Clean-in-Place) compatible.
- Chemical Processing: Heat exchangers, condensers, and evaporators in aggressive chemical environments.
- Pharmaceutical Equipment: GMP-compliant tubing for fluid transfer and heat exchange systems.
- Automotive & Refrigeration: Condenser and evaporator tubes for automotive AC systems and industrial refrigeration.
- Construction & Architecture: Structural tubing, handrails, and decorative elements in coastal or marine environments.
- Medical Devices: Autoclavable tubing for medical instrument manufacturing.
6. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent production quality |
| ISO 14001:2015 | Environmental Management System certification |
| EN 10204 3.1 | Material Test Certificate (MTC) — Manufacturer's declaration of compliance |
| CE Marking | Conformity with European Union directives for market access |
| ASTM A269 / A270 | American standard for austenitic stainless steel seamless, welded, and heavy-wall tubes |
| ASME SA-213 / SA-214 | Boiler and Pressure Vessel Code — Heat-Transfer and Heat-Treater Tubes |
| GB/T 14976 | Chinese national standard for seamless stainless steel tubes for fluid transport |
| 3-A Sanitary Standard | International Dairy, Food, and Beverage Equipment standards (for food-grade applications) |
7. Unique Selling Points
- Continuous Coil Configuration: Eliminates butt welds inherent in straight-length tubing, reducing leak points and improving structural integrity in heat exchanger and HVAC applications.
- Full Traceability: Each coil is heat-numbered with complete chemical and mechanical test data, enabling end-to-end quality traceability from mill to installation.
- Customization Capability: Flexible OD, WT, and coil diameter options tailored to specific fan coil unit designs and HVAC system requirements.
- Superior Corrosion Performance: Austenitic stainless steel grades provide exceptional resistance to atmospheric, chemical, and chloride-induced corrosion, ensuring extended service life in demanding environments.
- Thermal Efficiency: Optimized wall thickness and smooth internal surface minimize flow resistance and maximize heat transfer coefficient in fan coil heat exchangers.
- Sustainability: Stainless steel is 100% recyclable with no degradation of material properties, supporting circular economy and ESG (Environmental, Social, and Governance) goals.
8. Technical Notes & Recommendations
Installation Guidance: When integrating coil tubes into DC Brushless Fan Coil Units, ensure proper tube-to-fin contact via brazing or expansion fitting. Maintain minimum bend radius of 3× OD to prevent wall thinning and stress concentration. Post-installation passivation is recommended to restore surface protection after mechanical forming.
Storage Conditions: Store coils in a dry, well-ventilated warehouse at temperatures between 5°C and 40°C. Avoid stacking coils vertically beyond manufacturer-specified height limits. Protect from contact with carbon steel to prevent galvanic contamination and crevice corrosion.
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (序号 #473 Product Line)
Documentation Reference: Technical datasheet aligned with DC Brushless Fan Coil Motor integration requirements (直流无刷风机盘管电机学习心得).