Stainless Steel Coil Tube (Coiltube) – Product No. 1201
1. Product Overview
The Stainless Steel Coil Tube (Coiltube), designated as Product No. 1201, is a precision-engineered continuous-length tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for integration into Fan Coil Units (FCUs) and HVAC (Heating, Ventilation, and Air Conditioning) systems where superior thermal performance, corrosion resistance, and long-term structural integrity are critical. The coil tube is supplied in continuous coil form, enabling efficient downstream processing, heat exchanger fabrication, and seamless installation in thermal management applications.
The product knowledge base is informed by the research framework outlined in "Research on Test Methods for Thermal Performance of Fan Coil Units", which establishes rigorous methodologies for evaluating heat transfer efficiency, pressure drop characteristics, and overall thermal-hydraulic performance of coil assemblies. This research-driven approach ensures that the Coiltube product meets the demanding requirements of modern HVAC thermal performance standards.
2. Material & Properties
The Stainless Steel Coil Tube is fabricated from austenitic stainless steel grades, providing an optimal balance of mechanical strength, corrosion resistance, and thermal conductivity. Key material properties include:
- Material Grade: SUS304 (UNS S30400), SUS304L (UNS S30403), SUS316 (UNS S31600), or SUS316L (UNS S31603) — selected based on application-specific corrosion resistance requirements
- Chromium (Cr) Content: 18.0–20.0 wt% — provides primary corrosion resistance and passive film formation
- Nickel (Ni) Content: 8.0–10.5 wt% — stabilizes the austenitic microstructure and enhances ductility
- Molybdenum (Mo) Content: 2.0–3.0 wt% (in 316/316L grades) — provides enhanced resistance to pitting and crevice corrosion in aggressive environments
- Carbon (C) Content: ≤ 0.08 wt% (standard grade); ≤ 0.03 wt% (low-carbon "L" grade) — controls intergranular corrosion susceptibility
- Thermal Conductivity: 16–17 W/(m·K) at 20°C — adequate for heat exchanger and thermal transfer applications
- Operating Temperature Range: −196°C to +870°C — suitable for cryogenic and high-temperature HVAC applications
- Tensile Strength (UTS): ≥ 520 MPa (annealed condition)
- Yield Strength (0.2% offset): ≥ 205 MPa
- Elongation: ≥ 40% — ensures excellent formability for coil winding and bending operations
3. Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Designation | Product No. 1201 – Stainless Steel Coil Tube | — |
| Outer Diameter (OD) | 6.0 mm – 50.0 mm (customizable) | ASTM A213 / ASME SA-213 |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm (customizable) | ASTM A213 / ASME SA-213 |
| Inner Diameter (ID) | Calculated per OD and WT; tolerance ±0.1 mm | EN 10216-5 |
| OD Tolerance | ±0.1 mm (standard); ±0.05 mm (precision grade) | ASTM A213 |
| WT Tolerance | ±10% of nominal (standard); ±5% (precision grade) | ASTM A213 |
| Surface Finish | 2B (cold-rolled and annealed) or No. 1 (hot-rolled) | ASTM A480 / EN 10088-2 |
| Coil Form | Continuous coil; coil weight 500 kg – 2,000 kg | ISO 4035 |
| Coil Core | Wooden or steel core; ID 200 mm – 600 mm | — |
| Delivery Condition | Annealed (A), Solution Treated (ST), or Pickled & Passivated (PP) | ASTM A213 |
| End Condition | Plain, cut to length, or with coupling thread (optional) | — |
| Maximum Coil Length | Continuous up to 500 m (depending on OD/WT) | — |
| Heat Exchanger Suitability | Optimized for Fan Coil Unit (FCU) heat exchanger coil assemblies | ASHRAE 34 / EN 14511 |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube follows a multi-stage, precision-controlled manufacturing sequence to ensure consistent quality and dimensional accuracy:
- Raw Material Selection: High-purity stainless steel wire rod (billets) conforming to ASTM A276 / EN 10088-3 are procured from certified mills. Incoming material undergoes spectroscopic analysis to verify chemical composition within specified limits.
- Wire Rod Annealing & Pickling: The raw wire rod is subjected to controlled atmosphere annealing at 1050°C – 1100°C to achieve a fully austenitic, stress-free microstructure. Subsequent acid pickling removes oxide scale and forms a protective chromium oxide passive layer.
- Tube Forming (Seamless or Welded): Tubes are produced via either seamless piercing (for larger diameters) or precision welded drawing (for smaller diameters). The welding process employs TIG (Tungsten Inert Gas) welding with argon shielding to prevent oxidation at the weld seam.
- Multi-Pass Cold Drawing: The formed tubes pass through a series of precision-diameter drawing dies to achieve the target OD and WT with tight tolerances. Each pass reduces the cross-sectional area by 15–25%, maintaining uniform wall thickness.
- Intermediate Annealing: At strategic intervals during cold drawing, tubes are annealed to relieve accumulated work-hardening and restore ductility, preventing cracking during subsequent forming operations.
- Final Annealing & Passivation: Completed tubes undergo final solution annealing at 1050°C – 1100°C followed by rapid cooling (air or water quench). A final passivation treatment in nitric acid or citric acid solution ensures a clean, corrosion-resistant surface.
- Coil Winding: The continuous tube is wound onto a precision-balanced coil form using automated winding equipment that controls tension to prevent deformation or kinking. Coil geometry is optimized for downstream unwinding and processing.
- Non-Destructive Testing (NDT): Every coil undergoes 100% eddy current inspection (ECI) for internal and external defects, supplemented by hydrostatic pressure testing (HPT) to verify weld integrity and wall thickness uniformity.
- Dimensional Verification & Final Inspection: Statistical process control (SPC) measurements confirm OD, WT, straightness, and roundness compliance. Surface quality is visually inspected under controlled lighting.
- Packaging & Shipment: Coils are wrapped in moisture-proof packaging, secured on export-grade wooden pallets or steel stands, and labeled with mill test certificates (MTC) per EN 10204 3.1.
5. Applications
The Stainless Steel Coil Tube (Product No. 1201) is engineered for a wide range of thermal management and fluid transfer applications, with particular emphasis on HVAC and fan coil unit systems:
5.1 Primary Applications
- Fan Coil Units (FCUs): Used as heat exchanger tubes in both air-cooled and water-cooled fan coil units. The coil tube forms the serpentine or cross-flow coil assembly that transfers thermal energy between the refrigerant/water medium and the airstream. The product's thermal performance characteristics are validated against the test methodologies described in "Research on Test Methods for Thermal Performance of Fan Coil Units", ensuring compliance with ASHRAE and EN thermal performance standards.
- Chilled Water Coil Assemblies: Integral components of commercial HVAC chilled water distribution systems in office buildings, hospitals, and retail environments.
- Condenser & Evaporator Coils: Applied in unitary air conditioning systems, rooftop packaged units, and split-system air conditioners.
5.2 Secondary Applications
- Industrial Process Heating & Cooling: Heat exchanger coils in chemical processing, food and beverage pasteurization, pharmaceutical manufacturing, and semiconductor fabrication facilities.
- Refrigeration Systems: Evaporator and condenser coils in commercial refrigeration, cold storage, and cryogenic applications.
- Geothermal & Solar Thermal Systems: Heat transfer coils in ground-source heat pumps and solar thermal collectors.
- Automotive & Transportation: Intercooler coils, radiator components, and thermal management systems in commercial vehicles.
- Domestic Appliances: Heat exchanger coils in water heaters, dishwashers, and HVAC heat pump water heaters.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework to ensure product conformity with international standards:
- ISO 9001:2015 — Quality Management Systems certification, demonstrating systematic quality control across all production stages
- ISO 14001:2015 — Environmental Management Systems certification, ensuring environmentally responsible manufacturing practices
- ISO 45001:2018 — Occupational Health and Safety Management Systems certification
- EN 10204 Type 3.1 — Mill Test Certificates (MTC) provided with every shipment, documenting chemical composition, mechanical properties, and traceability
- ASTM A213 / ASME SA-213 — Compliance with American standards for seamless and welded austenitic stainless steel tubing
- EN 10216-5 — Compliance with European standards for welded austenitic stainless steel tubes
- GB/T 14976 — Compliance with Chinese national standards for seamless stainless steel tubing
- ASME BPV Code Section I — Pressure vessel and heat exchanger component compliance (where applicable)
- NSF/ANSI 61 — Drinking water system component certification (for potable water applications)
- RoHS & REACH Compliance — Restriction of hazardous substances and chemical regulation compliance for EU market access
7. Unique Selling Points
- Research-Validated Thermal Performance: The product's thermal-hydraulic characteristics are benchmarked against peer-reviewed research on Fan Coil Unit thermal performance test methods, ensuring reliable heat transfer coefficients and minimal pressure drop in coil assemblies.
- Precision Coil Form: Continuous coil delivery eliminates welding joints, reducing potential leak points and improving overall system reliability in heat exchanger applications.
- Full Traceability: Each coil is traceable to its original mill heat number, enabling complete supply chain transparency and quality accountability.
- Customization Capability: OD, WT, grade, surface finish, and coil configuration are customizable to meet specific OEM requirements and application specifications.
- 100% NDT Inspection: Every coil undergoes comprehensive non-destructive testing, providing confidence in product integrity for safety-critical HVAC and pressure vessel applications.
8. Conclusion
The Stainless Steel Coil Tube (Product No. 1201) from Wenzhou Jixing Metal Materials Co., Ltd represents a high-performance, standards-compliant tubular product purpose-built for thermal management applications — particularly in Fan Coil Unit and HVAC heat exchanger systems. Grounded in rigorous research on thermal performance test methodologies, this product delivers exceptional corrosion resistance, precise dimensional tolerances, and proven thermal efficiency, making it an ideal choice for OEM manufacturers and system integrators demanding reliability and compliance in critical thermal applications.