Stainless Steel Coil Tube — Dynamic Response Series (Product No. 1042)
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered continuous tube product designed for applications demanding superior thermal efficiency, mechanical integrity, and resistance to external dynamic disturbances. This coil tube is particularly suited for use in fan coil units (FCUs), heat exchangers, HVAC (Heating, Ventilation, and Air Conditioning) systems, and industrial process piping where stable performance under variable operating conditions is critical.
Based on extensive research into the dynamic response characteristics of coil tubes under external perturbations — including pressure fluctuations, thermal cycling, and mechanical vibration — this product line has been optimized to maintain consistent hydraulic and thermal performance even under transient operating conditions.
Material & Properties
Material Composition
- Base Material: Austenitic stainless steel (奥氏体不锈钢), conforming to ASTM A269 / ASME SA-269 specifications
- Common Grades: 304 (UNS S30408), 304L (UNS S30403), 316L (UNS S31603), 321 (UNS S32108)
- Carbon Equivalent (CE): ≤ 0.04% (low-carbon grades available to prevent intergranular corrosion)
Key Physical and Mechanical Properties
- Density: 8.00 g/cm³
- Thermal Conductivity: 14–16 W/(m·K) at 25°C
- Thermal Expansion Coefficient: 16–17.5 × 10⁻⁶ /°C
- Tensile Strength (UTS): ≥ 515 MPa (annealed condition)
- Yield Strength: ≥ 205 MPa
- Elongation: ≥ 40%
- Operating Temperature Range: −196°C to +870°C
- Corrosion Resistance: Excellent resistance to atmospheric, chemical, and pitting corrosion; superior chloride resistance in 316L grade
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Tube Outer Diameter (OD) | 6.00 mm – 32.00 mm | ASTM A269 / ISO 3507 |
| Wall Thickness | 0.50 mm – 2.50 mm | ASTM A269 |
| Coil Width (Bundle Width) | 150 mm – 1,200 mm (customizable) | Client-specific |
| Coil Length | Up to 5,000 m (continuous) | — |
| Surface Finish | Mirror (Ra ≤ 0.1 μm), Electropolished, Matte, or Hairline | ASTM A270 |
| Pressure Rating | Up to 4.0 MPa (design pressure, dependent on geometry) | ASME B31.3 |
| Dimensional Tolerance | ±0.1 mm (OD), ±10% (wall thickness) | ASTM A269 |
| Heat Treatment Condition | Annealed / Solution Annealed | ASTM A269 |
| Hydrostatic Test Pressure | 1.5 × Design Pressure (100% inspection available) | ASME SA-269 |
| Coil Inner Diameter | ≥ 500 mm (standard shipping coil) | — |
Manufacturing Process
- Raw Material Selection: High-purity stainless steel strips are sourced from certified mills with full traceability. Incoming material undergoes spectroscopic verification (OES) to confirm chemical composition.
- Coiling / Forming: Precision roll-forming or spiral-welding processes are employed to create the continuous coil geometry. For welded coil tubes, TIG (Tungsten Inert Gas) welding is used with argon shielding to ensure a clean, oxide-free weld seam.
- Heat Treatment: Tubes are solution annealed at 1050–1150°C followed by controlled cooling to achieve the desired austenitic microstructure and relieve residual stresses.
- Pickling & Passivation: Surface scale is removed via acid pickling (nitric/hydrofluoric acid blend), followed by passivation treatment to form a stable chromium oxide protective layer.
- Surface Finishing: Electropolishing, mechanical polishing, or brushing is applied to achieve the required surface roughness (Ra) and aesthetic appearance.
- Quality Inspection: Each coil undergoes dimensional inspection (laser micrometer), hydrostatic pressure testing, eddy current testing (ECT) for internal defect detection, and visual surface examination.
- Dynamic Response Validation: Product samples are subjected to controlled external disturbance testing — including variable pressure cycling, thermal shock, and mechanical vibration — to verify consistent dynamic response characteristics in fan coil unit and heat exchanger applications.
- Packaging: Coils are wrapped in protective film, secured on wooden pallets, and labeled with product identification, heat number, and certification documentation.
Applications
- Fan Coil Units (FCU): Primary application — coil tubes serve as the heat exchange element in commercial and residential FCUs, where dynamic response stability under varying airflow and water flow conditions is essential for maintaining thermal comfort.
- HVAC Systems: Chilled water coils, condenser coils, and evaporator coils in air handling units (AHUs) and rooftop units.
- Industrial Heat Exchangers: Shell-and-tube heat exchangers, plate-fin exchangers, and process cooling/heating systems.
- Refrigeration & Cryogenics: Evaporator and condenser coils requiring low-temperature performance.
- Food & Pharmaceutical Processing: Sanitary-grade coil tubes for hygienic fluid transfer and heat exchange (316L grade).
- Automotive: Intercooler tubes, oil coolers, and HVAC components for passenger and commercial vehicles.
- Chemical Processing: Corrosion-resistant piping and heat transfer coils in aggressive chemical environments.
Quality Certifications & Standards Compliance
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System
- ASTM A269 / ASME SA-269 — Standard Specification for Seamless and Wrought Stainless Steel Tubing for High Temperature Service
- ASTM A270 — Standard Specification for Stainless Steel Tubular Products (General Requirements for Boiler, Heat Exchanger, and Condenser Tubes)
- EN 10217-7 — European Standard for Stainless Steel Tubes for Technical Uses
- JIS G3445 — Japanese Industrial Standard for Austenitic Stainless Steel Tubes
- PED 2014/68/EU — Pressure Equipment Directive compliance (for pressure-rated applications)
- Third-Party Inspection: SGS, Bureau Veritas, or TUV verification available upon request
Unique Selling Points
1. Dynamic Response Optimization: Unlike conventional coil tubes, this product line has been specifically characterized and validated for stable dynamic response under external disturbances. Research-based design ensures minimal performance degradation during transient conditions such as rapid load changes, water hammer events, and variable-speed operation — critical for fan coil unit efficiency and occupant comfort.
2. Precision Manufacturing: Tight dimensional tolerances and consistent wall thickness ensure uniform flow distribution and predictable heat transfer coefficients across the entire coil bundle.
3. Full Traceability: Every coil is traceable to its mill heat number with complete documentation including chemical analysis, mechanical test reports, and non-destructive testing results.
4. Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd offers flexible customization of tube dimensions, surface finishes, and coil configurations to meet project-specific thermal and hydraulic requirements.
5. Corrosion Durability: Superior resistance to pitting, crevice corrosion, and intergranular corrosion ensures extended service life even in aggressive environments, reducing lifecycle maintenance costs.
Technical Note on Dynamic Response Performance
Studies on the dynamic response of fan coil units under external disturbances have demonstrated that coil tube geometry, material thermal diffusivity, and wall thickness significantly influence the system's ability to maintain steady-state thermal output during transient conditions. The coil tubes in this product series have been engineered with optimized wall thickness-to-diameter ratios to minimize thermal lag while maintaining structural integrity under cyclic loading. This results in faster response times to setpoint changes and reduced oscillation amplitude during external perturbations, contributing to improved energy efficiency and enhanced occupant thermal comfort in HVAC applications.