Stainless Steel Coil Tube — Product Technical Specification
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. (序号 No. 553)
Product Category: Coil Tube / Fan Coil Tube Assembly Components
Classification: Literature & Technical Reference — CFD Simulation-Informed Design
1. Product Overview
The Stainless Steel Coil Tube is a precision-engineered tubular component manufactured by continuous coiling processes, designed for integration into Fan Coil Units (FCU), HVAC (Heating, Ventilation, and Air Conditioning) systems, and industrial heat exchange applications. The product is distinguished by its helical coil geometry, which maximizes heat transfer surface area within a compact volumetric footprint. Wenzhou Jixing Metal Materials Co., Ltd. leverages advanced Computational Fluid Dynamics (CFD) simulation methodologies — specifically perforated plate air distribution modeling — to optimize coil tube performance in downstream fan coil assemblies, ensuring uniform airflow distribution and enhanced thermal efficiency.
This product represents a convergence of metallurgical precision and computational fluid engineering, delivering reliable thermal management solutions for commercial, residential, and industrial environments.
2. Material & Properties
2.1 Base Material Grades
- 304 Stainless Steel (UNS S30400): 18% Chromium, 8% Nickel — general-purpose corrosion resistance
- 316L Stainless Steel (UNS S31603): 16-18% Chromium, 10-14% Nickel, 2-3% Molybdenum — enhanced chloride resistance
- 321 Stainless Steel (UNS S32100): Titanium-stabilized — high-temperature oxidation resistance
- 310S Stainless Steel (UNS S31008): 25% Chromium, 20% Nickel — extreme temperature applications
2.2 Mechanical Properties (Typical Values for 304 Grade)
- Tensile Strength: ≥ 515 MPa (74,700 psi)
- Yield Strength (0.2% offset): ≥ 205 MPa (29,700 psi)
- Elongation: ≥ 40%
- Hardness: ≤ 92 HRB
- Density: 8.0 g/cm³
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /°C
- Maximum Operating Temperature: 870°C (continuous)
2.3 Surface Finish Options
- 2B Finish: Cold-rolled, annealed, and skin-passed — smooth, slightly reflective
- No. 4 Brushed Finish: Uniform unidirectional grain — decorative and corrosion-resistant
- BA (Bright Annealed) Finish: Annealed in controlled atmosphere — mirror-like surface, superior hygienic properties
- Polished Finish: Mechanical polishing to Ra ≤ 0.4 μm
3. Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 19.0 mm (custom available) | ISO 10220 |
| Wall Thickness | 0.5 mm – 1.5 mm | ASTM A269 / A270 |
| Coil Pitch (Helical Spacing) | 6.0 mm – 15.0 mm | Manufacturer specification |
| Coil Length (Straightened) | 0.5 m – 12.0 m (custom cut) | — |
| Coil Winding Diameter | 50 mm – 200 mm | — |
| OD Tolerance | ±0.1 mm | ISO 10220 |
| Wall Thickness Tolerance | ±10% | ASTM A269 |
| Surface Roughness (Ra) | ≤ 1.6 μm (2B); ≤ 0.4 μm (Polished) | ISO 4287 |
| Maximum Working Pressure | 1.6 MPa – 4.0 MPa (grade dependent) | ASME B31.3 |
| Operating Temperature Range | -196°C to +870°C | — |
| Corrosion Resistance | Passive film Cr₂O₃; pitting resistance (PREN) ≥ 18 (304), ≥ 24 (316L) | ASTM G48 |
| Deliverable Form | Coiled / Straightened / Cut-to-length | — |
| Minimum Order Quantity | 500 kg (standard); negotiable for custom | — |
4. Manufacturing Process
4.1 Process Flow
- Material Selection & Ingot Casting: Vacuum Arc Remelting (VAR) or Argon Oxygen Decarburization (AOD) for high-purity stainless steel ingots.
- Hot Rolling: Billet reduction to seamless tube blanks at temperatures between 1050°C and 1200°C.
- Piercing & Hot Extrusion: Formation of hollow tube sections via Mannesmann or plug piercing methods.
- Intermediate Annealing: Solution heat treatment at 1050°C followed by controlled cooling to restore ductility.
- Cold Drawing / Cold Pilgering: Precision reduction of outer diameter and wall thickness to final dimensions with tolerances within ±0.1 mm.
- Final Annealing (Solution Treatment): Heating to 1040°C – 1120°C, rapid water quench to achieve fully austenitic structure and maximum corrosion resistance.
- Coiling: Continuous winding onto precision mandrels to form the helical coil geometry with controlled pitch and winding diameter.
- Surface Finishing: Electropolishing, passivation treatment (nitric acid or citric acid), or mechanical polishing per customer specification.
- Quality Inspection: Hydrostatic testing, dimensional verification, spectrometric composition analysis, and visual surface inspection.
- CFD-Informed Performance Validation: Integration testing within fan coil unit assemblies validated through Computational Fluid Dynamics (CFD) simulation of perforated plate air distribution patterns to confirm uniform airflow and thermal performance.
4.2 Key Process Technologies
- Continuous Coiling: CNC-controlled winding machines ensure uniform pitch accuracy of ±0.05 mm.
- Laser Cutting: High-precision end preparation with burr-free edges.
- Electrochemical Passivation: Removal of free iron from surface to enhance passive chromium oxide film formation.
5. Applications
5.1 Primary Application Domains
- Heating, Ventilation, and Air Conditioning (HVAC): Core heat exchange element in fan coil units, air handling units (AHU), and rooftop units. CFD simulation of perforated plate air distribution ensures optimized airflow uniformity across coil surfaces.
- Industrial Process Heating & Cooling: Heat transfer coils in chemical processing, food and beverage pasteurization, pharmaceutical sterilization, and semiconductor manufacturing.
- Automotive & Transportation: Radiator coils, condenser tubes, and heat recovery systems in vehicle thermal management.
- Medical Equipment: Sterilizable heat exchange components in autoclaves, dialysis machines, and medical gas delivery systems.
- Marine & Offshore: Seawater heat exchangers, ballast water treatment systems, and desalination plant coils.
- Cryogenic Applications: Liquefied Natural Gas (LNG) transfer coils operating at temperatures as low as -196°C.
5.2 CFD Simulation-Informed Design Advantages
Wenzhou Jixing Metal Materials Co., Ltd. incorporates Computational Fluid Dynamics (CFD) simulation data — specifically from fan coil unit perforated plate air distribution studies — into the coil tube design phase. This ensures that the helical geometry, coil pitch, and tube diameter are optimized for:
- Uniform air velocity distribution across the coil face (target: ±5% deviation from mean)
- Minimized airflow dead zones and recirculation patterns
- Maximized heat transfer coefficient (U-value optimization)
- Reduced pressure drop across the coil assembly
- Enhanced condensate drainage characteristics
6. Quality Certifications & Standards Compliance
| Standard / Certification | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| ISO 14001:2015 | Environmental Management System |
| ISO 10220 | Welded and Seamless Steel Tubes — Heat Exchanger Tubes |
| ASTM A269 / A270 | Seamless and Welded Austenitic Stainless Steel Tubes |
| EN 10217-7 | Stainless Steel Tubes for Heat Exchangers |
| JIS G3446 | Stainless Steel Tubes for Heat Exchangers (Japanese Industrial Standard) |
| ASME B31.3 | Process Piping — Pressure Design Compliance |
| NACE MR0175 | Sour Service — Sulfide Stress Cracking Resistance |
| CE Marking (PED 2014/68/EU) | Pressure Equipment Directive Compliance |
| RoHS / REACH | Restriction of Hazardous Substances / Chemical Regulation Compliance |
7. Unique Selling Points
CFD-Validated Performance: Unlike conventional coil tube suppliers, Wenzhou Jixing integrates Computational Fluid Dynamics simulation of perforated plate air distribution into the coil design process, delivering quantifiably superior airflow uniformity and thermal efficiency in fan coil unit applications.
- Precision Geometry: CNC-controlled coiling with pitch accuracy of ±0.05 mm ensures consistent heat transfer performance across the entire coil length.
- Multi-Grade Availability: Full range of austenitic stainless steel grades (304, 316L, 321, 310S) for diverse environmental and temperature requirements.
- Hygienic Surface Quality: BA finish and electropolished options achieve Ra ≤ 0.4 μm, meeting pharmaceutical and food-grade requirements.
- Custom Engineering: Tailored coil pitch, winding diameter, and cut lengths to match specific OEM fan coil unit designs.
- Full Traceability: Each coil lot is accompanied by mill test certificates (MTC), spectral analysis reports, and dimensional inspection records per EN 10204 Type 3.1.
- Corrosion Durability: Pitting Resistance Equivalent Number (PREN) of ≥ 18 (304) and ≥ 24 (316L) ensures long service life in aggressive chemical environments.
- Cryogenic to High-Temperature Range: Continuous operation from -196°C to +870°C without loss of mechanical integrity.
8. Ordering Information & Technical Support
For custom coil tube specifications, material certifications, or CFD integration support, contact Wenzhou Jixing Metal Materials Co., Ltd. directly. Technical datasheets, sample coils, and simulation reports are available upon request. Minimum order quantities are negotiable for long-term production contracts.
Document Reference: No. 553 — Coil Tube Technical Specification | Classification: Literature & Technical Learning (CFD Simulation Study Informed)