Stainless Steel Coil Tube (Coiltube) — Model No. 501
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Classification: Literature Study & Technical Reference
Wenzhou Jixing Metal Materials Co., Ltd. is a leading manufacturer of stainless steel coil tubes (Coiltube), specializing in high-performance metallic coil products designed for advanced thermal management and heat exchange applications. This technical specification provides a comprehensive academic-level description of the company's stainless steel coil tube product line, informed by the research literature on R290 Coil-Type Ice Thermal Storage Air Conditioning Systems.
1. Product Overview
The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a continuously wound, helically formed tubular product manufactured from austenitic or duplex stainless steel grades. Unlike conventional straight pipe segments, the Coiltube is produced in a continuous coil configuration, eliminating the need for welding joints along its length and thereby preserving metallurgical integrity and mechanical strength throughout the entire product run.
The Coiltube product line is specifically engineered for applications in refrigeration systems, thermal energy storage, heat exchangers, automotive radiators, air conditioning evaporators and condensers, and industrial process piping. The product has been validated in theoretical and experimental research concerning R290 (Propane) refrigerant-based coil-type ice thermal storage air conditioning systems, demonstrating superior thermal performance, corrosion resistance, and long-term structural reliability under cyclic thermal loading conditions.
Key Unique Selling Points:
- Continuous Weld-Free Construction: Eliminates potential failure points associated with butt welds or brazed joints, ensuring uniform mechanical properties and leak-free performance.
- High Thermal Conductivity with Corrosion Resistance: Combines the thermal efficiency of metallic heat transfer surfaces with the inherent corrosion resistance of stainless steel, extending service life in aggressive chemical environments.
- Compact Helical Geometry: Maximizes heat transfer surface area per unit volume, enabling compact system design and improved heat exchange efficiency.
- Compatibility with Natural Refrigerants: Validated for use with R290 (Propane), R134a, R410A, and other refrigerants, supporting environmentally sustainable HVAC and refrigeration systems.
- Customizable Specifications: Available in a wide range of outer diameters, wall thicknesses, coil diameters, and stainless steel grades to meet diverse application requirements.
2. Material & Properties
2.1 Base Material Grades
The Coiltube is manufactured from high-quality stainless steel strip, with the following grades available depending on application requirements:
| Grade | UNS Designation | ASTM Standard | Primary Application Focus |
|---|---|---|---|
| 304 / 304L | S30400 / S30403 | ASTM A269 / A270 | General heat exchange, food-grade, moderate corrosion environments |
| 316 / 316L | S31600 / S31603 | ASTM A269 / A270 | Marine, chemical, high-chloride environments |
| 321 | S32100 | ASTM A269 | High-temperature service, stress-corrosion resistant |
| 310S | S31008 | ASTM A269 | Extreme temperature applications (>1000°C) |
| 2205 Duplex | S32205 | ASTM A790 | High-strength, chloride-resistant structural applications |
2.2 Mechanical Properties (Typical — Grade 304)
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (75 ksi) | ASTM A269 |
| Yield Strength (0.2% offset) | ≥ 205 MPa (30 ksi) | ASTM A269 |
| Elongation (in 50 mm) | ≥ 40% | ASTM A269 |
| Hardness (Brinell) | ≤ 217 HB | ASTM E10 |
| Impact Energy (Charpy V-Notch, −40°C) | ≥ 47 J (35 ft·lb) | ASTM E23 |
2.3 Physical & Thermal Properties
| Property | Value (Grade 304) | Value (Grade 316) | Unit |
|---|---|---|---|
| Density | 8.00 | 8.03 | g/cm³ |
| Thermal Conductivity (20°C) | 16.3 | 14.6 | W/(m·K) |
| Thermal Conductivity (100°C) | 21.5 | 19.8 | W/(m·K) |
| Specific Heat Capacity | 0.50 | 0.50 | kJ/(kg·K) |
| Linear Thermal Expansion (20–100°C) | 17.3 | 17.3 | ×10⁻⁶ /°C |
| Electrical Resistivity (20°C) | 0.72 | 0.78 | μΩ·m |
| Melting Range | 1400–1450 | 1375–1400 | °C |
2.4 Chemical Composition (Typical — Grade 304)
| Element | C | Mn | P | S | Si | Cr | Ni | N | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Maximum (%) | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | — | — | 0.10 | Balance |
| Minimum (%) | — | — | — | — | — | 18.0 | 8.0 | — | — |
2.5 Corrosion Resistance
The Coiltube exhibits excellent resistance to:
- Atmospheric Corrosion: Suitable for outdoor exposure in industrial and marine environments.
- Acid Corrosion: Resistant to dilute non-oxidizing acids (H₂SO₄, H₃PO₄) at ambient temperatures.
- Chloride-Induced Stress Corrosion Cracking (Cl-SCC): Grade 316 and 2205 Duplex options provide enhanced resistance in chloride-containing environments.
- Pitting and Crevice Corrosion: Grade 316L with molybdenum addition offers superior pitting resistance (PREN ≥ 24).
- Intergranular Corrosion: Low-carbon grades (304L, 316L) are resistant to sensitization-induced intergranular corrosion following welding.
3. Specifications
3.1 Dimensional Specifications
| Parameter | Range / Options | Tolerance | Standard |
|---|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 50.8 mm (⅛" – 2") | ±0.10 mm | ASTM A269 / EN 10216-5 |
| Wall Thickness | 0.3 mm – 3.0 mm | ±10% of nominal | ASTM A269 / EN 10216-5 |
| Inner Diameter (ID) | 2.0 mm – 47.8 mm | Derived from OD and wall thickness | — |
| Coil (Bundle) Outer Diameter | 200 mm – 2000 mm | ±2.0% | Manufacturer Specification |
| Coil Length (Uncoiled) | 10 m – 500 m (continuous) | ±1.0% | Manufacturer Specification |
| Coil Pitch (Helix Pitch) | 3.0 mm – 25.0 mm | ±0.5 mm | Manufacturer Specification |
| Number of Turns | Customizable (up to 1000+ turns) | — | Manufacturer Specification |
| End Form | Plain, Beveled, Flared, or Threaded | — | Per Customer Drawing |
3.2 Surface Finish Options
| Finish Type | Ra (Surface Roughness) | Description | Typical Application |
|---|---|---|---|
| Bright Annealed (BA) | 0.2 – 0.5 μm | Mirror-like finish, achieved in protective atmosphere furnace | Food processing, pharmaceutical, decorative |
| Pickled & Passivated (2B) | 0.4 – 0.8 μm | Matt finish with removed scale and passive oxide layer | General industrial, heat exchange |
| Polished (No. 4 / HL) | 0.2 – 0.4 μm | Directional satin finish | Architectural, visible applications |
| Electro-Polished (EP) | 0.05 – 0.2 μm | Ultra-smooth surface, enhanced corrosion resistance | Biomedical, semiconductor, high-purity fluid |
| Passivated (Pickled) | 0.8 – 1.6 μm | Chemical passivation to maximize passive film integrity | Corrosion-critical service |
3.3 Performance Specifications (Heat Exchange Context)
| Performance Parameter | Typical Value | Test Conditions |
|---|---|---|
| Overall Heat Transfer Coefficient (U-value) | 800 – 1500 W/(m²·K) | R290 refrigerant, shell-and-coil configuration |
| Pressure Drop (per meter, uncoiled equivalent) | 0.5 – 3.0 kPa/m | Refrigerant flow velocity 2–5 m/s |
| Maximum Operating Pressure | Up to 4.0 MPa (gauge) | Dependent on OD, wall thickness, and grade |
| Operating Temperature Range | −196°C to +870°C | Cryogenic to elevated temperature service |
| Design Life | ≥ 25 years (continuous duty) | Based on corrosion allowance and fatigue analysis |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous, multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical quality, and surface integrity. The process is aligned with ISO 9001:2015 quality management principles and applicable international standards.
4.1 Process Flow Overview
- Raw Material Inspection & Receiving: Incoming stainless steel strip is verified for chemical composition (via OES — Optical Emission Spectroscopy), mechanical properties, surface quality, and dimensional conformity against purchase specifications. Certificates of Analysis (CoA) and Mill Test Reports (MTR) are reviewed.
- Strip Slitting & Leveling: The parent coil is slit to the required tube blank width using precision slitting lines. The strip is then passed through a leveling mill to achieve flatness tolerances of ≤ 0.05% of width, ensuring uniform feed into the forming process.
- Tube Forming (Seamless or Welded):
- Seamless Process (for thicker walls): Strip is fed into a roll-forming die set that progressively bends the strip into a circular cross-section. The formed tube is then cold-drawn through a tungsten carbide (WC) or ceramic die to achieve final OD and wall thickness with tight tolerances.
- Welded Process (for thinner walls): Strip is formed into a U-shape, then