Stainless Steel Coil Tube — Cryogenic Cooling Coil (Coiltube)
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered spiral wound tube fabricated from high-grade austenitic stainless steel, specifically designed for cryogenic and low-temperature thermal exchange applications. This product is manufactured by Wenzhou Jixing Metal Materials Co., Ltd, a recognized specialist in stainless steel pipe and tube solutions. The coil tube serves as a critical heat transfer element in ice-making systems, refrigeration coils, cryogenic storage vessels, and industrial cooling circuits, where controlled cooling rates and thermal efficiency are paramount.
Based on experimental research into the relationship between coil tube density and cooling rate (取冷速率), the design parameters of this product have been optimized to achieve maximum heat exchange efficiency while maintaining structural integrity under extreme thermal cycling conditions. The coil geometry directly influences the surface-area-to-volume ratio, which governs the rate of heat extraction from the working medium.
2. Material & Properties
2.1 Base Material
The primary material grade is SUS304 / AISI 304 (UNS S30400), a fully austenitic stainless steel known for its excellent corrosion resistance, cryogenic toughness, and formability. Alternative grades include SUS316L / AISI 316L (UNS S31603) for enhanced resistance to chloride-induced pitting corrosion in marine or chemical environments.
2.2 Key Mechanical Properties
- Tensile Strength (UTS): ≥ 520 MPa (SUS304) / ≥ 515 MPa (SUS316L)
- Yield Strength: ≥ 205 MPa (0.2% offset)
- Elongation: ≥ 40% (minimum, at room temperature)
- Impact Toughness (Charpy V-Notch): ≥ 47 J at −196 °C (LNG temperature)
- Thermal Conductivity: 16.3 W/(m·K) at 20 °C
- Specific Heat: 500 J/(kg·K) at 20 °C
- Density: 8.0 g/cm³
2.3 Chemical Composition (SUS304, wt%)
| Element | C | Si | Mn | P | S | Cr | Ni | N | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Max / Range | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.030 | 18.0–20.0 | 8.0–10.5 | ≤0.10 | Balance |
3. Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Form | Spiral Coil Tube (盘管) | — |
| Outer Diameter (OD) | 6.0 – 50.8 mm (1/4" – 2") | ASTM A213 / ASME SA-213 |
| Wall Thickness (WT) | 0.5 – 3.0 mm | ASTM A269 / ASME SA-269 |
| Coil Diameter (CD) | 100 – 2000 mm | Custom per application |
| Coil Length | 5 – 500 m (per coil) | — |
| Surface Finish | Baer / Mirror Polished (Ra ≤ 0.4 μm) | ASTM A270 |
| Operating Temperature Range | −196 °C to +600 °C | — |
| Maximum Operating Pressure | Up to 4.0 MPa (design dependent) | ASME BPV Code |
| Coil Pitch | 5 – 25 mm (adjustable per cooling rate requirement) | — |
| End Treatment | Flat cut / Beveled / Threaded | — |
| Packaging | Wooden crate / Steel frame with moisture barrier | ISO 4180 |
4. Manufacturing Process
- Material Selection & Incoming Inspection: Certified stainless steel seamless or welded tube blanks are sourced from accredited mills. Each batch undergoes spectroscopic analysis (PMI) to verify chemical composition and mechanical property testing per ASTM E10 / E8.
- Coil Winding (Spiral Forming): The straight tube is precision-wound using CNC-controlled coil winding machines to achieve the specified coil diameter, pitch, and tube OD. The winding process maintains uniform curvature without introducing plastic deformation or micro-cracking in the tube wall.
- Heat Treatment (Solution Annealing): The formed coil undergoes solution annealing at 1050–1150 °C followed by rapid water quenching to dissolve carbide precipitates, restore full austenitic microstructure, and maximize corrosion resistance and ductility.
- Pickling & Passivation: Post-welding or post-forming surface contaminants are removed via acid pickling (nitric/hydrofluoric acid blend), followed by passivation to establish a protective chromium oxide film.
- Surface Finishing: Optional mechanical polishing or electrolytic polishing is applied to achieve the required surface roughness (Ra ≤ 0.4 μm for hygienic or cryogenic applications).
- Non-Destructive Testing (NDT): Eddy current testing (ASTM E709) or magnetic particle inspection is performed to detect surface and near-surface defects. Hydrostatic pressure testing per ASTM A269 is conducted at 1.5× the maximum operating pressure.
- Dimensional Verification & Packaging: Final dimensional checks (OD, WT, coil diameter, pitch) are performed using calibrated instruments. The coil is packaged with desiccant and protective wrapping to prevent contamination during transit.
5. Applications
5.1 Cryogenic & Refrigeration Systems
- Ice-Making Coils: The coil tube density directly influences the cooling rate (取冷速率) in ice production systems. Optimized pitch and coil diameter maximize the heat transfer coefficient between the refrigerant and the water/ice medium, reducing cycle time and energy consumption.
- LNG (Liquefied Natural Gas) Storage & Transfer: Wound coil heat exchangers in cryogenic tanks utilize SUS304/316L coil tubes for boil-off gas (BOG) management and thermal insulation layers.
- Industrial Refrigeration: Evaporator and condenser coils in ammonia or fluorocarbon refrigeration systems for food processing, pharmaceutical cold chains, and commercial cold storage.
5.2 Additional Applications
- Medical and pharmaceutical equipment (sterilizable heat exchange coils)
- Food and beverage processing (pasteurization, cooling, and freezing circuits)
- Chemical processing (corrosive fluid heat exchange under cryogenic conditions)
- Scientific research (cryostat coils for superconducting magnets, low-temperature physics experiments)
- Automotive and aerospace (fuel cooling, hydraulic system heat exchange)
6. Quality Certifications & Standards Compliance
| Standard / Certification | Scope of Compliance |
|---|---|
| ASTM A213 / ASME SA-213 | Seamless austenitic stainless steel tube for heat transfer |
| ASTM A269 / ASME SA-269 | Welded austenitic stainless steel tube for chemical and heat transfer |
| ASTM A270 | Seamless and welded austenitic stainless steel sanitary tubing |
| ISO 9001:2015 | Quality Management System certification |
| ISO 14001:2015 | Environmental Management System |
| EN 10216-5 | European standard for heat exchanger tubes |
| GB/T 12771 (Chinese National Standard) | Stainless steel seamless tubes for fluid transport |
| ASME BPV Code Section VIII | Pressure vessel design and fabrication compliance |
7. Unique Selling Points
- Optimized Coil Geometry for Maximum Cooling Rate: The coil tube density (pitch and diameter configuration) is engineered based on experimental research to maximize the heat transfer coefficient, directly improving cooling rate (取冷速率) and system efficiency.
- Exceptional Cryogenic Performance: Maintains full toughness and ductility down to −196 °C without brittle fracture risk, making it ideal for LNG and cryogenic applications.
- Superior Corrosion Resistance: The high chromium (18–20%) and nickel (8–10.5%) content provides outstanding resistance to pitting, crevice corrosion, and general corrosion in aggressive environments.
- Hygienic Surface Quality: Mirror-polished finish (Ra ≤ 0.4 μm) meets FDA and 3-A sanitary standards for food-grade and pharmaceutical applications.
- Customizable Specifications: Full flexibility in coil diameter, pitch, tube dimensions, and end treatments to meet specific application requirements.
- Full Traceability: Each coil is accompanied by a Mill Test Certificate (MTC) per EN 10204 3.1, with full heat number traceability from raw material to finished product.
8. Conclusion
The Stainless Steel Coil Tube (Coiltube) from Wenzhou Jixing Metal Materials Co., Ltd represents a high-performance solution for cryogenic and thermal exchange applications where cooling rate optimization, material integrity, and long-term reliability are critical. Backed by rigorous manufacturing controls, comprehensive quality certifications, and application-specific engineering expertise, this product delivers superior thermal performance across a wide range of industrial sectors.