Stainless Steel Coil Tube — Technical Product Specification
Product Code: 1447 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Classification: Literature & Technical Reference
1. Product Overview
Stainless steel coil tubes (also referred to as spiral wound tubing or helical coil tubing) are continuous-length tubular products formed by cold-drawing or hot-rolling stainless steel wire into a precise helical geometry. These products are distinguished from straight seamless tubes by their pre-formed spiral configuration, which offers significant advantages in heat transfer efficiency, space utilization, and mechanical flexibility. Coil tubes are widely employed in chemical reactors, heat exchangers, refrigeration systems, pharmaceutical processing, and energy-intensive industrial processes.
The present specification draws upon technical literature analyzing the performance degradation mechanisms observed in internal coil tube reactors (内盘管式反应器), specifically addressing fouling, flow maldistribution, and thermal boundary layer effects that impact long-term heat transfer effectiveness. Understanding these degradation modes is critical for proper coil tube selection, installation, and maintenance in high-performance thermal systems.
2. Material & Properties
2.1 Commonly Available Grades
- Austenitic Grades: 304 (UNS S30400), 304L (UNS S30403), 316 (UNS S31600), 316L (UNS S31603), 321 (UNS S32100), 316Ti (UNS S31635)
- Super-Austenitic Grades: 904L (UNS N08904), 2205 Duplex (UNS S32205), 2507 Super Duplex (UNS S32750)
- Custom / Alloy Grades: Available upon request for specialized corrosion or thermal environments
2.2 Mechanical Properties (Typical — Grade 316L Reference)
| Property | Specification |
|---|---|
| Tensile Strength (抗拉强度) | ≥ 485 MPa (70 ksi) |
| Yield Strength (屈服强度) | ≥ 170 MPa (25 ksi) |
| Elongation (延伸率) | ≥ 40% |
| Hardness (硬度) | ≤ 210 HB (Brinell) |
| Thermal Conductivity (导热系数) | 16.3 W/(m·K) at 20°C |
| Thermal Expansion Coefficient (热膨胀系数) | 17.3 × 10⁻⁶ /°C (20–100°C) |
| Maximum Operating Temperature (最高使用温度) | 870°C (1600°F) — continuous |
| Corrosion Resistance (耐腐蚀性) | Excellent resistance to pitting, crevice, and intergranular corrosion in chloride environments |
2.3 Surface Finish Options
- Pickled & Passivated (酸洗钝化): Standard mill finish, Ra ≤ 0.8 μm
- Commercial Polish (工业抛光): Ra ≤ 0.4 μm
- Mirror Polish (镜面抛光): Ra ≤ 0.1 μm — suitable for pharmaceutical and food-grade applications
- Electropolished (电抛光): Ra ≤ 0.25 μm — enhanced corrosion resistance and biocompatibility
3. Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) (外径) | Φ3.0 mm – Φ50.8 mm (1/8" – 2") | ASTM A269 / A213 |
| Wall Thickness (壁厚) | 0.3 mm – 3.0 mm | EN 10216-5 |
| Coil Diameter (盘管直径) | Φ50 mm – Φ2000 mm (customizable) | Manufacturer Standard |
| Coil Length (盘管长度) | 1 m – 500 m (continuous) | — |
| Pitch (螺距) | 2 mm – 50 mm (adjustable) | — |
| Number of Turns (圈数) | 1 – 10,000+ turns | — |
| OD Tolerance (外径公差) | ±0.05 mm to ±0.15 mm | ASTM A269 |
| Wall Thickness Tolerance (壁厚公差) | ±10% of nominal | ASTM A269 |
| Coil Diameter Tolerance (盘管直径公差) | ±0.5% | Manufacturer Standard |
| End Form (端部形式) | Plain, threaded (NPT/BSP), flanged, or socket-weld | ASME B1.20.1 |
4. Manufacturing Process
4.1 Production Workflow
- Material Preparation (材料准备): High-purity stainless steel wire rod is sourced from certified mills, subjected to incoming inspection (chemical composition analysis via OES, mechanical property verification), and annealed to achieve the desired cold-workability.
- Deep Drawing & Reduction (深拉拔减径): The wire rod is drawn through a series of tungsten carbide (WC) dies to reduce diameter and achieve precise wall thickness. Each draw pass is followed by intermediate annealing to prevent work hardening and cracking.
- Pipe Formation (制管成形): The reduced wire is formed into tubular geometry via rotary swaging or seamless drawing through a piercing die, producing a hollow seamless tube.
- Coiling / Spiral Winding (盘绕成形): The seamless tube is fed through a precision CNC-controlled coiling machine. The coil diameter, pitch, and number of turns are programmatically controlled to meet exact customer specifications. Tension control systems ensure uniform stress distribution throughout the coil.
- Pickling & Passivation (酸洗钝化): The coiled tube is immersed in a mixed acid bath (HNO₃ + HF) to remove surface oxides, followed by passivation to restore the passive chromium oxide layer.
- Surface Finishing (表面处理): Depending on specification, additional polishing, electropolishing, or peening operations are performed.
- Quality Inspection (质量检验): Every coil tube batch undergoes comprehensive testing including hydrostatic pressure testing, dimensional measurement (OD, wall thickness, coil diameter, pitch), visual inspection, and non-destructive testing (eddy current or ultrasonic).
- Marking, Packaging & Dispatch (标识包装发货): Each product is marked with heat number, grade, dimensions, and traceability information, then packaged in protective wrapping for shipment.
4.2 Process Quality Controls
- Online dimensional monitoring via laser gauges during coiling
- Hydrostatic test pressure: 1.5× maximum operating pressure, held for minimum 5 seconds
- Eddy current testing (ECT) for detection of internal wall thickness variations and surface defects
- Full chemical analysis per ASTM E415 (OES) on each heat lot
5. Applications
5.1 Chemical Reactor Applications (化学反应器应用)
Internal coil tube reactors represent a critical application domain. As documented in technical literature on heat transfer degradation in internal coil tube reactors (内盘管式反应器传热效果变差的原因分析), the helical geometry of coil tubes promotes secondary Dean flow (迪恩流), which enhances turbulent mixing and radial heat transfer coefficients compared to straight tubes. However, long-term operational performance may degrade due to:
- Fouling Accumulation (结垢沉积): Scale and polymer deposits on inner surfaces reduce effective flow area and increase thermal resistance. Coil tube design must account for accessible cleaning configurations and appropriate surface finish selection (electropolished surfaces exhibit reduced fouling tendency).
- Flow Maldistribution (流分布不均): In multi-pass coil configurations, uneven flow distribution between turns can create hot spots. Precision coil winding tolerances and proper inlet manifold design mitigate this effect.
- Thermal Boundary Layer Degradation (热边界层退化): Repeated thermal cycling may alter the internal surface roughness profile, progressively degrading the heat transfer coefficient. Material selection with appropriate thermal fatigue resistance is essential.
- Corrosion-Induced Wall Thinning (腐蚀减薄): Localized pitting or intergranular corrosion reduces wall integrity. Proper grade selection (e.g., 316L for chloride-containing media) and passivation maintenance address this concern.
5.2 Additional Application Domains
- Heat Exchangers (热交换器): Shell-and-coil heat exchangers, air-cooled condensers, and evaporators where compact geometry and high surface-area-to-volume ratios are required.
- Refrigeration & HVAC (制冷与暖通空调): Evaporator and condenser coils in industrial refrigeration systems, chiller units, and cryogenic applications.
- Pharmaceutical & Bioprocessing (制药与生物处理): Jacketed reactor coils, autoclave heating elements, and CIP/SIP-compatible process loops requiring sanitary-grade surface finishes.
- Food & Beverage Industry (食品饮料行业): Pasteurization coils, sterilization loops, and high-temperature short-time (HTST) processing equipment.
- Petrochemical & Oil & Gas (石油化工与油气): Downhole heating elements, subsea umbilical heating, and high-pressure process coils.
- Power Generation (发电): Supercritical steam generator coils, reheater tubes, and nuclear reactor cooling circuits (special grades).
- Automotive & Aerospace (汽车与航空航天): Turbocharger exhaust manifolds, fuel system lines, and thermal management circuits.
6. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification for manufacturing processes |
| ISO 14001:2015 | Environmental Management System certification |
| ASTM A269 | Standard specification for austenitic stainless steel seamless, cold-drawn or cold-rolled tubing |
| ASTM A213 | Standard specification for austenitic stainless steel seamless tubular products for high-temperature service |
| EN 10216-5 | European standard for seamless and welded stainless steel tubes for mechanical and thermal uses |
| JIS G3459 | Japanese Industrial Standard for cold-rolled seamless stainless steel tubes |
| ASME BPE | Bioprocessing Equipment standard for pharmaceutical-grade tubing (available for electropolished products) |
| CE / PED | European Pressure Equipment Directive compliance for pressure-containing applications |
| NSF / ANSI 61 | Drinking water system components certification (available upon request) |
7. Unique Selling Points
- Enhanced Heat Transfer Performance: The helical geometry inherently generates Dean vortices, increasing the Nusselt number (Nu) by 30–100% compared to equivalent straight tubes, translating to compact, high-efficiency thermal systems.
- Customization Flexibility: Coil diameter, pitch, number of turns, tube dimensions, and end configurations are fully customizable to match specific system integration requirements.
- Technical Literature Integration: Product selection is informed by peer-reviewed engineering analysis of heat transfer degradation mechanisms in coil tube reactors, enabling proactive design against long-term performance decline.
- Full Traceability: Each coil tube batch is traceable to the original steel mill heat number, with complete documentation of chemical composition, mechanical properties, and all manufacturing process parameters.
- Multi-Grade Availability: Stock and made-to-order availability across standard austenitic, super-austenitic, and duplex grades to address aggressive chemical and thermal environments.
- Sanitary & Pharmaceutical Grade Capability: Electropolished and mirror-polished options meet ASME BPE and FDA compliance requirements for pharmaceutical, food, and bioprocess applications.
8. Ordering Information
When requesting quotations or placing orders, please provide the following information:
- Material grade (e.g., 316L, 304, 2205)
- Outer diameter (OD) and wall thickness (WT)
- Coil diameter and pitch
- Total coil length or number of turns
- End form and connection type
- Surface finish requirement
- Applicable standards or specifications
- Intended operating conditions (temperature, pressure, medium)
Wenzhou Jixing Metal Materials Co., Ltd. — Committed to delivering precision-engineered stainless steel coil tube solutions backed by rigorous quality assurance and technical expertise.