Stainless Steel Coil Tube (盘管 / Coiltube) — Model No. 876
Product Overview
The Stainless Steel Coil Tube (Model No. 876) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered heat exchange component designed for high-efficiency thermal energy transfer in solar thermal collection systems and regenerative biogas engineering applications. This coiltube product combines the mechanical integrity and corrosion resistance of austenitic stainless steel with optimized geometric configurations to maximize surface-area-to-volume ratios, enabling superior thermal performance in both concentrated and low-grade heat recovery environments.
The coil tube architecture is particularly suited for regenerative heat exchange (回热换热) processes, where thermal energy is captured, stored, and redistributed across industrial or agricultural biogas production cycles. The product represents a critical interface between renewable energy harvesting technologies and sustainable biofuel infrastructure.
Material & Properties
Base Material Composition
- Primary Grade: Austenitic Stainless Steel — SUS304 / SUS316L (ASTM A213 TP304 / TP316L)
- Carbon (C): ≤ 0.08% (304) / ≤ 0.03% (316L)
- Chromium (Cr): 18.0% – 20.0%
- Nickel (Ni): 8.0% – 10.5%
- Molybdenum (Mo): 2.0% – 3.0% (316L grade)
Mechanical Properties
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (抗拉强度) | ≥ 520 MPa (SUS304) / ≥ 515 MPa (SUS316L) | ASTM A213 / GB/T 12771 |
| Yield Strength (屈服强度) | ≥ 205 MPa | ASTM A213 |
| Elongation (延伸率) | ≥ 40% | ASTM A213 |
| Thermal Conductivity (导热系数) | 16.3 W/(m·K) at 100°C | ASTM E153 |
| Operating Temperature Range (工作温度范围) | −196°C to +870°C | ISO 15530 |
| Corrosion Resistance (耐腐蚀性) | Excellent resistance to chlorides, acids, and biological media | ASTM G48 |
Surface Finish
- Internal Surface: Electropolished to Ra ≤ 0.4 μm for reduced fouling and enhanced heat transfer
- External Surface: 2B mill finish (Ra ≤ 1.6 μm) or optional heat-absorbing black coating for solar applications
- Passivation Treatment: Per ASTM A967 / AMS 2700 for maximum corrosion protection
Specifications
| Parameter | Specification | Tolerance |
|---|---|---|
| Product Code (产品编号) | 876 | — |
| Outer Diameter (外径) | φ6 mm – φ50 mm | ±0.15 mm |
| Wall Thickness (壁厚) | 0.5 mm – 3.0 mm | ±10% |
| Coil Pitch (盘管间距) | 15 mm – 60 mm (customizable) | ±1.0 mm |
| Coil Diameter (盘管直径) | φ100 mm – φ2000 mm | ±2.0 mm |
| Effective Length (有效长度) | Up to 500 m per continuous coil | — |
| End Connection (端部连接) | Butt-weld / Threaded (BSP/NPT) / Flanged | Per ASME B16.11 |
| Maximum Working Pressure (最大工作压力) | 1.6 MPa – 6.4 MPa (PN16 – PN64) | — |
| Hydrostatic Test Pressure (水压试验压力) | 1.5× Working Pressure | — |
| Heat Transfer Efficiency (换热效率) | U-value: 800 – 2,500 W/(m²·K) depending on fluid configuration | — |
| Coil Turns (盘圈数) | 10 – 500 turns (customizable) | ±2 turns |
Manufacturing Process
Process Flow Diagram
- Raw Material Selection: Certified stainless steel seamless tubes (无缝钢管) sourced from approved mills, verified via mill test certificates (MTC) and chemical composition analysis per ASTM E415.
- Tube Cutting & Preparation: Precision laser cutting to specified lengths with deburring and chamfering to ensure clean coil entry.
- Coil Forming (盘管成型): Cold coiling using CNC-controlled rotary bending machinery with synchronized feed and forming heads. The coiling process employs multi-axis control to maintain uniform curvature radius and pitch accuracy throughout the entire coil length.
- Welding (焊接): Inconel filler wire TIG (Tungsten Inert Gas) welding per AWS D10.9 for coil-to-header connections. Orbital welding automation ensures consistent weld bead geometry and minimal heat-affected zone (HAZ) distortion.
- Stress Relief Annealing (应力退火): Post-forming solution annealing at 1050°C – 1150°C followed by controlled air or water quenching to relieve residual stresses and restore full austenitic microstructure.
- Surface Treatment (表面处理): Acid pickling and passivation per ASTM A967 to remove oxide scale and form a protective chromium oxide film.
- Quality Inspection (质量检验): 100% hydrostatic testing, dimensional verification via laser scanning, and optional eddy current testing (ET) for wall thickness integrity.
- Packaging & Dispatch: Protective end caps, moisture-absorbent packaging, and wooden crate or export-standard container loading.
Key Manufacturing Advantages
- Continuous coiling without intermediate welds maximizes structural integrity and eliminates potential leak paths
- CNC precision control ensures geometric accuracy critical for heat exchanger shell fitting
- Full traceability from raw material heat number to finished product serial identification
Applications
Primary Application Domains
- Solar Thermal Collection Systems (太阳能集热系统): Coil tubes serve as the primary heat transfer elements in evacuated tube solar collectors and parabolic trough concentrators, absorbing concentrated solar radiation and transferring thermal energy to working fluids (water, heat transfer oil, or molten salt).
- Regenerative Biogas Engineering (回热盘管沼气工程): Integrated into anaerobic digestion systems to preheat incoming organic feedstock using waste heat from digester effluent, improving methanogenesis efficiency and reducing overall energy consumption of biogas production facilities.
- Industrial Heat Recovery (工业余热回收): Deployed in flue gas heat recovery units, condensate recovery systems, and process water preheating applications across petrochemical, pharmaceutical, and food processing industries.
- Geothermal Energy Systems (地热能系统): Utilized as wellbore heat exchange coils for enhanced geothermal systems (EGS) and binary cycle power generation.
- Agricultural Greenhouse Heating (农业温室供暖): Coiled configurations embedded in greenhouse soil beds or air ducts for low-grade thermal distribution.
System Integration Schematic
In solar-biogas hybrid systems, the coil tube functions as a dual-purpose thermal intermediary: capturing high-temperature solar heat during peak irradiance periods and redistributing stored thermal energy to maintain optimal anaerobic digestion temperatures (35°C – 55°C) during low-insolation hours. This regenerative heat management strategy improves biogas yield by 15% – 25% compared to conventional electrically-heated digesters.
Quality Certifications & Standards Compliance
| Certification / Standard | Scope | Applicability |
|---|---|---|
| ISO 9001:2015 | Quality Management System | Full manufacturing process |
| ISO 14001:2015 | Environmental Management System | Production and supply chain |
| GB/T 12771 | Stainless Steel Seamless Tubes for General Purposes | Material specification |
| ASTM A213 | Seamless Austenitic Stainless Steel Tubes for Heat-Transfer Equipment | Material and mechanical properties |
| EN 10216-5 | Welded Stainless Steel Tubes for Heat Exchangers | European market compliance |
| ASME BPV Section I | Pressure Vessel and Piping Standards | Pressure-rated applications |
| CE Marking (PED 2014/68/EU) | Pressure Equipment Directive | European Union export |
| SGS / TÜV Inspection | Third-party quality verification | Batch certification |
Unique Selling Points
- Superior Thermal Performance: Optimized coil geometry with variable pitch design achieves heat transfer coefficients up to 2,500 W/(m²·K), significantly outperforming conventional straight-tube heat exchangers in compact configurations.
- Exceptional Corrosion Resistance: SUS316L grade with molybdenum alloying provides outstanding resistance to chloride-induced stress corrosion cracking (SCC), ensuring service life exceeding 25 years in aggressive biogas and solar thermal environments.
- Customizable Geometry: Modular coil design allows customization of diameter, pitch, turns, and length to match specific heat exchanger shell dimensions and thermal load requirements.
- Energy Efficiency Contribution: In regenerative biogas systems, the coil tube heat recovery mechanism reduces auxiliary energy consumption by up to 30%, directly contributing to carbon emission reduction targets.
- Wenzhou Jixing Manufacturing Expertise: Leveraging the advanced metallurgical processing capabilities of Wenzhou — China's premier stainless steel industrial cluster — the product benefits from integrated supply chain advantages and competitive cost-performance ratios.
Technical Consultation & Ordering
For custom specifications, material certifications, or system integration support, contact Wenzhou Jixing Metal Materials Co., Ltd directly. Technical data sheets, material test reports (MTR), and dimensional drawings are available upon request for all production batches.