Finned Stainless Steel Coil Tube (Water-Cooled) — Technical Specification
1. Product Overview
The Finned Stainless Steel Coil Tube (Product No. 1648) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered heat transfer component designed for high-efficiency thermal exchange applications. This product integrates a seamless stainless steel coil tube with mechanically bonded or welded fins to maximize the external heat transfer surface area, enabling superior performance in water-cooled heat exchanger systems.
Based on advanced thermal calculation methodologies — specifically the Novel Method for Thermal Performance Calculation of Finned Water-Cooled Coils — the product is engineered with optimized fin geometry, tube diameter, and coil pitch to achieve maximum heat transfer efficiency while minimizing pressure drop across the coil assembly. This product represents a significant advancement in compact heat exchanger design, particularly for industrial process cooling, HVAC systems, and refrigeration applications.
2. Material & Properties
2.1 Base Tube Material
- Primary Material: Austenitic stainless steel conforming to AISI 304 (UNS S30400) or AISI 316L (UNS S31603) specifications
- Alternative Grades: AISI 321 (UNS S32100) for high-temperature service; AISI 310S (UNS S31008) for extreme thermal environments
- Chemical Composition (304): C ≤ 0.08%, Mn ≤ 2.0%, Si ≤ 1.0%, Cr 18.0–20.0%, Ni 8.0–10.5%, S ≤ 0.030%
- Chemical Composition (316L): C ≤ 0.03%, Mn ≤ 2.0%, Si ≤ 1.0%, Cr 16.0–18.5%, Ni 10.0–14.0%, Mo 2.0–3.0%, S ≤ 0.030%
2.2 Fin Material
- Fin Type: Aluminum alloy (1100 or 3003 grade) for standard applications; stainless steel fins (304/316) for corrosive environments
- Fin Bonding Method: Mechanically bonded (roll-on fin) or high-frequency welded fin configurations
- Corrosion Protection: Electro-galvanized, anodized, or passivated surface treatment available upon request
2.3 Mechanical Properties
- Tensile Strength (304): ≥ 515 MPa (annealed condition)
- Yield Strength (304): ≥ 205 MPa
- Elongation: ≥ 40% (minimum, per ASTM A269)
- Thermal Conductivity (304): 16.3 W/(m·K) at 100°C
- Thermal Expansion Coefficient: 17.2 × 10⁻⁶ /°C (20–100°C)
- Maximum Operating Temperature: 870°C (304); 1150°C (310S)
2.4 Thermal Performance Characteristics
The thermal performance of the finned coil tube is governed by the novel calculation methodology developed through extensive research and field validation. Key performance parameters include:
- Overall Heat Transfer Coefficient (U-value): Typically 250–850 W/(m²·K), depending on fluid type, velocity, and fin configuration
- Fin Efficiency (η_f): 0.75–0.92, calculated using the corrected fin surface area method
- Effective Heat Transfer Area: Enhanced by 3–6× compared to bare tube configurations
- Pressure Drop: Optimized through computational fluid dynamics (CFD) modeling to minimize pumping power requirements
3. Specifications
3.1 Tube Dimensions
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 / 8.0 / 9.5 / 12.0 / 15.9 / 19.1 / 21.3 / 25.4 mm | ASTM A269 / ASME B36.19M |
| Wall Thickness | 0.5 – 3.0 mm (customizable) | ASTM A269 |
| Tube Length (per coil) | 2.0 – 50.0 m (standard); up to 200 m (special order) | — |
| Coil Inner Diameter (ID) | 100 – 500 mm (customizable) | — |
| Tolerance on OD | ±0.05 mm (precision grade); ±0.10 mm (standard grade) | ASTM A269 |
| Tolerance on Wall Thickness | ±0.05 mm (precision grade); ±10% (standard grade) | ASTM A269 |
3.2 Fin Configuration
| Parameter | Specification | Notes |
|---|---|---|
| Fin Height | 3.0 – 10.0 mm | Optimized per thermal calculation |
| Fin Thickness | 0.10 – 0.30 mm | Aluminum: 0.10–0.15 mm; SS: 0.20–0.30 mm |
| Fin Density | 8 – 24 fins per inch (FPI) | 12–18 FPI standard; up to 24 FPI for high-efficiency |
| Fin Profile | Plain, Louvered, or Wave | Louvered fins offer 20–40% higher heat transfer |
| Fin Length (axial) | 100 – 3000 mm (continuous or segmented) | Segmented fins reduce thermal stress |
3.3 Performance Ratings
| Operating Parameter | Rating |
|---|---|
| Maximum Operating Pressure (Tube Side) | ≤ 2.5 MPa (standard); ≤ 6.3 MPa (reinforced) |
| Maximum Operating Pressure (Shell Side) | ≤ 1.6 MPa |
| Design Pressure | 1.5× maximum operating pressure |
| Hydrostatic Test Pressure | 1.5× design pressure, held for 30 minutes |
| Maximum Water Temperature (Tube Side) | 120°C (standard); 200°C (310S grade) |
| Maximum Gas Temperature (Shell Side) | 400°C (standard); 800°C (310S grade) |
| Service Life | ≥ 20 years under normal operating conditions |
4. Manufacturing Process
4.1 Process Flow
- Raw Material Inspection: Incoming stainless steel wire or tube stock is verified against mill certificates, with spectroscopic analysis confirming chemical composition compliance (ASTM A269 / EN 10216-5).
- Tube Forming: Cold-drawn seamless tubes are precision-formed to specified OD and wall thickness tolerances using CNC-controlled drawing equipment.
- Surface Preparation: Tubes undergo pickling and passivation treatment (nitric acid / citric acid cycle) to remove oxide scale and establish a protective chromium oxide film (Cr₂O₃), ensuring corrosion resistance and fin bonding integrity.
- Coiling: The formed tube is cold-coiled to the specified inner diameter using hydraulic coiling machines with controlled bending radii (minimum bend radius = 5× OD) to prevent ovality and wall thinning.
- Fin Application: Fins are applied via one of the following methods:
- Roll-on Fin: Aluminum fin strip is mechanically pressed onto the tube surface, achieving a metallurgical bond through cold working.
- Welded Fin: High-frequency induction welding or orbital TIG welding secures fins to the tube with full-penetration welds.
- Sleeved Fin: Slit fin sleeves are pushed onto the tube and expanded for a mechanical interference fit.
- Fin Tip Trimming: Precision CNC trimming ensures uniform fin height and clean edges across the entire coil length.
- Thermal Performance Verification: Each batch undergoes thermal performance testing using the novel calculation methodology, including:
- Effective heat transfer area calculation accounting for fin efficiency
- Corrected overall heat transfer coefficient determination
- Pressure drop verification against design targets
- Thermal imaging inspection for uniform heat distribution
- Non-Destructive Testing (NDT): 100% visual inspection; 10% ultrasonic testing (UT) on weld joints; dye penetrant testing (PT) on critical areas; eddy current testing (ET) on tube wall integrity.
- Hydrostatic Pressure Testing: 100% of coils subjected to hydrostatic testing at 1.5× design pressure for a minimum of 30 minutes with zero leakage tolerance.
- Final Inspection & Packaging: Coils are cleaned, protected with anti-corrosion wrapping, and packaged on wooden pallets with moisture barrier film for shipment.
4.2 Thermal Calculation Methodology
The product design incorporates a Novel Method for Thermal Calculation of Finned Water-Cooled Coils, which represents a significant advancement over traditional LMTD (Log Mean Temperature Difference) and NTU-ε (Number of Transfer Units – Effectiveness) methods. Key features of this methodology include:
- Segmented Analysis: The coil is divided into differential segments along its length, allowing for accurate modeling of varying temperature profiles and heat transfer coefficients throughout the coil.
- Corrected Fin Surface Area: Incorporates a modified fin efficiency factor that accounts for variable gas-side heat transfer coefficients, fluid properties, and geometric non-uniformities.
- Pressure Drop Integration: Simultaneous solution of energy balance and momentum equations enables accurate prediction of both thermal performance and hydraulic resistance.
- Empirical Validation: Calculation results are validated against experimental data from full-scale testing, with deviations typically within ±5% of measured values.
- Optimization Capability: The methodology supports parametric optimization of fin density, tube diameter, and coil geometry to achieve target performance at minimum cost.
5. Applications
The Finned Stainless Steel Coil Tube is engineered for demanding thermal management applications across multiple industries:
5.1 Industrial Process Cooling
- Heat recovery systems in chemical processing plants
- Waste heat recovery units in power generation facilities
- Process fluid coolers in petrochemical and refining operations
- Pharmaceutical process equipment requiring sanitary-grade materials
5.2 HVAC & Refrigeration
- Air source heat exchangers in commercial and industrial HVAC systems
- Chilled water coil assemblies for large-scale air conditioning
- Evaporator and condenser coils in refrigeration systems
- Indoor unit coils for precision temperature control applications
5.3 Marine & Offshore
- Sea water coolers utilizing 316L stainless steel for marine corrosion resistance
- Heat exchangers for shipboard auxiliary systems
- Offshore platform cooling systems exposed to salt spray environments
5.4 Food & Beverage Processing
- Sterilization and pasteurization equipment (304/316L sanitary grade)
- Product coolers and pre-heaters in dairy, brewing, and beverage processing
- Condensers for vacuum evaporation systems
5.5 Energy & Environmental
- Geothermal heat exchangers for renewable energy systems
- Solar thermal collectors with stainless steel coil absorbers
- Waste heat recovery for combined heat and power (CHP) systems
6. Quality Certifications & Standards Compliance
6.1 Manufacturing Certifications
- ISO 9001:2015 — Quality Management Systems (QMS)
- ISO 14001:2015 — Environmental Management Systems (EMS)
- ISO 45001:2018 — Occupational Health and Safety Management Systems
- ASME (American Society of Mechanical Engineers) — Section VIII, Division 1 (Pressure Vessels, where applicable)
- TÜV Certification — Product quality and safety verification
6.2 Material & Product Standards
| Standard | Description | Applicability |
|---|---|---|
| ASTM A269 / A269M | Welded and Seamless Austenitic Stainless Steel Tubing | Tube material specification |
| ASME B36.19M | Welded and Seamless Wrought Stainless Steel Pipe | Dimensional specifications |
| EN 10216-5 | Seamless Stainless Steel Tubes for Technical Uses | European standard compliance |
| GB/T 14976 | Seamless Stainless Steel Tubes for Fluid Transport | Chinese national standard |
| GB/T 12771 | Welded Stainless Steel Tubes for Fluid Transport |