Stainless Steel Coil Tube for Closed-Circuit Cooling Tower Heat Exchangers
Product Overview
The Stainless Steel Coil Tube (Model No. 977) is a precision-engineered coiled tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, specifically designed for heat exchange applications in closed-circuit cooling towers (Closed-Circuit Cooling Tower, CCCT). This product leverages advanced coil-forming technology to deliver superior thermal performance, enhanced fluid dynamics, and exceptional corrosion resistance in demanding industrial cooling environments.
Based on rigorous numerical simulation studies (Numerical Simulation of Heat Transfer in Closed Cooling Tower Coil Tubes), this coil tube product has been optimized to maximize heat transfer efficiency while minimizing pressure drop across the heat exchange surface. The design integrates Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) findings to ensure optimal geometric parameters for industrial-grade thermal management systems.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its outstanding combination of mechanical strength, corrosion resistance, and thermal conductivity in cooling tower environments.
- Base Material: Austenitic Stainless Steel — SUS304 (ASTM A240 Type 304), SUS316L (ASTM A240 Type 316L), or SUS321 (ASTM A240 Type 321), selected according to application-specific corrosion requirements.
- Corrosion Resistance: Excellent resistance to chloride-induced pitting (Pitting Resistance Equivalent Number, PREN ≥ 19 for 316L grade), acid condensation, and humid atmospheric corrosion.
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, ensuring efficient heat dissipation in closed-loop water systems.
- Mechanical Strength: Yield strength (Yield Strength) ≥ 205 MPa; Ultimate Tensile Strength (UTS) ≥ 515 MPa (SUS304 grade, cold-worked condition).
- Operating Temperature Range: −196°C to +870°C, suitable for both cryogenic and high-temperature cooling applications.
- Surface Finish: 2B (cold-rolled and annealed) or No. 1 (hot-rolled and pickled), with surface roughness (Surface Roughness, Ra) ≤ 0.8 μm for reduced fouling tendency.
- Hygienic & Non-Toxic: Food-grade compliance available (FDA-compliant, EC 1935/2004) for applications requiring potable water contact.
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Category | Coil Tube (盘管 / Coiltube) | — |
| Outer Diameter (OD) | φ12 mm – φ50 mm (customizable) | ASTM A269 / GB/T 12771 |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm | ASTM A269 |
| Coil Diameter | 100 mm – 1200 mm (customizable) | Customer-specified |
| Coil Length | Up to 200 m per continuous coil (Continuous Coil Length) | — |
| Material Grades | SUS304, SUS304L, SUS316, SUS316L, SUS321, SUS310S | ASTM A269 / ASME SA-269 |
| Seam Type | Welded (Welded Tube) or Seamless (Seamless Tube) | ASTM A269 |
| Tolerance — OD | ±0.05 mm (±0.5%) | ASTM A269 |
| Tolerance — WT | ±10% | ASTM A269 |
| Surface Treatment | Passivated (Passivation Treatment), Pickled (Acid Pickling), or Polished | ASTM A967 |
| Heat Treatment | Solution Annealed (Solution Annealing) at 1050°C – 1150°C, water quenched | — |
| Coil Forming Process | Continuous Cold Coiling / Hot Coiling with Controlled Springback Compensation | — |
| Maximum Operating Pressure | Up to 2.5 MPa (depending on OD and WT) | ASME B31.5 |
| Heat Transfer Coefficient | Optimized via CFD simulation; U-value up to 8,500 W/(m²·K) in cross-flow configuration | Numerical Simulation Validation |
| Pressure Drop | Minimized through spiral pitch optimization (Pressure Drop Reduction) | CFD-validated |
Manufacturing Process
The production of the Model 977 Stainless Steel Coil Tube follows a multi-stage precision manufacturing process, incorporating numerical simulation-guided design optimization:
- Raw Material Selection & Incoming Inspection: Stainless steel strip or seamless tube stock is sourced from certified mills. Incoming materials undergo spectroscopic analysis (Spectroscopic Analysis) to verify chemical composition, along with mechanical testing and ultrasonic inspection (Ultrasonic Testing, UT) for internal defects.
- Tube Forming: Seamless tubes are drawn or cold-rolled to precise OD and WT dimensions. Welded tubes are formed via roll-forming from precision strip, followed by high-frequency induction welding (High-Frequency Induction Welding, HF-IW) with in-line weld inspection.
- Heat Treatment & Stress Relief: Tubes are solution-annealed at 1050°C–1150°C followed by rapid water quenching to achieve full austenitic microstructure, ensuring maximum corrosion resistance and ductility.
- Surface Treatment: Acid pickling and passivation are performed to remove scale, oxides, and surface contaminants, establishing a stable chromium oxide passive film (Chromium Oxide Passive Film) for long-term corrosion protection.
- Coil Forming (Coiling): Tubes are coiled using CNC-controlled coiling equipment with springback compensation algorithms derived from numerical simulation data. The coil pitch (Coil Pitch) and helix angle (Helix Angle) are precisely controlled to optimize heat transfer area density while maintaining structural integrity.
- Quality Inspection: Each coil undergoes 100% hydrostatic pressure testing (Hydrostatic Pressure Testing), dimensional verification, and visual inspection. Sampling includes hardness testing (Hardness Testing), intergranular corrosion testing (Intergranular Corrosion Testing, per ASTM A240), and dye penetrant testing (Dye Penetrant Testing, PT) for weld integrity.
- Packaging & Dispatch: Coils are wrapped in moisture-proof protective film, secured on wooden pallets or steel supports, and shipped in crates or containers with proper labeling and documentation.
Applications
The Model 977 Stainless Steel Coil Tube is engineered for a broad spectrum of industrial heat exchange and thermal management applications:
- Closed-Circuit Cooling Towers (Closed-Circuit Cooling Tower, CCCT): Primary application — the coil tube serves as the core heat exchange element in evaporative closed-loop cooling systems, where process fluid circulates through the coil while ambient air and water spray provide evaporative cooling.
- Industrial Process Cooling: Heat dissipation for chemical reactors, polymerization processes, and high-temperature manufacturing equipment.
- Power Generation: Condenser tubes and heat recovery coils in power plants, including nuclear-grade applications (with appropriate certification).
- Food & Beverage Industry: Product pasteurization, brewing, and refrigeration systems where sanitary-grade materials are required.
- Pharmaceutical Manufacturing: Clean-in-Place (CIP) compatible heat exchange coils for pharmaceutical process cooling.
- Oil & Gas Industry: Heat exchangers in offshore platforms and refineries, where chloride resistance is critical.
- HVAC Systems: Chilled water coils and air handling unit heat exchangers in commercial and industrial building systems.
- Marine Applications: Seawater cooling systems and heat recovery units on vessels, leveraging superior chloride corrosion resistance of 316L grade.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and holds the following certifications and standards compliances:
- ISO 9001:2015 — Quality Management System (Quality Management System) certification, ensuring consistent production quality and process control.
- ISO 14001:2015 — Environmental Management System (Environmental Management System) certification.
- ISO 45001:2018 — Occupational Health and Safety Management System (Occupational Health and Safety Management System).
- CE Marking — European Conformity (European Conformity) certification for market access in the European Economic Area.
- Material Standards: ASTM A269 (Specification for Seamless and Welded Austenitic Stainless Steel Tubing for Boilers, Heaters, and Exchangers); ASME SA-269; GB/T 12771; EN 10217-7.
- Testing Standards: ASTM A240 (Chemical and Mechanical Requirements); ASTM A967 (Passivation); ASME BPV Section II (Pressure Vessel Materials); EN 10204 3.1/3.2 (Material Test Certificates).
- Third-Party Inspection: Available upon request — SGS, Bureau Veritas, or TÜV Rheinland inspection and certification for international project requirements.
Unique Selling Points
- CFD-Optimized Geometry: Coil pitch, helix angle, and tube layout are derived from validated numerical simulation models, delivering up to 15–20% improvement in heat transfer efficiency (Heat Transfer Efficiency) compared to conventionally designed coils.
- Minimized Pressure Drop: Numerical simulation-guided design reduces system pressure drop (Pressure Drop) by up to 10%, lowering pumping energy consumption and operating costs.
- Superior Corrosion Longevity: Available in 316L and 321 grades for aggressive environments, providing a design life exceeding 20 years in typical cooling tower applications.
- Continuous Coil Production: Capability to produce coils up to 200 meters in continuous length, reducing field welding requirements and potential leak points.
- Customization Flexibility: Full customization of OD, wall thickness, coil diameter, material grade, and surface treatment to match specific project requirements and OEM specifications.
- Comprehensive Documentation: Full traceability with mill certificates, heat number tracking, and EN 10204 3.1/3.2 material test certificates provided with every shipment.
Note: All specifications are subject to engineering verification based on specific project requirements. Wenzhou Jixing Metal Materials Co., Ltd reserves the right to modify product specifications with prior notification. For detailed technical data sheets, material certificates, and project-specific design support, please contact our engineering team directly.