Stainless Steel Coil Tube for Heat Exchange and Slurry Ice Systems
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 635) manufactures high-performance Stainless Steel Coil Tubes (盘管) engineered specifically for demanding heat exchange applications, including slurry ice generation systems, refrigeration coils, and thermal management equipment. These coil tubes are designed to optimize fluid dynamics and thermal transfer efficiency under varying flow velocity conditions, making them suitable for industrial refrigeration, marine cooling systems, and process engineering where precise temperature control is critical.
The coil tube geometry provides a compact heat transfer surface area within a confined installation footprint, offering superior thermal performance compared to straight-tube alternatives. The helical configuration promotes turbulent flow at lower Reynolds numbers, enhancing convective heat transfer coefficients and reducing fouling accumulation on tube surfaces.
Material & Properties
The coil tubes are fabricated from premium-grade austenitic stainless steel, selected for their exceptional corrosion resistance, mechanical strength, and thermal stability across extreme temperature ranges.
- Primary Material Grades: AISI 304 (SAE 304 / UNS S30408), AISI 316 (UNS S31603), AISI 316L (UNS S31603), AISI 321 (UNS S32100), AISI 347 (UNS S34700)
- Chemical Composition (304 Grade): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 0.75%, Phosphorus (P) ≤ 0.045%, Sulfur (S) ≤ 0.030%
- Chemical Composition (316 Grade): Carbon (C) ≤ 0.08%, Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%
- Mechanical Properties: Tensile Strength (UTS) ≥ 515 MPa; Yield Strength ≥ 205 MPa; Elongation ≥ 40%; Hardness (HB) ≤ 217
- Thermal Conductivity: 14.5–16.3 W/(m·K) at 25°C
- Operating Temperature Range: −196°C to +870°C (304); −196°C to +870°C (316)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, organic acids, and chloride-containing environments (316/316L grades)
Specifications
| Parameter | Specification |
|---|---|
| Product Category | Coil Tube (盘管) |
| Product Number | 635 |
| Outer Diameter (OD) | φ6 mm – φ51 mm (customizable) |
| Wall Thickness | 0.3 mm – 3.0 mm |
| Coil Diameter | φ100 mm – φ2000 mm (customizable) |
| Coil Length | Up to 5000 m per coil (continuous) |
| Coil Pitch | 4 mm – 50 mm (adjustable per design requirement) |
| Material Grade | AISI 304 / 316 / 316L / 321 / 347 |
| Surface Finish | Pickled & Passivated (2B), Polished (Ra ≤ 0.4 μm), or Custom |
| Welding Method | Orbital TIG (Tungsten Inert Gas) Welding, Autogenous or with Filler |
| Pressure Rating | Up to 4.0 MPa (design dependent) |
| Tolerance (OD) | ±0.05 mm – ±0.15 mm |
| Tolerance (Wall Thickness) | ±10% of nominal |
| Helix Angle | Standard helical configuration; variable pitch available |
| End Treatment | Plain ends, Beveled, Flanged, or Threaded (per customer specification) |
| Standards Compliance | ASTM A213/A269, EN 10216-5, GB/T 12771, JIS G3459 |
| Packaging | Wooden crate, moisture-proof wrapping, desiccant included |
Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and surface quality.
- Raw Material Procurement & Inspection: Stainless steel seamless tubes are sourced from certified mills (e.g., Outokumpu, Sandvik, or domestic Grade A suppliers). Incoming material undergoes spectroscopic analysis (OES) to verify chemical composition, along with mechanical testing including tensile, hardness, and impact tests.
- Tube Straightening & Cutting: The parent tube is straightened to eliminate residual curvature from the coiling process during rolling. Precision cutting to required lengths is performed using cold saws to minimize thermal distortion.
- Coil Winding (Forming): Using computer-controlled helical winding machines, the straight tube is wound onto precision mandrels to form the desired coil geometry. The winding process is programmed to maintain consistent coil pitch, helix angle, and dimensional tolerances throughout the entire length. CNC-controlled systems ensure repeatability and minimize plastic deformation.
- Welding (if required): Where continuous coils are joined or spliced, orbital TIG welding is employed with argon shielding gas to produce high-quality, leak-tight welds. Weld parameters (current, travel speed, gas flow) are optimized for each tube diameter and wall thickness combination.
- Pickling & Passivation: The formed coil tubes undergo pickling in a nitric-hydrofluoric acid solution to remove oxide scale and surface contaminants. Subsequent passivation in a citric or nitric acid bath forms a protective chromium oxide layer, enhancing corrosion resistance. The passivation layer is verified using blue-white drop tests (ASTM A967).
- Surface Finishing: Depending on application requirements, the coil surface may be subjected to mechanical polishing, electropolishing, or electropolishing for ultra-smooth finish (Ra ≤ 0.2 μm for sanitary applications).
- Quality Inspection: Final inspection includes dimensional verification (OD, wall thickness, coil diameter, pitch), visual inspection for surface defects, hydrostatic pressure testing, and optional eddy current testing for internal flaw detection.
- Coating & Packaging: Coils are wrapped in moisture-barrier materials, placed in wooden crates, and shipped with certificates of conformity.
Applications
Wenzhou Jixing's stainless steel coil tubes are engineered for a broad spectrum of industrial and commercial applications:
- Refrigeration & Cold Chain Systems: Evaporator coils, condenser coils, and heat exchangers for industrial refrigeration plants, cold storage facilities, and frozen food processing. The helical geometry enhances heat transfer efficiency, particularly in slurry ice (ice slurry) generation systems where flow velocity optimization is critical for uniform ice crystal formation.
- Marine & Offshore Equipment: Heat exchangers for shipboard cooling systems, ballast water management, and offshore platform thermal management, leveraging the superior chloride resistance of 316/316L grades.
- Food & Beverage Industry: Sanitary-grade heat exchangers for pasteurization, UHT processing, CIP (Clean-in-Place) systems, and cold fill operations. Surface finishes meeting FDA and EHEDG standards ensure hygienic compliance.
- Pharmaceutical & Biotechnology: Process heat exchangers, reactor cooling jackets, and fermentation temperature control systems requiring precise thermal regulation and high purity surface conditions.
- Chemical & Petrochemical Processing: Reactor cooling, distillation column condensers, and heat recovery systems handling corrosive process streams.
- HVAC & Building Services: Chiller coils, heat pump components, and district heating/cooling systems.
- Automotive & Transportation: Battery thermal management coils for electric vehicle (EV) battery cooling/heating systems, leveraging the lightweight and corrosion-resistant properties of stainless steel.
- Power Generation: Condenser tubes, feedwater heaters, and cooling water systems in thermal and nuclear power plants.
Unique Selling Points
Optimized Flow Dynamics for Slurry Ice Systems: Research and development focused on the influence of flow velocity on slurry ice (ice slurry) flow behavior and heat transfer characteristics within coil tube geometries. This expertise enables Wenzhou Jixing to design coil tubes with optimized helix parameters that promote uniform slurry distribution, minimize stratification, and maximize heat transfer efficiency in refrigeration applications.
- Superior Heat Transfer Performance: The helical coil geometry inherently promotes secondary flow (Dean vortices) within the tube, increasing turbulence intensity and convective heat transfer coefficients by up to 25–40% compared to straight tubes at equivalent Reynolds numbers.
- Customizable Geometry: Flexible manufacturing capabilities allow for tailored coil diameters, pitches, and lengths to match specific heat exchanger design requirements and installation constraints.
- Corrosion-Resistant Material Selection: Availability of multiple stainless steel grades (304, 316, 316L, 321, 347) ensures material compatibility with a wide range of process fluids, from potable water to aggressive chemical solutions.
- Compact Installation Footprint: The coiled configuration maximizes heat transfer area per unit volume, enabling space-efficient installations in constrained environments.
- Long Service Life: The combination of high-quality austenitic stainless steel, precision manufacturing, and rigorous quality control ensures extended operational life with minimal maintenance requirements.
- Scalable Production: Capable of producing coils ranging from short custom runs to continuous lengths exceeding 5000 meters, accommodating both prototype and large-scale production needs.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications and compliance credentials:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO 45001:2018 — Occupational Health and Safety Management System Certification
- NADCAP — National Aerospace and Defense Contractors Accreditation Program (for aerospace-grade applications)
- CE Marking — European Conformity for pressure equipment (PED 2014/68/EU)
- ASME — American Society of Mechanical Engineers certification for pressure vessel components
- Material Certifications: Mill Test Certificates (MTC) in accordance with EN 10204 3.1 / 3.2 for every batch of material supplied
- Hydrostatic Testing: All coil tubes undergo 100% hydrostatic pressure testing prior to shipment
- Non-Destructive Testing (NDT): Eddy current testing, magnetic particle inspection, and ultrasonic testing available upon request for critical applications
- Traceability: Full heat-number traceability from raw material mill to finished product, with digital documentation and batch records
Technical Notes & Design Considerations
When integrating stainless steel coil tubes into heat exchange systems, the following engineering parameters should be considered:
- Flow Velocity Optimization: For slurry ice systems, flow velocity directly influences ice crystal size distribution, slurry concentration uniformity, and overall heat transfer rate. Lower velocities may result in stratification and reduced heat transfer, while excessively high velocities increase pressure drop and pumping power requirements. Optimal design balances these competing factors.
- Pressure Drop: The helical geometry introduces additional centrifugal forces, resulting in higher pressure drop compared to equivalent-length straight tubes. The Fanning friction factor for helical coils is typically 1.5–2.5 times that of straight tubes, depending on the coil diameter-to-tube diameter ratio (D/d).
- Thermal Expansion: Stainless steel exhibits a coefficient of thermal expansion of approximately 16–18 × 10⁻⁶ /°C. Adequate expansion loops or flexible connections should be incorporated in the system design to accommodate thermal growth.
- Solidification Risk: In refrigeration applications operating below 0°C, the risk of ice formation within the coil tube must be managed through adequate flow velocity, proper insulation, and drainage provisions during shutdown.
Wenzhou Jixing Metal Materials Co., Ltd. provides comprehensive technical support, including computational fluid dynamics (CFD) analysis, thermal performance modeling, and custom engineering consultation to ensure optimal coil tube design for each specific application.