Stainless Steel Coil Tube (Coiltube) — Optimized Wire Coil Condenser Component
Product Overview
The Stainless Steel Coil Tube, catalogued as product series 1597 by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered coiled tubular component designed primarily for use in wire coil condensers, heat exchangers, and thermal management systems. This product represents the culmination of advanced metallurgical research and optimized coil geometry design, drawing upon principles detailed in the technical study "Optimized Design of Wire Coil Condensers" (《钢丝盘管式冷凝器的优化设计》). The coil tube is manufactured from high-grade austenitic stainless steel and is wound into a continuous helical configuration to maximize surface-area-to-volume ratios, thereby enhancing heat transfer efficiency in refrigeration, HVAC (Heating, Ventilation, and Air Conditioning), and industrial cooling applications.
Material & Properties
The coil tube is fabricated from premium austenitic stainless steel grades, selected for their superior combination of corrosion resistance, mechanical strength, and thermal conductivity. The primary material grades include:
- SUS 304 (ASTM A213 TP304) — 18% Chromium, 8% Nickel; the most widely used grade for general-purpose heat exchange applications, offering excellent weldability and resistance to atmospheric and chemical corrosion.
- SUS 316 (ASTM A213 TP316) — 18% Chromium, 12% Nickel, 2.5% Molybdenum; provides enhanced pitting and crevice corrosion resistance, ideal for marine, chemical processing, and pharmaceutical environments.
- SUS 321 (ASTM A213 TP321) — Ti-stabilized variant; suitable for high-temperature applications where sensitization and intergranular corrosion must be avoided.
Mechanical & Physical Properties (Typical, SUS 304)
- Tensile Strength: ≥ 520 MPa (75,400 psi)
- Yield Strength: ≥ 205 MPa (29,700 psi)
- Elongation: ≥ 40%
- Thermal Conductivity: 16.3 W/(m·K) at 100 °C
- Operating Temperature Range: −196 °C to +870 °C
- Surface Finish: 2B, BA (Bright Annealed), or No. 4 / Mirror polished, depending on application requirements
Specifications
| Parameter | Specification / Range |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") |
| Wall Thickness | 0.3 mm – 2.5 mm |
| Coil Pitch (Helical Spacing) | 5.0 mm – 25.0 mm (customizable) |
| Coil Diameter (Mean) | 50 mm – 600 mm (customizable) |
| Total Coil Length | 1 m – 50 m (configurable per order) |
| Number of Turns | 10 – 500 turns |
| End Form | Open ends, U-bend, S-bend, or custom flared/expanded |
| Tolerance on OD | ±0.1 mm |
| Tolerance on Pitch | ±0.5 mm |
| Material Grade | SUS 304 / 316 / 321 / 316L |
| Surface Treatment | Pickling & Passivation (P&P), BA finish, or passivated |
| Standard Reference | ASTM A213, ASME SA-213, EN 10216-5, GB/T 12771 |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and optimal thermal performance:
- Material Selection & Inspection: Raw stainless steel seamless or welded pipe stock is sourced from certified mills. Incoming material undergoes spectrographic analysis (PMI — Positive Material Identification), visual inspection, and ultrasonic testing to verify grade compliance and detect internal defects.
- Cold Drawing / Threading: The pipe is cold-drawn through precision tungsten carbide dies to achieve the required outer diameter and wall thickness within tight tolerances. This process improves surface finish and mechanical properties through work hardening.
- Coil Winding: The drawn tube is wound onto a CNC-controlled mandrel or helical winding machine at a controlled speed and tension. The coil pitch and diameter are precisely governed by the machine's servo system to maintain uniformity across the entire coil length. Winding tension is carefully calibrated to prevent spring-back deformation and ensure consistent inter-coil spacing.
- Heat Treatment / Solution Annealing: Where required, the coil tube is solution-annealed at 1050 °C – 1150 °C followed by rapid water quenching to restore full austenitic microstructure, eliminate residual stresses from cold working, and achieve maximum corrosion resistance.
- Pickling & Passivation: The coil tube is immersed in a mixed acid solution (HNO₃ + HF) to remove scale and oxidation, followed by a nitric acid passivation bath to form a stable chromium oxide protective layer on the surface.
- End Processing: Ends are cut, deburred, and formed into the required configuration (U-bend, S-bend, flared, or plain) using dedicated end-forming equipment.
- Final Quality Control: Each coil tube undergoes dimensional verification (OD, wall thickness, pitch, coil diameter), hydrostatic pressure testing, visual surface inspection, and optional eddy current testing for internal flaw detection.
Applications
The optimized Stainless Steel Coil Tube finds extensive application across multiple industries due to its superior heat transfer characteristics and corrosion resistance:
- Refrigeration & Air Conditioning: Wire coil condensers and evaporators in commercial refrigeration units, chiller systems, and split-system HVAC units. The helical coil geometry maximizes convective heat transfer between the refrigerant and ambient air.
- Automotive Thermal Management: Engine oil coolers, transmission fluid coolers, and intercooler components in passenger and commercial vehicles.
- Industrial Process Cooling: Heat exchangers in chemical processing, petrochemical, and pharmaceutical manufacturing where corrosion-resistant heat exchange media are essential.
- Food & Beverage Processing: Pasteurization equipment, milk coolers, and brewing systems where sanitary-grade stainless steel surfaces are mandated.
- Marine & Offshore: Heat exchangers and condensers in marine propulsion systems, ballast water treatment, and offshore platform cooling circuits.
- Medical & Laboratory Equipment: Cryogenic transfer lines, laboratory cooling systems, and medical device manufacturing where ultra-pure fluid handling is required.
- Solar Thermal Systems: Heat collection coils in concentrated solar power (CSP) installations and solar water heating systems.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system to ensure every coil tube product meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ISO 45001:2018 — Occupational Health and Safety Management System
- CE Marking (EU Conformity) — Compliance with European machinery and pressure equipment directives
- EN 10204 3.1 — Mill test certificates and material certification per European standards
- ASME SA-213 — American Society of Mechanical Engineers specification for seamless austenitic stainless steel tubes
- ASTM A213 / A269 — American Society for Testing and Materials standards for stainless steel tubing
- GB/T 12771 — Chinese national standard for stainless steel seamless tubes for fluid transport
- JIS G3446 — Japanese Industrial Standard for stainless steel seamless tubes
Unique Selling Points
- Optimized Helical Geometry: Coil pitch and diameter are engineered based on thermal-hydraulic optimization principles derived from academic research on wire coil condenser design, resulting in improved heat transfer coefficients and reduced pressure drop compared to conventional straight-tube heat exchangers.
- Full Customization: Coil diameter, pitch, length, OD, wall thickness, and end configurations are fully customizable to meet specific OEM (Original Equipment Manufacturer) requirements.
- Multi-Grade Material Availability: SUS 304, 316, 316L, and 321 grades available to address diverse environmental and performance demands.
- Precision Manufacturing: CNC-controlled winding ensures dimensional consistency with pitch tolerance of ±0.5 mm, critical for proper coil packing and heat exchanger core assembly.
- Superior Surface Integrity: Pickling and passivation treatment ensures a clean, oxide-free surface that maximizes thermal conductivity and prevents contamination in sanitary applications.
- Comprehensive Quality Assurance: Every production lot undergoes hydrostatic testing, dimensional verification, and material certification to guarantee compliance with applicable international standards.
- Cost-Effective Alternative: Compared to brazed plate heat exchangers or finned tube assemblies, the coil tube offers a simpler, more compact, and lower-cost solution for many heat exchange applications while maintaining high performance.
Technical Note: The design philosophy behind this coil tube product is informed by the academic study "Optimized Design of Wire Coil Condensers" (《钢丝盘管式冷凝器的优化设计》), which investigated the relationship between coil geometry parameters (pitch, diameter, tube OD) and overall thermal efficiency. The findings demonstrated that optimizing the coil pitch-to-diameter ratio and tube-to-coil diameter ratio can increase heat transfer performance by 15–30% while simultaneously reducing refrigerant charge volume and system pressure drop. Wenzhou Jixing Metal Materials Co., Ltd. incorporates these optimization principles into every coil tube production batch, ensuring that customers receive components engineered for peak thermal performance.