Stainless Steel Coil Tube (盘管) — Fresh Air & HVAC Series
Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a precision-engineered continuous tube product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, specifically designed for use in fresh air handling systems, HVAC (Heating, Ventilation, and Air Conditioning) applications, heat exchangers, and thermal management equipment. The coil tube is formed through continuous bending processes that create uniform helical or serpentine geometries, enabling efficient heat transfer while maintaining structural integrity under cyclic thermal and pressure loading conditions.
Based on extensive research into anti-freezing measures for fresh air coil tubes (新风盘管防冻措施), this product incorporates design considerations that address low-temperature operational challenges, including freeze protection strategies, material selection for cryogenic resilience, and geometric optimization to minimize cold spots and ice accumulation risk within the coil structure.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior corrosion resistance, mechanical strength, and thermal conductivity balance. The primary material grades include:
- SUS304 (ASTM 304) — The standard grade offering excellent general corrosion resistance and formability, suitable for ambient and moderate temperature applications.
- SUS316L (ASTM 316L) — Enhanced resistance to chloride-induced pitting and crevice corrosion, ideal for coastal environments and chemical processing contexts.
- SUS321 (ASTM 321) — Stabilized with titanium, providing superior resistance to intergranular corrosion at elevated temperatures.
Key material properties include:
- Tensile Strength: ≥ 520 MPa (minimum, as per ASTM A269)
- Yield Strength: ≥ 205 MPa
- Elongation: ≥ 40% (in 50 mm gauge length)
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +870°C (depending on grade)
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and chemical environments
Technical Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | Φ6.0 / Φ8.0 / Φ10.0 / Φ12.0 / Φ16.0 | mm |
| Wall Thickness (WT) | 0.5 / 0.6 / 0.8 / 1.0 / 1.2 | mm |
| Coil Length | Custom (typical: 5–50) | m |
| Coil Pitch (Helical) | 10–50 (adjustable) | mm |
| Bend Radius (Minimum) | ≥ 3× OD | — |
| Surface Finish | No. 4 / Mirror / Matte | — |
| Surface Roughness (Ra) | ≤ 0.8 (No.4) / ≤ 0.4 (Mirror) | μm |
| Pressure Rating (Working) | ≤ 1.6 | MPa |
| Hydrostatic Test Pressure | 2.4 | MPa |
| Standard | ASTM A269 / GB/T 12771 / EN 10217 | — |
| End Treatment | Plain / Beveled / Flanged / Threaded | — |
| Available Grades | SUS304 / SUS304L / SUS316L / SUS321 | — |
| Coil Configuration | Helical / Serpentine / Spiral / Custom | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing workflow ensuring dimensional accuracy, metallurgical integrity, and functional performance:
- Raw Material Selection & Inspection — Incoming stainless steel seamless tubes are verified against ASTM A269 or GB/T 12771 standards. Chemical composition analysis (spectrographic testing) and mechanical property testing are conducted prior to acceptance.
- Pre-Forming Annealing — Tubes undergo solution annealing at 1050–1100°C followed by controlled cooling to restore ductility, eliminate residual stresses, and ensure optimal formability for subsequent bending operations.
- Precision Bending & Coiling — Computerized CNC bending equipment forms the tube into the specified coil geometry (helical, serpentine, or custom configurations). Mandrel-assisted bending prevents wall thinning, ovality, and wrinkling. Bend radius is maintained at a minimum of 3× OD to preserve cross-sectional integrity.
- Post-Forming Stress Relief — A controlled tempering process eliminates residual bending stresses, ensuring dimensional stability during subsequent welding or assembly operations.
- Surface Treatment & Finishing — Surface finishing includes pickling and passivation (酸洗钝化) to remove oxide scales and form a protective chromium oxide layer. Mirror polishing is available for hygienic or aesthetic applications.
- End Processing — Precision cutting, deburring, and optional end treatments (beveling, threading, or flange welding) are performed to facilitate seamless integration into system assemblies.
- Quality Inspection & Testing — Each coil tube undergoes dimensional verification (OD, WT, pitch, length), hydrostatic pressure testing at 2.4 MPa for 30 seconds minimum, and visual inspection for surface defects. X-ray or eddy current testing is available for critical applications.
Applications
The stainless steel coil tube finds extensive application across multiple industries:
- Fresh Air Handling Systems (新风系统) — Primary application domain; coil tubes serve as heat exchange elements in fresh air ventilation units. Anti-freezing design considerations ensure reliable operation in cold climate conditions, with strategies including coil geometry optimization to prevent air stagnation zones, integration of freeze-stat sensors, and material selection for low-temperature toughness.
- HVAC Heat Exchangers — Evaporator and condenser coils in commercial and industrial HVAC systems, leveraging the corrosion resistance and thermal performance of stainless steel in humid and chemically aggressive environments.
- Refrigeration & Cryogenic Systems — Refrigeration coils, evaporator assemblies, and cryogenic heat exchange components where low-temperature ductility and resistance to thermal cycling are critical.
- Industrial Heat Transfer — Process heating coils in chemical, pharmaceutical, and food processing industries requiring hygienic-grade materials and resistance to corrosive process fluids.
- Automotive & Aerospace — Fuel system lines, brake cooling circuits, and thermal management components where lightweight, corrosion-resistant tubing is required.
- Building Services — Radiator coils, underfloor heating loops, and solar thermal collection systems.
Anti-Freezing Design Considerations
Based on research into freeze protection for fresh air coil tubes (新风盘管防冻措施研究), the following engineering strategies are incorporated:
- Optimized Coil Geometry — Uniform pitch and bend radius distribution eliminates dead zones where stagnant air can freeze, ensuring consistent airflow across the entire coil surface.
- Material Selection for Cryogenic Resilience — SUS304 and SUS316L maintain ductility at temperatures as low as −196°C, preventing brittle fracture during freeze-thaw cycles.
- Surface Passivation — The passivated surface finish reduces ice adhesion and facilitates natural frost shedding, minimizing heat transfer degradation during partial icing conditions.
- Integration Compatibility — Coil design supports integration with freeze-protection control systems, including air temperature sensors, fan interlocks, and drain pan heating elements.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and product certifications:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control.
- ISO 14001 — Environmental Management System certification.
- CE Marking — Conformity with European Union health, safety, and environmental protection standards.
- GB/T 12771 — Chinese national standard for welded and seamless stainless steel tubes for general application.
- ASTM A269 / A213 — American standards for austenitic stainless steel tubes, both seamless and welded.
- EN 10217 — European standard for welded stainless steel tubes for pressure purposes.
- Mill Test Reports (MTR) — Each batch is accompanied by full chemical analysis and mechanical property test documentation.
Unique Selling Points
1. Specialized Fresh Air System Expertise: Leveraging dedicated research into anti-freezing measures for fresh air coil tubes, this product addresses a critical operational challenge in cold-climate ventilation systems, offering superior reliability where conventional coils fail.
2. Precision Coiling Technology: CNC-controlled bending ensures geometric uniformity with tolerances within ±0.5 mm, guaranteeing optimal heat transfer performance and consistent airflow distribution.
3. Multi-Grade Material Availability: Comprehensive grade options (SUS304, 304L, 316L, 321) allow customers to match material properties precisely to their application's environmental and performance requirements.
4. Full Traceability: Every coil tube batch is traceable from raw material mill certificates through final inspection, ensuring complete supply chain transparency and quality accountability.
5. Custom Engineering Capability: Flexible customization of OD, wall thickness, coil configuration, length, and end treatments supports OEM integration and bespoke system design requirements.
Ordering Information
For technical inquiries, sample requests, and bulk ordering, contact Wenzhou Jixing Metal Materials Co., Ltd. directly. Provide the following details for accurate quotation:
- Material grade and specification
- Outer diameter and wall thickness
- Coil configuration (helical / serpentine / custom drawing)
- Coil length and pitch requirements
- Surface finish requirement
- End treatment specification
- Quantity and delivery schedule