Stainless Steel Coil Tube (Coiltube) — Product No. 573
1. Product Overview
The Stainless Steel Coil Tube (Coiltube), Product No. 573, manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered continuous coil tube designed for demanding thermal-fluid transfer applications. This product is engineered to meet the rigorous performance requirements of HVAC (Heating, Ventilation, and Air Conditioning) systems, particularly in fan coil unit (FCU) assemblies where air heat metering accuracy and thermal efficiency are critical. The coil tube is supplied in a continuous helical coil configuration, enabling seamless integration into heat exchanger cores, chiller coils, condenser units, and specialized air-heat metering systems.
The design philosophy behind this product draws from advanced research in fan coil unit performance testing and air heat metering optimization, ensuring that the coil tube delivers superior thermal conductivity, uniform heat distribution, and long-term dimensional stability under cyclic thermal loading conditions.
2. Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, thermal conductivity, and mechanical integrity. The primary material grades include:
- AISI 304 (UNS S30400) — General-purpose grade with balanced corrosion resistance and formability, suitable for standard HVAC and domestic hot water applications.
- AISI 316 (UNS S31600) — Enhanced corrosion resistance with added molybdenum (Mo ≥ 2.0%), ideal for aggressive chemical environments, marine applications, and food-grade processing.
- AISI 321 (UNS S32100) — Titanium-stabilized grade offering superior resistance to intergranular corrosion at elevated temperatures (up to 870 °C), suitable for high-temperature heat exchanger applications.
Key Material Properties (AISI 304 Reference Values)
- Density: 8.00 g/cm³
- Thermal Conductivity: 16.3 W/(m·K) at 20 °C
- Specific Heat Capacity: 500 J/(kg·K) at 20 °C
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /K (20–100 °C)
- Tensile Strength: ≥ 520 MPa (annealed condition)
- Yield Strength: ≥ 205 MPa (0.2% proof stress)
- Elongation: ≥ 40%
- Operating Temperature Range: −196 °C to +870 °C
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Product Code | 573 |
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Tube Material | AISI 304 / 316 / 321 Stainless Steel |
| Outer Diameter (OD) | 6.0 mm – 25.0 mm (customizable) |
| Wall Thickness | 0.3 mm – 1.5 mm (customizable) |
| Coil Diameter | 100 mm – 500 mm (configurable) |
| Coil Length | 10 m – 500 m per coil (standard); custom lengths available |
| Surface Finish | 2B Annealed / BA (Bright Annealed) / Electropolished (Ra ≤ 0.4 μm) |
| Pressure Rating | Up to 1.6 MPa (standard); up to 4.0 MPa (thick-wall configuration) |
| Temperature Rating | −40 °C to +350 °C (standard); up to +870 °C (AISI 321 grade) |
| Tolerance (OD) | ±0.05 mm (precision grade) |
| Tolerance (Wall Thickness) | ±10% of nominal |
| End Condition | Open ends / Flat cut / Beveled ends |
| Coating / Passivation | Acid pickling and passivation treatment (ASTM A967) |
| Standard References | ASTM A213 / ASME SA-213 / EN 10216-5 / GB/T 12771 |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube follows a multi-stage precision manufacturing workflow designed to ensure dimensional accuracy, metallurgical homogeneity, and surface integrity:
- Raw Material Selection & Inspection: Cold-rolled stainless steel strip is sourced from certified mills and subjected to spectroscopic analysis (OES) to verify chemical composition compliance with ASTM/EN specifications.
- Slitting & Leveling: The strip is slit to the required width and precision-leveled to eliminate coil set and ensure uniform flatness prior to forming.
- Spiral Forming & Welding: The strip is helically formed around a mandrel and continuously welded using high-frequency resistance welding (HFWR) or TIG (Tungsten Inert Gas) welding. The weld seam is ground flush to achieve a smooth internal surface, minimizing flow turbulence and pressure drop.
- Heat Treatment (Solution Annealing): The formed tube undergoes solution annealing at 1050 °C – 1150 °C in a controlled atmosphere furnace, followed by controlled cooling, to relieve residual stresses and restore full austenitic microstructure.
- Precision Sizing: Post-annealing cold drawing or expanding operations refine the outer diameter and wall thickness to within ±0.05 mm tolerance.
- Surface Treatment: Acid pickling and passivation per ASTM A967 removes mill scale and oxidation, forming a protective chromium oxide layer. Electropolishing is available for critical applications requiring ultra-low surface roughness.
- Coil Winding & Packaging: The finished tube is wound into the specified coil configuration, secured with stainless steel strapping, and packaged with moisture-absorbent desiccant to prevent corrosion during storage and transit.
- Final Quality Inspection: Each coil undergoes hydrostatic pressure testing (1.5× working pressure), dimensional verification using laser gauging, and visual inspection of the weld seam and surface finish.
5. Applications
The Stainless Steel Coil Tube (Product No. 573) is engineered for a broad spectrum of industrial and commercial applications:
- HVAC Fan Coil Units (FCUs): Primary heat exchange coils in commercial and residential HVAC systems, where optimized air heat metering and thermal efficiency are essential.
- Chiller & Condenser Coils: Evaporator and condenser tubes in refrigeration systems and industrial chillers.
- Air Heat Metering Systems: Precision coils for air-side heat metering in energy management systems, enabling accurate thermal energy measurement and billing.
- Food & Beverage Processing: Heat exchange coils in pasteurization, sterilization, and brewing equipment (AISI 316L grade preferred).
- Pharmaceutical Manufacturing: Sanitary-grade heat exchanger coils for GMP-compliant production environments.
- Marine & Offshore Systems: Corrosion-resistant coils for marine HVAC, ballast water systems, and offshore platform heating/cooling.
- Automotive Industry: Compact heat exchanger coils for engine cooling, cabin HVAC, and electric vehicle battery thermal management systems.
- Industrial Process Heating & Cooling: Custom coils for chemical processing, textile manufacturing, and polymer extrusion temperature control.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that every batch of coil tube meets international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ISO/TS 22163 — Automotive Quality Management System (IATF 16949 aligned)
- CE Marking — Compliance with European Machinery and Pressure Equipment Directives
- EN 10204 3.1 — Material Test Certificates (MTC) provided for every shipment
- ASTM A213 / ASME SA-213 — Compliance with American specifications for seamless and welded austenitic stainless steel boiler, heat-exchanger, and superheater tubes
- GB/T 12771 — Chinese national standard for welded austenitic stainless steel tubes for general applications
- PED 2014/68/EU — Pressure Equipment Directive compliance for pressure-containing applications
7. Unique Selling Points
Thermal Optimization for Air Heat Metering: The coil geometry and surface finish are specifically optimized for high-efficiency air-side heat transfer, drawing on advanced research in fan coil unit performance testing. This ensures superior thermal accuracy in energy metering applications.
Precision Weld Seam Technology: High-frequency resistance welding with flush ground seams minimizes internal flow resistance, reducing pressure drop by up to 15% compared to conventional welded tubes.
Customizable Coil Configuration: Flexible manufacturing capabilities allow for bespoke coil diameters, lengths, and pitch configurations to match specific heat exchanger core designs.
Full Traceability: Each coil is batch-traced with complete material test certificates, manufacturing records, and inspection reports, ensuring end-to-end supply chain transparency.
8. Ordering & Customization
Standard coil tube configurations are available for immediate dispatch. Custom orders — including non-standard dimensions, specialized surface treatments, and proprietary alloy grades — are accommodated with a typical lead time of 15–30 business days. Technical consultation and application-specific engineering support are provided by the manufacturer's R&D team to ensure optimal product selection for each project.