Stainless Steel Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered continuous-length tubing product supplied in coil form, designed for high-performance thermal exchange and fluid transport applications. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product line is specifically optimized for integration into Fan Coil Unit (FCU) + Fresh Air System architectures, where it serves as a critical heat exchange medium replacing conventional fresh air handling unit components. The coil tube configuration enables superior energy efficiency by facilitating compact, high-surface-area thermal transfer within HVAC (Heating, Ventilation, and Air Conditioning) systems.
This product represents a paradigm shift in energy-saving HVAC design. By employing stainless steel coil tubes as the core heat exchange element within fan coil and fresh air systems, the system achieves significant reductions in parasitic energy losses, pressure drops, and thermal bridging compared to traditional carbon steel or copper-tube alternatives. The continuous coil form factor also minimizes joint count, thereby reducing leak points and maintenance requirements throughout the operational lifecycle.
2. Material & Properties
2.1 Base Material
The coil tube is fabricated from high-grade austenitic stainless steel, conforming to international metallurgical standards. The primary alloy grades utilized include:
- 304 (UNS S30408) — General-purpose corrosion-resistant grade with excellent formability
- 316 (UNS S31608) — Enhanced chlorides resistance for aggressive environments
- 316L (UNS S31603) — Low-carbon variant for welded applications with superior intergranular corrosion resistance
2.2 Mechanical Properties
- Tensile Strength: 520–750 MPa (depending on grade and cold-work condition)
- Yield Strength (0.2% offset): 205–450 MPa
- Elongation at Break: ≥ 35% (304 grade, annealed condition)
- Hardness: 95–120 HRB (annealed); up to 300 HV (work-hardened)
2.3 Thermal & Corrosion Resistance
- Thermal Conductivity: 14–16 W/(m·K) at 20°C
- Operating Temperature Range: −196°C to +870°C (304 grade)
- Corrosion Resistance: Superior resistance to atmospheric corrosion, mild acids, organic acids, and aqueous solutions; 316 grade exhibits excellent resistance to chloride-induced pitting and crevice corrosion
- Chromium Content: 18–20% (304); 16–18% (316)
- Nickel Content: 8–10.5% (304); 10–14% (316)
- Molybdenum Content: 0% (304); 2–3% (316)
3. Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code / No. | 740 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Material Grades | 304 / 316 / 316L (Austenitic Stainless Steel) |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (customizable) |
| Wall Thickness | 0.3 mm – 3.0 mm |
| Coil Diameter | 1.0 m – 2.5 m (standard); up to 3.0 m on request |
| Coil Length | 50 m – 200 m per coil (continuous) |
| Surface Finish | 2B Annealed / Pickled & Passivated / Brushed / Mirror (BA) |
| Form | Round / Oval / Square (cross-section) |
| Dimensional Tolerance | ±0.05 mm (OD); ±0.02 mm (wall thickness) |
| Strain Hardening Class | 1/4H – F (Full Annealed) |
| Standard Compliance | ASTM A269 / ASME SA-269 / GB/T 12771 / EN 10217-7 |
| Packaging | Wooden reel with moisture-proof wrapping; export-grade palletized |
| Minimum Order Quantity | 500 kg (negotiable for bulk orders) |
4. Manufacturing Process
4.1 Raw Material Procurement & Inspection
Stainless steel strip is sourced from certified mills with full chemical composition and mechanical property verification. Incoming material undergoes spectrometric analysis (OES — Optical Emission Spectroscopy) to confirm alloy grade conformance prior to processing.
4.2 Precision Coiling Process
- Slitting: Hot-rolled or cold-rolled stainless steel coils are slit to the required strip width with precise edge quality control.
- Edge Trimming & Cleaning: Slit edges are trimmed to remove burrs and contaminants; strips are degreased and chemically cleaned.
- Forming & Seaming: The strip is fed through precision roller-forming dies to create the desired cross-sectional profile (round, oval, or square). The longitudinal seam is formed via high-frequency induction welding (HFW — High-Frequency Welding) or laser welding, achieving weld strength equivalent to the base metal.
- In-Line Annealing: Post-weld annealing at 1050–1150°C in a controlled atmosphere furnace relieves residual stresses, restores ductility, and homogenizes the microstructure.
- Pickling & Passivation: Tubes are subjected to pickling (removal of oxide scale) and passivation (formation of protective chromium oxide layer) to ensure maximum corrosion resistance.
- Coiling & Reeling: The finished tubing is coiled onto precision-machined reels at controlled tension to prevent deformation or ovality.
- Final Inspection & Packaging: Dimensional verification (OD, wall thickness, coil diameter), surface quality assessment, and pressure testing (hydrostatic at 3.0–5.0 MPa) are performed before export-grade packaging.
4.3 Process Advantages
- Continuous production eliminates butt welds, reducing leak points by up to 90% compared to cut-and-welded pipe systems
- High-frequency welding achieves full-penetration welds with minimal heat-affected zone (HAZ)
- Computer-controlled tensioning ensures consistent coil geometry and dimensional accuracy
5. Applications
5.1 Primary Application: HVAC Energy-Saving Systems
The defining application domain for this product is the Fan Coil Unit + Fresh Air System, where stainless steel coil tubes serve as the heat exchange core, enabling the system to function as an energy-efficient alternative to conventional fresh air handling units (AHU — Air Handling Unit). Key performance characteristics in this application include:
- Enhanced Thermal Efficiency: The continuous coil configuration maximizes heat transfer surface area per unit volume, achieving coefficient of performance (COP) improvements of 15–25% over traditional systems
- Reduced Pressure Drop: Smooth inner surface finish (Ra ≤ 0.4 μm) minimizes flow resistance, reducing fan energy consumption
- Corrosion-Free Operation: Eliminates scale buildup and tube degradation in humid or chemically aggressive environments, extending service life to 20+ years
- Hygienic Performance: Non-reactive surface prevents microbial colonization and biofilm formation, ensuring indoor air quality (IAQ) compliance
5.2 Additional Applications
- Industrial Heat Exchangers: Shell-and-tube, plate-fin, and air-cooled heat exchanger assemblies
- Refrigeration & Air Conditioning: Evaporator and condenser coils for commercial and industrial systems
- Chemical Processing: Fluid transport of corrosive media in pharmaceutical, food-grade, and chemical plants
- Automotive Thermal Management: Radiator cores, intercooler tubes, and HVAC ducting for electric and hybrid vehicles
- Medical Equipment: Sterilizable fluid lines and heat exchange components in medical devices
- Building Services: Radiator coils, underfloor heating circuits, and central air distribution systems
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management and compliance framework to ensure product reliability and regulatory adherence:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification covering all manufacturing and supply chain processes |
| ISO 14001:2015 | Environmental Management System certification ensuring sustainable manufacturing practices |
| CE Marking | European Conformity for compliance with EU directives on pressure equipment and machinery safety |
| EN 10217-7 | European standard for stainless steel tubes and pipes for pressure purposes |
| ASTM A269 / ASME SA-269 | American standards for wrought austenitic stainless steel seamless and welded tubing |
| GB/T 12771 | Chinese national standard for stainless steel tubes for general industrial and mechanical use |
| PED 2014/68/EU | Pressure Equipment Directive compliance for applications involving pressurized fluid containment |
| Mill Test Certificates (MTC) | En 10204 Type 3.1 certificates provided for every shipment with full chemical and mechanical analysis |
7. Unique Selling Points
- Energy-Saving Architecture Integration: Purpose-engineered for Fan Coil + Fresh Air System configurations, delivering quantifiable energy savings of 18–30% compared to conventional AHU-based systems — validated through comparative thermodynamic analysis
- Continuous-Coil Integrity: Seamless, joint-free construction eliminates the primary failure mode of traditional segmented pipe systems, ensuring zero-leak performance over extended operational cycles
- Premium Material Selection: Exclusive use of 304/316/316L austenitic stainless steel guarantees exceptional resistance to pitting, crevice, and intergranular corrosion, even in high-humidity HVAC environments
- Precision Dimensional Control: Advanced forming and welding technology achieves tolerances of ±0.05 mm on OD and ±0.02 mm on wall thickness, ensuring optimal fit in heat exchanger assemblies
- Customization Flexibility: Full range of cross-sectional profiles (round, oval, square), dimensions, surface finishes, and coil configurations available to meet specific system design requirements
- Full Traceability: Every coil is traceable from raw material mill to final shipment, supported by digital quality documentation and third-party inspection options
- Sustainability Commitment: ISO 14001-certified manufacturing, recyclable stainless steel construction (100% recyclable at end-of-life), and reduced material waste through continuous production methodology
Note: This technical specification is based on standard product configurations. Custom specifications, non-standard dimensions, and specialized surface treatments are available upon request. All product data is subject to verification through current Mill Test Certificates and third-party laboratory testing.