Stainless Steel Coil Tube — Fan Coil Unit (FCU) Integration Series
1. Product Overview
The Stainless Steel Coil Tube (Product No. 1413) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tube product specifically designed for integration into Fan Coil Unit plus Fresh Air (FCU + Fresh Air) systems, particularly under winter operating conditions. This coil tube serves as the core heat exchange element within air-conditioning terminal units, facilitating efficient thermal transfer between the circulating refrigerant/heat-transfer medium and the ambient air stream.
The product is engineered to withstand the demanding thermal cycling and condensation challenges inherent in winter-mode HVAC (Heating, Ventilation, and Air Conditioning) operations, where the coil must simultaneously deliver sensible and latent heat while maintaining structural integrity under variable flow conditions.
2. Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior corrosion resistance, mechanical strength, and thermal conductivity — critical attributes for long-term service in HVAC environments where moisture, condensate, and chemical contaminants are prevalent.
- Base Material: Austenitic stainless steel (typical grades: SUS304 / SUS316L equivalent)
- Corrosion Resistance: Excellent resistance to chloride-induced pitting and general atmospheric corrosion
- Thermal Conductivity: Optimized for efficient heat exchange at both heating and cooling duty cycles
- Mechanical Strength: Maintains dimensional stability under thermal expansion and contraction
- Hygienic Surface: Smooth inner and outer surfaces minimize fouling and facilitate cleaning
- Non-magnetic: Austenitic structure ensures non-magnetic properties
- Temperature Range: Operational from -40 °C to +200 °C without loss of mechanical integrity
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管) |
| Product Code | 1413 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Material Grade | SUS304 / SUS316L (Austenitic Stainless Steel) |
| Tube Outer Diameter (OD) | 6.35 mm – 15.88 mm (standard series available) |
| Wall Thickness | 0.4 mm – 1.0 mm |
| Coil Diameter | Customizable per HVAC design requirement |
| Fin Pitch | 2.0 mm – 4.0 mm (adjustable for heat transfer optimization) |
| Maximum Operating Pressure | ≤ 1.6 MPa (gauge) |
| Operating Temperature Range | -40 °C to +200 °C |
| Surface Finish | 2B / BA (Bright Annealed) / Custom |
| Connection Type | Flanged, threaded, or soldered (per application) |
| Compliance Standards | GB/T, ASTM, EN, JIS |
4. Manufacturing Process
The coil tube undergoes a rigorous multi-stage manufacturing process to ensure dimensional accuracy, surface quality, and metallurgical integrity:
- Material Selection & Inspection: Certified stainless steel strip/tube stock is selected and subjected to incoming quality control, including spectrographic analysis and mechanical testing.
- Coil Winding: Precision CNC-controlled winding machinery forms the tube into the required coil geometry with controlled inter-pass spacing to optimize airflow distribution and heat transfer efficiency.
- Fin Attachment: Aluminum or copper fins are mechanically or brazed onto the tube surface to maximize the effective heat exchange area, critical for winter-mode latent heat removal.
- Brazing & Sealing: End connections and header assemblies are brazed under controlled atmospheric conditions to ensure leak-tight joints capable of withstanding system pressure cycles.
- Hydrostatic Pressure Testing: Each coil assembly undergoes 100% hydrostatic testing at 1.5× the maximum operating pressure to verify structural integrity and weld soundness.
- Surface Treatment: Optional passivation and polishing treatments are applied to enhance corrosion resistance and maintain a hygienic surface condition.
- Final Inspection & Certification: Dimensional verification, visual inspection, and functional performance testing are conducted prior to shipment, accompanied by full material traceability documentation.
5. Applications
The coil tube is purpose-designed for the following application domains:
- Fan Coil Unit + Fresh Air Systems (Winter Operation): Primary application — serving as the heating and dehumidification element in commercial and residential HVAC terminal units during winter conditions, where precise temperature and humidity control is required.
- Commercial Building HVAC: Office buildings, hotels, hospitals, and educational facilities requiring year-round climate control with seasonal mode switching.
- Industrial Process Cooling/Heating: Temperature regulation in manufacturing environments where corrosion resistance is critical.
- Food Processing & Pharmaceutical Facilities: Hygienic-grade applications demanding cleanable, non-contaminating heat exchange surfaces.
- Marine & Coastal Environments: SUS316L grade coils for applications exposed to salt-laden atmospheres.
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product conformity to international and national standards:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001 — Environmental Management System
- CE Marking — Conformity with European health, safety, and environmental protection standards
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- ASTM A269 / A270 — American standards for austenitic stainless steel tubing
- EN 10217 — European standard for stainless steel tubes for pressure purposes
- JIS G3459 — Japanese Industrial Standard for austenitic stainless steel tubes
7. Unique Selling Points
Winter-Mode Optimization: The coil tube design is specifically validated for the complex thermodynamic conditions of winter HVAC operation — including simultaneous heating, dehumidification, and fresh air integration — ensuring stable performance across the full seasonal operating envelope.
- Superior Corrosion Durability: Stainless steel construction eliminates the risk of internal/external corrosion common in carbon steel alternatives, extending service life beyond 20 years with minimal maintenance.
- Hygienic & Food-Safe: Smooth, non-porous surfaces prevent microbial growth and biofilm formation — essential for pharmaceutical, food, and healthcare applications.
- Thermal Cycling Resilience: Engineered to withstand repeated heating and cooling cycles without fatigue failure, maintaining dimensional accuracy and heat transfer performance over the product lifecycle.
- Custom Engineering: Full design flexibility in coil diameter, fin configuration, tube layout, and connection types to match specific HVAC system architectures.
- Full Traceability: Each product batch is accompanied by material certificates (MTC), heat treatment records, and non-destructive testing (NDT) reports ensuring complete supply chain transparency.