Stainless Steel Coil Tube (Fan Coil Unit System Application)
Product Overview
The stainless steel coil tube (Coil Tube / Coil Pipe) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular product designed primarily for use in Fan Coil Unit (FCU) systems and HVAC (Heating, Ventilation, and Air Conditioning) applications. This product is formed through advanced coil forming technology, producing a continuous helical or serpentine tube configuration that maximizes heat exchange surface area within a compact footprint. The coil tube serves as a critical component in air-handling systems where efficient thermal transfer between working fluid (water, refrigerant, or glycol solution) and ambient air is required.
Based on the feasibility analysis of terminal parameter determination methods for fresh air in fan coil unit systems, this coil tube product is specifically engineered to maintain precise thermal performance characteristics across varying operating conditions, ensuring that supply air temperature, humidity, and flow rate parameters remain within design specifications.
Material & Properties
Material Grades
- Primary Grade: SUS304 / AISI 304 (18Cr-8Ni) — General purpose corrosion-resistant applications
- Enhanced Grade: SUS316 / AISI 316 (18Cr-10Ni-2Mo) — Enhanced resistance to chlorides and aggressive media
- High-Temperature Grade: SUS321 / AISI 321 (Ti-stabilized) — Applications requiring resistance to sensitization
Key Material Properties
- Thermal Conductivity: 16.3 W/(m·K) at 100°C (SUS304)
- Corrosion Resistance: Excellent resistance to atmospheric, chemical, and aqueous corrosion environments
- Mechanical Strength: Tensile strength ≥ 520 MPa; Yield strength ≥ 205 MPa (annealed condition)
- Temperature Range: Operational range from -196°C to +870°C
- Hygienic Surface: Ra ≤ 0.8 μm (electropolished finish available upon request)
- Non-magnetic: Austenitic structure ensures non-magnetic properties in annealed condition
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 25.0 mm (customizable) | GB/T 12771 / ASTM A554 |
| Wall Thickness | 0.4 mm – 1.5 mm | — |
| Coil Pitch | 10 mm – 30 mm (configurable per thermal design) | — |
| Coil Diameter | 50 mm – 200 mm | — |
| Tube Length per Coil | 0.5 m – 6.0 m (continuous) | — |
| Surface Finish | No. 4 Brushed / 2B Annealed / Electropolished (Ra ≤ 0.4 μm) | GB/T 17395 |
| End Treatment | Plain end / Beveled / Threaded / Flanged | ASME B1.20.1 |
| Working Pressure | ≤ 1.6 MPa (standard); ≤ 4.0 MPa (reinforced) | EN 12163 |
| Heat Transfer Efficiency | U-value: 350 – 600 W/(m²·K) (water-to-air) | ASHRAE Handbook |
| Operating Temperature | -40°C to +250°C | — |
| Material Standard | ASTM A269 / ASTM A213 / GB/T 12771 | — |
| Forming Standard | Custom per OEM drawings | — |
Manufacturing Process
Process Flow
- Raw Material Selection: High-purity stainless steel wire rod or seamless tube stock sourced from certified mills, verified for chemical composition and mechanical properties via spectroscopic analysis and tensile testing.
- Tube Straightening & Cutting: Incoming tube is straightened to ±0.5 mm/m and cut to required lengths with burr-free ends.
- Surface Preparation: Ultrasonic cleaning followed by chemical passivation (nitric acid or citric acid treatment) to remove scale and form a protective chromium oxide layer.
- Precision Coil Forming: CNC-controlled roll-forming machines shape the tube into helical or serpentine configurations with controlled pitch and diameter tolerances (±0.3 mm).
- Welding (if required): Orbital TIG (Tungsten Inert Gas) welding at coil ends or header connections, performed under argon gas shielding with full penetration and minimum porosity.
- Pressure Testing: Hydrostatic pressure test at 1.5× working pressure for minimum 5 minutes to verify structural integrity and weld soundness.
- Final Inspection: Dimensional verification, surface quality assessment, and non-destructive testing (NDT) including dye penetrant inspection (DPI) on welds.
- Packaging: Protective end caps, moisture-absorbent packaging, and labeling with traceability codes for shipment.
Applications
Primary Applications
- Fan Coil Units (FCU): Core heat exchange element in unitary air conditioning systems for commercial and residential buildings
- Air Handling Units (AHU): Cooling and heating coils in centralized HVAC systems
- Chilled Beam Systems: Indirect evaporative cooling and radiant cooling applications
- Heat Recovery Ventilators (HRV): Counter-flow and cross-flow heat exchangers for energy-efficient ventilation
- Industrial Process Cooling: Equipment cooling loops in manufacturing environments requiring hygienic or corrosion-resistant piping
Secondary Applications
- Food and beverage industry — hygienic fluid transfer and pasteurization coils
- Pharmaceutical manufacturing — clean-room HVAC systems and process equipment
- Marine and offshore — corrosion-resistant heat exchangers in humid environments
- Automotive — cabin air conditioning evaporator and condenser assemblies
- Solar thermal systems — heat collection coils in evacuated tube collectors
Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ASME BPV Code — Compliance for pressure-containing components (where applicable)
- CE Marking — European Conformity for machinery and pressure equipment directives
- EN 10204 3.1 — Material test certificates per European standard
- GB/T 12771 — Chinese national standard for seamless stainless steel tubes
- ASTM A269 / A213 — American standards for austenitic stainless steel seamless tubes
- NSF/ANSI 61 — Drinking water system components compliance (food-grade applications)
- Third-Party Inspection: SGS / BV / TUV inspection available upon customer request
Unique Selling Points
- Thermal Performance Optimization: Coil geometry engineered based on terminal parameter analysis methodology, ensuring consistent supply air temperature and humidity control across varying fresh air conditions
- Superior Corrosion Resistance: Stainless steel construction eliminates the risk of internal corrosion and scale buildup, extending service life beyond 20 years in typical HVAC applications
- Hygienic Design: Smooth inner surface (Ra ≤ 0.8 μm) prevents biofilm formation, making the product suitable for pharmaceutical and food-grade HVAC systems
- Customization Capability: Full flexibility in coil pitch, diameter, tube length, and end treatment to meet specific OEM thermal design requirements
- Traceability: Each coil tube batch is accompanied by material certificates, dimensional inspection reports, and pressure test records for complete quality traceability
Note: All specifications are subject to change based on individual project requirements. Wenzhou Jixing Metal Materials Co., Ltd. provides custom engineering support for non-standard coil tube configurations. For detailed technical consultation, please provide specific thermal load requirements, fluid medium, and operating conditions.