Stainless Steel Coil Tube for HVAC Fan Coil Unit Systems
1. Product Overview
The Stainless Steel Coil Tube (SSCT) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing product specifically designed for integration into Fan Coil Unit (FCU) and Fresh Air Air Conditioning Systems. As a critical heat exchange component, this coil tube serves as the core medium for thermal energy transfer within distributed HVAC (Heating, Ventilation, and Air Conditioning) architectures. The product is supplied in continuous coil form, enabling seamless fabrication into serpentine heat exchangers, evaporator coils, and condenser assemblies commonly found in commercial and industrial air conditioning installations.
Compliant with the design methodology outlined in "Design Methods for Fan Coil Unit with Fresh Air Air Conditioning Systems", this coil tube is engineered to optimize thermal efficiency, minimize pressure drop, and ensure long-term operational reliability under cyclic thermal loading conditions typical of HVAC environments.
2. Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior corrosion resistance, thermal conductivity, and mechanical integrity under repeated heating and cooling cycles.
- Grade Options: AISI 304 (UNS S30400), AISI 316 (UNS S31600), and 316L (UNS S31603) — the latter recommended for high-chloride environments.
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, deionized water, and refrigerant fluids (R-134a, R-410A, R-22).
- Operating Temperature Range: −40°C to +250°C (−40°F to +482°F), suitable for both heating and cooling service.
- Thermal Conductivity: 14–16 W/(m·K) at 20°C, ensuring efficient heat transfer between the working fluid and ambient air.
- Mechanical Properties: Tensile strength ≥ 520 MPa; elongation ≥ 40%; yield strength ≥ 205 MPa.
- Surface Finish: Electropolished or passivated finish with surface roughness Ra ≤ 0.4 μm, facilitating fluid flow and reducing fouling.
3. Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | Ø 6.35 mm (¼"), Ø 9.53 mm (⅜"), Ø 12.7 mm (½") | ASME B36.19M |
| Wall Thickness | 0.5 mm – 1.2 mm (customizable) | ASTM A269 / A270 |
| Coil Diameter | 100 mm – 500 mm (customizable per application) | — |
| Coil Length | Up to 200 m per continuous coil | — |
| Manufacturing Method | Seamless (cold-drawn) or Welded (TIG/Orbital) | ASTM A213 |
| End Condition | Cut-to-length, chamfered, or formed (bent to specified geometry) | — |
| Surface Treatment | Electropolished / Passivated / Mirror Finish | ASTM A967 |
| Pressure Rating | Up to 4.0 MPa (580 psi) at operating temperature | ASME BPV Code |
| Compliance | EN 10216-5, ISO 3506, JIS G3459 | — |
| Packaging | Wooden pallet, VCI (Vapor Corrosion Inhibitor) wrapped, desiccant sealed | ISO 14617 |
4. Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorously controlled multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: Certified stainless steel strip or seamless tube stock is sourced from accredited mills with full traceability documentation (Mill Test Reports, MTRs).
- Coiling & Forming: Precision CNC-controlled coiling machines wind the tube into specified diameters with controlled springback compensation, maintaining uniform bend radius and eliminating plastic deformation or wall thinning.
- Welding (if applicable): Orbital TIG (Tungsten Inert Gas) welding is employed for longitudinal seam fabrication, utilizing high-purity argon shielding to prevent oxidation and ensure weld integrity.
- Heat Treatment: Solution annealing at 1050–1150°C followed by controlled cooling to achieve uniform austenitic microstructure and relieve residual stresses.
- Surface Finishing: Electropolishing removes surface contaminants and creates a passive chromium oxide layer, enhancing corrosion resistance and reducing microbial adhesion.
- Quality Inspection: 100% dimensional verification via laser measurement; helical ultrasonic testing (UT) for internal defects; hydrostatic pressure testing at 1.5× working pressure; visual and dye penetrant inspection of welds.
- Packaging & Shipping: Coils are secured on protective wooden pallets with anti-corrosion wrapping to ensure delivery in pristine condition.
5. Applications
The Stainless Steel Coil Tube is purpose-engineered for the following application domains:
- Commercial HVAC Systems: Primary heat exchange element in Fan Coil Units (FCUs), air handling units (AHUs), and rooftop packaged units for office buildings, hotels, and retail spaces.
- Fresh Air Systems: Integral component in ventilation coils within fresh air handling units, enabling precise temperature and humidity control in occupied zones.
- Industrial Process Cooling/Heating: Chilled water coils for process equipment in food processing, pharmaceutical manufacturing, and chemical plants.
- Domestic & Residential HVAC: Underfloor heating coil loops and split-system condenser/evaporator assemblies.
- Marine & Offshore Applications: Corrosion-resistant heat exchanger coils in marine HVAC systems where saltwater exposure demands 316/316L grade stainless steel.
- Cleanroom Environments: Low-particulate coil assemblies for pharmaceutical and semiconductor facility HVAC, benefiting from the electropolished surface finish.
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality assurance framework ensuring that every coil tube batch meets international and industry-specific standards:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing processes.
- ISO 14001:2015 — Environmental Management System ensuring sustainable production practices.
- EN 10204 3.1 — Full third-party inspection certificates available upon request.
- ASTM A269 / A270 / A213 — Compliance with American standards for welded and seamless stainless steel tubing.
- ASME BPV Code Section I — Pressure vessel and heat exchanger component certification.
- CE Marking (EU) — Conformity with European directives for pressure equipment (PED 2014/68/EU).
- HACCP / FDA Compliant — Suitable for food-grade and pharmaceutical applications.
- Third-Party Testing: Available through SGS, BV (Bureau Veritas), and TÜV for independent verification.
7. Unique Selling Points
Optimized for HVAC Thermal Performance: Engineered specifically for fan coil unit and fresh air system integration, with geometry and material properties calibrated to minimize ΔP (pressure drop) while maximizing heat transfer coefficients (U-value).
- Customizable Coil Geometry: Flexible manufacturing capability allows bespoke coil diameters, lengths, and bend configurations tailored to specific AHU or FCU design layouts.
- Extended Service Life: Austenitic stainless steel construction provides 20–30 year operational lifespan under normal HVAC duty cycles, significantly outperforming copper or carbon steel alternatives in corrosive environments.
- Low Maintenance: Passivated surface finish resists scaling, biofilm formation, and chemical degradation, reducing cleaning frequency and total cost of ownership (TCO).
- Full Traceability: Every coil batch is traceable to mill origin with complete material certification, ensuring compliance with regulatory and project-specific documentation requirements.
- Scalable Supply: Manufacturing capacity supports both prototype orders and large-scale project supply for commercial HVAC installations.