Stainless Steel Coil Tube (Coiltube) — HVAC Fan Coil System Application
Product Overview
The Stainless Steel Coil Tube (Model Series: Coiltube, Catalog No. 1121) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular component designed for use in air conditioning and HVAC (Heating, Ventilation, and Air Conditioning) fan coil systems. This coiltube is formed into a serpentine or helical configuration, serving as the primary heat exchange medium within fan coil units (FCUs) deployed in commercial, industrial, and residential environments.
The product is specifically engineered to optimize thermal performance under partial load conditions, where conventional systems often suffer from reduced efficiency and excessive energy consumption. By leveraging the superior corrosion resistance and thermal conductivity of stainless steel, this coiltube ensures long-term operational reliability and energy savings throughout its service life.
Material & Properties
The coil tube is fabricated from high-grade stainless steel, selected for its exceptional combination of mechanical strength, corrosion resistance, and thermal transfer characteristics.
- Primary Material: Austenitic stainless steel (e.g., SUS304 / ASTM A269 Grade 304), offering excellent resistance to atmospheric and chemical corrosion.
- Alternative Grades: SUS316 / ASTM A269 Grade 316 available for aggressive chemical environments or marine applications.
- Thermal Conductivity: Approximately 14–16 W/(m·K) at 20°C, providing efficient heat dissipation in cooling and heating cycles.
- Operating Temperature Range: −40°C to +150°C, suitable for both refrigeration and hot water heating applications.
- Surface Finish: Electro-polished or passivated interior and exterior surfaces to minimize fouling and reduce hydraulic resistance.
- Corrosion Resistance: Superior resistance to chlorides, condensate, and microbial growth compared to carbon steel alternatives.
- Hygienic Compliance: Smooth inner bore eliminates dead zones, preventing biofilm accumulation and ensuring sanitary fluid transport.
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Catalog No. | 1121 |
| Material Grade | SUS304 / SUS316 (ASTM A269) |
| Outer Diameter (OD) | 9.52 mm / 12.7 mm / 15.88 mm (3/8", 1/2", 5/8") |
| Wall Thickness | 0.5 mm – 1.0 mm |
| Tube Length (Per Coil) | 2 m – 12 m (customizable) |
| Coil Pitch | 10 mm – 25 mm (adjustable per design requirements) |
| Number of Rows | 2-row, 3-row, or 4-row configurations |
| Fin Type (if finned) | Aluminum or stainless steel corrugated fins |
| Fin Density | 10 FPI – 16 FPI (Fins Per Inch) |
| Operating Pressure | Up to 1.6 MPa (232 psi) |
| Maximum Flow Rate | Dependent on OD and configuration; typically 0.5–5.0 L/min |
| End Connection | Flared, brazed, or threaded fittings |
| Surface Treatment | Electro-polishing / Passivation / Chemical cleaning |
| Applicable Refrigerants | R-134a, R-410A, R-32, R-407C, R-22 |
| Applicable Fluids | Chilled water, hot water, glycol solutions |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, structural integrity, and surface quality:
- Raw Material Selection: Cold-rolled stainless steel strips conforming to ASTM A269 / GB/T 14976 standards are inspected for chemical composition and mechanical properties prior to processing.
- Pipe Forming: Precision roll-forming machines convert flat strip into seamless tubular stock with controlled wall thickness and roundness tolerance (±0.05 mm).
- Coil Bending: The formed tube is bent into the designated serpentine or helical coil geometry using CNC-controlled bending equipment, ensuring uniform bend radii and minimizing wall thinning.
- Fin Attachment (if applicable): Corrugated aluminum or stainless steel fins are mechanically expanded onto the tube surface through a hydraulic fin-expanding process, achieving tight thermal contact.
- Hydrostatic Testing: Each coil assembly undergoes pressure testing at 1.5× the maximum operating pressure to verify leak-tightness and structural soundness.
- Surface Finishing: Electro-polishing or passivation treatment is applied to remove surface contaminants, reduce roughness to Ra ≤ 0.4 μm, and enhance corrosion resistance.
- Final Inspection: Visual examination, dimensional verification, and non-destructive testing (NDT) confirm compliance with all quality benchmarks.
Applications
The stainless steel coil tube is integral to a wide range of thermal management systems, particularly in scenarios demanding high efficiency under variable and partial load conditions:
- Fan Coil Units (FCUs): Primary heat exchanger element in both cooling and heating modes for commercial buildings, hotels, hospitals, and residential complexes.
- Chiller Systems: Evaporator and condenser coils in centrifugal, screw, and rotary chillers.
- VRF/VRV Systems: Indoor unit coils in Variable Refrigerant Flow systems for zoned climate control.
- Industrial Process Cooling: Heat exchangers in chemical processing, food and beverage production, and pharmaceutical manufacturing.
- Marine HVAC: Corrosion-resistant coil assemblies for shipboard air conditioning and refrigeration.
- Heat Recovery Systems: Coils in energy recovery ventilators (ERV) and heat exchanger air handlers.
Energy Efficiency Under Partial Load: Research published in HVAC engineering literature confirms that fan coil systems operating under partial load conditions can achieve significant energy savings when equipped with high-performance stainless steel coil tubes. The superior thermal conductivity and reduced fouling factor of stainless steel coils maintain a higher coefficient of performance (COP) even at 30%–70% capacity, compared to traditional copper or carbon steel alternatives. This is particularly relevant for buildings with fluctuating thermal loads, such as office complexes and retail spaces.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd adheres to internationally recognized quality management and product standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent production quality and process control.
- ASTM A269 / A270 — Compliance with American standards for seamless and welded austenitic stainless steel tubing.
- GB/T 14976 — Chinese national standard for cold-rolled stainless steel seamless tubes.
- EN 10216-5 — European standard for welded stainless steel tubes for general engineering purposes.
- ASME B31.5 — Adherence to pressure piping and piping components code requirements.
- RoHS Compliance — Restriction of Hazardous Substances directive compliance for environmentally responsible manufacturing.
- Mill Test Certificates (MTC) — Each batch accompanied by EN 10204 3.1 material certification documenting chemical analysis and mechanical test results.
Unique Selling Points
- Extended Service Life: Stainless steel construction provides 2–3× the service life of copper coil alternatives in corrosive environments, reducing lifecycle replacement costs.
- Partial Load Optimization: Engineered for sustained thermal efficiency at reduced operating capacity, directly addressing the energy waste identified in HVAC partial-load operation studies.
- Hygienic Interior Surface: Electro-polished bore eliminates microbial growth pathways, making the product suitable for food-grade and pharmaceutical applications.
- Customizable Geometry: Flexible coil pitch, row count, and overall dimensions allow OEM integration into diverse system architectures.
- Reduced Hydraulic Resistance: Smooth inner surface lowers pressure drop across the coil, reducing pump energy consumption in hydronic systems.
- Environmental Sustainability: Stainless steel is 100% recyclable, and the extended product lifespan minimizes material waste over the building's lifecycle.