Stainless Steel Coil Tube — Coil Tube for Fan Coil Unit Applications
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular component designed primarily for use in Fan Coil Units (FCUs) and hydronic heating, ventilation, and air conditioning (HVAC) systems. The coil tube serves as the core heat exchange element, facilitating efficient thermal transfer between circulating fluid (water or refrigerant) and ambient air. This product is engineered to maximize the Coefficient of Performance (COP) and Energy Efficiency Ratio (EER) of the overall fan coil system, addressing critical industry concerns regarding energy consumption and operational sustainability.
As a continuous-length coiled tube, it eliminates the need for field welding or brazing at installation sites, thereby reducing labor costs, minimizing leak risks, and ensuring long-term system reliability in demanding HVAC environments.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior combination of corrosion resistance, thermal conductivity, mechanical strength, and hygienic properties.
- Material Grade: SUS 304 (ASTM A269 / ASTM A312), with optional SUS 316 (ASTM A312) for enhanced chloride resistance in coastal or chemical environments
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, condensate water, and mild chemical exposure; pitting resistance equivalent number (PREN) ≥ 19 for SUS 304
- Thermal Conductivity: 16.3 W/(m·K) at 20°C, ensuring efficient heat transfer performance in heat exchange applications
- Mechanical Properties: Yield strength ≥ 205 MPa; tensile strength ≥ 515 MPa; elongation ≥ 40%
- Operating Temperature Range: −196°C to +870°C (SUS 304), accommodating extreme thermal cycling
- Hygienic Surface Finish: Ra ≤ 0.5 μm (electropolished or passivated), meeting food-grade and pharmaceutical-grade cleanliness standards
- Non-Magnetic: Austenitic microstructure ensures non-magnetic behavior, suitable for MRI environments and sensitive instrumentation
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Code | 1309 |
| Material | SUS 304 / SUS 316 (ASTM A269, ASTM A312) |
| Outer Diameter (OD) | φ3.0 mm – φ12.7 mm (customizable) |
| Wall Thickness | 0.3 mm – 1.5 mm (customizable) |
| Coil Inner Diameter (ID) | φ100 mm – φ1200 mm (customizable per application) |
| Coil Length | 5 m – 200 m (continuous coil, spooled) |
| Surface Finish | Mirror polished / Electropolished / Passivated / Mill finish |
| Manufacturing Method | Continuous cold coiling (precision spiral winding) |
| End Preparation | Plain end / Beveled / Flanged / Threaded / Brazed fitting |
| Pressure Rating | Up to 1.6 MPa (standard); up to 4.0 MPa (thick-wall specification) |
| Standard Reference | ASTM A269, ASTM A312, GB/T 12771, EN 10217-7 |
| Packaging | Wooden spool / Steel drum with moisture-proof wrapping |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorously controlled multi-stage process to ensure dimensional accuracy, material integrity, and consistent performance:
- Raw Material Procurement: Selection of certified stainless steel strip or seamless tube stock from approved mills, accompanied by full material test certificates (MTC) per EN 10204 Type 3.1.
- Heat Treatment (Solution Annealing): The material is solution-annealed at 1050°C – 1100°C followed by rapid quenching to dissolve carbides and achieve a uniform austenitic microstructure, restoring full corrosion resistance and ductility.
- Precision Cold Coiling: The tube or strip is wound onto a precision mandrel using computer-controlled (CNC) coiling machinery. The winding tension, speed, and pitch are continuously monitored to maintain uniform coil geometry, consistent turn-to-turn spacing, and zero mechanical stress accumulation.
- Surface Treatment: Depending on application requirements, the coil tube undergoes passivation (acid pickling to remove surface contaminants and form a passive chromium oxide layer), electropolishing (for ultra-smooth, hygienic surfaces), or mechanical polishing (for mirror finishes).
- Quality Inspection: Each coil undergoes dimensional verification (OD, wall thickness, coil ID, and pitch), hydrostatic pressure testing (per ASTM A269), visual inspection, and surface roughness measurement. Spectroscopic analysis (OES) confirms chemical composition compliance.
- Packaging and Dispatch: Coils are secured on wooden spools or steel drums, wrapped in moisture-proof film, and labeled with product identification, material grade, heat number, and compliance documentation.
Applications
The stainless steel coil tube is designed for a broad spectrum of high-performance applications, with particular emphasis on HVAC and energy efficiency:
- Fan Coil Units (FCUs): Primary application — the coil tube serves as the heat exchange coil in commercial and residential fan coil units, enabling efficient heating and cooling through optimized fluid-air thermal exchange. The continuous coil design maximizes surface area per unit volume, directly improving the Energy Efficiency Ratio (EER) and Seasonal Energy Efficiency Ratio (SEER) of the system.
- Chilled Water and Hot Water Systems: Used in central air conditioning (CAC) systems, district heating networks, and radiant floor heating systems where long-term corrosion resistance is paramount.
- Refrigeration and Cryogenic Systems: Suitable for low-temperature applications including cold storage, industrial refrigeration, and cryogenic fluid handling, owing to the material's excellent low-temperature toughness.
- Food and Beverage Processing: The hygienic surface finish and non-reactive material make the coil tube ideal for pasteurization, brewing, dairy processing, and pharmaceutical heat exchange equipment.
- Chemical and Petrochemical Industry: SUS 316 grade coils provide resistance to acidic and chloride-containing process fluids in chemical reactors, heat exchangers, and distillation columns.
- Marine and Coastal Applications: Enhanced corrosion resistance in saltwater environments for shipboard HVAC systems, offshore platform utilities, and desalination plants.
Energy Efficiency Considerations
The design and performance of the stainless steel coil tube directly influence the overall energy efficiency of fan coil unit systems. Key factors include:
- Optimized Heat Transfer Area: The continuous coil geometry maximizes the surface-to-volume ratio, reducing the temperature differential required for effective heat exchange and lowering fan and pump power consumption.
- Low Fouling Resistance: The smooth, passivated surface finish minimizes scale and biofilm accumulation, maintaining thermal performance over extended operating cycles and reducing cleaning/maintenance frequency.
- Material Thermal Stability: The consistent thermal conductivity of austenitic stainless steel across the operating temperature range ensures predictable and stable heat transfer coefficients, enabling precise system control and reducing energy waste from thermal lag.
- System Integration: The pre-formed coil design eliminates field joints, reducing thermal bridging losses and improving the overall Seasonal Coefficient of Performance (SCOP) of the HVAC system.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains rigorous quality management systems and product certifications to ensure compliance with international and domestic standards:
- ISO 9001:2015 — Quality Management System certification, ensuring consistent product quality and continuous improvement
- ISO 14001:2015 — Environmental Management System certification, reflecting commitment to sustainable manufacturing practices
- ISO 45001:2018 — Occupational Health and Safety Management System certification
- CE Marking — Compliance with European Union directives for market access
- Material Test Certificates (MTC) — Provided per EN 10204 Type 3.1 for every production batch
- Hydrostatic Testing — Per ASTM A269 / GB/T 12771, with test reports available upon request
- Chemical Composition Verification — Spectroscopic (OES) analysis reports confirming grade compliance
- Third-Party Inspection — Available upon customer request (SGS, Bureau Veritas, TÜV, etc.)
Unique Selling Points
- Continuous Coil Design: Eliminates field welding, reducing installation time, labor costs, and potential leak points by up to 90% compared to segmented tube assemblies.
- Superior Corrosion Longevity: Expected service life exceeding 25 years in standard HVAC environments, significantly outperforming carbon steel alternatives and reducing lifecycle replacement costs.
- Customizable Geometry: Flexible manufacturing capability to produce coils with varying OD, wall thickness, coil ID, and pitch to match specific heat exchanger design requirements.
- Energy Efficiency Optimization: Engineered to maximize EER and SCOP in fan coil unit applications, contributing to lower operational energy costs and reduced carbon footprint.
- Hygienic and Food-Safe: Electropolished and passivated surfaces meet FDA and 3-A sanitary standards, expanding application scope beyond HVAC into food and pharmaceutical processing.
- Full Traceability: Every coil is traceable to its raw material heat number, with complete documentation from mill certificate to final inspection report.