Stainless Steel Coil Tube (Coiltube) for Fan Coil Unit Systems
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered heat exchanger component designed primarily for Fan Coil Unit (FCU) systems in commercial and industrial HVAC (Heating, Ventilation, and Air Conditioning) applications. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product represents an advanced solution for thermal energy transfer, offering superior corrosion resistance, extended service life, and high thermal efficiency compared to conventional copper or carbon steel coil alternatives.
The coil tube is fabricated from high-grade austenitic stainless steel tubing, cold-formed into serpentine or spiral configurations to maximize surface area and optimize heat exchange performance within compact installation envelopes. This product is specifically engineered to meet the rigorous demands of chilled water cooling and hot water heating circuits in modern building climate control systems.
Material & Properties
The Coil Tube is constructed from premium austenitic stainless steel, providing exceptional mechanical integrity and chemical resistance across a wide range of operating conditions.
- Base Material: Austenitic Stainless Steel (304 / 316L grade available)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, condensate, and moderate chemical exposure; 316L grade offers enhanced pitting and crevice corrosion resistance for aggressive environments
- Thermal Conductivity: 14–16 W/(m·K) at 20°C — sufficient for efficient heat exchange in HVAC duty cycles
- Operating Temperature Range: −196°C to +870°C (304 grade); −273°C to +870°C (316L grade)
- Mechanical Properties: Tensile strength ≥ 520 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%
- Hygienic Performance: Non-toxic, non-contaminating surface suitable for potable water contact and food-grade environments
- Longevity: Design service life exceeding 25 years under normal operating conditions without degradation of thermal performance
Technical Specifications
| Parameter | Specification |
|---|---|
| Tube Material | Austenitic Stainless Steel (ASTM A270 / EN 10217-7) |
| Available Grades | 304 (0Cr18Ni9), 316L (00Cr17Ni14Mo2) |
| Tube Outer Diameter (OD) | 6.35 mm / 8.00 mm / 9.53 mm / 12.00 mm (custom available) |
| Tube Wall Thickness | 0.50 mm – 1.20 mm |
| Coil Pitch (Center-to-Center Spacing) | 15.0 mm – 25.0 mm |
| Number of Rows | 1 to 8 rows (configurable) |
| Coil Height | 150 mm – 600 mm (custom fabrication available) |
| Coil Width | 300 mm – 1200 mm |
| Fin Material | Aluminum (standard); Stainless Steel fins (optional) |
| Fin Density | 10 FPI – 14 FPI (Fins Per Inch) |
| Fin Thickness | 0.10 mm – 0.15 mm |
| Hydraulic Pressure Rating | 1.0 MPa – 2.5 MPa (working pressure) |
| Pressure Test | 1.5× working pressure, 30-minute hold with zero leakage |
| Cooling Capacity Range | 1.5 kW – 25.0 kW (dependent on configuration) |
| Heating Capacity Range | 1.0 kW – 20.0 kW |
| Flow Rate | 0.2 L/s – 3.5 L/s |
| Connection Type | Flare, threaded (G1/2" – G1"), or brazed headers |
| Surface Treatment | Polished interior; passivated exterior (optional coating available) |
| Weight | 2.5 kg – 18.0 kg (depending on dimensions) |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing protocol ensuring dimensional accuracy, structural integrity, and consistent thermal performance:
- Material Procurement and Inspection: Raw stainless steel tubing is sourced from certified mills and subjected to spectroscopic analysis to verify chemical composition compliance with ASTM A270 / EN 10217-7 standards.
- Tube Straightening and Cutting: Incoming tubing is straightened using a rotary straightening machine and cut to precise lengths using high-precision sawing equipment with tolerance of ±0.5 mm.
- Cold Bending (Coiling): Tubes are cold-bent into the required serpentine or spiral configuration using CNC-controlled bending machines. Bending radii are maintained at a minimum of 3× tube diameter to prevent wall thinning and stress concentration.
- Fin Insertion: Aluminum or stainless steel fins are inserted between tube rows using a fin-insertion machine, ensuring uniform fin spacing and minimal tube-fin contact resistance.
- Fin-Tube Bonding: The coil assembly undergoes a bonding process (mechanical crimping or low-temperature brazing) to establish thermal continuity between fins and tubes while maintaining structural rigidity.
- Header Fabrication: Inlet and outlet headers are fabricated and welded to the coil ends using TIG (Tungsten Inert Gas) welding under argon shielding to prevent oxidation.
- Hydrostatic Pressure Testing: Each coil unit is pressure-tested at 1.5× the rated working pressure for a minimum of 30 minutes to verify zero leakage and structural soundness.
- Surface Finishing and Passivation: Exterior surfaces are polished and chemically passivated to enhance corrosion resistance and ensure a hygienic surface finish.
- Final Inspection and Packaging: Completed units undergo dimensional verification, visual inspection, and performance data documentation before protective packaging for shipment.
Applications
The Stainless Steel Coil Tube is engineered for versatile deployment across multiple HVAC and thermal management sectors:
- Commercial HVAC Systems: Primary heat exchanger in Fan Coil Units (FCUs) for office buildings, hotels, hospitals, and shopping centers — handling both chilled water cooling and hot water heating duties.
- Residential Climate Control: Integration into compact FCU packages for high-end residential applications requiring silent, efficient, and maintenance-free thermal conditioning.
- Industrial Process Cooling: Application in process air conditioning systems for electronics manufacturing, pharmaceutical cleanrooms, and data centers where corrosion resistance is critical.
- Food and Beverage Industry: Use in hygienic air handling systems for food processing plants, breweries, and dairy facilities where product safety and sanitary standards are paramount.
- Marine and Offshore Environments: Deployment in HVAC systems for ships, offshore platforms, and coastal facilities where high humidity and salt spray demand superior corrosion resistance.
- Chilled Water Distribution Systems: Integration into Variable Air Volume (VAV) terminal units and constant volume systems for large-scale commercial buildings.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring every Coil Tube product meets international standards:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing quality and process control
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices
- CE Marking — Compliance with European directives for machinery and pressure equipment safety
- EN 1283 — Conformity with European standard for heat exchangers for HVAC and refrigeration applications
- ASHRAE Standards — Performance data validated against ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) test procedures
- ASTM A270 — Material compliance with American standard for seamless austenitic stainless steel tubing
- GB/T 14976 — Compliance with Chinese national standard for seamless stainless steel tubes
- Hydrostatic Testing Report — Individual test certificates provided for each production batch confirming pressure integrity
Unique Selling Points
Superior Corrosion Resistance: Unlike conventional copper coil tubes, the stainless steel construction eliminates the risk of galvanic corrosion when in contact with aluminum fins, extending service life significantly in humid and aggressive environments.
Hygienic and Food-Grade Safe: The austenitic stainless steel surface is non-toxic, non-reactive, and easily sanitized — making it the ideal choice for food processing, pharmaceutical, and medical facility applications.
Long Service Life: Designed for a minimum 25-year operational lifespan with no degradation of thermal transfer efficiency, reducing total cost of ownership (TCO) over the system lifecycle.
Customizable Configurations: Flexible manufacturing capability allows tailoring of coil dimensions, row configurations, and connection types to meet specific project requirements and OEM specifications.
Environmental Sustainability: Stainless steel is 100% recyclable, and the extended service life reduces material waste and replacement frequency compared to shorter-lived alternatives.
Selection Guidelines for Fan Coil Unit Integration
When selecting the appropriate Coil Tube configuration for a Fan Coil Unit system, the following engineering considerations should be observed:
- Thermal Load Calculation: Determine the peak cooling and heating loads for the served zone, accounting for solar gains, internal heat gains, and infiltration rates.
- Water Side Parameters: Specify supply and return water temperatures (typically 6°C/12°C for cooling; 45°C/40°C for heating) to ensure proper coil sizing.
- Air Side Parameters: Define air flow rates, entering air dry-bulb and wet-bulb temperatures, and desired leaving air conditions.
- Row Selection: For cooling-dominated applications, 2-row or 4-row configurations provide optimal performance; for heating-only or balanced applications, 1-row or 2-row configurations suffice.
- Corrosion Environment Assessment: Select 316L grade for coastal, chemical, or marine environments; 304 grade is adequate for standard indoor commercial applications.
- Physical Space Constraints: Verify that coil dimensions (height, width, depth) are compatible with the FCU housing and installation location.
This technical specification document is intended for professional reference by HVAC engineers, system integrators, and procurement specialists. All specifications are subject to verification against the latest product datasheet issued by Wenzhou Jixing Metal Materials Co., Ltd.