Stainless Steel Coil Tube for HVAC Fan Coil Unit (FCU) Applications
Product Overview
The stainless steel coil tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing product specifically designed for use in Heating, Ventilation, and Air Conditioning (HVAC) systems, with particular emphasis on Fan Coil Units (FCUs). These coil tubes serve as the core heat exchange elements within fan coil units, facilitating efficient thermal transfer between circulating refrigerant or hot water and the ambient air stream. The product is available in a pre-coiled configuration, eliminating the need for on-site bending and reducing installation labor and time.
Stainless steel coil tubes represent a significant advancement over traditional copper and aluminum coil tubes in HVAC applications due to their superior corrosion resistance, extended service life, and compliance with stringent hygiene standards. The coiled geometry maximizes the heat transfer surface area within a compact footprint, making it ideal for space-constrained installations in commercial buildings, hospitals, hotels, and industrial facilities.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, primarily conforming to the following material specifications:
- Grade 304 (UNS S30400): The most commonly specified grade, offering excellent general-purpose corrosion resistance, good formability, and weldability. Suitable for standard HVAC applications involving water-based heat transfer fluids.
- Grade 316 (UNS S31600): Contains 2–3% molybdenum, providing enhanced resistance to pitting and crevice corrosion, particularly in chloride-rich environments or where aggressive cleaning agents are used.
- Grade 316L (UNS S31603): Low-carbon variant of 316, preferred for welded assemblies requiring excellent resistance to intergranular corrosion.
Key Material Properties:
- Non-magnetic (in annealed condition)
- High resistance to oxidation and scaling at elevated temperatures
- Excellent hygienic properties — smooth surface prevents bacterial adhesion, compliant with sanitary standards
- Thermal conductivity: approximately 16.3 W/(m·K) for Grade 304
- Thermal expansion coefficient: approximately 17.3 × 10⁻⁶ /°C
- Non-toxic and environmentally recyclable
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) for FCU |
| Item No. | 462 |
| Material Grade | 304 / 304L / 316 / 316L (per customer requirement) |
| Outer Diameter (OD) | 6.35 mm – 25.4 mm (¼" – 1") |
| Wall Thickness | 0.5 mm – 2.0 mm |
| Coil Diameter | Customizable; typically 150 mm – 600 mm |
| Coil Length | Customizable per project requirement |
| Surface Finish | Ba & E (Bright & Annealed), No. 4 Finish, or Mirror Polish |
| Tolerance (OD) | ±0.1 mm |
| Tolerance (Wall Thickness) | ±10% |
| Standards | ASTM A213, ASTM A269, EN 10217-7, GB/T 14976 |
| Operating Temperature Range | -196 °C to +450 °C (Grade 304); -196 °C to +425 °C (Grade 316) |
| Maximum Operating Pressure | Dependent on OD, wall thickness, and grade; typically up to 2.5 MPa |
| Connection Type | Flared, Soldered, Brazed, or Welded (per application) |
| Packaging | Export-grade wooden crates or bundled with protective wrapping |
Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorous, multi-stage manufacturing process to ensure dimensional accuracy, material integrity, and surface quality:
- Raw Material Selection: High-purity stainless steel wire rod is sourced from certified mills, with chemical composition verified through spectrometric analysis to ensure conformance to specified ASTM or EN grades.
- Tube Drawing: The wire rod is formed into seamless tube blanks through cold drawing or hot forming processes, ensuring uniform wall thickness and precise outer diameter throughout the tube length.
- Pipe Annealing: Drawn tubes undergo solution annealing in a controlled atmosphere furnace to relieve residual stresses, restore ductility, and achieve the desired grain structure and mechanical properties.
- Surface Treatment: Tubes are acid-pickled and passivated to remove scale, oxides, and contaminants, followed by the application of a protective chromium oxide passive film that enhances corrosion resistance.
- Precision Coiling: Tubes are coiled using CNC-controlled coiling machines to achieve the specified coil diameter, pitch, and turn count with high repeatability. The coiling process is carefully controlled to prevent kinking, flattening, or ovality distortion.
- End Forming: Tube ends may be pre-flared, beveled, or threaded depending on the intended connection method in the fan coil unit assembly.
- Quality Inspection: Each batch undergoes dimensional inspection, hydrostatic pressure testing, visual examination, and, where required, chemical and mechanical property verification.
Applications
Stainless steel coil tubes for fan coil units find extensive application across multiple sectors:
- Commercial HVAC Systems: Chilled water and hot water coil tubes in fan coil units for office buildings, shopping malls, and retail spaces, providing precise temperature and humidity control.
- Hospital and Medical Facilities: Hygienic-grade coil tubes in cleanroom HVAC systems, operating theater air handling units, and pharmaceutical manufacturing environments where microbial control is critical.
- Food and Beverage Industry: Coil tubes in refrigeration systems and process cooling loops where contact with food-grade fluids demands non-toxic, corrosion-resistant materials.
- Hotel and Hospitality: Fan coil units in guest rooms and public areas, where the silent operation of stainless steel coils and long service life minimize maintenance disruptions.
- Industrial Applications: Heat exchangers in chemical processing, semiconductor manufacturing, and electronics cooling systems where aggressive media or high-purity requirements are present.
- Residential HVAC: Premium-grade fan coil units for high-end residential installations where durability and low lifecycle cost are prioritized.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that every coil tube product meets international standards:
- ISO 9001:2015 — Quality Management System certification, ensuring consistent product quality and process control throughout manufacturing.
- ISO 14001 — Environmental Management System certification, demonstrating commitment to sustainable and environmentally responsible production practices.
- CE Marking — Compliance with European Union directives for safety, health, and environmental protection requirements.
- Material Certification: Full chemical composition and mechanical property test reports provided for each batch, traceable to the mill certificate of the raw material.
- Hydrostatic Testing: All tubes undergo 100% hydrostatic pressure testing to verify weld integrity and structural soundness.
- Third-Party Inspection: Products available for inspection by recognized third-party agencies including SGS, BV (Bureau Veritas), and TÜV upon customer request.
Unique Selling Points
- Superior Corrosion Resistance: Unlike copper or carbon steel alternatives, stainless steel coil tubes exhibit exceptional resistance to corrosion from condensation, chemical cleaning agents, and humid environments, significantly extending the service life of fan coil units beyond 20 years.
- Hygienic Surface: The smooth, non-porous surface of annealed stainless steel prevents biofilm formation and bacterial growth, making these coils ideal for healthcare and food-grade applications without additional lining or coating.
- Pre-Coiled Configuration: Delivered in ready-to-install coiled form, reducing on-site fabrication time, minimizing labor costs, and ensuring consistent coil geometry that optimizes airflow distribution and heat transfer efficiency.
- Environmental Sustainability: Stainless steel is 100% recyclable with no loss of material properties. The long service life reduces replacement frequency and associated waste, contributing to lower lifecycle carbon footprint.
- Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd. offers full customization of tube diameter, wall thickness, coil dimensions, surface finish, and end treatments to meet specific fan coil unit design requirements.
- Thermal Stability: Maintains mechanical integrity and dimensional stability across the full HVAC operating temperature range, resisting thermal fatigue that can compromise less robust materials over time.
Note: All specifications are subject to verification against the latest product data sheets provided by Wenzhou Jixing Metal Materials Co., Ltd. Customers are advised to specify exact requirements during the ordering process to ensure optimal product-performance alignment for their specific fan coil unit and HVAC system design.