Stainless Steel Coil Tube (Coil Tube) — FP-68LMZC Fan Coil Unit Application Series
Product Overview
The Stainless Steel Coil Tube (Coil Tube) is a precision-engineered, continuously formed tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 833). This coil tube is specifically designed for integration into FP-68LMZC Fan Coil Units (FCU), serving as the primary heat exchange medium in commercial and residential HVAC (Heating, Ventilation, and Air Conditioning) systems. The coil tube is supplied in continuous coil form, enabling efficient downstream processing such as bending, cutting, and forming into serpentine or double-row configurations optimized for air-side heat transfer performance.
As a critical component within the fan coil unit assembly, the stainless steel coil tube provides superior corrosion resistance, thermal conductivity, and mechanical durability compared to conventional carbon steel or copper alternatives, making it ideal for demanding indoor air handling applications.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, typically conforming to the following material specifications:
- Base Material: AISI 304 / AISI 316L (ASTM A269 / ASTM A213)
- Alloy Designation: S30408 (304) or S31603 (316L)
- Key Alloying Elements: Chromium (Cr) 18–20%, Nickel (Ni) 8–10.5%, Molybdenum (Mo) 2–3% for 316L grade
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, condensate water, and mild chemical exposure in HVAC environments
- Thermal Conductivity: 16.3 W/(m·K) at 300 K (AISI 304)
- Operating Temperature Range: −196 °C to +870 °C (continuous service)
- Surface Finish: 2B cold-rolled finish or No. 4 brushed finish; available in mirror polish upon request
- Mechanical Properties: Tensile Strength ≥ 520 MPa; Yield Strength ≥ 205 MPa; Elongation ≥ 40%
Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (Coil Tube) | — |
| Product Number | 833 | — |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. | — |
| Outer Diameter (OD) | 6.35 mm / 8.00 mm / 9.53 mm (1/4" / 5/16" / 3/8") | ASTM A269 / GB/T 12771 |
| Wall Thickness | 0.30 mm – 1.00 mm (selectable) | ASTM A269 |
| Coil Inner Diameter (ID) | 150 mm – 600 mm (configurable) | — |
| Coil Length | 50 m – 500 m per coil (standard) | — | Dimensional Tolerance | OD: ±0.10 mm; Wall Thickness: ±0.05 mm | ASTM A269 / EN 10217 |
| Welding Method | High-Frequency Induction Welding (HF-W) / TIG Welding | ASME B31.3 |
| Heat Treatment | Solution Annealing at 1050–1150 °C followed by water quench | ASTM A269 |
| Applicable Application | FP-68LMZC Fan Coil Unit Heat Exchanger | ASHRAE Standard 15 / EN 14511 |
| Surface Treatment | Pickling & Passivation; optional electropolishing | ASTM A967 |
| Packaging | Wooden pallet with moisture-proof wrapping; coil secured with steel bands | ISO 17712 |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: Cold-rolled stainless steel strip is sourced from certified mills, with mill test certificates (MTC) verified for chemical composition and mechanical properties per ASTM A269.
- Slitting & Edge Preparation: The strip is slit to precise width tolerances and edge-burred to prevent defects during forming.
- Continuous Forming (Tube Milling): The strip is fed through a series of progressively die-set rolls that shape the flat strip into a seamless or welded tubular geometry. High-frequency induction welding (HF-W) is employed for the longitudinal seam, achieving weld strength equivalent to base material.
- In-Line Heat Treatment: The formed tube undergoes solution annealing at temperatures between 1050 °C and 1150 °C in a controlled atmosphere to relieve residual stresses and restore full austenitic microstructure.
- Pickling & Passivation: The annealed tube is subjected to acid pickling to remove oxide scales, followed by passivation treatment (per ASTM A967) to establish a protective chromium oxide film on the surface.
- Coiling & Sizing: The finished tube is wound onto a precision-driven coiler at controlled tension to produce uniform coil geometry with specified inner diameter and length.
- Non-Destructive Testing (NDT): 100% helical eddy current inspection and hydrostatic pressure testing are performed to detect any internal or external discontinuities.
- Final Inspection & Packaging: Each coil is inspected for dimensional conformity, surface finish, and packaging integrity prior to shipment.
Applications
The stainless steel coil tube is engineered for the following primary and secondary applications:
- FP-68LMZC Fan Coil Units: Serves as the heat exchange tubing within serpentine coil assemblies, transferring thermal energy between the circulating refrigerant/water and the airstream for precise indoor temperature control.
- Commercial HVAC Systems: Suitable for chiller-connected fan coil units in office buildings, hotels, hospitals, and data centers.
- Residential Air Handling: Used in concealed ducted fan coil units and cassette-type indoor units for residential and light commercial applications.
- Industrial Process Cooling: Applicable in food processing, pharmaceutical manufacturing, and electronics production where corrosion-resistant heat exchange tubing is required.
- Marine & Coastal Environments: The 316L grade offers exceptional resistance to chloride-induced pitting corrosion, making it suitable for coastal and marine HVAC installations.
- Clean Room & Laboratory Systems: The hygienic surface finish and non-reactive properties make this coil tube ideal for pharmaceutical clean rooms and analytical laboratories.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that every coil tube product meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- CE Marking — Conformity with European health, safety, and environmental protection standards
- EN 10204-3.1 — Material Test Certificate (Mill Certificate) provided with each shipment
- ASME B31.3 — Compliance with Process Piping Code requirements
- ASTM A269 / ASTM A213 — Standard specifications for seamless and welded austenitic stainless steel tubing
- GB/T 12771 — Chinese national standard for seamless stainless steel tubes for general use
- ASHRAE Standard 15 — Safety standard for HVAC equipment (applicable to fan coil unit integration)
Unique Selling Points
1. Superior Corrosion Resistance: Unlike conventional copper or carbon steel tubing, the stainless steel coil tube resists degradation from condensate water, cleaning chemicals, and humid indoor air, significantly extending service life to 20–25 years.
2. Seamless Coil Form: Delivered in continuous coil form, enabling seamless downstream integration into serpentine heat exchanger assemblies without the need for field butt-welding, reducing installation time and leak risk.
3. Precision Dimensional Control: Tight tolerances on outer diameter (±0.10 mm) and wall thickness (±0.05 mm) ensure optimal fin-to-tube contact resistance, maximizing heat transfer efficiency in fan coil unit applications.
4. Hygienic Surface Finish: The pickled and passivated surface (or optionally electropolished) prevents microbial growth and biofilm formation, making it ideal for healthcare and food-grade HVAC environments.
5. Environmental Sustainability: Stainless steel is 100% recyclable without loss of material properties, aligning with global sustainability goals and green building certifications such as LEED and Green Star.
6. Proven Application Track Record: Specifically validated for FP-68LMZC Fan Coil Unit integration, with documented thermal performance data confirming consistent heat exchange efficiency across the full operating range.
Conclusion
The Stainless Steel Coil Tube (Product No. 833) by Wenzhou Jixing Metal Materials Co., Ltd. represents a state-of-the-art solution for heat exchange tubing in fan coil unit applications. Combining metallurgical excellence, precision manufacturing, and rigorous quality assurance, this product delivers unmatched reliability, longevity, and thermal performance for commercial, residential, and industrial HVAC systems worldwide.