Stainless Steel Coil Tube — HVAC Fan Coil Unit Application Grade
Product Overview
The Stainless Steel Coil Tube (Product No. 966) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered tubular component designed for integration into BACnet (Building Automation and Control Network) networked fan coil unit (FCU) systems. This coil tube serves as the primary heat exchange medium within HVAC (Heating, Ventilation, and Air Conditioning) terminal units, facilitating efficient thermal transfer between refrigerant and air streams. The product is engineered to meet the stringent requirements of modern building automation systems, ensuring long-term reliability, corrosion resistance, and seamless compatibility with intelligent control architectures.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional resistance to corrosion, thermal fatigue, and mechanical degradation under continuous cyclic operating conditions.
- Base Material: SUS304 / SUS316L austenitic stainless steel (ASTM A269 / ASTM A312 compliance)
- Chemical Composition: Chromium (Cr) ≥ 18%, Nickel (Ni) ≥ 8%, Carbon (C) ≤ 0.08% (SUS304); Molybdenum (Mo) 2.0–3.0% (SUS316L variant)
- Corrosion Resistance: Superior resistance to chlorides, humid environments, and condensate attack inherent in HVAC applications
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, ensuring efficient heat transfer performance
- Operating Temperature Range: −40°C to +150°C (continuous); transient peaks up to +200°C
- Surface Finish: Electropolished interior (Ra ≤ 0.4 μm) to minimize fouling and pressure drop
Specifications
| Parameter | Specification | Standard / Tolerance |
|---|---|---|
| Outer Diameter (OD) | 9.52 mm / 12.70 mm / 15.88 mm | ±0.15 mm (ASTM A213) |
| Wall Thickness | 0.81 mm / 1.02 mm / 1.24 mm | ±0.10 mm |
| Coil Diameter | 100 mm – 600 mm (configurable) | ±5 mm |
| Tube Length (Developed) | Up to 60,000 mm (continuous coil) | ±100 mm |
| Pitch / Fin Spacing | 2.5 mm – 4.0 mm (with aluminum fins) | ±0.3 mm |
| Pressure Rating | 1.6 MPa (16 bar) design; 2.4 MPa burst | ISO 4413 / EN 12266 |
| Heat Transfer Coefficient | ≥ 2,500 W/(m²·K) (water-to-air) | ASHRAE 90.1 |
| Seam Type | Welded (TIG) or seamless (depending on OD) | ASTM A269 / A312 |
| End Condition | Plain, flared, or brazed fittings (Cu/Ag) | Custom per drawing |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and performance consistency:
- Material Selection & Verification: Ingot-grade stainless steel strips undergo spectroscopic analysis (PMI — Positive Material Identification) to confirm chemical composition compliance.
- Rolling & Forming: Precision cold-rolling processes shape the strip into tubular geometry. For smaller diameters, a continuous forming die system is employed; for larger diameters, a roll-bending method is utilized.
- Welding (where applicable): High-frequency TIG (Tungsten Inert Gas) welding creates the longitudinal seam with a nitrogen-backed interior to prevent oxidation. Weld penetration is verified via eddy current testing.
- Coiling & Pitch Setting: The formed tube is coiled at controlled tension using CNC (Computer Numerical Control) coiling machines to achieve precise helical geometry and consistent pitch.
- Fin Insertion (if finned): Aluminum fins are mechanically inserted or bonded into the tube array to maximize surface area for convective heat transfer.
- Heat Treatment: Solution annealing at 1,050°C–1,100°C followed by controlled cooling to relieve residual stresses and restore full austenitic microstructure.
- Surface Treatment: Pickling and passivation remove oxide scale; electropolishing achieves the required interior surface roughness for low-flow resistance.
- Quality Inspection: Each coil undergoes hydrostatic pressure testing (1.5× design pressure for 30 minutes), dimensional verification via laser scanning, and visual examination of weld quality.
Applications
The stainless steel coil tube is purpose-engineered for deployment in advanced HVAC terminal systems, with particular suitability for the following applications:
- BACnet Networked Fan Coil Units (FCUs): The coil tube serves as the core heat exchanger element within FCUs that communicate via the BACnet protocol (ASHRAE Standard 135), enabling centralized building management system (BMS) integration for optimized temperature, humidity, and energy control.
- Commercial & Institutional Buildings: Office towers, hospitals, educational facilities, and hospitality venues where hygienic, corrosion-resistant heat exchange is critical.
- Pharmaceutical & Cleanroom Environments: SUS316L grade coil tubes resist microbial growth and withstand aggressive cleaning agents used in GMP (Good Manufacturing Practice) facilities.
- Food Processing & Beverage Industry: Sanitary-grade coil tubes maintain product purity while delivering precise thermal regulation in processing halls.
- Smart Building IoT Integrations: Compatibility with sensor-equipped FCU controllers that leverage BACnet/IP for real-time monitoring, predictive maintenance, and energy management analytics.
- Chilled Water & Hot Water Systems: Dual-purpose coil tubes designed for both cooling (chilled water, 6–12°C) and heating (hot water, 45–80°C) circuits.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that every coil tube product meets or exceeds international standards:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing processes
- ISO 14001:2015 — Environmental Management System certification for sustainable production practices
- ASTM A269 / A312 — Full compliance with American standards for stainless steel tubular products
- EN 10216-5 — European standard compliance for austenitic stainless steel heat exchanger tubes
- GB/T 14976 — Chinese national standard compliance for seamless stainless steel tubes
- ASHRAE Standard 135 (BACnet) — System-level compatibility certification for integration with BACnet networked HVAC controllers
- CE Marking — European Conformity for market access within the European Economic Area
- RoHS & REACH Compliance — Restricted Substances compliance for environmentally responsible material sourcing
Unique Selling Points
- BACnet-Ready Architecture: Designed specifically for seamless integration with BACnet networked fan coil units, enabling intelligent building automation with minimal retrofit effort.
- Enhanced Corrosion Longevity: SUS304/SUS316L stainless steel construction provides 2–3× the service life of conventional copper tube assemblies in aggressive HVAC environments.
- Low Pressure Drop Design: Electropolished interior surfaces reduce friction losses by up to 15%, translating to lower pumping energy consumption across the building system.
- Customizable Coil Geometry: CNC-driven coiling allows precise adaptation to specific FCU cabinet dimensions and airflow configurations.
- Traceable Manufacturing: Each production lot carries full material traceability documentation, including mill certificates, heat numbers, and test reports.
Note: This product is intended for professional HVAC system integration. Installation should be performed by certified technicians in accordance with local building codes and manufacturer guidelines. For BACnet protocol configuration, refer to the respective FCU controller documentation and ASHRAE Standard 135 specifications.