Stainless Steel Coil Tube for HVAC Fan Coil Unit Systems
Product Overview
The Stainless Steel Coil Tube (Model: JX-STCT Series) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered heat exchanger component designed specifically for dry-condition fan coil unit (FCU) systems integrated with fresh air handling. These coil tubes serve as the core thermal transfer medium in commercial and industrial air conditioning processes, delivering superior heat exchange efficiency under dry-bulb temperature control conditions. The product is engineered to meet the demanding requirements of modern HVAC (Heating, Ventilation, and Air Conditioning) systems where moisture control, corrosion resistance, and thermal performance are paramount.
Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steel, primarily utilizing grades 304 (UNS S30400) and 316L (UNS S31603) per ASTM A269 and ASTM A213 standards. The material selection ensures exceptional resistance to condensation-induced corrosion, chemical degradation from refrigerants, and long-term structural integrity under cyclic thermal loading.
- Base Material: Austenitic Stainless Steel — Grade 304 / 316L
- Tensile Strength: ≥ 515 MPa (Grade 304); ≥ 485 MPa (Grade 316L)
- Yield Strength: ≥ 205 MPa
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and intergranular corrosion
- Operating Temperature Range: −196°C to +870°C
- Chromium Content: 18.0–20.0% (Grade 304); 16.0–18.0% (Grade 316L)
- Nickel Content: 8.0–10.5% (Grade 304); 10.0–14.0% (Grade 316L)
Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.70 mm (¼", ⅜", ½") | ASTM A269 / ASME B36.19M |
| Wall Thickness | 0.50 mm – 1.50 mm | ASTM A213 |
| Tube Length | 2,000 mm – 12,000 mm (customizable) | Per Customer Specification |
| Coil Pitch | 12 mm – 25 mm | Internal Standard |
| Number of Rows | 2 – 6 rows | Per Application Requirement |
| Fin Type | Aluminum L-Fin / V-Groove Fin / Micro-Channel Fin | ASTM B209 (Fin Material) |
| Fin Density | 10 – 14 fins per inch (FPI) | Internal Standard |
| Operating Pressure | Up to 1.6 MPa (232 psi) | ASME BPV Code |
| Refrigerant Compatibility | R-410A, R-32, R-134a, R-407C | ASHRAE Standard 34 |
| Surface Treatment | Pickled & Passivated / Electropolished (Ra ≤ 0.4 μm) | ASTM A967 |
| End Form | Flat / Mitered / Flanged / Brazed | Per Customer Specification |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing process to ensure dimensional accuracy, surface integrity, and thermal performance consistency:
- Wire Drawing: High-purity stainless steel billet is converted into seamless tube stock via continuous tube drawing on state-of-the-art wire mills, achieving precise outer diameter tolerances of ±0.05 mm.
- Heat Treatment & Annealing: Tubes undergo solution annealing at 1050°C–1100°C followed by controlled water quenching to achieve a fully austenitic microstructure free of carbide precipitation.
- Coil Forming: Precision CNC coil bending machines form the tubes into serpentine or helical coil configurations with controlled spring-back compensation algorithms.
- Finning: High-conductivity aluminum fins are applied via a slitting-and-insertion process, creating a compact heat transfer surface with minimal flow resistance.
- Pickling & Passivation: The finished coil assembly is treated with nitric acid pickling solution followed by passivation to remove scale, mill residue, and to establish a protective chromium oxide layer.
- Pressure Testing: Each coil tube undergoes hydrostatic pressure testing at 1.5× the maximum operating pressure for a minimum of 60 seconds to verify structural integrity and absence of leaks.
- Final Inspection: Dimensional verification, visual surface inspection, and material certification documentation are completed prior to packaging.
Applications
The JX-STCT Series stainless steel coil tubes are purpose-engineered for the following critical applications:
- Dry-Condition Fan Coil Units: Primary heat exchanger medium in dry-bulb temperature control systems where latent heat removal is managed by separate fresh air handling units, enabling precise indoor humidity control.
- Commercial HVAC Systems: Installation in office buildings, hotels, hospitals, and retail environments requiring high-performance air conditioning with minimal moisture generation.
- Cleanroom Environments: Pharmaceutical and semiconductor manufacturing facilities demanding non-corrosive, non-particulate-generating heat transfer surfaces.
- Food & Beverage Processing: Temperature-controlled storage and processing areas where hygienic stainless steel surfaces are mandated by food safety regulations.
- Marine & Coastal Facilities: Air conditioning systems in environments with high humidity and salt-laden air where corrosion resistance is critical.
- Integrated Fresh Air Systems: Components in dual-duct or dedicated outdoor air system (DOAS) architectures that separate sensible and latent cooling loads.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains comprehensive quality management systems and holds the following certifications:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ASME (American Society of Mechanical Engineers) — Manufacturer Stamp Authorization
- EN 10204 3.1 — Material Test Certification for all delivered products
- CE Marking — Conformity with European Machinery Directive
- UL / CSA — Component-level safety listing for HVAC applications
- RoHS & REACH Compliance — Restriction of Hazardous Substances and Chemical Registration
Unique Selling Points: The JX-STCT Series coil tubes offer a 25% improvement in heat transfer efficiency over conventional carbon steel alternatives while providing 10–15 times greater corrosion resistance. The electropolished surface finish (Ra ≤ 0.4 μm) eliminates biofilm formation, making these tubes ideal for hygienic applications. The precision coil geometry, manufactured with CNC-controlled spring-back compensation, ensures consistent airflow distribution and eliminates performance degradation over the system's operational lifetime. The dual-material construction (stainless steel tubes with aluminum fins) optimizes the thermal-to-cost ratio while maintaining full corrosion resistance in the fluid-carrying component.