Stainless Steel Coil Tube — Fan Coil Unit Heat Exchanger Coil
Product Overview
The Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled tubing solution designed primarily for use in fan coil units (FCU), floor radiant coupling systems, and hydronic air conditioning applications. This product is engineered to deliver superior thermal transfer performance, exceptional corrosion resistance, and long-term structural integrity in demanding environmental conditions — particularly in hot and humid regions where conventional carbon steel coils are prone to accelerated degradation.
Based on experimental research into the cooling characteristics of floor radiant coupled fan coil unit air conditioning systems, the coil tube is optimized to operate efficiently across a wide range of wet-bulb temperatures and relative humidity levels, ensuring reliable dehumidification and sensible cooling performance.
Material & Properties
The coil tube is fabricated from high-purity austenitic stainless steel, selected for its outstanding combination of mechanical strength, thermal conductivity, and resistance to pitting and crevice corrosion.
- Primary Material Grade: SUS304 / AISI 304 (UNS S30400) — general purpose austenitic stainless steel
- Alternative Grade: SUS316 / AISI 316 (UNS S31600) — enhanced molybdenum alloy for aggressive chemical environments
- Chemical Composition (SUS304): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%
- Chemical Composition (SUS316): Carbon (C) ≤ 0.08%, Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%
- Density: 8.0 g/cm³
- Thermal Conductivity (at 20°C): 16.3 W/(m·K) for SUS304; 14.6 W/(m·K) for SUS316
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and mildly acidic environments; superior performance in high-humidity and chlorinated conditions (SUS316 grade)
- Operating Temperature Range: −196°C to +870°C
- Magnetic Properties: Non-magnetic (austenitic structure)
Specifications
| Parameter | Specification | Standard / Tolerance |
|---|---|---|
| Tube Outer Diameter (OD) | 6.35 mm, 9.53 mm, 12.70 mm (1/4", 3/8", 1/2") | ASTM A213 / EN 10216-5 |
| Tube Wall Thickness | 0.50 mm – 1.50 mm | ±0.10 mm tolerance |
| Coil Inner Diameter (ID) | 150 mm – 600 mm (customizable) | ±5 mm tolerance |
| Coil Length | 5 m – 100 m (continuous coil) | Custom per project requirement |
| Surface Finish | 2B (Cold Rolled and Annealed) or No.4 Brushed | Ra ≤ 0.8 μm |
| Operating Pressure | Up to 1.6 MPa (standard); 2.5 MPa (reinforced) | Hydrostatic test at 1.5× working pressure |
| Design Temperature | −20°C to +120°C (hydronic) | EN 12828 compliant |
| Welding Method | Orbital TIG (Tungsten Inert Gas) welding | ASTM A213 / AWS D10.9 |
| Fin Type (if applicable) | Hydrophilic aluminum fins, 2.0 mm pitch | Fin-to-tube bonding resistance ≤ 0.01 Ω |
| Thread / Connection | Flared, brazed, or compression fittings | ASME B16.3 |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage process designed to ensure dimensional accuracy, metallurgical integrity, and consistent performance:
- Raw Material Inspection: Ingot certification verification, spectroscopic analysis (PMI) for elemental composition confirmation, and visual inspection of coil stock.
- Cold Drawing: Seamless stainless steel tubes are cold-drawn through precision dies to achieve the required outer diameter and wall thickness with tight tolerances.
- Coil Forming: The drawn tubes are wound into the specified coil geometry using CNC-controlled coiling machines, ensuring uniform pitch and consistent curvature without work-hardening or micro-cracking.
- Welding & Fabrication: Orbital TIG welding is employed for all tube joints and header connections, producing high-integrity, leak-free welds with minimal heat-affected zone (HAZ) distortion.
- Surface Treatment: Tubes are pickled and passivated to remove scale and contaminants, forming a stable chromium oxide passive layer for enhanced corrosion protection.
- Finning (if applicable): Hydrophilic aluminum fins are mechanically bonded to the tube surface using high-frequency induction brazing or mechanical crimping, maximizing the heat transfer area.
- Quality Testing: Each coil undergoes hydrostatic pressure testing, eddy current inspection for wall thickness verification, and visual/dimensional inspection in accordance with applicable standards.
Applications
The stainless steel coil tube finds extensive application across multiple industries, with particular suitability for the following:
- HVAC Systems: Fan coil units, air handling units (AHU), and heat recovery ventilators (HRV) in commercial and residential buildings.
- Floor Radiant Coupled Systems: Hybrid heating and cooling systems combining floor radiant panels with fan coil units, especially effective in hot and humid climates where latent heat removal is critical.
- Chilled Water Distribution: Secondary loop piping and terminal heat exchangers in central air conditioning plants.
- Food & Beverage Processing: Sanitary-grade heat exchangers for pasteurization, refrigeration, and process cooling.
- Pharmaceutical & Laboratory: Cleanroom air conditioning and temperature-controlled storage systems.
- Marine & Coastal Environments: Corrosion-resistant heat exchanger coils for ships, offshore platforms, and coastal facilities.
- Industrial Process Cooling: Heat rejection coils in chemical processing, electronics manufacturing, and data center cooling systems.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and adheres to the following international standards and certifications:
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- ASTM A213 / A269 — Standard specifications for seamless austenitic stainless steel tube
- EN 10216-5 — Technical delivery conditions for welded austenitic stainless steel tubes
- GB/T 14976 — Chinese national standard for cold-rolled or cold-drawn seamless stainless steel tubes
- GB/T 21830 — Standard for stainless steel tubes for heat exchangers
- ASME B31.5 — Pressure Piping, Process Plants (applicable for high-pressure applications)
- NSF/ANSI 61 — Drinking water system components (available for potable water applications)
- CE Marking — European Conformity for pressure equipment (PED 2014/68/EU)
All products are accompanied by a full Mill Test Certificate (MTC) and EN 10204 3.1 Certificate verifying chemical composition, mechanical properties, and dimensional compliance.
Unique Selling Points
- Superior Corrosion Resistance in Humid Environments: Engineered specifically for hot and humid regional conditions, the SUS304/SUS316 grades provide exceptional resistance to condensation-induced corrosion that commonly plagues carbon steel alternatives, extending service life by 5–10×.
- Optimized for Floor Radiant Coupled FCU Systems: Based on experimental research into cooling characteristics, the coil geometry and material selection are calibrated to achieve balanced sensible and latent heat removal, improving system COP (Coefficient of Performance) in high-humidity conditions.
- Precision Orbital Welding: Fully automated orbital TIG welding ensures consistent weld quality, zero leakage, and minimal oxide inclusion — critical for maintaining long-term thermal efficiency.
- Customizable Coil Geometry: Flexible manufacturing capabilities allow tailored coil diameters, pitches, and lengths to match specific AHU or FCU chassis dimensions, reducing installation complexity.
- Full Traceability: Every coil is traceable to the raw material lot, with complete documentation of all manufacturing and testing stages.
- Hygienic & Food-Grade Available: Surface finish and material grade options meet sanitary requirements for food, pharmaceutical, and beverage processing applications.
Technical Note: The design parameters of this coil tube have been validated through experimental research on the cooling performance of floor radiant coupled fan coil unit systems in hot and humid regions. Results demonstrate that stainless steel coils maintain stable heat transfer coefficients across a wide range of entering air wet-bulb temperatures (18°C–26°C) and relative humidity levels (50%–80% RH), outperforming conventional materials in long-term reliability and seasonal energy efficiency.