Stainless Steel Coil Tube for Fan Coil Unit (FCU) Systems
Product Overview
The Stainless Steel Coil Tube (Product No. 658) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered coiled piping product designed for integration into Fan Coil Unit (FCU) air-conditioning systems combined with fresh air ventilation. This product serves as a critical heat-exchange and fluid-transport component within HVAC (Heating, Ventilation, and Air Conditioning) installations, offering superior corrosion resistance, thermal conductivity, and mechanical durability compared to conventional carbon steel alternatives.
The coil tube is engineered to withstand the cyclic thermal loading, condensation, and chemical exposure inherent in modern fan coil plus fresh air (FC + FA) air-conditioning systems. Its coiled geometry facilitates compact installation within fan coil units, chillers, and terminal units while maintaining optimal hydraulic and thermal performance.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of mechanical strength, corrosion resistance, and thermal stability in HVAC service environments.
- Base Material: Austenitic Stainless Steel (e.g., SUS304 / SUS316L / ASTM A213 TP304)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, condensation-induced pitting, and chemical attack from HVAC refrigerants and water treatment agents
- Thermal Conductivity: Sufficient thermal transfer capability for efficient heat exchange in chilled water and hot water circulation loops
- Mechanical Strength: High yield strength and fatigue resistance under repeated thermal cycling conditions
- Hygienic Surface: Smooth inner wall finish to minimize fouling, scaling, and biofilm accumulation
- Temperature Range: Operational capability from cryogenic temperatures to approximately 350°C
Specifications
| Parameter | Specification |
|---|---|
| Product Designation | Stainless Steel Coil Tube (Coiltube) |
| Product No. | 658 |
| Material Grade | SUS304 / SUS316L / Custom Grade Available |
| Outer Diameter (OD) | 6.35 mm – 50.8 mm (1/4" – 2") |
| Wall Thickness | 0.5 mm – 3.0 mm (customizable) |
| Coil Length | 10 m – 200 m (configurable per application) |
| Surface Finish | Bright Annealed (BA) / Pickled & Passivated |
| Applicable Standards | ASTM A213 / ASTM A269 / GB/T 14976 / EN 10216-5 |
| Operating Pressure | Up to 1.6 MPa (standard); higher on request |
| Operating Temperature | -40°C to +350°C |
| End Treatment | Plain / Beveled / Threaded / Flanged |
| Coating Option | None (bare stainless) / PTFE-lined (special order) |
| Packaging | Wooden crate / Pallet with moisture-proof wrapping |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: Cold-rolled stainless steel strip of certified grade is sourced from approved mills with full mill test certificates (MTC) compliant with ISO 3760.
- Coil Forming (Roll Forming): The flat strip is fed through a series of precision rollers in a progressive bending sequence, gradually forming the circular cross-section and coiling it onto a mandrel at controlled curvature radii.
- Welding (Where Applicable): For seamless-free coil production, the longitudinal joint is welded using Automatic TIG (Tungsten Inert Gas) welding with argon gas shielding to achieve a smooth, oxide-free weld seam.
- Heat Treatment: Solution annealing at 1050°C–1150°C followed by controlled cooling to restore full austenitic microstructure and relieve residual stresses from forming.
- Pickling & Passivation: The coiled tube undergoes acid pickling to remove scale and oxide, followed by passivation treatment to establish a protective chromium oxide film on the surface.
- Quality Inspection: Each coil batch undergoes dimensional verification, hydrostatic pressure testing (per ASTM A213), visual surface inspection, and spectroscopic material verification (PMI — Positive Material Identification).
- Packaging & Dispatch: Coils are wrapped in moisture-proof polyethylene film, secured on wooden pallets or crates, and labeled with traceability documentation.
Applications
The Stainless Steel Coil Tube (No. 658) is specifically engineered for use in Fan Coil Unit (FCU) and fresh air air-conditioning systems, with the following primary application domains:
- Fan Coil Units (FCU): Used as coil tubes within FCU heat exchangers for chilled water distribution in commercial and residential HVAC systems.
- Fresh Air Handling Units (AHU): Integrated into air handling units for fresh air pre-conditioning, cooling, and heating loops.
- Chilled Water Circulation: Serves as piping in secondary chilled water loops connecting chillers to terminal units.
- Hydronic Heating Systems: Employed in hot water coil assemblies for space heating in hospitals, laboratories, and clean rooms.
- Process Cooling: Utilized in industrial process cooling circuits where corrosion resistance and hygiene are critical.
- Marine & Coastal HVAC: Ideal for HVAC installations in coastal environments where chloride-induced corrosion is a concern.
- Food & Pharmaceutical Facilities: Suitable for HVAC systems in hygienic environments requiring corrosion-resistant, cleanable piping.
Unique Selling Points
- Enhanced Corrosion Resistance: Superior to carbon steel coil tubes in humid and condensation-prone HVAC environments, extending service life by 5–10 times.
- Compact Coiled Geometry: Pre-formed coil configuration reduces installation time, minimizes on-site fitting, and enables space-efficient routing within FCU cabinets.
- Hygienic Surface Quality: Bright annealed and passivated surface finish prevents microbial growth and facilitates cleaning in sanitary applications.
- Full Traceability: Each batch is accompanied by material test certificates and production lot numbers for complete supply chain traceability.
- Customization Capability: Wenzhou Jixing Metal Materials Co., Ltd offers flexible customization in OD, wall thickness, coil length, end treatment, and material grade to meet project-specific requirements.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework to ensure product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System certification for consistent manufacturing quality
- ISO 14001 — Environmental Management System certification
- CE Marking — Conformity with European health, safety, and environmental protection standards
- Material Compliance: ASTM A213 / ASTM A269 / GB/T 14976 / EN 10216-5
- Pressure Testing: Hydrostatic testing per ASTM A213 specifications with 100% batch verification
- Third-Party Inspection: Available upon request (SGS, BV, or equivalent accredited bodies)
- Mill Test Certificate (MTC): EN 10204 Type 3.1 certificates provided with every shipment
Manufacturer's Note: Wenzhou Jixing Metal Materials Co., Ltd is committed to delivering high-performance stainless steel coil tube products that meet the rigorous demands of modern HVAC engineering. The Coiltube (No. 658) represents a reliable, long-lasting solution for fan coil unit and fresh air system installations, combining metallurgical excellence with practical manufacturing precision.