Stainless Steel Coil Tube for Fan Coil Unit Systems — Model JC-1367
Product Overview
The JC-1367 Stainless Steel Coil Tube is a precision-engineered coil tube product manufactured by Wenzhou Jixing Metal Materials Co., Ltd., specifically designed for integration into fan coil unit (FCU) centralized air conditioning systems. This coil tube serves as the core heat exchange element within chilled water metering and charging devices, enabling efficient thermal transfer between the circulating coolant and the conditioned air stream. The product complies with the technical requirements outlined in the standard "Cold Metering and Charging Devices for Fan Coil Central Air Conditioning Systems", ensuring reliable performance in commercial and industrial HVAC (Heating, Ventilation, and Air Conditioning) installations.
As a critical component in energy-efficient building systems, the JC-1367 coil tube facilitates accurate cold metering by maintaining consistent hydraulic flow characteristics and thermal conductivity over extended service life. Its stainless steel construction provides superior corrosion resistance compared to conventional carbon steel alternatives, making it particularly suitable for environments with high humidity, aggressive water chemistry, or stringent hygiene requirements.
Material & Properties
Base Material
- Primary Alloy: Austenitic Stainless Steel, Grade 304 (UNS S30400) or Grade 316L (UNS S31603) upon request
- Chromium (Cr) Content: 18.0–20.0% (Grade 304); 16.0–18.0% (Grade 316L)
- Nickel (Ni) Content: 8.0–10.5% (Grade 304); 10.0–14.0% (Grade 316L)
- Molybdenum (Mo): ≤0.08% (Grade 304); 2.0–3.0% (Grade 316L)
- Carbon (C) Maximum: 0.08% (Grade 304); 0.03% (Grade 316L)
Mechanical Properties
- Tensile Strength (Rm): ≥520 MPa (annealed condition)
- Yield Strength (Rp0.2): ≥205 MPa
- Elongation (A50): ≥40%
- Hardness: ≤187 HB (annealed)
Physical & Thermal Properties
- Density: 7.93 g/cm³
- Thermal Conductivity: 16.3 W/(m·K) at 20°C
- Specific Heat Capacity: 500 J/(kg·K) at 20°C
- Thermal Expansion Coefficient: 17.3 × 10⁻⁶ /K (10–100°C)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, weak acids, alkalis, and chlorinated water solutions
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.70 mm (1/4" / 3/8" / 1/2") | GB/T 14976 |
| Wall Thickness | 0.50 mm – 1.00 mm (tolerance ±0.05 mm) | GB/T 14976 |
| Coil Pitch (Helix Diameter) | 38 mm – 127 mm (configurable) | Enterprise Standard |
| Coil Length | 100 mm – 5000 mm (customizable) | Per customer drawing |
| Surface Finish | Mirror polished (Ra ≤ 0.4 μm) or industrial passivated (Ra ≤ 1.6 μm) | ASTM A270 |
| Operating Temperature Range | -40°C to +200°C | — |
| Maximum Operating Pressure | 1.6 MPa (standard); 2.5 MPa (reinforced) | GB/T 50274 |
| Working Fluid | Chilled water, glycol-water mixture (≤50% ethylene glycol), or compatible HVAC refrigerants | — |
| Heat Transfer Coefficient | ≥2,500 W/(m²·K) (water-to-air configuration) | ASHRAE Handbook |
| Fin Configuration (if applicable) | Aluminum or copper fins, 8–12 fins per inch | Enterprise Standard |
| End Connection | Flared, brazed, threaded (G1/4", G1/2"), or welded | EN 1254-1 |
| Packaging | Protective wrapping + export-grade wooden crate or roll packaging | ISO 4180 |
Manufacturing Process
- Raw Material Selection: High-purity stainless steel strip is sourced from certified mills, with each batch undergoing spectroscopic verification (OES — Optical Emission Spectroscopy) to confirm chemical composition compliance.
- Slitting & Leveling: The steel strip is slit to precise width tolerances (±0.1 mm) and cold-rolled to achieve the required thickness with uniform mechanical properties throughout the cross-section.
- Pipe Forming: Precision roll-forming machines shape the flat strip into a seamless tube with controlled ovality (≤0.5% of OD) and consistent wall thickness. The seam is resistance-welded or induction-welded and subsequently ground flush.
- Coiling (Helical Forming): The formed tube is passed through CNC-controlled coiling dies that impart the helical geometry. Computer numerical control ensures uniform pitch, consistent helix diameter, and minimal residual stress. Post-coiling straightening eliminates springback distortion.
- Heat Treatment (if required): Solution annealing at 1050–1100°C followed by controlled water quenching restores full austenitic structure and optimizes corrosion resistance. Stress-relief annealing at 450°C may be applied for dimensional stability.
- Surface Finishing: Pickling and passivation (acid immersion in HNO₃/HF blend) removes mill scale and forms a protective chromium oxide film. Mirror polishing employs multi-stage abrasive belts achieving Ra ≤ 0.4 μm.
- Quality Inspection: Each coil tube undergoes dimensional verification (OD, wall thickness, pitch, length), hydrostatic pressure testing at 3.0 MPa for 30 seconds, and visual/eddy current inspection for weld integrity.
- Fin Attachment (optional): For enhanced heat exchange, aluminum or copper fins are mechanically expanded or mechanically bonded onto the coil tube surface, ensuring metal-to-metal contact without solder residue.
- Final Assembly & Testing: End fittings are brazed or welded, followed by leak testing (helium sniff test or soap bubble method at 0.5 MPa). Thermal performance is verified against design heat duty.
Applications
- Central Air Conditioning Systems: Primary heat exchange coil in fan coil units (FCUs) for commercial buildings, office towers, hospitals, and hotels, enabling precise cold metering and billing in multi-tenant environments.
- Energy Metering Devices: Integration into sub-metering and energy management systems where accurate chilled water consumption measurement is critical for utility cost allocation.
- Process Cooling: Low-temperature fluid circulation in pharmaceutical, food and beverage, and semiconductor manufacturing facilities requiring hygienic-grade heat exchangers.
- Marine & Offshore HVAC: Corrosion-resistant coil tubes for shipboard air conditioning systems exposed to saltwater-laden atmospheres.
- Data Center Cooling: Precision temperature control in server rooms where reliability and long service life minimize maintenance downtime.
- Industrial Chiller Systems: Condenser and evaporator coils in packaged chillers operating with glycol-water mixtures.
Quality Certifications & Standards Compliance
- ISO 9001:2015 — Quality Management System certification covering the entire manufacturing and supply chain
- ISO 14001:2015 — Environmental Management System, ensuring sustainable production practices
- GB/T 14976 — Chinese national standard for seamless and welded stainless steel tubes
- ASTM A269 / A270 — American standards for austenitic stainless steel seamless and welded tubing
- EN 10216-5 — European standard for welded stainless steel tubes for general applications
- GB 50736 — Chinese standard for design of ventilation and air conditioning systems
- GB/T 17167 — Chinese standard for energy metering devices in HVAC systems
- CE Marking — Conformity with European directives for construction products
- RoHS Compliance — Restriction of Hazardous Substances, ensuring environmental safety
- Mill Test Reports (MTR) — Provided with every shipment, documenting chemical analysis, mechanical test results, and traceability
Unique Selling Points
1. Superior Corrosion Durability: Unlike carbon steel alternatives that require periodic replacement due to internal corrosion, the JC-1367 coil tube delivers a service life exceeding 15 years under standard HVAC operating conditions, significantly reducing total cost of ownership.
2. Precision Cold Metering Capability: The uniform hydraulic characteristics and consistent internal surface finish enable accurate flow measurement, supporting reliable sub-metering and energy billing in multi-tenant buildings.
3. Customizable Geometry: Full configurability of coil pitch, diameter, length, and fin density allows optimal thermal performance matching to specific system design requirements.
4. Hygienic Construction: Mirror-polished internal surfaces prevent biofilm accumulation and scale buildup, maintaining peak heat transfer efficiency throughout the operational life.
5. Complete Traceability: Each unit is serialized with material heat number traceability, ensuring full supply chain transparency from raw steel mill to end installation.