Stainless Steel Coil Tube for Fan Coil Unit Chilled Water Systems
Product Overview
The stainless steel coil tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product Code: 1522) is a precision-engineered heat exchanger component designed for integration into fan coil unit (FCU) chilled water systems. This product is specifically engineered to address the demanding operational requirements of high heat-humidity ratio (high latent load) conditions, where efficient dehumidification and thermal exchange performance are critical. The coil tube serves as the core heat transfer element within the FCU, facilitating the exchange of thermal energy between the chilled water circuit and the circulating air stream, thereby maintaining precise indoor temperature and humidity control in commercial, industrial, and institutional HVAC (Heating, Ventilation, and Air Conditioning) environments.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional corrosion resistance, mechanical durability, and thermal conductivity characteristics. The material composition and resulting properties are as follows:
- Base Material: Austenitic stainless steel conforming to ASTM A269 / ASTM A270 standards, typically Grade 304 (UNS S30400) or Grade 316 (UNS S31600) for enhanced chloride resistance in high-humidity environments.
- Corrosion Resistance: Superior resistance to pitting and crevice corrosion under sustained high heat-humidity ratio conditions, ensuring long-term structural integrity without degradation of heat transfer surfaces.
- Mechanical Properties: High tensile strength and elongation capacity, providing resistance to mechanical fatigue and vibration-induced stress during continuous FCU operation.
- Thermal Conductivity: Optimized for efficient heat transfer between the chilled water medium and the ambient air stream, minimizing thermal losses and maximizing system COP (Coefficient of Performance).
- Surface Finish: Smooth internal and external surface finish to minimize flow resistance and prevent fouling accumulation, maintaining consistent heat exchange efficiency over the product lifecycle.
- Hygienic Compliance: Non-toxic, non-reactive material surface suitable for applications requiring sanitary and hygienic standards.
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Code | 1522 | Wenzhou Jixing Internal Catalog |
| Product Name | Coil Tube (盘管) | — |
| Material Grade | Stainless Steel Grade 304 / 316 (UNS S30400 / S31600) | ASTM A269 / ASTM A270 |
| Tube Outer Diameter (OD) | 6.35 mm – 9.53 mm (1/4" – 3/8") | ASME B8.18 |
| Tube Wall Thickness | 0.5 mm – 1.2 mm | Manufacturer Specification |
| Tube Pitch | 12 mm – 25 mm (configurable) | ASHRAE Standard 90.1 |
| Fin Spacing | 2.0 mm – 4.0 mm (adjustable per application) | ASHRAE Standard 15 |
| Fin Material | Aluminum or Stainless Steel (matched to tube material) | — |
| Operating Pressure | Up to 1.6 MPa (16 bar) rated | EN 12828 |
| Operating Temperature Range | -10°C to +120°C | Manufacturer Specification |
| Chilled Water Supply Temperature | 6°C – 12°C (typical FCU application) | ASHRAE Standard 90.1 |
| Heat Transfer Coefficient | Optimized for high latent load conditions | ASHRAE Fundamentals Handbook |
| Connection Type | Threaded, Flanged, or Brazed (configurable) | ASME B16.11 / B16.5 |
| Surface Treatment | Passivated / Polished (optional: epoxy coated) | ASTM A967 |
| Compliance Standard | EN 12828, ASHRAE 15, ISO 9001:2015 | — |
Manufacturing Process
The coil tube is produced through a precisely controlled multi-stage manufacturing process designed to ensure dimensional accuracy, material integrity, and optimal heat transfer performance:
- Material Selection & Inspection: Raw stainless steel coil stock is sourced from certified mills and subjected to incoming quality control (IQC) inspection, including spectroscopic analysis for chemical composition verification and mechanical property testing.
- Coil Forming & Bending: The stainless steel tubing is cold-formed into the required coil geometry using precision CNC (Computer Numerical Control) bending machines. The forming process is carefully controlled to prevent material thinning, cracking, or work hardening that could compromise structural integrity or heat transfer efficiency.
- Fin Insertion & Assembly: Heat transfer fins are inserted into the coil tube channels using a precision fin insertion process. The fins are securely crimped or brazed to the tube surface to ensure minimal thermal contact resistance between the fin and tube materials.
- Welding & Brazing: Tube joints and connection ports are welded or brazed using appropriate filler materials compatible with the base stainless steel grade. All welds undergo non-destructive testing (NDT), including visual inspection and dye penetrant testing, to verify weld integrity and absence of defects.
- Pressure Testing: Each completed coil tube unit undergoes hydrostatic pressure testing at 1.5 times the rated operating pressure to verify leak-tightness and structural soundness under operational conditions.
- Surface Finishing & Passivation: The finished product is subjected to chemical passivation treatment in accordance with ASTM A967 to remove surface contaminants and enhance the passive chromium oxide layer, thereby maximizing corrosion resistance for high-humidity environments.
- Final Quality Assurance (FQA): Comprehensive final inspection includes dimensional verification, pressure test documentation review, material traceability confirmation, and visual quality assessment prior to packaging and shipment.
Applications
This stainless steel coil tube is purpose-engineered for high-performance fan coil unit (FCU) systems operating under high heat-humidity ratio conditions, where the latent heat load significantly exceeds the sensible heat load. Key application domains include:
- Commercial HVAC Systems: Office buildings, shopping malls, hospitality venues, and retail spaces requiring precise temperature and humidity control in high-moisture environments.
- Industrial Facilities: Manufacturing plants, laboratories, and process industries where ambient air contains elevated moisture levels and corrosion-resistant heat exchanger components are mandatory.
- Healthcare & Institutional Buildings: Hospitals, clinics, and pharmaceutical facilities requiring hygienic, corrosion-resistant coil components for critical air handling applications.
- High-Humidity Regional Installations: Geographic regions with persistently high ambient humidity (e.g., tropical and subtropical climates) where coil tube corrosion resistance is a primary design consideration.
- Energy-Efficient Chilled Water Systems: Integrated chilled water distribution systems designed to meet ASHRAE 90.1 energy efficiency standards, where optimized coil tube geometry minimizes pumping energy while maximizing thermal exchange capacity.
Quality Certifications & Compliance
The coil tube product line from Wenzhou Jixing Metal Materials Co., Ltd. adheres to internationally recognized quality management and product standards:
- ISO 9001:2015: Certified Quality Management System ensuring consistent product quality, process control, and continuous improvement across all manufacturing stages.
- EN 12828: Compliance with European standards for heating systems in buildings, including component specifications for heat exchangers.
- ASHRAE Standard 15: Alignment with American Society of Heating, Refrigerating and Air-Conditioning Engineers safety standards for HVAC equipment.
- ASTM A269 / A270: Conformance to American Society for Testing and Materials specifications for welded, seamless, and forged austenitic stainless steel pipe, tube, and fittings.
- ASTM A967: Compliance with standard practices for chemical passivation of stainless steel parts.
- Material Traceability: Full traceability from raw material mill certificates through to finished product, enabling complete supply chain quality documentation and audit readiness.
Unique Selling Points
The distinguishing advantage of this coil tube product lies in its purpose-built design for high heat-humidity ratio operational conditions. Unlike conventional coil tubes optimized primarily for sensible heat exchange, this product integrates material selection, geometric optimization, and surface treatment specifically to maximize latent heat transfer capacity while maintaining long-term corrosion resistance. The combination of austenitic stainless steel construction, precision-engineered coil geometry, and optimized fin configuration enables superior dehumidification performance with minimal pressure drop, directly contributing to improved system energy efficiency and reduced total cost of ownership (TCO) over the product lifecycle. The manufacturer's adherence to rigorous quality certification standards and full material traceability further reinforces product reliability for mission-critical HVAC installations.