Stainless Steel Coil Tube — FP-5 Series Fan Coil Unit (FCU) Component
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered heat exchange component designed specifically for integration into FP-5 Series Fan Coil Units (Fan Coil Units, FCU). Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this coil tube serves as the core thermal transfer medium within HVAC (Heating, Ventilation, and Air Conditioning) systems. The product is classified under industrial literature and technical documentation (Category: Technical Reference, Item No. 1636) and represents a critical component in the design and development of high-efficiency fan coil assemblies.
Unlike conventional copper or aluminum coil tubes, the stainless steel variant offers superior corrosion resistance, extended service life, and enhanced hygienic performance, making it particularly suitable for demanding industrial, commercial, and institutional HVAC applications where longevity and reliability are paramount.
2. Material & Properties
The coil tube is fabricated from high-grade stainless steel, selected for its exceptional mechanical, thermal, and chemical properties. The following table outlines the key material characteristics:
- Base Material: Austenitic stainless steel (e.g., SUS304 / AISI 304 or SUS316 / AISI 316), providing excellent resistance to oxidation, pitting, and general corrosion.
- Tensile Strength: 520–720 MPa (Megapascal), ensuring structural integrity under thermal cycling and pressure loading.
- Yield Strength: 205–310 MPa, providing adequate deformation resistance during operation.
- Thermal Conductivity: 14.2–16.3 W/(m·K) (Watts per Meter-Kelvin), offering efficient heat transfer performance while maintaining material stability.
- Operating Temperature Range: −40 °C to +200 °C, accommodating both heating and cooling cycles typical of fan coil unit operation.
- Corrosion Resistance: Superior resistance to chloride-induced pitting (particularly in SUS316 grade), acid environments, and condensation-induced degradation.
- Hygienic Properties: Non-toxic, non-porous surface finish suitable for potable water loops and indoor air quality (IAQ) sensitive environments.
- Surface Finish: Electropolished or passivated interior surface (Ra ≤ 0.8 μm) to minimize fouling and facilitate cleaning.
3. Specifications
| Parameter | Specification | Unit | Notes |
|---|---|---|---|
| Product Designation | FP-5 Series Coil Tube | — | Compatible with FP-5 Fan Coil Unit |
| Tube Outer Diameter (OD) | 9.52 / 12.70 | mm | 3/8" or 1/2" nominal bore |
| Tube Wall Thickness | 0.50 – 0.80 | mm | Dependent on pressure rating |
| Coil Diameter | 150 – 450 | mm | Adaptable to unit footprint |
| Number of Rows | 2 – 6 | Rows | Configurable for heat exchange capacity |
| Effective Heat Transfer Length | 3.0 – 12.0 | m | Per coil assembly |
| Maximum Working Pressure | 1.0 – 1.6 | MPa | Hydrostatic test at 1.5× rated pressure |
| Fins per Inch (FPI) | 10 – 14 | FPI | Aluminum or stainless steel fins |
| Fan Coil Unit Capacity | 2.0 – 8.0 | kW | Cooling / Heating output range |
| Refrigerant / Water Side Flow Rate | 0.5 – 2.0 | L/s | Design nominal flow |
| Corrosion Protection | Passivation / Electropolishing | — | ISO 15001 compliant |
4. Manufacturing Process
The production of the FP-5 Series stainless steel coil tube follows a rigorous, multi-stage manufacturing protocol to ensure dimensional accuracy, mechanical integrity, and thermal performance:
- Material Selection & Inspection: Incoming stainless steel strip or seamless tubing undergoes chemical composition analysis (via Optical Emission Spectrometry, OES) and mechanical property verification per ASTM A270 / ASTM A312 standards.
- Forming & Bending: Precision tube bending is executed using CNC-controlled hydraulic bending machines to achieve the required coil geometry with minimal wall thinning and deformation. Bending radii are optimized to prevent kinking and maintain uniform cross-sectional integrity.
- Fin Attachment: High-conductivity fins are applied via a brazing or mechanical clamping process. For stainless steel coils, brazing temperatures are carefully controlled to avoid grain structure alteration or stress sensitization.
- Welding & Joining: Orbital TIG (Tungsten Inert Gas) welding is employed at all critical joints, ensuring full-penetration welds with minimal heat-affected zone (HAZ) distortion. Weld seams are ground smooth to reduce flow turbulence and pressure drop.
- Surface Treatment: Post-fabrication passivation using nitric or citric acid solutions removes free iron and forms a stable chromium oxide (Cr₂O₃) passive layer, enhancing long-term corrosion resistance.
- Pressure Testing & Leak Detection: Each coil tube assembly undergoes hydrostatic pressure testing at 1.5 times the rated working pressure, followed by helium leak detection (sensitivity ≤ 1×10⁻⁹ Pa·m³/s) to guarantee zero-defect integrity.
- Final Inspection & Documentation: Dimensional verification via Coordinate Measuring Machine (CMM), surface roughness profiling, and compilation of traceability documentation (Mill Test Reports, MTRs) per ISO 9001 requirements.
5. Applications
The FP-5 Series stainless steel coil tube is engineered for versatile deployment across a broad spectrum of HVAC applications:
- Commercial Buildings: Office complexes, retail centers, and hospitality facilities requiring reliable, low-maintenance heating and cooling.
- Healthcare Facilities: Hospitals, clinics, and laboratories where hygienic standards and corrosion resistance are critical (particularly SUS316 grade for chemical resistance).
- Industrial Processes: Manufacturing plants, food processing facilities, and pharmaceutical environments demanding robust thermal management under aggressive chemical exposure.
- Residential High-End Systems: Premium residential HVAC installations prioritizing longevity and indoor air quality.
- Marine & Coastal Environments: Applications in salt-laden atmospheres where chloride resistance is essential.
- Data Centers: Precision temperature control systems requiring high thermal efficiency and minimal maintenance intervals.
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring that every FP-5 Series coil tube meets or exceeds international benchmarks:
- ISO 9001:2015 — Quality Management Systems certification covering design, manufacturing, and inspection processes.
- ISO 14001:2015 — Environmental Management Systems certification, reflecting sustainable manufacturing practices and waste minimization.
- ASTM A270 / A312 — Compliance with American Society for Testing and Materials standards for austenitic stainless steel tubing.
- GB/T 14976 — Conformity with Chinese national standards for seamless stainless steel tubes.
- EN 10216 — European standard compliance for seamless stainless steel tubes for general applications.
- ASME B31.5 — Adherence to piping and piping components standards for refrigeration and air-conditioning service.
- Mill Test Reports (MTRs): Full chemical and mechanical property traceability documentation provided with each production batch.
7. Unique Selling Points
Why the FP-5 Series Stainless Steel Coil Tube Stands Apart:
- Exceptional Durability: Stainless steel construction provides a service life exceeding 25 years under normal operating conditions — significantly outperforming copper or aluminum alternatives in corrosive environments.
- Hygienic & Food-Safe: Non-porous, electropolished surfaces prevent bacterial colonization and biofilm formation, making the product suitable for pharmaceutical, food, and healthcare applications.
- Reduced Lifecycle Cost: Although the initial material cost is higher than copper, the elimination of frequent replacement, lower maintenance requirements, and reduced downtime result in a superior total cost of ownership (TCO).
- Environmental Sustainability: Stainless steel is 100% recyclable with minimal property degradation, supporting circular economy objectives and reducing the carbon footprint of HVAC installations.
- Thermal Stability: Maintains consistent thermal conductivity across the full operating temperature range without the risk of oxidation-induced performance degradation common in copper coils.
- Customizability: Configurable coil dimensions, fin density, and row count allow tailored solutions for specific heat exchange capacity requirements within the FP-5 FCU platform.
8. Technical Reference
This product specification is derived from the "FP-5 Fan Coil Unit Development Report" (《FP—5型风机盘管机组研制报告》), a comprehensive engineering document encompassing design rationale, performance validation, and field application data. The report serves as the authoritative technical foundation for the FP-5 Series coil tube design, incorporating lessons learned from iterative prototyping, thermal simulation, and commissioning feedback.
For detailed engineering drawings, performance curves, and installation guidelines, refer to the complete FP-5 Series technical documentation package available from Wenzhou Jixing Metal Materials Co., Ltd.