Energy-Saving Fan Coil Tube (Stainless Steel Coil Pipe) — Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Energy-Saving Fan Coil Tube (Product No. 344) is a precision-engineered stainless steel coil pipe specifically designed for use in high-efficiency fan coil unit (FCU) systems within commercial and industrial HVAC (Heating, Ventilation, and Air Conditioning) applications. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product represents the convergence of advanced metallurgical processing and thermal-exchange optimization, delivering superior energy efficiency while maintaining long-term structural integrity under demanding operating conditions.
The coil tube serves as the primary heat-transfer element within fan coil units, facilitating the exchange of thermal energy between a refrigerant or hydronic fluid medium and the ambient air stream. Its spiral-wound geometry maximizes the surface-area-to-volume ratio, thereby enhancing convective and radiative heat transfer coefficients compared to conventional straight-tube configurations. This design philosophy aligns with the principles of thermodynamic efficiency and compact heat exchanger design as described in standard references such as ASHRAE Handbook — Fundamentals.
Material & Properties
The coil tube is fabricated from high-grade Austenitic Stainless Steel, selected for its exceptional combination of corrosion resistance, thermal conductivity, and mechanical ductility. The primary alloy grades utilized include:
- ASTM A213 TP304 (UNS S30400) — General-purpose austenitic stainless steel with 18% Chromium and 8% Nickel, offering excellent resistance to atmospheric and mild chemical corrosion.
- ASTM A213 TP316 (UNS S31600) — Enhanced austenitic grade containing 2.5% Molybdenum, providing superior resistance to pitting and crevice corrosion in aggressive environments.
- ASTM A213 TP304L (UNS S30403) — Low-carbon variant of 304, reducing the risk of intergranular corrosion during welding operations.
| Property | 304 Grade | 316 Grade |
|---|---|---|
| Tensile Strength (ASTM) | ≥ 515 MPa | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa | ≥ 205 MPa |
| Elongation at Break | ≥ 40% | ≥ 40% |
| 16.3 W/(m·K) | 16.3 W/(m·K) | |
| Specific Heat Capacity | 500 J/(kg·K) | 500 J/(kg·K) |
| Density | 8.00 g/cm³ | 8.00 g/cm³ |
| Maximum Operating Temperature | 870°C | 870°C |
| Corrosion Resistance (Equivalent Salt Spray Test) | > 200 hours (ASTM B117) | > 500 hours (ASTM B117) |
Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.35 mm, 9.53 mm, 12.70 mm (¼", ⅜", ½") |
| Wall Thickness | 0.50 mm – 1.00 mm (customizable) |
| Coil Pitch | 12 mm – 25 mm (adjustable per design requirement) |
| Coil Diameter (Bundle) | 150 mm – 600 mm |
| Tube Length per Coil | 1.0 m – 12.0 m |
| Number of Passes | 1, 2, or 4 (multi-pass configurations available) |
| Operating Pressure (Hydrostatic Test) | ≤ 1.5 × Design Pressure (minimum 2.0 MPa) |
| Maximum Working Pressure | 1.6 MPa (standard); up to 4.0 MPa (reinforced) |
| Refrigerant Compatibility | R-22, R-410A, R-32, R-134a, R-407C |
| Water Quality Requirement | Conductivity ≤ 15 µS/cm; pH 6.5 – 8.5 |
| Surface Finish | Mirror Polish (Ra ≤ 0.4 µm) or Matte Finish (Ra ≤ 1.6 µm) |
| Welding Method | TIG (Tungsten Inert Gas) Welding — ASTM A240 compliant |
| Standard Reference | ASTM A213, EN 10216-5, GB/T 12771 |
Manufacturing Process
The production of the Energy-Saving Fan Coil Tube follows a rigorously controlled multi-stage manufacturing workflow, ensuring dimensional accuracy, metallurgical homogeneity, and surface quality in accordance with ISO 9001:2015 quality management standards.
- Raw Material Inspection — Incoming stainless steel coil stock is verified against mill test certificates (MTC) for chemical composition (spectrographic analysis per ASTM E415), grain size, and mechanical properties. Rejected batches are quarantined per non-conformance procedures.
- Coil Forming and Cold Bending — Precision CNC-controlled coil forming machines shape the straight tube into the specified helical geometry. The bending radius is maintained at a minimum of 3× the outer diameter (OD) to prevent wall thinning and microstructural distortion. Tension and compression stresses are monitored in real time.
- Heat Treatment (Solution Annealing) — Tubes requiring enhanced corrosion resistance undergo solution annealing at 1040°C – 1100°C followed by rapid water quenching. This process dissolves carbide precipitates and restores full austenitic microstructure, maximizing resistance to intergranular corrosion (IGC).
- TIG Welding of U-Bends and Headers — Multi-pass coil assemblies are connected via U-bends and header connections using Tungsten Inert Gas (TIG) welding under a continuous Argon (Ar) or Helium (He) shielding atmosphere. Pre-weld passivation and post-weld pickling ensure weld integrity and corrosion resistance at fusion zones.
- Pickling and Passivation — Post-welding, the entire assembly is subjected to acid pickling (nitric-hydrofluoric acid blend) to remove oxide scale, followed by passivation treatment to establish a chromium-rich passive film on the surface. This step is critical for long-term corrosion performance.
- Hydrostatic Pressure Testing — Each completed coil tube assembly undergoes hydrostatic testing at 1.5× the maximum design pressure for a minimum dwell time of 15 minutes. Any leakage or dimensional deformation results in immediate rejection.
- Final Surface Finishing and Cleaning — Internal and external surfaces are cleaned using high-purity deionized water and validated for cleanliness per ASME BPE (Bioprocessing Equipment) standards where applicable. Surface roughness is verified via profilometry.
- Non-Destructive Testing (NDT) — Select samples undergo ultrasonic testing (UT) per ASTM E317 and dye penetrant testing (PT) per ASTM E709 to detect subsurface and surface discontinuities.
Applications
The Energy-Saving Fan Coil Tube is engineered for a broad spectrum of HVAC and thermal management applications:
- Commercial Building HVAC Systems — Fan coil units deployed in office buildings, shopping malls, hospitals, and hotels for zone-level temperature control with variable refrigerant flow (VRF) or chilled water systems.
- Industrial Process Cooling — Precision temperature control in pharmaceutical manufacturing, food and beverage processing, and semiconductor cleanroom environments where material purity and corrosion resistance are paramount.
- Data Center Thermal Management — High-density cooling solutions for server rooms and data centers, where compact coil geometries maximize heat dissipation within constrained floor space.
- Marine and Offshore HVAC — Saltwater-resistant 316-grade coil tubes for shipboard air conditioning systems and offshore platform climate control.
- Residential HVAC — Ducted and ductless mini-split fan coil units for premium residential installations requiring long service life and low maintenance.
- Heat Recovery Ventilators (HRV) — Integrated coil tubes within energy recovery systems that pre-condition incoming ventilation air, reducing overall energy consumption by up to 40%.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality assurance framework validated through international accreditation bodies:
| Certification / Standard | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System — Design, Manufacturing, and Supply |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health and Safety Management |
| EN 10216-5 | European Standard for Seamless Steel Tubes — Heat Exchanger Tubes |
| ASME BPV Section I | American Society of Mechanical Engineers — Pressure Vessel Code |
| CE Marking (EU Directive 2014/68/EU — PED) | Pressure Equipment Directive Compliance |
| GB/T 12771 | Chinese National Standard — Stainless Steel Seamless Tubes for Heat Exchangers |
| TÜV Certified Manufacturing Facility | Third-party audit of production processes and quality controls |
Unique Selling Points
"Precision Engineering Meets Energy Efficiency"
- Enhanced Thermal Efficiency — The optimized helical coil geometry with variable pitch design increases the effective heat transfer area by up to 35% compared to standard straight-tube coil configurations, directly translating to lower compressor power consumption and reduced operating costs.
- Exceptional Corrosion Longevity — The use of premium austenitic stainless steel (304/316 grade) combined with rigorous post-weld passivation ensures a design service life exceeding 25 years, even in high-humidity and chemically aggressive environments.
- Energy-Saving Integration — Designed specifically for compatibility with modern Variable Refrigerant Flow (VRF) and Variable Speed Drive (VSD) systems, enabling precise thermal modulation and significant reductions in standby power consumption.
- Customizable Engineering — Full customization of coil diameter, pitch, tube OD, wall thickness, and number of passes to match specific system design parameters, ensuring optimal thermal performance for each application.
- Zero-Leakage Guarantee — 100% hydrostatic pressure testing on every unit, supplemented by ultrasonic and dye penetrant NDT on sampled batches, providing absolute assurance of structural integrity.
- Sustainable Manufacturing — Production processes incorporate recycled stainless steel feedstock and low-emission welding procedures, contributing to reduced carbon footprint in alignment with global sustainability objectives.
Technical Notes
For optimal performance, the Energy-Saving Fan Coil Tube should be installed in accordance with manufacturer guidelines and applicable local building codes. System water quality must be maintained within the specified parameters to prevent scale formation and galvanic corrosion. Regular inspection intervals (recommended every 12 months) should include visual examination of weld joints, pressure testing, and verification of surface finish integrity. In applications involving chlorinated water or high-chloride environments, the 316-grade variant with Molybdenum addition is strongly recommended to mitigate the risk of stress corrosion cracking (SCC).
All product data presented in this specification is subject to revision without prior notice as Wenzhou Jixing Metal Materials Co., Ltd. continues to invest in research and development to enhance product performance and compliance with evolving international standards.