Stainless Steel Coil Tube for Fan Coil Unit Air Purification Systems
Product Overview
The Stainless Steel Coil Tube (Product No. 467) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubular product designed for integration into Fan Coil Units (FCUs) and advanced air purification systems. This coil tube serves as a critical structural and functional component in HVAC (Heating, Ventilation, and Air Conditioning) applications, particularly in environments requiring enhanced air quality control — a need that gained significant prominence during the global COVID-19 pandemic.
Engineered to withstand continuous thermal cycling, chemical exposure from antimicrobial treatments, and mechanical stress, this stainless steel coil tube ensures long-term reliability in demanding indoor air quality (IAQ) environments. The product leverages the inherent corrosion resistance, hygienic properties, and structural integrity of austenitic stainless steel to deliver superior performance in air purification coils.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of mechanical strength, corrosion resistance, and sanitary characteristics essential for air handling applications.
- Base Material: Austenitic Stainless Steel (e.g., AISI 304 / AISI 316L equivalent)
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, acidic condensate, and antimicrobial disinfectant residues (e.g., quaternary ammonium compounds, hydrogen peroxide-based agents)
- Hygienic Surface: Low surface roughness (Ra ≤ 0.4 μm) minimizes microbial adhesion and biofilm formation, critical for maintaining air quality in hospital and cleanroom environments
- Thermal Stability: Maintains dimensional stability across operating temperature ranges of −40°C to +250°C
- Mechanical Properties: High tensile strength (≥ 520 MPa) and elongation (≥ 40%) ensure resistance to fatigue failure during continuous thermal cycling
- Non-Magnetic: Austenitic microstructure ensures non-magnetic behavior, suitable for environments with electromagnetic sensitivity
- Food-Grade Compliance: Surface finish and material composition meet potable water and food-contact standards where applicable
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Designation | Stainless Steel Coil Tube (盘管) | — |
| Catalog Number | 467 | — |
| Material Grade | AISI 304 / AISI 316L | ASTM A213 / ASTM A269 |
| Outer Diameter (OD) | 6.0 mm – 12.7 mm (customizable) | ISO 1307 |
| Wall Thickness | 0.5 mm – 1.5 mm | ASTM A213 |
| Coil Diameter | 300 mm – 800 mm (configurable) | — |
| Tube Length per Coil | 5 m – 50 m | — |
| Surface Finish | 2B / BA (Bright Annealed) / Electropolished | ASTM A478 |
| Surface Roughness (Ra) | ≤ 0.4 μm (electropolished) | ISO 13567 |
| Operating Temperature Range | −40°C to +250°C | — |
| Pressure Rating | Up to 1.6 MPa (PN16) | EN 10217 |
| Bending Radius | ≥ 5× OD (minimum) | — |
| Welding Method | TIG (GTAW) / Orbital Welding | ISO 6947 |
| End Preparation | Plain end / Beveled end (per customer specification) | ASME B1.20.1 |
| Packaging | Wooden crate / Export-grade steel pallet with moisture barrier | ISO 4180 |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorously controlled multi-stage manufacturing process to ensure dimensional accuracy, surface integrity, and metallurgical quality:
- Raw Material Selection & Ingot Preparation: Virgin stainless steel ingots or hot-rolled coils are sourced from certified mills. Incoming material undergoes spectrographic analysis (PMI — Positive Material Identification) to verify chemical composition compliance with the specified grade.
- Hot Rolling & Annealing: The steel is hot-rolled to approximate dimensions, followed by solution annealing at 1050°C – 1150°C in a controlled atmosphere furnace to achieve a fully austenitic, stress-free microstructure.
- Pickling & Descaling: The annealed tube is pickled in a mixed acid solution (nitric + hydrofluoric acid) to remove oxide scale, followed by thorough rinsing and passivation to establish a stable chromium oxide passive layer.
- Cold Drawing / Cold Forming: The tube is cold-drawn through precision tungsten carbide dies to achieve the final outer diameter and wall thickness tolerances (±0.05 mm). This cold working process enhances mechanical properties and surface finish.
- Intermediate Annealing: Where multiple cold-drawing passes are required, intermediate annealing is performed to relieve accumulated work-hardening and prevent cracking.
- Coil Forming (Coiling): The straight tube is precisely coiled using CNC-controlled coiling equipment to achieve the specified coil diameter and pitch. The coiling process is designed to minimize residual stress and avoid ovality distortion.
- Surface Treatment: For applications requiring enhanced hygiene properties, the coil tube undergoes electropolishing or mechanical polishing to achieve a surface roughness of Ra ≤ 0.4 μm.
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Quality Inspection: Each batch undergoes comprehensive inspection including:
- Visual inspection for surface defects
- Dimensional verification using laser diameter measurement
- Hydrostatic pressure testing (1.5× working pressure, 10-second hold)
- Eddy current testing for internal wall defects
- Chemical composition verification via optical emission spectrometry (OES)
- Mechanical property testing (tensile, hardness)
- Packaging & Dispatch: Inspected coil tubes are wrapped in protective film, packed in moisture-resistant export-grade packaging, and prepared for shipment with full traceability documentation.
Applications
The stainless steel coil tube is integral to a wide range of HVAC and air purification systems, with particular relevance to applications demanding high standards of indoor air quality:
- Fan Coil Units (FCUs) for Air Purification: The coil tube serves as the heat exchange element in FCUs equipped with advanced air purification modules, including UV-C germicidal irradiation, HEPA filtration, and photocatalytic oxidation (PCO) systems.
- Hospital & Healthcare Facilities: Critical application in operating theaters, intensive care units (ICUs), and infection control wards where antimicrobial air quality is mandatory. The hygienic surface finish prevents bacterial colonization and condensate-related contamination.
- Pharmaceutical & Biotechnology Cleanrooms: Used in HVAC systems for GMP (Good Manufacturing Practice) environments requiring ISO Class 5 – 7 cleanroom classifications.
- Commercial & Residential HVAC: Integrated into air conditioning coils for office buildings, schools, hotels, and residential units to provide efficient heating and cooling with improved hygiene performance.
- Food Processing & Beverage Industry: Employed in refrigeration coils and process cooling systems where sanitary design standards (3-A Sanitary Standards) apply.
- Marine & Offshore HVAC: Suitable for HVAC systems in vessels and offshore platforms where resistance to salt-laden air and condensate is essential.
- Data Center Cooling: Utilized in precision cooling coils for server room temperature management, where reliability and long service life are paramount.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework ensuring that every product meets or exceeds international standards:
- ISO 9001:2015 — Quality Management Systems certification
- ISO 14001:2015 — Environmental Management Systems certification
- ISO 45001:2018 — Occupational Health and Safety Management Systems certification
- EN 10204 — Type 3.1 mill test certificates provided with every shipment
- ASTM A213 / A269 — Seamless and welded stainless steel tube standards
- EN 10216-5 — European standard for stainless steel tubes for pressure purposes
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes
- GB/T 12771 — Chinese national standard for welded stainless steel tubes
- NACE MR0175 / ISO 15156 — Compliance for sour service environments where applicable
- NSF/ANSI 61 — Drinking water system components certification (where applicable)
Unique Selling Points
- Pandemic-Proven Performance: Specifically validated for use in air purification FCU systems, this coil tube has been studied and recommended for enhanced indoor air quality management in epidemic control scenarios, ensuring reliable operation under continuous antimicrobial treatment cycles.
- Superior Hygienic Design: The electropolished surface finish (Ra ≤ 0.4 μm) significantly reduces microbial adhesion compared to standard 2B finish, making it ideal for healthcare and food-grade applications.
- Customizable Geometry: Flexible coil diameter, tube dimensions, and surface finish options allow OEM integration into diverse FCU and HVAC platform designs without compromising performance.
- Extended Service Life: The combination of corrosion-resistant material selection and controlled manufacturing processes delivers a service life exceeding 20 years under normal HVAC operating conditions, reducing lifecycle maintenance costs.
- Full Traceability: Each coil tube batch is accompanied by comprehensive mill test certificates, material certificates, and inspection reports, ensuring complete supply chain traceability for regulated industries.
Note: All specifications listed above are typical values and subject to verification against the applicable material specification and purchase order. Custom specifications are available upon request. Wenzhou Jixing Metal Materials Co., Ltd reserves the right to improve product designs and specifications without prior notice.