Stainless Steel Coil Tube (Coiltube) — Fan Coil Unit Grade
Product Overview
The Stainless Steel Coil Tube (Product No. 674) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered, cold-formed continuous coil tube designed for demanding industrial and commercial applications. This product is specifically engineered to meet the rigorous requirements of Fan Coil Unit (FCU) Plasma Air Disinfection Systems, where structural integrity, corrosion resistance, and thermal conductivity are paramount. The coil tube is supplied in continuous coil form to facilitate automated bending, cutting, and forming operations, thereby minimizing material waste and maximizing production efficiency in downstream fabrication processes.
Unlike conventional seamless or welded tubing, the coil tube format enables high-throughput production of complex geometries including serpentine heat exchanger coils, serpentine flow channels for plasma discharge chambers, and compact fluid circulation loops used in medical-grade air purification equipment. The product represents a critical component in the construction of plasma-based air disinfection devices, where the tube must withstand repeated thermal cycling, exposure to reactive plasma species, and sustained mechanical stress without degradation.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional balance of corrosion resistance, formability, and mechanical strength. The material composition and mechanical properties are detailed below:
Chemical Composition (Typical)
| Element | Specification | Notes |
|---|---|---|
| Carbon (C) | ≤ 0.08% | Low carbon for weldability and resistance to intergranular corrosion |
| Chromium (Cr) | 18.0 – 20.0% | Primary corrosion-resistant alloying element |
| Nickel (Ni) | 8.0 – 10.5% | Stabilizes austenitic microstructure; enhances ductility |
| Molybdenum (Mo) | 2.0 – 3.0% | Improves pitting and crevice corrosion resistance |
| Nitrogen (N) | ≤ 0.10% | Contributes to solid solution strengthening |
| Sulfur (S) | ≤ 0.030% | Controlled for improved machinability if required |
Mechanical Properties
- Tensile Strength (UTS): ≥ 520 MPa (75,400 psi)
- Yield Strength (0.2% Offset): ≥ 205 MPa (29,700 psi)
- Elongation at Break: ≥ 40% (measured on 50 mm gauge length)
- Hardness: ≤ 95 HRB (Rockwell B scale)
- Density: 8.00 g/cm³
- Thermal Conductivity (25°C): 16.3 W/(m·K)
- Thermal Expansion Coefficient (20–100°C): 16.5 × 10⁻⁶ /°C
Surface Finish Options
- Bright Annealed (BA): For applications requiring high surface reflectivity and aesthetic quality
- Pickled and Passivated: For maximum corrosion resistance in aggressive environments
- Electropolished: Surface roughness Ra ≤ 0.4 μm; suitable for sanitary and medical-grade applications
- 2B Cold Rolled: Standard industrial finish with moderate surface quality
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) | — |
| Product No. | 674 | — |
| Material Grade | SUS316L / ASTM 316L | JIS G4315 / ASTM A213 / EN 10216-5 |
| Outer Diameter (OD) | 6.0 mm – 50.8 mm (¼" – 2") | Custom sizes available upon request |
| Wall Thickness (WT) | 0.5 mm – 3.0 mm | Tolerance: ±10% |
| Coil Inner Diameter (ID) | 500 mm – 1000 mm | Adaptable to customer unwinding equipment |
| Coil Length | 50 m – 500 m (continuous) | Variable; batch-specific |
| Tolerance on OD | ±0.1 mm (for OD ≤ 25 mm); ±0.15 mm (for OD > 25 mm) | ISO 4413 |
| Tolerance on WT | ±0.05 mm (for WT ≤ 1.0 mm); ±0.08 mm (for WT > 1.0 mm) | ISO 4413 |
| Roundness | ≤ 0.5% of OD | — |
| Length Tolerance | ±2.0% of total coil length | — |
| Maximum Working Pressure | 1.6 MPa (standard); up to 4.0 MPa (thick-wall variants) | Calculated per ASME BPV Code |
| Operating Temperature Range | −196°C to +600°C | Cryogenic to high-temperature service |
| Welding Suitability | Excellent (TIG, MIG, laser welding compatible) | ASTM A213 |
| Corrosion Resistance | Excellent in atmospheric, marine, and chemical environments | Pitting Resistance Equivalent Number (PREN) ≥ 24 |
| Package | Steel drum or wooden crate with protective wrapping | ISO 4180 |
| Place of Origin | Wenzhou, Zhejiang, China | — |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous, multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and surface quality. The process encompasses the following critical stages:
- Raw Material Selection and Incoming Inspection: Hot-rolled stainless steel strip is sourced from certified mills and subjected to spectroscopic analysis (OES), tensile testing, and visual inspection to verify conformance with specified chemical composition and mechanical properties.
- Strip Preparation: The incoming strip undergoes edge trimming, leveling, and surface cleaning to remove scale, oxidation, and surface contaminants. Coil-to-coil handling is employed to maintain continuity and minimize defects.
- Forming and Bending: The strip is fed through a series of progressive roll-forming stations where it is incrementally bent into the desired circular cross-section. Precision die sets ensure uniform wall thickness and roundness throughout the forming process.
- Welding (if applicable): For welded coil tubes, a high-frequency induction welding or laser welding process is applied to the seam. The welding parameters are continuously monitored to ensure seam integrity, with online eddy current testing employed for real-time seam inspection.
- Heat Treatment (Annealing): The formed coil tube undergoes solution annealing at temperatures between 1050°C and 1100°C, followed by controlled cooling. This process dissolves carbide precipitates, relieves residual stresses from cold working, and restores full austenitic microstructure, thereby ensuring optimal corrosion resistance and ductility.
- Surface Treatment: Post-annealing, the tube undergoes pickling and passivation to remove any residual scale and form a protective chromium oxide layer. Electropolishing may be applied for applications requiring ultra-low surface roughness.
- Dimensional Verification and Quality Control: Each coil is inspected for OD, wall thickness, roundness, and surface defects using automated optical inspection (AOI) systems, ultrasonic thickness gauges, and dimensional measurement instruments. Sampling protocols follow ASTM E10 and ISO 3079 standards.
- Coiling and Packaging: The finished tube is coiled onto a core of specified diameter, wrapped with protective film or paper, and secured in steel drums or wooden crates to prevent mechanical damage and moisture exposure during transit.
Applications
The Stainless Steel Coil Tube is designed for a diverse range of industrial and commercial applications, with particular emphasis on the following sectors:
1. Fan Coil Unit Plasma Air Disinfection Systems
This is a primary application domain for this product. In Plasma Air Disinfection Devices integrated into Fan Coil Units, the coil tube serves as the structural backbone for the plasma discharge chamber. The tube must:
- Withstand repeated exposure to reactive plasma species including ozone (O₃), hydroxyl radicals (·OH), nitrogen oxides (NOx), and ultraviolet radiation
- Maintain dimensional stability under thermal cycling conditions as air flows through the unit
- Provide electrical insulation properties compatible with high-voltage plasma generation electrodes
- Resist corrosion from byproducts of plasma discharge to ensure long-term operational reliability
- Facilitate efficient heat exchange between the plasma discharge zone and the circulating air stream
2. HVAC and Refrigeration Systems
- Serpentine heat exchanger coils for air handlers, chillers, and condensers
- Refrigerant line tubing for low-pressure and medium-pressure refrigeration circuits
- Condensate drainage coils for dehumidification systems
3. Medical and Pharmaceutical Equipment
- Fluid circulation loops in medical-grade air filtration and sterilization systems
- Process tubing in pharmaceutical cleanroom HVAC systems
- Components in hospital air purification and infection control equipment
4. Food and Beverage Processing
- Heat exchanger coils for pasteurization and sterilization equipment
- Process piping for CIP (Clean-in-Place) systems
- Steam coils for cooking and heating applications
5. Chemical and Petrochemical Industry
- Corrosion-resistant tubing for chemical processing and transport
- Heat exchanger coils for aggressive chemical environments
- Instrumentation and sample line tubing
6. Marine and Offshore Applications
- Seawater cooling coils for marine HVAC systems
- Corrosion-resistant tubing for ballast water treatment systems
- Fire suppression system piping
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications to ensure product reliability and compliance with international standards:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent product quality and customer satisfaction |
| ISO 14001:2015 | Environmental Management System certification demonstrating commitment to environmental responsibility |
| ISO 45001:2018 | Occupational Health and Safety Management System certification |
| CE Marking (EU) | European Conformity marking indicating compliance with EU health, safety, and environmental protection standards |
| EN 10216-5 | European standard for welded and seamless ferritic, austenitic, and duplex stainless steel tubes |
| ASTM A213 / A269 | American standards for austenitic stainless steel seamless, welded, and heavily cold-worked tubes |
| JIS G4315 | Japanese Industrial Standard for austenitic stainless steel seamless and welded tubes |
| NB (National Bureau) Certification | China National Boiler and Pressure Vessel Inspection and Research Institute certification for pressure vessel components |
| Mill Test Certificate (MTC) | Third-party material test certificates provided with each batch, including chemical analysis, mechanical testing, and dimensional verification |
Unique Selling Points
- Continuous Coil Format: Enables automated, high-throughput downstream fabrication with minimal material waste and reduced labor costs
- Premium 316L Grade Material: Superior corrosion resistance with PREN ≥ 24, ideal for plasma discharge environments and aggressive chemical exposure
- Plasma-Resistant Surface Integrity: Engineered to withstand repeated exposure to reactive plasma species without degradation of mechanical or surface properties
- Full Traceability: Each coil is accompanied by a Mill Test Certificate (MTC) with complete chemical and mechanical data, enabling full supply chain traceability
- Customizable Dimensions: Flexible OD and wall thickness ranges accommodate a wide variety of application-specific requirements
- Cryogenic to High-Temperature Capability: Operational range from −196°C to +600°C ensures versatility across diverse thermal environments
- Compliant with International Standards: Manufactured to meet ASTM, EN, JIS, and ISO standards, ensuring global market acceptance
- Manufacturer Direct Supply: Direct sourcing from Wenzhou Jixing Metal Materials Co., Ltd eliminates intermediary markups and ensures quality control from raw material to finished product
Maintenance and Service Life
Based on the operational characteristics of Fan Coil Unit Plasma Air Disinfection Systems and general industrial applications, the following maintenance guidelines and service life expectations apply