Stainless Steel Coil Tube (Coiltube) — Model 1302 | Flexible Ducting & Fan Coil Connection System
Product Overview
The Stainless Steel Coil Tube (Coiltube), designated as Model 1302, is a high-performance flexible ducting component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically engineered for ventilation and air-conditioning (HVAC) installation engineering, serving as a critical interface between fan coil units (FCUs) and air supply grilles. The coil tube integrates flexible hose and soft joint technology to accommodate thermal expansion, vibration damping, and misalignment tolerances inherent in complex ventilation systems. Its coiled configuration provides exceptional flexibility while maintaining structural integrity under continuous operational loads.
This product addresses the engineering challenges identified in ventilation installation practices, particularly concerning the reliability of soft connections, the sealing performance of flexible joints, and the aerodynamic efficiency of fan coil unit to grille transitions. The Model 1302 represents a comprehensive solution that ensures long-term operational stability, acoustic attenuation, and compliance with international mechanical ventilation standards.
Material & Properties
The coil tube is constructed from premium-grade austenitic stainless steel, selected for its superior combination of corrosion resistance, mechanical strength, and thermal stability. The following material characteristics define the product's performance envelope:
- Base Material: Austenitic stainless steel (grades including SUS304, SUS316, and SUS316L), providing excellent resistance to oxidation, chemical attack, and high-temperature deformation.
- Corrosion Resistance: The chromium (Cr) and nickel (Ni) alloying elements form a passive oxide layer, ensuring service life in humid, chemically aggressive, and saline environments typical of HVAC systems.
- Mechanical Properties: Tensile strength exceeding 520 MPa with elongation of ≥40%, enabling the coil tube to withstand cyclic loading and thermal fatigue without permanent deformation.
- Thermal Conductivity: Low thermal conductivity (approximately 15–16 W/m·K for SUS304) minimizes heat transfer losses along the duct run, contributing to system energy efficiency.
- Hygienic Surface: Surface roughness (Ra) maintained below 0.8 μm, preventing particulate accumulation and facilitating cleaning in pharmaceutical, food-grade, and cleanroom ventilation applications.
- Temperature Range: Operational range from −196°C to +870°C, accommodating extreme thermal cycling in specialized industrial HVAC systems.
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Designation | Coiltube Model 1302 | Internal Product Catalog |
| Material Grade | SUS304 / SUS316 / SUS316L (Selectable) | ASTM A240 / EN 10088 / JIS G4305 |
| Outer Diameter Range | Φ50 mm – Φ630 mm | Customer-Specific |
| Wall Thickness | 0.3 mm – 1.5 mm | ASTM A269 |
| Coil Pitch (Helical Spacing) | 3 mm – 12 mm (Configurable) | Engineering Design Basis |
| Effective Length | 0.5 m – 6.0 m (Customizable) | Project-Specific |
| Surface Finish | Ba & Pickle (BP) / Electropolished (EP) / Brushed | ASTM A403 |
| End Connections | Flanged, Welded, Grooved, or Clamp-Type | ISO 1161 / EN 1092 |
| Pressure Rating | Up to 0.6 MPa (gauge) | ASME B31.9 |
| Flexibility (Bend Radius) | Minimum 3× OD | Engineering Tolerance |
| Acoustic Attenuation | ≥15 dB (A-weighted) at 250–1000 Hz | ISO 10848 |
| Fire Rating | Non-combustible; A1 classification | EN 13501-1 |
| Compliance Standards | GB 50243, SMACNA, ISO 15707 | Multi-Standard Conformity |
Manufacturing Process
The production of the Model 1302 Coil Tube follows a rigorous multi-stage manufacturing protocol designed to ensure dimensional accuracy, metallurgical integrity, and consistent performance:
- Raw Material Procurement & Verification: Certified stainless steel coil stock is sourced from accredited mills. Incoming material undergoes spectroscopic analysis (optical emission spectrometry) to verify chemical composition compliance with ASTM/EN specifications.
- Surface Preparation: The steel coil is subjected to mechanical cleaning and chemical pickling to remove mill scale, oxidation, and surface contaminants. This step is critical for ensuring weldability and corrosion resistance.
- Forming & Coiling: The prepared strip is fed through precision-rolled forming dies to achieve the helical coil geometry. Computer Numerical Control (CNC) machinery ensures consistent coil pitch, wall thickness uniformity, and diameter tolerance within ±0.1 mm.
- Welding (if applicable): For seamless helical configurations, continuous helical welding is performed using Tungsten Inert Gas (TIG) or Gas Metal Arc Welding (GMAW) processes under inert gas shielding. Weld seams are inspected via dye penetrant testing (DPT) or ultrasonic testing (UT).
- Post-Weld Heat Treatment: Solution annealing at 1050–1150°C followed by controlled cooling relieves residual stresses, restores full austenitic structure, and maximizes corrosion resistance.
- End Processing: End connections (flanges, grooves, or fittings) are fabricated and welded with full penetration welds. Each joint undergoes non-destructive testing (NDT) to confirm structural soundness.
- Final Inspection & Testing: Completed coil tubes undergo dimensional verification, pressure testing at 1.5× working pressure for 30 minutes, visual inspection, and documentation of traceability records.
Applications
The Model 1302 Stainless Steel Coil Tube is deployed across a broad spectrum of HVAC and ventilation engineering applications:
- Fan Coil Unit (FCU) Connections: Primary application in connecting fan coil units to air supply grilles and diffusers, absorbing vibration from rotating fan assemblies and accommodating thermal expansion of ductwork.
- Flexible Duct Transitions: Used as short flexible connectors between rigid duct sections where minor misalignment or differential movement is anticipated.
- Industrial Ventilation Systems: Deployed in manufacturing facilities, laboratories, and process plants requiring corrosion-resistant and hygienic air transport.
- Cleanroom & Pharmaceutical HVAC: The electropolished surface finish meets ISO 14644 cleanroom requirements for particulate control in pharmaceutical manufacturing, semiconductor fabrication, and biotechnology facilities.
- Food & Beverage Processing: Compliant with FDA and 3-A Sanitary Standards for air handling systems in food processing environments where microbial contamination must be prevented.
- Marine & Offshore HVAC: SUS316/SUS316L grades provide chloride resistance for ventilation systems on naval vessels, offshore platforms, and coastal installations.
- High-Temperature Exhaust Systems: Suitable for HVAC exhaust applications involving elevated temperatures in industrial furnaces, kilns, and thermal processing equipment.
- Building Services Engineering: Integrated into commercial and institutional building ventilation systems as specified in GB 50243 (Code for Acceptance of Construction Quality of Ventilation and Air-Conditioning Engineering).
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring the Model 1302 Coil Tube meets international and domestic standards:
- ISO 9001:2015: Quality Management System certification covering all stages of design, manufacturing, and delivery.
- ISO 14001:2015: Environmental Management System certification demonstrating commitment to sustainable manufacturing practices.
- ISO 45001:2018: Occupational Health and Safety Management System certification.
- CE Marking (EU): Conformity with European directives for pressure equipment and mechanical ventilation components.
- GB/T 12771: Compliance with Chinese national standards for welded stainless steel pipes and tubes.
- Material Traceability: Full mill certification (EN 10204 Type 3.1) provided for every batch, including chemical analysis, mechanical test results, and heat treatment records.
- Third-Party Inspection: Available upon request for client-designated inspection agencies (e.g., SGS, Bureau Veritas, TÜV).
Unique Selling Points
The Model 1302 Coil Tube distinguishes itself in the competitive HVAC flexible connector market through the following value propositions:
- Integrated Vibration Isolation: The helical coil geometry inherently provides mechanical decoupling, reducing transmitted vibration by up to 90% compared to rigid connections, thereby extending the service life of fan coil units and associated equipment.
- Thermal Expansion Accommodation: Engineered to absorb axial and lateral thermal displacement without inducing stress concentrations, preventing fatigue failure at connection points over the system's operational lifetime.
- Superior Acoustic Performance: The coiled configuration acts as a natural acoustic barrier, attenuating fan-generated noise and contributing to compliance with workplace noise regulations (ISO 1996).
- Hygienic & Food-Safe Construction: Available in electropolished finish with Ra < 0.4 μm, meeting the most stringent sanitary requirements for pharmaceutical and food-grade applications.
- Customization Capability: Full dimensional and material customization to match project-specific design requirements, reducing the need for field modifications and ensuring optimal system performance.
- Extended Service Life: Corrosion-resistant alloy selection and robust manufacturing quality ensure service life exceeding 25 years under normal operating conditions, minimizing lifecycle replacement costs.
Conclusion: The Wenzhou Jixing Metal Materials Co., Ltd. Model 1302 Stainless Steel Coil Tube represents a technically advanced solution for flexible HVAC connections, combining metallurgical excellence, precision engineering, and comprehensive quality assurance. Its application in ventilation installation engineering directly addresses the technical challenges of soft joint reliability, fan coil integration, and long-term system performance documented in industry best practice literature.