Stainless Steel Coil Tube (Coiltube) — Series 1020 | Wenzhou Jixing Metal Materials Co., Ltd.
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered, continuous-length tubular product manufactured in a coiled configuration, specifically designed for integration into HVAC (Heating, Ventilation, and Air Conditioning) fan coil unit systems. This product represents a next-generation solution for thermal exchange applications, compatible with advanced floating-point electric heating valve control systems for precise temperature regulation.
Product Overview
The Stainless Steel Coil Tube is a seamless or welded tubular component wound into a continuous coil form, enabling efficient storage, transportation, and on-site deployment in industrial and commercial HVAC installations. The coiled geometry maximizes surface area within a compact footprint, making it ideal for use in fan coil units (FCUs), chiller systems, radiant floor heating circuits, and process heat exchange applications.
This product line is engineered to work synergistically with the Next-Generation Fan Coil Unit Temperature Control Valve — Floating-Point Electric Heating Valve, which provides high-precision, modulating control of coolant flow through the coil tube assembly. The combination delivers superior thermal efficiency, rapid response times, and energy optimization in climate control systems.
Key Features
- Continuous Coil Configuration: Eliminates field welding joints, reducing potential leak points and enhancing system reliability
- High Thermal Conductivity: Optimized wall thickness and material grade ensure efficient heat transfer performance
- Corrosion Resistance: Superior resistance to oxidation, scale formation, and chemical degradation in water-based heat transfer media
- Dimensional Consistency: Precision manufacturing tolerances ensure uniform flow characteristics throughout the entire coil length
- Modular Compatibility: Designed for seamless integration with floating-point electric heating valve systems for intelligent temperature modulation
Material & Properties
Material Grades
| Property | Specification | Standard Reference |
|---|---|---|
| Base Material | Austenitic Stainless Steel (304 / 304L / 316 / 316L) | ASTM A269 / ASTM A270 |
| Chromium (Cr) | 18.0% – 20.0% (304 series); 16.0% – 18.0% (316 series) | ASTM A240 |
| Nickel (Ni) | 8.0% – 10.5% (304 series); 10.0% – 14.0% (316 series) | ASTM A240 |
| Molybdenum (Mo) | — (304); 2.0% – 3.0% (316) | ASTM A240 |
| Carbon (C) Max | 0.08% (304); 0.03% (304L/316L) | ASTM A240 |
| Surface Finish | Bright Annealed (BA) / Electropolished (EP) / Passivated | ASTM A967 |
| Thermal Conductivity | 14.6 – 16.3 W/(m·K) at 20°C | — |
| Operating Temperature Range | −196°C to +870°C (304); −196°C to +870°C (316) | — |
| Maximum Working Pressure | Up to 1.6 MPa (16 bar) — typical HVAC application | ASME B31.9 |
Material Selection Guidance
- 304 / 304L: Suitable for general HVAC applications with standard water glycol mixtures; low-carbon grade (304L) recommended for welded assemblies to prevent intergranular corrosion
- 316 / 316L: Required for applications involving chlorinated cooling fluids, marine environments, or high-salinity condensate; molybdenum addition provides enhanced pitting and crevice corrosion resistance
Technical Specifications
| Parameter | Specification | Tolerance |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm / 8.0 mm / 9.52 mm / 12.0 mm / 15.88 mm | ±0.10 mm |
| Wall Thickness (WT) | 0.50 mm / 0.65 mm / 0.80 mm / 1.00 mm / 1.20 mm | ±0.05 mm |
| Coil Diameter (CD) | 100 mm / 150 mm / 200 mm / 300 mm | ±3 mm |
| Coil Length (Per Spool) | 50 m / 100 m / 200 m / 500 m (custom available) | ±2% |
| Minimum Bend Radius | 3D (3 × Outer Diameter) | — |
| Coil Pitch (Spacing) | 2.0 mm – 5.0 mm (adjustable per application) | ±0.2 mm |
| End Preparation | Deburred / Beveled / Flanged (upon request) | — |
| Surface Roughness (Ra) | ≤ 0.4 μm (BA finish); ≤ 0.2 μm (EP finish) | — |
| Hydrostatic Test Pressure | 1.5 × Working Pressure | — |
| Packaging | Wooden reel with moisture-proof wrapping; export-grade palletized | — |
Dimensional Tolerance Standards
All dimensional tolerances conform to ASTM A269/A269M (Seamless Austenitic Stainless Steel Tubing) and ASTM A270/A270M (Welded Austenitic Stainless Steel Tubing) unless otherwise specified. Coil geometry tolerances follow ISO 1155 requirements for tubular products in coiled form.
Manufacturing Process
Production Workflow
- Raw Material Procurement: Cold-rolled stainless steel strip or seamless tube stock sourced from certified mill producers (e.g., POSCO, Outokumpu, Tsingshan, Baowu), with full chemical composition and mechanical property certification (Mill Test Report — MTR).
- Slitting & Leveling: Raw coil or strip is slit to precise width using high-speed slitting lines, followed by leveling to eliminate residual stress and ensure flatness within ±0.05 mm/m.
- Forming & Welding (for welded variants): Precision roll-forming machines shape the strip into tube geometry; TIG (Tungsten Inert Gas) welding or automatic orbital welding creates the longitudinal seam with argon shielding on both interior and exterior surfaces.
- Continuous Coiling: The formed tube is wound onto precision-mandrel reels using CNC-controlled coiling heads that maintain uniform coil pitch, consistent tension, and dimensional accuracy throughout the entire spool length.
- Heat Treatment & Annealing: Solution annealing at 1050°C – 1150°C followed by controlled air or water quenching to achieve full austenitic microstructure, relieve residual stresses, and restore ductility.
- Surface Treatment: Bright annealing (BA) in a reducing atmosphere furnace (NH₃/H₂ or vacuum) to achieve a clean, oxide-free surface; optional electropolishing for ultra-low roughness applications.
- Passivation: Chemical passivation per ASTM A967 using nitric acid or citric acid solutions to enhance corrosion resistance by forming a stable chromium oxide layer.
- Quality Inspection: 100% hydrostatic testing, dimensional verification (OD, WT, coil diameter), visual inspection, and optional eddy current testing for weld integrity.
- Packaging & Dispatch: Protective wrapping (VCI film + bubble wrap), wooden reel assembly, moisture indicator cards, and documentation package (MTR, CoC, dimensional report).
Process Control Points
| Control Point | Inspection Method | Acceptance Criteria |
|---|---|---|
| Incoming Material | Spectroscopic analysis (PMI — Positive Material Identification) | Full chemical composition within ASTM specification limits |
| Forming Stage | In-line laser diameter gauge + wall thickness gauge | OD ±0.10 mm; WT ±0.05 mm |
| Weld Quality | Eddy current testing + visual inspection | No cracks, porosity, or undercut exceeding 0.1 mm |
| Coil Geometry | CNC mandrel verification + pitch measurement | Coil diameter ±3 mm; pitch ±0.2 mm |
| Hydrostatic Test | Automated pressure testing station | No leakage at 1.5 × working pressure for 30 seconds |
| Final Surface | Surface roughness profilometer + visual | Ra ≤ 0.4 μm (BA); no scratches, dents, or discoloration |
Applications
Primary Applications
- HVAC Fan Coil Units (FCUs): Primary heat exchange medium in commercial and residential fan coil units, working in conjunction with floating-point electric heating valves for precise temperature modulation. The coil tube serves as the refrigerant or hot water circuit through which thermal energy is transferred to or from the airstream.
- Radiant Floor & Wall Heating Systems: Continuous coil tube configurations enable uniform heat distribution in underfloor and wall-mounted radiant systems, eliminating the need for in-field pipe joining.
- Chilled Water Distribution: Used in building services for chilled water loops in commercial HVAC plants, where corrosion resistance and long service life are critical.
- Process Heat Exchangers: Integrated into shell-and-tube or plate-fin heat exchangers in food processing, pharmaceutical, and chemical manufacturing facilities.
- Industrial Cooling Systems: Deployed in process cooling circuits for machine tools, injection molding equipment, and electronic cooling applications.
Integration with Floating-Point Electric Heating Valve System
The Stainless Steel Coil Tube (Series 1020) is specifically designed for integration with the Next-Generation Fan Coil Unit Temperature Control Valve — Floating-Point Electric Heating Valve. This valve system provides:
- Continuous Modulating Control: Unlike traditional on/off solenoid valves, the floating-point electric heating valve offers proportional flow regulation, enabling precise temperature setpoint maintenance within ±0.5°C.
- Energy Efficiency: By modulating coolant flow rate rather than cycling the entire system, the valve reduces energy consumption by 15%–30% compared to conventional control methods.
- Compatibility: The coil tube's consistent inner diameter and uniform wall thickness ensure laminar flow characteristics that complement the valve's precision flow modulation capability.
Quality Certifications & Compliance
Product Certifications
| Certification / Standard | Scope | Status |
|---|---|---|
| ISO 9001:2015 | Quality Management System | Certified |
| ISO 14001:2015 | Environmental Management System | Certified |
| ISO 45001:2018 | Occupational Health & Safety Management System | Certified |
| CE Marking | European Conformity (Pressure Equipment Directive 2014/68/EU where applicable) | Compliant |
| EN 10216-5 | Technical Delivery Conditions for Seamless and Welded Tubes of Stainless Steels |