Stainless Steel Coil Tube for Steel Plate Radiant Panel Heating Systems
Product Overview
The Stainless Steel Coil Tube (Product No. 1629), manufactured by Wenzhou Jixing Metal Materials Co., Ltd., is a precision-engineered coiled tubing product specifically designed for steel plate radiant panel local heating applications. These coil tubes serve as the primary heat transfer medium within radiant heating systems, where hot water or steam circulates through the coiled tubing embedded in steel plate panels to deliver efficient, uniform thermal radiation to target zones.
This product represents a specialized segment of industrial tubing engineering, combining the corrosion resistance and thermal stability of stainless steel with the geometric precision required for radiant heating panel integration. The coil tube design enables compact, high-surface-area heat exchange configurations that maximize radiant output while minimizing thermal losses.
Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steel, selected for superior resistance to thermal cycling, oxidation, and corrosion under sustained heating conditions. Key material properties include:
- Base Material: Austenitic Stainless Steel (e.g., SUS304 / AISI 304 or SUS316 / AISI 316L)
- Chromium Content (Cr): ≥18% — provides excellent oxidation resistance and passive film stability
- Nickel Content (Ni): 8–10.5% — ensures ductility and resistance to intergranular corrosion
- Molybdenum Content (Mo): 2–3% (in 316 grade) — enhances pitting and crevice corrosion resistance
- Maximum Service Temperature: 800–870°C (oxidation resistance threshold)
- Thermal Conductivity: 14–16 W/(m·K) at 20°C
- Thermal Expansion Coefficient: 16–17 × 10⁻⁶ /°C (0–100°C)
- Tensile Strength (UTS): ≥520 MPa (annealed condition)
- Yield Strength (0.2% Proof Stress): ≥205 MPa
- Elongation at Break: ≥40%
- Surface Finish: 2B (cold-rolled and annealed) or No. 1 (hot-rolled and pickled)
Specifications
| Parameter | Specification | Unit | Standard Reference |
|---|---|---|---|
| Outer Diameter (OD) | 6.0 – 25.4 (customizable) | mm | ASTM A213 / GB/T 12771 |
| Wall Thickness | 0.5 – 2.0 | mm | ASTM A213 / GB/T 12771 |
| Coil Winding Diameter | 100 – 500 | mm | Custom per application |
| Coil Pitch (Spacing) | 8 – 25 | mm | Per radiant panel design |
| Coil Length per Spool | 10 – 100 | m | As required |
| Operating Pressure | 0.2 – 1.6 (up to 4.0 for heavy-wall) | MPa | GB/T 12459 |
| Operating Temperature Range | -50 to +180 (sustained) | °C | — |
| Surface Roughness (Ra) | ≤ 1.6 | μm | GB/T 1031 |
| End Treatment | Plain end / Beveled / Threaded | — | Per customer drawing |
| Heat Treatment | Solution Annealed (1050–1100°C) | °C | ASTM A213 |
| Hydrostatic Test Pressure | 1.5 × Operating Pressure | MPa | GB/T 12459 |
Manufacturing Process
The production of stainless steel coil tubes for radiant heating panels follows a rigorous multi-stage manufacturing sequence:
- Raw Material Procurement: High-purity stainless steel strip or seamless tube blanks are sourced from certified mills, with full chemical composition analysis (spectrometric verification) and mechanical property certification.
- Forming & Welding (for welded tube): Cold-rolled strip is formed into a tubular cross-section and joined via high-frequency resistance welding (HFW) or automatic argon arc welding (TIG), with online seam inspection.
- Coil Bending & Forming: Straight tubes are precisely coiled using CNC-controlled bending machines to achieve the specified winding diameter, pitch, and helix geometry. Spring-back compensation algorithms ensure dimensional accuracy within ±0.5 mm tolerance.
- Welding of Coil Joints: Where continuous coil length exceeds single-tube supply, butt-welded or socket-welded joints are fabricated with 100% radiographic testing (RT) or ultrasonic testing (UT) inspection.
- Heat Treatment: The coiled assembly undergoes solution annealing in a protective atmosphere (vacuum or argon) at 1050–1100°C followed by controlled cooling to eliminate residual stresses and restore full austenitic properties.
- Surface Finishing: Pickling and passivation treatment removes heat scale and establishes a stable chromium oxide passive layer (minimum 10⁻⁶ g/cm² Cr₂O₃ thickness).
- Quality Inspection: Dimensional verification (laser scan or CMM), hydrostatic pressure testing, visual inspection (VT), and optional eddy current testing (ECT) for wall thickness uniformity.
- Protective Packaging: Coils are wrapped in moisture-barrier film, padded, and secured on wooden pallets for shipment.
Applications
These stainless steel coil tubes are purpose-engineered for the following application domains:
- Industrial Radiant Heating Panels: Primary heat transfer medium in steel plate radiant panels for factory floors, workshops, and large-span industrial halls where zone-specific heating is required.
- Commercial Local Heating Systems: Under-floor or suspended radiant panels in retail spaces, restaurants, and exhibition halls requiring localized thermal comfort.
- Agricultural Greenhouse Heating: Corrosion-resistant coil tubes embedded in radiant panels for greenhouse temperature regulation, withstanding high-humidity and nutrient-rich environments.
- Food Processing & Pharmaceutical Facilities: Sanitary-grade coil tube assemblies for process heating panels in environments requiring CIP (Clean-in-Place) compatibility and resistance to chemical cleaning agents.
- Marine & Offshore Applications: 316L-grade coil tubes for radiant heating systems on vessels and platforms where chloride-induced corrosion is a primary design concern.
- Research & Development Platforms: Test articles for academic and engineering research on steel plate radiant panel thermal performance, heat flux distribution, and system efficiency optimization.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring traceability and compliance across the production lifecycle:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System
- ASME Section IX — Welding Procedure Qualification (WPQ/WPS)
- EN 10204 3.1 Certificate — Third-party verified material test reports
- ASTM A213/A269 — Seamless and welded austenitic stainless steel tube specifications
- GB/T 12771 — Chinese national standard for stainless steel seamless tubes
- GB/T 12459 — Steel pipe fittings pressure rating and testing
- NADCAP — Special process certification (welding, heat treatment) — available upon request
Unique Selling Points:
• Application-specific coil geometry optimized for maximum radiant heat flux density in steel plate panel configurations
• Full traceability from mill certificate through final coil inspection with digital batch tracking
• Customizable coil pitch and diameter to match proprietary radiant panel designs
• Enhanced fatigue resistance through optimized solution annealing parameters validated by thermal cycling testing (≥5,000 cycles without degradation)
• Integrated test summary documentation supporting engineering validation of radiant panel thermal performance
Test Summary & Performance Validation
Based on the research study "Coil Tube – Steel Plate Radiant Panel Local Heating Test Summary", performance validation of these coil tube assemblies includes:
- Heat Flux Distribution: Measured surface heat flux uniformity of ≥85% across the panel active zone, demonstrating effective thermal spreading through the steel plate medium.
- Thermal Efficiency: System radiant efficiency exceeding 60% under standard operating conditions (supply temperature 70–90°C, ambient 20°C).
- Thermal Cycling Durability: No measurable degradation in mechanical properties or weld integrity after 5,000 thermal cycles (20°C ↔ 120°C).
- Pressure Drop: Internal pressure drop across coil assemblies maintained below design threshold of 0.05 MPa at nominal flow rates, ensuring compatibility with standard circulation pumps.
- Corrosion Performance: Zero pitting or intergranular corrosion observed after 1,000-hour salt spray testing (5% NaCl, 35°C) for 316L-grade assemblies.
Conclusion
The Stainless Steel Coil Tube (No. 1629) from Wenzhou Jixing Metal Materials Co., Ltd. represents a precision-engineered solution for steel plate radiant panel heating systems, combining material integrity, geometric precision, and validated thermal performance. Its compliance with international standards and application-specific design flexibility make it suitable for demanding industrial, commercial, and research-grade heating applications where reliability and corrosion resistance are paramount.