Stainless Steel Coil Tube — HVAC Fan Coil & Radiator Heat Metering System
Product Code: 1138 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Classification: Technical Literature & Application Engineering
1. Product Overview
The Stainless Steel Coil Tube (盘管Coiltube) is a precision-engineered tubular component designed for integration into single-pipe forward-flow heating systems (单管顺流式系统) that incorporate heat metering (热计量) capabilities. This product serves as a critical heat exchange element within the combination of Fan Coil Units (FCU, 风机盘管) and Radiators (散热器), enabling efficient thermal distribution, precise energy metering, and optimized temperature control in both residential and commercial building environments.
Wenzhou Jixing Metal Materials Co., Ltd. has developed this coil tube specifically to address the engineering challenges identified in the study "Discussion on the Combination of Fan Coil Units and Radiators in Single-Pipe Forward-Flow System Heat Metering" (《单管顺流式系统热计量中风机盘管与散热器组合的探讨》). The design philosophy centers on maximizing heat transfer efficiency while maintaining compatibility with existing single-pipe hydronic distribution architectures.
2. Material & Properties
The coil tube is fabricated from high-grade Stainless Steel (不锈钢), selected for its superior resistance to corrosion, thermal fatigue, and chemical degradation under prolonged exposure to water-based heating media.
- Base Material: Austenitic Stainless Steel (奥氏体不锈钢), conforming to international standards including AISI 304 and AISI 316 grades
- Corrosion Resistance: Exceptional resistance to pitting, crevice corrosion, and intergranular attack in chlorinated heating water environments
- Thermal Conductivity: Moderate thermal conductivity (approximately 16–20 W/m·K for AISI 304), balanced with long-term structural integrity
- Temperature Tolerance: Operational range from −40°C to +250°C, accommodating both heating and cooling cycle demands
- Mechanical Strength: High tensile strength and yield strength ensuring dimensional stability under cyclic thermal stress
- Hygienic Surface: Smooth, non-porous interior surface preventing biofilm accumulation and scale formation
- Non-Magnetic: Suitable for environments where electromagnetic interference must be minimized
3. Technical Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (盘管Coiltube) | — |
| Material Grade | AISI 304 / AISI 316L (1Cr18Ni9 / 022Cr17Ni12Mo2) | ASTM A269 / EN 10217-7 |
| Tube Outer Diameter (OD) | 6.35 mm / 8.00 mm / 9.53 mm (1/4" / 5/16" / 3/8") | EN 10217-7 |
| Tube Wall Thickness | 0.50 mm – 1.20 mm | ISO 4414 |
| Coil Pitch (螺旋间距) | 8 mm – 15 mm (adjustable based on heat load requirements) | Manufacturer Specification |
| Coil Diameter | 100 mm – 350 mm (customizable) | Manufacturer Specification |
| Effective Heat Transfer Area | 0.15 m² – 1.20 m² (per unit) | ASHRAE Handbook — HVAC Systems |
| Maximum Operating Pressure | 1.6 MPa (232 PSI) | EN 12828 |
| Hydrostatic Test Pressure | 2.4 MPa (348 PSI) — 100% tested | ISO 11114 |
| Heat Transfer Coefficient | 200 – 450 W/m²·K (depending on flow velocity and configuration) | ASHRAE Fundamentals |
| Surface Finish | Electropolished / Pickled & Passivated (Ra ≤ 0.4 μm) | ASTM A967 |
| Connection Type | Welded / Flanged / Threaded (G1/2", G3/4", G1") | ISO 7-1 |
| System Compatibility | Single-Pipe Forward-Flow (单管顺流式) / Two-Pipe (双管) | EN 12828 / GB 50015 |
| Design Service Life | ≥ 25 years | EN 12828 |
4. Manufacturing Process
The production of the stainless steel coil tube follows a rigorous, multi-stage manufacturing protocol to ensure dimensional accuracy, material integrity, and consistent performance:
- Raw Material Selection & Inspection: Stainless steel strip (不锈钢带材) is sourced from certified mills with full material traceability. Incoming material undergoes spectroscopic analysis (光谱分析) to verify chemical composition compliance with ASTM A269 requirements.
- Cold Forming & Coil Winding (冷弯成型): The stainless steel strip is precision-formed into the required tube cross-section using calibrated roll-forming equipment. The tube is then wound into the specified coil geometry with controlled pitch and diameter tolerances (±0.5 mm).
- Welding (焊接): Longitudinal seams are welded using TIG Welding (Tungsten Inert Gas Welding, 钨极氩弧焊) or continuous high-frequency welding (高频焊接) with internal argon gas shielding to prevent oxidation. Weld bead height is controlled to ≤ 0.1 mm to minimize flow resistance.
- Heat Treatment (热处理): Post-weld annealing (焊后退火) at 1050°C – 1100°C followed by controlled cooling restores the full austenitic microstructure and eliminates residual welding stresses.
- Surface Treatment (表面处理): The coil tube undergoes pickling (酸洗) and passivation (钝化) to remove oxide scale and establish a protective chromium oxide film. Electropolishing (电解抛光) is available as an optional upgrade for critical applications.
- Quality Inspection (质量检验): Each unit undergoes 100% hydrostatic pressure testing, dimensional verification using coordinate measuring machines (CMM, 三坐标测量机), and visual/weld inspection in accordance with ISO 11114.
- Packaging & Traceability: Finished products are individually labeled with batch codes, material certificates, and test reports, then packaged with corrosion-inhibiting desiccants for shipment.
5. Applications
The stainless steel coil tube is engineered for deployment in a wide range of hydronic heating and cooling systems:
- Single-Pipe Forward-Flow Heating Systems with Heat Metering (单管顺流式系统热计量): Serves as the primary heat exchange element within fan coil units and radiator combinations, enabling accurate thermal energy metering per zone or per unit in multi-apartment residential buildings.
- Fan Coil Units (FCU, 风机盘管): Integrated as the coil element in ceiling-mounted, wall-mounted, or concealed FCUs for precise temperature regulation in commercial offices, hotels, and hospitals.
- Convector Radiators (对流散热器): Used as the internal coil within panel convectors and under-floor heating units for efficient radiant and convective heat distribution.
- Hydronic Heating Loops (水暖回路): Deployed in closed-loop hydronic systems for district heating networks, industrial process heating, and geothermal heat exchange applications.
- Food & Pharmaceutical Processing: The hygienic surface finish and corrosion resistance make this coil tube suitable for sanitary heat exchange in food processing, brewing, and pharmaceutical manufacturing environments.
- Marine & Offshore Applications: AISI 316L grade coil tubes provide enhanced resistance to chloride-induced corrosion in marine HVAC systems and offshore platform heating installations.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring full compliance with international and national standards:
- ISO 9001:2015 — Quality Management System Certification (质量管理体系认证)
- ISO 14001:2015 — Environmental Management System Certification (环境管理体系认证)
- ISO 45001:2018 — Occupational Health & Safety Management System (职业健康安全管理体系)
- CE Marking — Conformity with European Directive 2009/142/EC (Construction Products Regulation)
- EN 12828 — Compliance with European standard for heating systems in buildings
- GB 50015 — Compliance with Chinese National Standard for building water supply and drainage engineering
- ASME — American Society of Mechanical Engineers compliance for pressure-containing components
- Mill Test Certificates (MTC) — Full material traceability with EN 10204 3.1 certificates provided for every batch
7. Unique Selling Points
Engineered for Precision Heat Metering: Unlike conventional coil tubes, this product is specifically designed and optimized for single-pipe forward-flow systems requiring accurate per-unit heat metering. The controlled coil geometry and uniform heat transfer characteristics ensure reliable thermal output measurement, reducing billing disputes in multi-tenant buildings.
- Superior Corrosion Longevity: The austenitic stainless steel construction provides a design service life of 25+ years, significantly outperforming carbon steel alternatives in chlorinated or high-pH heating water environments.
- Minimal Flow Resistance: Precision-welded seams with controlled bead height and electropolished internal surfaces reduce pressure drop across the coil by up to 15% compared to standard welded tubes, improving system pump efficiency.
- Customizable Geometry: Coil diameter, pitch, tube size, and connection configurations are fully customizable to match specific heat load calculations and equipment integration requirements.
- Full Traceability: Every coil tube is accompanied by material test certificates, dimensional inspection reports, and pressure test records, ensuring complete supply chain transparency and regulatory compliance.
- Application-Validated Design: The product design is informed by peer-reviewed engineering research on fan coil and radiator combinations in heat-metered single-pipe systems, ensuring proven performance in real-world deployment scenarios.
8. Technical Reference
This product specification is informed by the technical study: "Discussion on the Combination of Fan Coil Units and Radiators in Single-Pipe Forward-Flow System Heat Metering" (《单管顺流式系统热计量中风机盘管与散热器组合的探讨》), which addresses the thermodynamic optimization of combined heat exchange configurations for accurate energy accounting in distributed heating networks.
For detailed engineering calculations, system integration guidance, and custom specification inquiries, please contact Wenzhou Jixing Metal Materials Co., Ltd. directly with reference to Product Code 1138.