Stainless Steel Coil Tube — Fan Coil Unit Application Series
Product Overview
The Stainless Steel Coil Tube (盘管Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous stainless steel tube product, specifically designed and optimized for integration into fan coil units (FCUs), heat exchanger assemblies, and HVAC (Heating, Ventilation, and Air Conditioning) systems. The coil tube is supplied in a continuous coiled configuration, enabling seamless forming, bending, and fabrication into compact heat exchange geometries without the need for welded seams or joints, thereby maximizing thermal transfer efficiency and structural integrity.
This product line represents a specialized segment within the broader category of stainless steel tube products, where the coiled delivery format and material composition are tailored to meet the demanding operational conditions of air-handling and thermal regulation equipment.
Material & Properties
Material Grades
- AISI 304 (UNS S30408) — The standard-grade austenitic stainless steel offering excellent corrosion resistance, formability, and weldability, suitable for general HVAC and commercial building applications.
- AISI 316 (UNS S31603) — Enhanced austenitic grade with added molybdenum (Mo) content, providing superior resistance to chlorides and aggressive chemical environments, ideal for coastal or industrial installations.
- AISI 316L (UNS S31603) — Low-carbon variant of 316, minimizing sensitization risk during welding and fabrication processes.
Key Mechanical Properties
| Property | AISI 304 | AISI 316 / 316L |
|---|---|---|
| Tensile Strength (Ultimate) | ≥ 515 MPa | ≥ 515 MPa |
| Yield Strength (0.2% Offset) | ≥ 205 MPa | ≥ 205 MPa |
| Elongation at Break | ≥ 40% | ≥ 40% |
| Density | 7.93 g/cm³ | 7.98 g/cm³ |
| Thermal Conductivity (at 100°C) | 16.3 W/(m·K) | 16.3 W/(m·K) |
| Maximum Service Temperature | 870°C (oxidation) | 870°C (oxidation) |
| Corrosion Resistance (Pitting) | Moderate | Excellent (Mo-enhanced) |
Chemical Composition (Typical, wt%)
| Element | C (Carbon) | Cr (Chromium) | Ni (Nickel) | Mn (Manganese) | Mo (Molybdenum) | Si (Silicon) | P (Phosphorus) | S (Sulfur) |
|---|---|---|---|---|---|---|---|---|
| AISI 304 | ≤ 0.08 | 18.0–20.0 | 8.0–10.5 | ≤ 2.0 | — | ≤ 1.0 | ≤ 0.045 | ≤ 0.030 |
| AISI 316 | ≤ 0.08 | 16.0–18.0 | 10.0–14.0 | ≤ 2.0 | 2.0–3.0 | ≤ 1.0 | ≤ 0.045 | ≤ 0.030 |
| AISI 316L | ≤ 0.03 | 16.0–18.0 | 10.0–14.0 | ≤ 2.0 | 2.0–3.0 | ≤ 1.0 | ≤ 0.045 | ≤ 0.030 |
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (盘管Coiltube) |
| Product Code | WX-CT-1159 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Tube Form | Continuous Coil (Coiled Length) |
| Outer Diameter (OD) | Φ 6.0 mm – Φ 19.0 mm (customizable) |
| Wall Thickness | 0.3 mm – 1.5 mm |
| Coil Diameter | Standard: 500 mm – 1200 mm |
| Coil Weight | 50 kg – 500 kg (per coil) |
| Surface Finish | No.1 (Hot Rolled), 2B (Cold Rolled & Annealed), BA (Bright Annealed), No.4 (Brushed), HL (Hairline) |
| Surface Roughness (Ra) | ≤ 0.8 μm (2B finish); ≤ 0.4 μm (BA finish) |
| Internal Surface | Smooth, clean; optional electropolished to Ra ≤ 0.2 μm |
| Applicable Standards | ASTM A213 / A269, GB/T 12771, EN 10217-7, JIS G 3446 |
| Delivery Condition | Annealed and Pickled (AP), Cold Worked and Annealed (CW&A) |
| Welding Type | Continuous Welded (AW) — Automatic Welding Process |
| Packaging | Wooden pallet with moisture-proof wrapping; custom export packaging available |
| Minimum Order Quantity (MOQ) | 1 ton (negotiable) |
Manufacturing Process
The production of the Stainless Steel Coil Tube follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical consistency, and surface quality:
- Strip Preparation: Cold-rolled stainless steel strip is sourced from certified mill suppliers and subjected to incoming inspection for chemical composition (via spectroscopic analysis), mechanical properties, and surface quality.
- Forming & Rolling: The flat strip is passed through a series of precision roll-forming stations (typically 12–20 passes) that progressively shape the strip into a seamless tube profile with tight dimensional tolerances.
- Continuous Welding: The formed tube edges are joined using a high-frequency (HF) induction welding process or a continuous laser welding process, producing a uniform weld seam with minimal heat-affected zone (HAZ) distortion.
- Coiling: The continuous welded tube is wound onto a precision mandrel in a controlled coil configuration, with tension regulation to prevent ovality, kinking, or surface marking.
- Heat Treatment (Annealing): The coiled tube undergoes solution annealing (typically at 1050°C – 1150°C) followed by controlled cooling to relieve residual stresses, restore full ductility, and achieve the desired microstructure.
- Pickling & Passivation: Post-annealing pickling in a mixed acid solution (HNO₃/HF or HNO₃/H₂SO₄) removes oxide scale and contamination. A subsequent passivation treatment forms a stable chromium oxide (Cr₂O₃) passive film on the surface, enhancing long-term corrosion resistance.
- Dimensional Inspection: Each coil is inspected for outer diameter, wall thickness, roundness, straightness, and weld seam quality using ultrasonic testing (UT), optical measurement, and visual examination.
- Final Packaging: Approved coils are wrapped, labeled with traceability markings (heat number, grade, dimensions, production date), and secured on wooden pallets for shipment.
Applications
The Coil Tube product is engineered for diverse industrial and commercial applications, with particular emphasis on thermal management and fluid conveyance systems:
- Fan Coil Units (FCUs): Primary application — the coil tube serves as the heat exchange element in commercial and residential HVAC fan coil units. The coiled configuration enables compact, high-surface-area heat exchangers that efficiently transfer thermal energy between refrigerant/cooling water and circulating air. Simulation studies (as referenced in the product's associated technical literature) demonstrate that optimized coil geometry significantly reduces energy consumption while maintaining desired indoor air temperatures.
- Air Conditioning Systems: Condenser and evaporator coils for split-system and packaged air conditioners.
- Heat Exchangers: Shell-and-tube, plate-and-fin, and cross-flow heat exchanger assemblies in industrial process cooling and heating.
- Refrigeration Systems: Evaporator and condenser coils in commercial refrigeration, cold storage, and cold chain logistics equipment.
- Boiler & Heating Systems: Hot water coil heaters, underfloor heating manifolds, and radiant heating circuits.
- Automotive & Transportation: Automotive radiator cores, transmission cooler coils, and engine cooling circuit tubing.
- Chemical & Pharmaceutical Processing: Fluid transport lines, reactor cooling jackets, and process heat exchangers where corrosion resistance is critical.
- Food & Beverage Industry: Sanitary-grade fluid conveyance, pasteurization heat exchangers, and brewing equipment.
- Marine & Offshore: Seawater cooling coils and heat exchangers where chloride resistance (316/316L grade) is essential.
Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System — ensuring consistent product quality and continuous improvement across all production processes. |
| ISO 14001:2015 | Environmental Management System — demonstrating commitment to environmentally responsible manufacturing practices. |
| CE Marking | Compliance with European health, safety, and environmental protection standards for products sold within the European Economic Area. |
| ASTM A213 / A269 | Material conformance to American Society for Testing and Materials specifications for seamless and welded austenitic stainless steel tubes. |
| GB/T 12771 | Chinese national standard for stainless steel seamless and welded tubes for general engineering and industrial applications. |
| EN 10217-7 | European standard for non-ferrous metal tubes and pipes — technical delivery conditions for stainless steel tubes. |
| MTC (Mill Test Certificate) | Every batch is accompanied by a comprehensive Mill Test Certificate (EN 10204 Type 3.1) documenting chemical analysis, mechanical test results, and traceability data. |
| Third-Party Inspection | Available upon request — SGS, BV (Bureau Veritas), or TÜV inspection services for pre-shipment verification. |
Unique Selling Points
1. Seamless Coiled Configuration for Maximum Thermal Efficiency
The continuous coil format eliminates the need for additional joining or splicing during downstream fabrication. This reduces the number of potential leak points and thermal resistance interfaces, directly contributing to improved heat exchange performance and system reliability in fan coil unit applications.
2. Precision Dimensional Control
Advanced roll-forming and welding technology ensures tight tolerances on outer diameter (±0.05 mm) and wall thickness (±0.02 mm), enabling precise fitting into fin-and-tube heat exchanger assemblies with optimal contact pressure and minimal air bypass.
3. Full Traceability and Documentation
Each coil is assigned a unique heat number and batch identifier, enabling complete traceability from raw material mill through final delivery. Comprehensive test documentation supports compliance audits and quality assurance requirements in regulated industries.
4. Energy Efficiency Contribution
Based on simulation and performance analysis studies of fan coil unit systems, the use of high-quality stainless steel coil tubes with optimized geometry and surface finish can reduce overall system energy consumption by 15%–25% compared to inferior tubing alternatives, due to superior thermal conductivity, reduced fouling, and lower pressure drop characteristics.
5. Customization Capability
Wenzhou Jixing Metal Materials Co., Ltd. offers flexible customization of tube dimensions, coil diameter, surface finish, and material grade to meet specific OEM (Original Equipment Manufacturer) requirements, supporting both standard and bespoke engineering projects.
Technical Notes & Recommendations
- Storage: Coils should be stored in a dry, well-ventilated area away from direct sunlight and moisture. Avoid stacking multiple coils vertically to prevent deformation of the outer layers.
- Handling: Use appropriate lifting equipment (chain hoist with spreader bar) to prevent coil slippage or surface damage during unloading and positioning.
- Fabrication: When bending or forming the coil tube into final heat exchanger geometries, use minimum bend radii of ≥ 3× OD to avoid wall thinning or cracking. Post-forming annealing may be required for tight-radius configurations.
- Welding: Use TIG (Tungsten Inert Gas) welding with appropriate filler metal (e.g., ER308L for 304, ER316L for 316/