Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd.
Product Catalog No.: 920 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Classification: Industrial Technical Literature
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered, continuous-length tubular product manufactured through seamless or welded processes, coiled into a compact, transportable form for downstream processing. This product line is specifically designed for applications in HVAC (Heating, Ventilation, and Air Conditioning), heat exchangers, refrigeration systems, and industrial thermal management. The coil tube configuration enables high-efficiency heat transfer through maximized surface area within a confined volume, making it an ideal component for cabinet-type fan coil units such as the ADAT-30 series.
Wenzhou Jixing Metal Materials Co., Ltd. leverages advanced metallurgical expertise and precision rolling technology to deliver coil tubes with consistent dimensional tolerances, superior surface finish, and exceptional corrosion resistance — meeting the rigorous demands of modern HVAC and industrial equipment manufacturing.
2. Material & Properties
2.1 Material Grades
- 304 Stainless Steel (AISI 304 / UNS S30400): The most widely used austenitic stainless steel grade, offering excellent general corrosion resistance, formability, and weldability. Suitable for non-aggressive environments and food-grade applications.
- 316L Stainless Steel (AISI 316L / UNS S31603): Enhanced molybdenum (Mo) content provides superior resistance to pitting and crevice corrosion in chloride-containing environments, making it ideal for marine and chemical processing applications.
- 321 Stainless Steel (AISI 321 / UNS S32100): Titanium-stabilized grade offering improved resistance to intergranular corrosion at elevated temperatures, suitable for high-temperature heat exchanger applications.
2.2 Mechanical Properties (Typical Values for 304 Grade)
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (抗拉强度) | ≥ 520 MPa | ASTM A213 / GB/T 14976 |
| Yield Strength (屈服强度) | ≥ 205 MPa | ASTM A213 / GB/T 14976 |
| Elongation (延伸率) | ≥ 35% | ASTM A213 |
| Hardness (硬度) | ≤ 217 HB (Annealed) | ASTM A92 |
| Thermal Conductivity (热导率) | 16.3 W/(m·K) at 20°C | ASTM E1225 |
| Thermal Expansion Coefficient (热膨胀系数) | 17.3 × 10⁻⁶ /°C (10–100°C) | ASTM E228 |
2.3 Chemical Composition (304 Grade — Typical)
| Element | Specification (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Chromium (Cr) | 18.0 – 20.0 |
| Nickel (Ni) | 8.0 – 10.5 |
| Manganese (Mn) | ≤ 2.0 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Iron (Fe) | Balance |
3. Technical Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) Range | 3.0 mm – 50.8 mm (1/8" – 2") |
| Wall Thickness (WT) Range | 0.3 mm – 3.0 mm |
| Coil Length | Up to 200 m per coil (custom lengths available) |
| OD Tolerance | ±0.05 mm (precision grade) / ±0.1 mm (standard grade) |
| Wall Thickness Tolerance | ±10% (standard) / ±5% (precision) |
| Surface Finish | 2B, BA (Bright Annealed), No. 4 Brushed, Mirror (8K) |
| Heat Treatment Condition | Annealed (Solution Annealed), Pickled & Passivated |
| Coil Core Diameter | 150 mm / 200 mm (customizable) |
| Maximum Coil Weight | Up to 5,000 kg |
| Standard Length (Cut-to-Length) | 1 m – 6 m (custom on request) |
| Reference Standards | ASTM A213, ASTM A269, GB/T 14976, GB/T 13296, EN 10216-5 |
4. Manufacturing Process
4.1 Production Workflow
- Raw Material Selection (原材料选择): High-purity stainless steel strip (cold-rolled coil) is sourced from certified mill suppliers, undergoes incoming inspection for chemical composition (OES/Spectroscopy) and mechanical properties verification.
- Strip Preparation & Annealing (带材预处理与退火): The cold-rolled strip is annealed at 1050°C – 1100°C in a controlled atmosphere furnace to relieve residual stresses, restore ductility, and achieve the desired grain structure.
- Coil Winding (盘管成型): The prepared strip is precision-wound onto a forming mandrel using CNC-controlled winding equipment. Tension control systems ensure uniform winding density and consistent dimensional accuracy throughout the coil length.
- Welding (焊接) — For Welded Coil Tubes: TIG (Tungsten Inert Gas) or orbital welding is employed to create the longitudinal seam. Helium leak testing (氦检漏) is performed to verify weld integrity at pressures up to 25 MPa.
- Post-Weld Annealing & Pickling (焊后退火与酸洗): Welded coils undergo post-weld heat treatment to homogenize the microstructure. Subsequent acid pickling removes oxide scale and surface contaminants.
- Passivation Treatment (钝化处理): A passivation layer is applied using nitric acid or citric acid solutions to enhance surface corrosion resistance by forming a stable chromium oxide (Cr₂O₃) passive film.
- Surface Finishing (表面处理): Depending on the specification, coils may undergo mechanical polishing, electrolytic polishing, or passivation finishing to achieve the required surface roughness (Ra ≤ 0.4 μm for mirror finish).
- Quality Inspection & Testing (质量检测): Comprehensive inspection including dimensional measurement (calipers, bore gauges), hydrostatic pressure testing (水压试验), eddy current testing (涡流检测), and visual inspection.
- Packaging & Shipping (包装与运输): Coils are wrapped in moisture-proof PE film, placed on wooden pallets with protective edge guards, and secured for transport.
4.2 Process Control Highlights
The manufacturing process incorporates Statistical Process Control (SPC) at critical control points, ensuring consistent product quality across production batches. Automated monitoring systems track winding tension, temperature profiles, and dimensional parameters in real-time, with data logging for full traceability.
5. Applications
5.1 Primary Application Domains
- HVAC Systems (暖通空调系统): The coil tube serves as the core heat exchange element in fan coil units (FCU), including cabinet-type units such as the ADAT-30 series. The coiled configuration maximizes heat transfer surface area within compact equipment enclosures, enabling efficient air conditioning and heating in commercial and industrial buildings.
- Heat Exchangers (换热器): Used in shell-and-tube heat exchangers, plate-fin heat exchangers, and air-cooled condensers for industrial process cooling and refrigeration systems.
- Refrigeration & Air Conditioning (制冷与空调): Coil tubes function as evaporators and condensers in chillers, dehumidifiers, and precision temperature control systems.
- Food & Pharmaceutical Processing (食品与制药加工): 304/316L grade coil tubes meet sanitary requirements for food-grade heat transfer applications, pasteurization systems, and pharmaceutical clean-room HVAC installations.
- Chemical & Petrochemical Industry (化工与石化): 316L grade coil tubes provide corrosion-resistant heat transfer solutions in chemical reactors, distillation columns, and process piping systems.
- Automotive & Aerospace (汽车与航空航天): Lightweight, high-strength coil tubes for automotive heating systems, intercooler assemblies, and aerospace thermal management systems.
- Power Generation (发电): Steam generator tubes and condenser tubes in power plants, leveraging the corrosion resistance and thermal stability of stainless steel.
5.2 Application in ADAT-30 Cabinet Fan Coil Unit
The ADAT-30 cabinet fan coil unit represents a representative application scenario for this coil tube product. In this system, the stainless steel coil tube is formed into a serpentine or helical configuration, integrated with aluminum fins to create an efficient air-side heat exchanger. The unit operates with either chilled water (cooling mode) or hot water (heating mode) circulating through the coil tube circuit, transferring thermal energy to/from the air stream drawn by the integrated centrifugal fan. Key performance advantages include:
- Compact cabinet design with minimal floor footprint
- High energy efficiency ratio (EER) achieved through optimized coil geometry
- Corrosion-resistant coil construction ensuring long service life in humid environments
- Low noise operation suitable for occupied spaces
6. Quality Certifications & Compliance
6.1 Certifications
- ISO 9001:2015 — Quality Management System (质量管理体系)
- ISO 14001:2015 — Environmental Management System (环境管理体系)
- ISO 45001:2018 — Occupational Health & Safety Management System (职业健康安全管理体系)
- CE Marking — Conformity with European Health, Safety, and Environmental Protection Standards
- EN 10204 3.1 — Inspection Certificate (第三类检验证书) available upon request
- Mill Test Certificates (MTC) — Full chemical and mechanical property documentation for each production batch
6.2 Quality Assurance Measures
- 100% hydrostatic pressure testing for all welded coil tubes (per ASTM A269)
- Eddy current flaw detection (ECT) for seamless coil tubes to detect internal and surface defects
- Corrosion testing: Salt spray test (ASTM B117, ≥ 200 hours), intergranular corrosion test (ASTM A262 Practice E)
- Third-party inspection available (SGS, BV, TUV)
- Full material traceability from raw material to finished product
7. Unique Selling Points
- Precision Manufacturing: Tight dimensional tolerances (±0.05 mm OD) ensure seamless integration into precision-engineered HVAC and heat exchanger assemblies.
- Multi-Grade Flexibility: Comprehensive grade availability (304, 316L, 321, and custom alloys) allows customers to match material selection to specific environmental and performance requirements.
- Custom Coil Configuration: Flexible coil winding parameters (length, core diameter, winding density) enable optimization for downstream manufacturing processes including bending, finning, and brazing.
- Surface Quality Excellence: Available in BA, 2B, brushed, and mirror finishes with controlled surface roughness, reducing fouling and enhancing heat transfer efficiency.
- Environmental Responsibility: Manufacturing processes incorporate energy-efficient furnaces, closed-loop water treatment, and recyclable packaging materials in alignment with ISO 14001 standards.
- Technical Support & Engineering Consultation: Dedicated engineering team provides application-specific design support, material selection guidance, and integration recommendations for complex system requirements.
8. Storage & Handling Recommendations
- Store in a dry, well-ventilated warehouse with relative humidity below 65%
- Coils must be kept off the ground on wooden pallets with protective padding between layers
- Avoid contact with carbon steel to prevent galvanic contamination and