Stainless Steel Coil Tube — Coiltube Series (Product No. 649)
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous tube product formed into helical or serpentine coil configurations. This product is specifically designed for integration into direct evaporative cooling systems, heat exchangers, and fluid distribution networks where corrosion resistance, thermal efficiency, and mechanical integrity are critical performance parameters. The coil tube architecture enables compact heat transfer surface area within constrained installation volumes, making it an optimal solution for industrial and commercial refrigeration applications.
Based on comprehensive performance analysis of direct evaporative coolers incorporating coil tube configurations, this product demonstrates superior thermal-hydraulic characteristics, including enhanced heat transfer coefficients, reduced pressure drop across the coil loop, and improved evaporative efficiency compared to conventional straight-tube heat exchange assemblies.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of corrosion resistance, mechanical strength, and thermal conductivity. The material composition and mechanical properties conform to internationally recognized standards.
Base Material Grades
- ASTM A269 / ASME SA-269 — Austenitic Stainless Steel Tubing (UNS S30400 / S31600)
- EN 10217-7 — Heat-Exchange and Radiator Tubes of Non-ferrous Metals and Stainless Steel
- GB/T 12771 — Seamless Stainless Steel Tubing for General Applications (Chinese National Standard)
Key Material Properties
- Corrosion Resistance: Superior resistance to pitting, crevice corrosion, and intergranular corrosion in aqueous and evaporative environments
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20 °C, ensuring efficient heat transfer in evaporative cooling cycles
- Tensile Strength: Minimum 515 MPa (ASTM S30408 / S31608 annealed condition)
- Operating Temperature Range: −196 °C to +870 °C (oxidation resistance in continuous air service)
- Surface Finish: Ra ≤ 0.4 μm (electro-polished or mechanically polished interior surface)
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Product Designation | Coiltube — Product No. 649 | Wenzhou Jixing Internal Catalog |
| Outer Diameter (OD) | 6.0 – 38.1 mm (1/4" – 1-1/2" NPS) | ASTM A269 / EN 10217-7 |
| Wall Thickness | 0.5 – 3.0 mm | ASTM A269, Schedule 10S – 40S |
| Coil Pitch (Center-to-Center Spacing) | 15 – 100 mm (customizable) | Application-specific engineering design |
| Coil Diameter (Helix Mean Diameter) | 50 – 500 mm | Custom configuration per customer requirement |
| Tube Length per Coil | Up to 30 m continuous | Manufacturing capability specification |
| Material Grade | SUS 304 / SUS 316L / SUS 321 | ASTM A269 / GB/T 12771 |
| Surface Treatment | Passivated, Electro-polished, or Mill Finish | ASTM A967 (Passivation) |
| End Preparation | Plain, Beveled, Threaded, or Flanged | ASME B1.20.1 / ASME B16.5 |
| Tolerance — OD | ±0.05 mm (precision rolled) | ISO 286-2 |
| Tolerance — Wall Thickness | ±10% of nominal | ASTM A269, Table M1 |
Manufacturing Process
The production of the Coiltube series follows a rigorously controlled multi-stage manufacturing workflow to ensure dimensional accuracy, metallurgical integrity, and functional performance:
- Raw Material Procurement & Inspection: Hot-rolled or cold-rolled stainless steel strips/round bars are sourced from certified mills. Incoming material undergoes spectroscopic analysis (PMI — Positive Material Identification) and mechanical property verification per ASTM E1476 and ASTM A370.
- Tube Forming: Seamless tubes are produced via the Aplival (Automatic Pipe Line and Valve) or Plug Rolling method, or welded tubes are manufactured using Automatic Welding (AW) or Automatic Argon Arc (AAA) processes with 100% visual and ultrasonic inspection of the weld seam.
- Heat Treatment: Solution annealing at 1050–1150 °C followed by rapid water quenching to achieve a fully austenitic microstructure with maximum corrosion resistance. Stress-relief annealing at 870–900 °C is performed where required to minimize residual stresses.
- Coil Forming (Cold Bending): Tubes are cold-formed into the required helical or serpentine geometry using precision CNC-controlled coiling machines. The forming process maintains minimum bend radius of 3D (three times the tube OD) to prevent wall thinning, ovality, or micro-cracking. Springback compensation algorithms ensure dimensional accuracy within ±0.5 mm.
- Surface Finishing & Passivation: Tubes undergo mechanical polishing (interior and exterior) followed by electro-polishing and chemical passivation per ASTM A967 to establish a stable chromium oxide protective layer.
- Non-Destructive Testing (NDT): 100% ultrasonic thickness testing, eddy current inspection of weld seams, and pneumatic/hydrostatic pressure testing at 1.5× the maximum design pressure to verify leak-tightness and structural integrity.
- Final Inspection & Packaging: Dimensional verification using CMM (Coordinate Measuring Machine), surface roughness profiling, and material certification documentation. Products are packaged with desiccant protection and wrapped in anti-corrosion film for transit.
Applications
The Coiltube product series is engineered for demanding thermal-fluid applications, with particular emphasis on the following sectors:
Direct Evaporative Cooling Systems
- Industrial evaporative coolers where coil tubes serve as the primary heat exchange medium for air-water contact cooling
- Performance-optimized coil configurations that maximize wetted surface area while minimizing fan power consumption and pressure losses
- Applications in data center cooling, warehouse climate control, and agricultural greenhouse temperature regulation
Heat Exchanger Manufacturing
- Shell-and-tube heat exchangers for chemical processing, petrochemical, and pharmaceutical industries
- Plate-and-frame heat exchanger internals and gasket-sealed coil assemblies
- Air-to-liquid and liquid-to-liquid heat recovery systems
Additional Application Domains
- Food and beverage processing — sanitary-grade fluid conveyance and heat transfer
- Pharmaceutical manufacturing — GMP-compliant process piping
- Marine and offshore — ballast water systems and cooling loops resistant to seawater corrosion
- Automotive thermal management — intercooler and radiator coil assemblies
- HVAC (Heating, Ventilation, and Air Conditioning) — chilled water distribution coils
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring product conformity with international standards:
- ISO 9001:2015 — Quality Management Systems Certification
- ISO 14001:2015 — Environmental Management Systems Certification
- ISO 45001:2018 — Occupational Health and Safety Management Systems
- CE Marking — Conformity with European Directive 2014/68/EU (Pressure Equipment Directive — PED)
- EN 10204 3.1 — Material Test Certificate (MTC) provided with each shipment
- Mill Test Reports (MTR) — Full chemical composition and mechanical property documentation per ASTM A923
- Pressure Vessel Compliance: Products suitable for use in ASME Section VIII Div. 1 pressure vessels where applicable
- Sanitary Standards: Compliance with 3-A Sanitary Standards and FDA 21 CFR Part 178 for food-contact applications
Unique Selling Points
- Thermally Optimized Coil Geometry: Engineered based on performance analysis of direct evaporative coolers, achieving superior heat transfer coefficients (enhanced by 15–25% over standard configurations) through optimized coil pitch and helix diameter ratios.
- Precision Cold-Forming Capability: CNC-controlled coiling ensures dimensional repeatability within ±0.5 mm, critical for automated heat exchanger assembly lines.
- Full Material Traceability: From raw steel coil to finished product, complete traceability is maintained through heat number tracking, ensuring accountability at every production stage.
- Custom Configuration Flexibility: Wide range of OD, wall thickness, coil geometry, and end-preparation options to meet specific engineering requirements without compromising material integrity.
- Extended Service Life: Superior corrosion resistance of austenitic stainless steel in evaporative environments ensures operational longevity exceeding 20 years with minimal maintenance.
"Performance analysis of direct evaporative coolers incorporating coil tube configurations demonstrates that optimized helical geometry significantly improves the thermodynamic efficiency of the cooling cycle, reducing both specific cooling power and total cost of ownership compared to conventional straight-tube alternatives."