Stainless Steel Evaporative Cooling Coil Tube — Product Technical Specification
1. Product Overview
The Stainless Steel Evaporative Cooling Coil Tube (Ref. No. 246) is a precision-engineered coiled tubing product manufactured by Wenzhou Jixing Metal Materials Co., Ltd, designed primarily for evaporative cooling systems, heat exchange applications, and industrial refrigeration circuits. This product is engineered to ensure optimal water distribution uniformity across the coil surface under varying airflow configurations and pipe diameter conditions — a critical performance parameter validated through rigorous experimental research on wind-arrangement-dependent water film distribution characteristics.
The coil tube integrates the superior corrosion resistance of austenitic stainless steel with geometric precision coiling to deliver consistent thermal transfer efficiency, extended service life, and reduced maintenance intervals in demanding industrial and commercial environments.
2. Material Composition & Properties
2.1 Base Material
- Primary Alloy: Austenitic Stainless Steel (e.g., AISI 304 / AISI 316L / AISI 321)
- Chromium (Cr): ≥ 18% — provides passive oxide layer for corrosion resistance
- Nickel (Ni): ≥ 8% — stabilizes austenitic microstructure
- Molybdenum (Mo): ≥ 2% (for 316L grade) — enhances resistance to pitting and crevice corrosion
- Carbon (C): ≤ 0.03% (L-grade) — minimizes intergranular corrosion risk during welding
2.2 Mechanical Properties
| Property | Specification | Test Standard |
|---|---|---|
| Tensile Strength (UTS) | ≥ 520 MPa (75 ksi) | ASTM A270 / GB/T 12771 |
| Yield Strength (0.2% Offset) | ≥ 205 MPa (30 ksi) | ASTM A270 / GB/T 12771 |
| Elongation (% Elat.) | ≥ 35% | ASTM A270 |
| Hardness (HBW) | ≤ 217 (Annealed Condition) | ASTM A276 |
| Thermal Conductivity | 16.3 W/(m·K) at 20°C | ASTM E1530 |
| Corrosion Resistance | PASS 72h (5% NaCl, 35°C) | ASTM A967 |
2.3 Surface Condition
- Inside surface: Electropolished (Ra ≤ 0.4 μm) or bright annealed
- Outside surface: 2B finish (Ra ≤ 0.5 μm) or passivated
- Passivation treatment per ASTM A967 to restore and stabilize the chromium oxide passive film
3. Geometric Specifications
| Parameter | Specification | Tolerance |
|---|---|---|
| Outer Diameter (OD) | 6.0 / 8.0 / 10.0 / 12.0 / 15.0 mm (customizable) | ± 0.05 mm |
| Wall Thickness (WT) | 0.5 / 0.8 / 1.0 / 1.5 mm | ± 0.05 mm |
| Coil Diameter (Coil ID) | 100 – 500 mm (configurable per application) | ± 2 mm |
| Coil Length (Uncoiled) | 3 – 50 m per coil (standard); up to 200 m (special order) | ± 1% |
| Pitch (Center-to-Center Spacing) | 10 – 40 mm | ± 0.5 mm |
| Number of Rows | 1 – 6 rows (multi-row configurations available) | — |
| End Forming | Plain, flanged, or crimped connection ends | — |
| Operating Temperature Range | −196°C to +600°C | — |
| Maximum Operating Pressure | ≤ 2.5 MPa (363 psi) (design dependent) | — |
4. Manufacturing Process
- Raw Material Selection: Certified stainless steel strip or seamless pipe stock sourced from qualified mills, with full heat number traceability and mill test certificates (MTC) per EN 10204 Type 3.1.
- Dimensional Forming: Precision roll forming or drawing operations to achieve exact OD and wall thickness tolerances. For coil tubes, continuous forming ensures uniform cross-section along the entire length.
- Coiling Operation: CNC-controlled coiling machines wind the formed tubing into precise helical or spiral configurations with controlled pitch and coil diameter. Coiling force is calibrated to prevent ovality and kinking.
- Welding (if applicable): Argon arc welding (TIG) or orbital welding for end connections and multi-row assembly. Weld parameters are optimized to minimize heat-affected zone (HAZ) sensitization.
- Pickling & Passivation: Immersion or spray passivation per ASTM A967 to remove scale, restore chromium content at the surface, and establish a stable passive oxide film.
- Surface Finishing: Electropolishing or mechanical polishing to achieve required surface roughness for optimal water film distribution and flow characteristics.
- Quality Inspection: Dimensional verification (OD, WT, coil diameter, pitch), hydrostatic pressure testing, visual inspection, and optional eddy current testing for wall thickness uniformity.
5. Water Distribution Uniformity — Performance Characteristics
A distinguishing performance attribute of this coil tube product relates to its capacity for achieving uniform water film distribution across the coil surface under varying airflow (wind) arrangements. Research findings indicate that:
- Coil tube geometry with optimized pitch-to-diameter ratio minimizes wind-induced water redistribution effects
- Stainless steel surface finish (Ra ≤ 0.4 μm) promotes consistent water film formation through controlled wettability
- Multi-row configurations with staggered arrangements reduce cross-row wind interference and maintain uniform heat transfer coefficients
- Pipe diameter selection (smaller OD with thinner wall) improves thermal response dynamics while maintaining structural integrity
These characteristics are directly relevant to evaporative cooling coil performance, where water distribution uniformity is a primary determinant of overall heat transfer efficiency and energy consumption.
6. Applications
- Evaporative Cooling Systems: Primary heat exchange element in industrial and commercial evaporative coolers
- Chilled Water Systems: Coil elements in air handling units (AHUs) and fan coil units (FCUs)
- Industrial Refrigeration: Evaporator coils in cold storage, process cooling, and cryogenic applications
- Food & Beverage Processing: Heat exchangers requiring high sanitary standards and corrosion resistance
- Pharmaceutical Manufacturing: Clean-in-place (CIP) compatible coils for process cooling
- HVAC Systems: Condenser and evaporator coils in commercial and industrial HVAC installations
- Marine & Offshore: Corrosion-resistant heat exchange coils in seawater cooling circuits
7. Quality Certifications & Compliance
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification for manufacturing operations |
| ISO 14001:2015 | Environmental Management System certification |
| GB/T 12771 | Chinese National Standard for seamless stainless steel tubes for general purposes |
| ASTM A269 / A270 | American standards for seamless and welded austenitic stainless steel tubes |
| EN 10217-7 | European standard for austenitic stainless steel tubes for pressure purposes |
| EN 10204 Type 3.1 | Mill Test Certificate documentation standard |
| CE Marking | Conformity with European regulatory requirements for pressure equipment |
| NSF/ANSI 61 | Drinking water system components certification (where applicable) |
8. Unique Selling Points
Research-Validated Performance: This coil tube product line is informed by dedicated research into water distribution uniformity under varying wind configurations and pipe diameter parameters — translating academic findings into optimized geometric and material specifications.
- Superior Corrosion Resistance: Austenitic stainless steel construction provides exceptional resistance to atmospheric, chemical, and waterborne corrosion — extending service life by 3–5× compared to carbon steel alternatives
- Precision Geometry: CNC-controlled coiling ensures dimensional consistency critical for uniform water distribution and optimal heat transfer performance
- Customizable Configurations: Flexible range of OD, wall thickness, coil diameter, pitch, and row arrangements to match specific application requirements
- Full Traceability: Complete material and process documentation with heat-number traceability from raw material to finished product
- Sanitary Grade Available: Electropolished and passivated surfaces suitable for food-grade and pharmaceutical applications
- Thermal Efficiency: Optimized surface finish and geometry maximize heat transfer coefficients while minimizing pressure drop
9. Packaging & Delivery
- Standard packaging: Wood pallet with moisture-proof wrapping and corner protection
- Coils secured with steel bands and protective end caps to prevent deformation during transit
- Custom packaging available for export orders (ISPM-15 compliant wood)
- Delivery terms: FOB / CIF / CFR as per buyer specification
10. Technical Support & Customization
Wenzhou Jixing Metal Materials Co., Ltd offers comprehensive technical support including:
- Custom coil geometry design based on thermal load calculations and airflow parameters
- Material selection guidance for specific corrosive environments
- Sample fabrication and performance testing prior to bulk production
- On-site installation guidance and system integration consultation