Stainless Steel Evaporator Coil Tube for Marine Refrigeration Systems
Product Overview
The Stainless Steel Evaporator Coil Tube (Product Code: JX-CT-642) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered coiled piping component specifically designed for low-temperature refrigeration applications in marine environments. This product is engineered to serve as the core heat exchange element in fishing vessel refrigerated fish holds, where it facilitates efficient thermal transfer between the refrigerant medium and the ambient air within the cold storage compartment.
Based on extensive simulation research and empirical validation of heat transfer characteristics in evaporator coil tube assemblies, this product integrates advanced geometric configurations and material selections to maximize cooling capacity while ensuring long-term corrosion resistance in harsh marine conditions. The coil tube design optimizes surface area-to-volume ratios, enabling superior convective heat exchange performance under variable thermal loads typical of commercial fishing operations.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional combination of mechanical strength, corrosion resistance, and thermal conductivity properties required for marine refrigeration service.
- Primary Material Grade: AISI 304 (UNS S30400) / AISI 316L (UNS S31603) — selected based on application-specific chloride exposure requirements
- Corrosion Resistance: Demonstrated resistance to salt spray environments exceeding 1,000 hours per ASTM B117 standard; pitting resistance equivalent number (PREN) ≥ 19 for 316L grade
- Thermal Conductivity: 16.3 W/(m·K) at 20°C, ensuring efficient heat transfer between refrigerant and evaporated medium
- Operating Temperature Range: −60°C to +150°C, accommodating ultra-low-temperature blast freezing and ambient refrigeration cycles
- Mechanical Properties: Tensile strength ≥ 515 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%
- Cryogenic Performance: Retains ductility and impact resistance down to −196°C (liquid nitrogen temperature), preventing brittle fracture under thermal cycling
- Surface Finish: Electropolished interior surface (Ra ≤ 0.4 μm) to minimize fouling and maximize heat transfer coefficient
Specifications
| Parameter | Specification | Standard / Tolerance |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm / 9.53 mm / 12.70 mm / 15.88 mm / 19.05 mm (customizable) | ±0.05 mm |
| Wall Thickness | 0.50 mm / 0.80 mm / 1.00 mm / 1.20 mm | ±0.05 mm |
| Coil Diameter (Pitch) | 50 mm – 300 mm (configurable per thermal load) | ±1.0 mm |
| Coil Length | 3 m – 30 m (continuous or segmented) | ±50 mm |
| Number of Turns | 50 – 500 turns (application-dependent) | ±2 turns |
| End Connection Type | Flared / Welded / Threaded (M14×1.5, M16×1.5) | ASME B1.20.1 |
| Refrigerant Compatibility | R-404A, R-507A, R-134a, R-290, R-717 (Ammonia) | — |
| Maximum Operating Pressure | 2.5 MPa (25 bar) | ASME BPVC Section I |
| Hydrostatic Test Pressure | 3.75 MPa (1.5× working pressure) | EN 10217-7 |
| Surface Treatment | Pickled & Passivated (P&P) or Electropolished (EP) | ASTM A967 |
| Welding Method | Orbital TIG (GTAW) / Laser Welding | ISO 6947 |
| Applicable Standards | ASTM A269, EN 10217-7, GB/T 12771 | — |
Manufacturing Process
The production of the JX-CT-642 Evaporator Coil Tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and functional reliability:
- Raw Material Procurement & Inspection: Stainless steel seamless or welded pipe stock is sourced from certified mills and subjected to spectroscopic analysis (PMI verification) and mechanical property testing prior to acceptance.
- Precision Cutting: Pipe stock is cut to predetermined lengths using CNC-controlled cold saw machines with nitrogen-assisted cooling to prevent thermal distortion and oxidation of cut surfaces.
- Coil Forming (Bending): A specialized CNC coil-bending machine forms the pipe into the prescribed helical geometry with controlled bend radii to prevent wall thinning, ovality, or cross-sectional deformation. The bending process employs internal mandrel support to maintain circularity within ±0.5% of nominal diameter.
- Welding & Joining: Orbital TIG welding (GTAW) with inert gas (argon) shielding is employed for all longitudinal and circumferential welds. Weld parameters are calibrated to ensure full penetration, minimal heat-affected zone (HAZ) distortion, and consistent microstructure.
- Surface Treatment: Post-forming pickling and passivation removes mill scale, bend-induced discoloration, and chromium-depleted zones, restoring full corrosion resistance. Electropolishing may be applied for critical applications requiring ultra-smooth interior surfaces.
- Non-Destructive Testing (NDT): 100% visual inspection, dye penetrant testing (DPT) for surface defects, and ultrasonic testing (UT) for volumetric flaws are performed in accordance with ISO 17637.
- Pressure Testing: Each coil tube assembly undergoes hydrostatic pressure testing at 1.5× the maximum working pressure, held for a minimum of 30 minutes with zero leakage tolerance.
- Dimensional Verification: Final coil diameter, pitch, length, and end alignment are verified using CMM (Coordinate Measuring Machine) or laser scanning equipment.
Applications
The JX-CT-642 Stainless Steel Evaporator Coil Tube is purpose-engineered for demanding thermal management applications, with primary deployment in the following sectors:
- Fishing Vessel Refrigerated Fish Holds: Primary application — serves as the evaporator coil within blast-freezing chambers and ambient refrigeration holds, enabling rapid catch preservation at temperatures ranging from −40°C to +4°C. Simulation studies have validated the coil geometry's effectiveness in achieving uniform temperature distribution across fish hold volumes, minimizing hot spots that compromise product quality.
- Marine Cold Storage Systems: Integration into shipboard cold rooms, refrigerated containers, and offshore platform storage units where space constraints and corrosion resistance are paramount.
- Process Refrigeration: Application in food processing, pharmaceutical cold chain, and chemical industry heat exchange circuits requiring hygienic-grade stainless steel construction.
- Heat Exchanger Coils: Utilization as the tube-side or shell-side element in plate-fin and air-cooled heat exchangers for industrial cooling systems.
- Cryogenic Systems: Deployment in liquid nitrogen and liquid natural gas (LNG) transfer systems where cryogenic ductility is essential.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring full traceability and regulatory compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 3834-2 — Quality Requirements for Welding of Metallic Materials
- EN 10204 3.1 — Third-Party Inspection Certification (Material Test Reports)
- EN 10217-7 — Heat Exchangers and Refrigeration Components — Seamless Tubes
- ASTM A269 / A270 — Seamless and Welded Austenitic Stainless Steel Tubing
- ASME BPVC Section VIII — Pressure Vessel Code Compliance (where applicable)
- GB/T 12771 — Chinese National Standard for Seamless Stainless Steel Tubes
- CRN (Canadian Registration Number) — Available upon request for North American installations
- CE Marking — Conformity with European Pressure Equipment Directive (PED 2014/68/EU)
- Material Traceability: Full heat-number traceability from mill certificate through final product dispatch
Unique Selling Points
Simulation-Validated Thermal Performance: The coil geometry and configuration have been optimized through computational fluid dynamics (CFD) and finite element analysis (FEA) simulations specifically modeling evaporator heat transfer characteristics in refrigerated fish holds. This data-driven design approach ensures that the product delivers predictable and superior cooling performance under real-world operating conditions, including variable air velocity, partial load scenarios, and icing accumulation.
Marine-Grade Corrosion Durability: With material grades and surface treatments specifically selected for prolonged exposure to salt spray, high humidity, and chloride-rich marine atmospheres, this product significantly outperforms standard industrial coil tubes in service life and maintenance intervals.
Customizable Geometric Configuration: Modular design flexibility allows adaptation to diverse hold geometries, refrigeration capacities, and refrigerant types without compromising structural integrity or thermal efficiency.