Stainless Steel Coil Tube for Refrigeration Systems — Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Stainless Steel Coil Tube (Product Code No. 1354) is a precision-engineered tubular component manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (温州吉兴金属材料有限公司). This product is specifically designed for use in multi-zone refrigeration systems, including three-door, three-temperature refrigerators and similar appliance architectures. The coil tube serves as the core evaporator and condenser element, facilitating efficient heat exchange through its optimized helical geometry. Its spiral configuration maximizes surface area within a compact volumetric envelope, enabling superior thermal transfer performance while maintaining structural integrity under repeated thermal cycling.
Unlike conventional straight-tube heat exchangers, the coil tube architecture provides enhanced turbulence within the refrigerant flow path, which significantly improves heat transfer coefficients. This makes it particularly well-suited for applications demanding precise temperature control across multiple compartments, such as dual-cooling or triple-zone refrigeration units.
Material and Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional corrosion resistance, thermal conductivity, and mechanical durability. The material composition ensures long-term reliability in humid, chemically aggressive environments typical of refrigeration systems.
- Base Material: Austenitic Stainless Steel (Grade 304 / AISI 304 or Grade 316 / AISI 316L)
- Chromium Content (Cr): 18.0%–20.0% (Grade 304); 16.0%–18.0% (Grade 316)
- Nickel Content (Ni): 8.0%–10.5% (Grade 304); 10.0%–14.0% (Grade 316)
- Molybdenum Content (Mo): ≤0.08% (Grade 304); 2.0%–3.0% (Grade 316)
- Tensile Strength (UTS): ≥520 MPa (annealed condition)
- Yield Strength: ≥205 MPa
- Elongation at Break: ≥40%
- Thermal Conductivity: 16.3 W/(m·K) at 25°C
- Operating Temperature Range: −196°C to +870°C
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and intergranular corrosion
Technical Specifications
| Parameter | Specification | Unit | Standard / Reference |
|---|---|---|---|
| Outer Diameter (OD) | 6.35 / 8.0 / 9.52 / 12.7 | mm | ASTM A751 |
| Wall Thickness | 0.5 / 0.6 / 0.8 / 1.0 | mm | ASTM A751 |
| Inner Diameter (ID) | 5.35 / 6.8 / 7.92 / 10.7 | mm | — |
| Coil Winding Diameter | 150 – 400 (configurable) | mm | — |
| Coil Length (Uncoiled) | 2.0 – 15.0 | m | — |
| Winding Pitch | 1.5 – 3.0 | mm | — |
| Surface Finish | Bright Annealed / Mirror Polish (Ra ≤ 0.4 μm) | — | ASTM A478 |
| Pressure Rating (Hydrostatic) | ≥ 2.5 MPa (365 psi) | MPa | — |
| Refrigerant Compatibility | R134a, R600a, R404A, R410A | — | — |
| Helix Angle Tolerance | ± 0.5° | ° | — |
| Roundness Tolerance | ± 0.02 mm | mm | ISO 1128 |
| End Preparation | Deburred, chamfered (15°–30°) | — | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing protocol designed to ensure dimensional accuracy, metallurgical homogeneity, and surface quality:
- Hot Rolling (Hot-Rolled Strip Production): Stainless steel ingots are cast and hot-rolled into strip stock at temperatures exceeding 1,000°C, establishing the initial grain structure and approximate dimensions.
- Cold Rolling: The hot-rolled strip is cold-rolled to achieve precise thickness tolerances and improve mechanical properties through strain hardening.
- Intermediate Annealing: The strip is annealed to relieve accumulated cold-work stresses and restore ductility for subsequent forming operations.
- Tube Forming and Welding: The strip is formed into a circular cross-section and longitudinally welded using Automated Optical-Frequency (AOF) or TIG (Tungsten Inert Gas) welding. The weld seam is ground and polished to achieve full-penetration integrity.
- Solution Annealing: The formed tube undergoes solution heat treatment at 1,050°C–1,150°C followed by rapid water quenching. This eliminates carbide precipitation and restores full austenitic corrosion resistance.
- Precision Coiling: The straight tube is wound into a helical coil using CNC-controlled coiling machinery. The winding parameters (pitch, diameter, tension) are controlled to within ±0.1 mm tolerance.
- Surface Treatment: Final surface finishing is applied, including pickling, passivation, and optionally mirror polishing, to achieve the required surface roughness and chemical passivity.
- Quality Inspection: Each coil undergoes hydrostatic pressure testing, dimensional verification, surface inspection, and spectral material analysis.
Applications
The stainless steel coil tube is engineered for demanding refrigeration and thermal management applications:
- Three-Door, Three-Temperature Refrigerators: Serves as the primary evaporator coil in multi-zone refrigeration units, enabling independent temperature control across freezer, fresh-keeping, and variable-temperature compartments.
- Commercial Refrigeration Equipment: Used in display cases, walk-in coolers, and blast freezers where corrosion resistance and long service life are critical.
- Automotive Refrigeration: Deployed in truck-mounted refrigerated units and mobile cold-chain logistics systems.
- Industrial Heat Exchangers: Applied in process cooling systems, chiller units, and HVAC (Heating, Ventilation, and Air Conditioning) equipment.
- Medical and Pharmaceutical Cold Storage: Utilized in vaccine storage systems and laboratory refrigeration where contamination resistance is paramount.
- Food Processing Equipment: Integrated into pasteurization systems, ice-making machines, and frozen food processing lines.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains comprehensive quality management systems and product certifications to ensure international compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- CE Marking — European Conformity for machinery and appliances
- ASTM A751 — Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip
- ASTM A478 — Standard Specification for Stainless Steel Bar and Shapes
- EN 10217 — European Standard for Welded Stainless Steel Tubes
- GB/T 14976 — Chinese National Standard for Seamless and Welded Steel Tubes for General Cold-Rolled Use
- GB/T 12771 — Chinese National Standard for Welded Stainless Steel Tubes for Fluid Transport
Unique Selling Points
The coil tube product from Wenzhou Jixing Metal Materials Co., Ltd. distinguishes itself through several key advantages validated by practical field experience data:
- Enhanced Thermal Efficiency: The helical geometry increases turbulent flow by up to 35% compared to straight-tube configurations, improving heat transfer coefficients (U-value) significantly in multi-zone refrigeration applications.
- Proven Field Performance: Practical repair and replacement data from three-door, three-temperature refrigerator applications confirms a service life exceeding 10,000 thermal cycles without degradation of thermal performance or structural integrity.
- Compact Installation Footprint: The coiled configuration reduces installation space requirements by up to 40% compared to equivalent-capacity serpentine or plate-fin heat exchangers.
- Superior Corrosion Resistance: The austenitic stainless steel construction eliminates the need for internal coatings or passivation treatments, reducing maintenance requirements and total cost of ownership (TCO).
- Multi-Refrigerant Compatibility: Engineered to operate safely with all major HFC (Hydrofluorocarbon) and HFO (Hydrofluoroolefin) refrigerants, ensuring forward compatibility with evolving environmental regulations.
- Precision Engineering: CNC-controlled coiling ensures consistent winding geometry across all units, guaranteeing uniform refrigerant distribution and balanced thermal performance.
Note: All specifications are subject to confirmation based on specific project requirements. Custom configurations, including non-standard diameters, coil geometries, and surface finishes, are available upon request. Wenzhou Jixing Metal Materials Co., Ltd. welcomes technical consultation and provides comprehensive engineering support for system integration.