Stainless Steel Coil Tube for Household Refrigerator Evaporators
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1710) is a precision-engineered refrigeration-grade tubing solution specifically designed for household refrigerator evaporator systems. This coiltube product represents a significant advancement in domestic refrigeration technology, leveraging the superior thermal conductivity, corrosion resistance, and mechanical durability of stainless steel alloys to deliver enhanced cooling performance and extended service life.
Unlike conventional copper or aluminum evaporator coils, the stainless steel coil tube offers exceptional resistance to ammonia-based refrigerants, hydrofluorocarbon (HFC) refrigerants, and hydrofluoroolefin (HFO) refrigerants, making it compatible with a wide range of modern refrigeration cycles. The coiltube is pre-formed into continuous spiral or serpentine configurations, enabling efficient heat exchange within compact appliance footprints.
Material & Properties
The coil tube is fabricated from high-purity austenitic stainless steel, primarily conforming to SUS304 (AISI 304 / UNS S30400) and SUS316 (AISI 316 / UNS S31600) grades, selected based on application-specific requirements.
- Chemical Composition (SUS304): Carbon (C) ≤ 0.08%, Chromium (Cr) 18.0–20.0%, Nickel (Ni) 8.0–10.5%, Manganese (Mn) ≤ 2.0%, Silicon (Si) ≤ 1.0%
- Chemical Composition (SUS316): Carbon (C) ≤ 0.08%, Chromium (Cr) 16.0–18.0%, Nickel (Ni) 10.0–14.0%, Molybdenum (Mo) 2.0–3.0%
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C, ensuring efficient heat transfer during evaporative cooling cycles
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and refrigerant-induced corrosion; superior to copper in ammonia (NH₃) environments
- Mechanical Properties: Tensile strength (Rm) ≥ 520 MPa (annealed condition); elongation (A50) ≥ 40%
- Operating Temperature Range: −196°C to +870°C, fully compatible with deep-freeze and rapid-cooling applications
- Surface Finish: Bright annealed (BA) or electropolished finish with surface roughness (Ra) ≤ 0.8 μm, promoting efficient refrigerant flow and minimizing fouling
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) | — |
| Product Code | 1710 | — |
| Material Grade | SUS304 / SUS316 / SUS304L / SUS316L | — |
| Outer Diameter (OD) | 3.0 / 3.5 / 4.0 / 5.0 / 6.0 / 7.0 / 8.0 | mm |
| Wall Thickness | 0.3 / 0.4 / 0.5 / 0.6 / 0.8 | mm |
| Bend Radius (Min.) | 1.5 × OD (cold bent) | — |
| Coil Length | Custom (typically 2.0 – 15.0) | m |
| Coil Diameter | 200 – 600 (customizable) | mm |
| Surface Treatment | Bright Annealed / Electropolished / Passivated | — |
| Refrigerant Compatibility | R600a, R134a, R404A, R410A, R290, NH₃ | — |
| Pressure Rating | Up to 4.0 | MPa |
| Standard Conformity | GB/T 14976, GB/T 21830, ASTM A213, EN 10216-5 | — |
| Finish | Mirror / Matte / Industrial | — |
| Packaging | Wooden crate / Plastic film wrapped coil | — |
Manufacturing Process
The production of the stainless steel coil tube follows a rigorous multi-stage manufacturing protocol to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Raw Material Selection: High-grade stainless steel strips are sourced from certified mills, undergo spectroscopic analysis (PMI — Positive Material Identification), and are inspected for chemical composition compliance.
- Slitting & Edge Preparation: Continuous coils are precision-slitted to specified width tolerances (±0.1 mm), with edges deburred to prevent weld defects.
- Tube Forming: The strip is fed through a high-precision roll-forming die set to create the required tube cross-section (circular, rectangular, or oval), with online diameter monitoring via laser sensors.
- Seam Welding: A high-frequency induction resistance welding (HFRW) process is employed to achieve full-penetration weld seams with minimal heat-affected zone (HAZ), ensuring leak-tight integrity.
- Heat Treatment (Solid Solution Annealing): Tubes are annealed at 1050–1150°C followed by controlled cooling to relieve residual stresses, refine grain structure, and restore full corrosion resistance.
- Precision Bending & Coiling: CNC-controlled bending stations form the tube into the required serpentine or spiral evaporator geometry with controlled bend radii to prevent wall thinning and ovalization.
- Surface Finishing: Electropolishing or chemical passivation removes surface contaminants, forming a stable chromium oxide (Cr₂O₃) passive layer for enhanced corrosion protection.
- Hydrostatic Pressure Testing: Each coil tube assembly undergoes 100% hydrostatic testing at 1.5× working pressure to verify leak-tightness and structural integrity.
- Final Inspection & Packaging: Dimensional verification (CMM — Coordinate Measuring Machine), visual inspection, and protective packaging ensure product readiness for shipment.
Applications
- Household Refrigerators: Primary evaporator coil tubing for top-freezer, bottom-freezer, side-by-side, and French-door refrigerator configurations; compatible with isobutane (R600a) and propane (R290) refrigerant systems
- Commercial Refrigeration: Freezer cabinets, display cases, and walk-in cooling units requiring high durability and food-safe materials
- Medical & Laboratory Equipment: Vaccine refrigerators, sample storage units, and cryogenic equipment where biocompatibility and corrosion resistance are critical
- Automotive Refrigeration: Refrigerated transport units for pharmaceutical and food logistics
- Industrial Heat Exchangers: Compact evaporator coils in process cooling, chemical processing, and pharmaceutical manufacturing
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework ensuring product reliability and regulatory compliance:
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- CE Marking — European Conformity for household appliance components
- RoHS Compliance — Restriction of Hazardous Substances Directive (EU 2011/65/EU)
- GB/T 14976-2012 — Chinese National Standard for seamless stainless steel tubes
- GB/T 21830-2008 — Chinese National Standard for welded stainless steel tubes for heat exchangers
- NSF/ANSI 61 — Drinking Water System Components (where applicable for food-contact applications)
- SGS Testing Reports — Independent third-party material verification and mechanical property testing
Unique Selling Points
The stainless steel coil tube from Wenzhou Jixing Metal Materials Co., Ltd. distinguishes itself through the following competitive advantages:
- Superior Corrosion Longevity: Stainless steel evaporator coils exhibit a service life exceeding 20 years under normal operating conditions — significantly outperforming copper (8–12 years) and aluminum (5–8 years) alternatives, particularly in high-humidity or ammonia-refrigerant environments.
- Food Safety & Hygiene: The non-toxic, non-reactive surface of austenitic stainless steel eliminates any risk of metal migration into food products, making it ideal for direct food-contact evaporator applications.
- Thermal Performance Optimization: Precision wall thickness control and optimized coil geometry ensure uniform refrigerant distribution, minimizing hot spots and maximizing heat exchange efficiency (COP — Coefficient of Performance improvement of 3–7% over standard copper coils).
- Customization Capability: Full customization of OD, wall thickness, coil pitch, total length, and bend geometry to meet specific appliance OEM requirements, with rapid prototyping and short lead times.
- Environmental Sustainability: Stainless steel is 100% recyclable with no loss of material properties, supporting circular economy principles and reducing the environmental footprint of refrigeration systems.
- Wide Refrigerant Compatibility: Unlike copper tubing, which is incompatible with ammonia refrigerants, stainless steel coil tubes function reliably across all major refrigerant classes, offering future-proofing for transitioning refrigerant technologies.