Stainless Steel Evaporator Coil Tube (Coil Tube) — Technical Specification
1. Product Overview
The Stainless Steel Evaporator Coil Tube (Coil Tube) is a precision-engineered tubular component designed for refrigeration, air conditioning, and thermal exchange systems. Manufactured by Wenzhou Jixing Metal Materials Co., Ltd., this product is specifically optimized for evaporator applications where frosting resistance, thermal conductivity, and long-term durability under cryogenic conditions are critical performance parameters.
Extensive experimental research on the frosting characteristics of evaporator coil tubes has informed the design and material selection of this product line. The coil tube exhibits superior frost management properties, reducing ice accumulation rates and maintaining efficient heat transfer over extended operational cycles. This makes it particularly suitable for low-temperature environments, cold storage facilities, and industrial refrigeration systems where consistent thermal performance is essential.
2. Material & Properties
2.1 Base Material
The coil tube is fabricated from high-grade austenitic stainless steel, primarily conforming to AISI 304 (UNS S30400) and AISI 316L (UNS S31603) grades, selected for their exceptional corrosion resistance, cryogenic toughness, and thermal stability.
2.2 Key Mechanical Properties
- Tensile Strength: ≥ 520 MPa (AISI 304) / ≥ 485 MPa (AISI 316L)
- Yield Strength: ≥ 205 MPa (AISI 304) / ≥ 170 MPa (AISI 316L)
- Elongation: ≥ 40% (AISI 304) / ≥ 35% (AISI 316L)
- Cryogenic Impact Strength: Maintains ductility down to −196°C (Liquid Nitrogen Temperature)
2.3 Thermal Properties
- Thermal Conductivity: 14.9–16.3 W/(m·K) at 20°C
- Thermal Expansion Coefficient: 17.3×10⁻⁶ /K (10–100°C)
- Specific Heat Capacity: 500 J/(kg·K) at 20°C
2.4 Corrosion Resistance
- Excellent resistance to atmospheric, industrial, and marine environments
- Superior resistance to chlorides and de-icing chemicals (AISI 316L grade)
- Anti-frosting surface treatment reduces ice nucleation and adhesion
3. Specifications
| Parameter | Specification | Unit | Standard/Reference |
|---|---|---|---|
| Outer Diameter (OD) | 6.0 – 32.0 | mm | ASTM A213 / ASME SA-213 |
| Wall Thickness | 0.5 – 2.0 | mm | ASTM A213 / ASME SA-213 |
| Coil Diameter | 50 – 500 | mm | Customizable |
| Tube Length (Coiled) | 10 – 200 | m | Customizable |
| Surface Finish | Mirror Polish / Brushed / Passivated | — | Ra ≤ 0.4 μm (Mirror) |
| Material Grade | AISI 304 / 304L / 316 / 316L | — | ASTM A269 / ASME SA-269 |
| Operating Temperature Range | −196 to +400 | °C | — |
| Maximum Operating Pressure | Up to 25 | MPa | ASME BPVC Section VIII |
| Coil Pitch | 1.5 – 3.0 × OD | — | Customizable |
| End Treatment | Plain / Beveled / Flared / Threaded | — | Per customer drawing |
| Surface Roughness (Internal) | Ra ≤ 0.8 μm (standard); Ra ≤ 0.4 μm (polished) | μm | ASTM A269 |
| Weight Tolerance | ±5% | % | — |
4. Manufacturing Process
4.1 Production Workflow
- Material Selection & Inspection: Certified stainless steel seamless tubes sourced from reputable mills, subject to spectroscopic verification and mechanical property testing.
- Cold Drawing & Sizing: Tubes are cold-drawn through precision dies to achieve exact dimensional tolerances (±0.05 mm on OD) and surface finish requirements.
- Coiling: Tubes are coiled on CNC-controlled coiling machines with programmable coil diameter, pitch, and length to meet application-specific geometries.
- Heat Treatment (if required): Solution annealing at 1050–1150°C followed by controlled cooling to restore full austenitic microstructure and relieve cold-work stresses.
- Surface Treatment: Passivation, electropolishing, or mechanical polishing applied to enhance corrosion resistance and reduce frost adhesion.
- Hydrostatic Pressure Testing: Each coil tube is pressure-tested at 1.5× the maximum operating pressure to ensure weld integrity and absence of defects.
- Final Inspection & Packaging: Dimensional verification, visual inspection, and protective packaging for shipment.
4.2 Frost-Resistant Design Features
Informed by experimental research on evaporator coil frosting characteristics, the product incorporates design optimizations that minimize frost formation:
- Smooth internal and external surface finish reduces ice nucleation sites
- Optimized coil pitch promotes uniform airflow distribution, reducing stagnant zones where frost preferentially accumulates
- Passivated surface layer reduces moisture adhesion and accelerates frost sublimation during defrost cycles
- Consistent wall thickness ensures uniform heat flux distribution, preventing cold spots that promote localized frosting
5. Applications
- Industrial Refrigeration: Evaporators in cold storage warehouses, freezing tunnels, and blast chillers
- Air Conditioning Systems: Chilled water coils, air handling unit (AHU) evaporators, and heat exchangers
- Cryogenic Systems: Liquefied Natural Gas (LNG) processing, liquid nitrogen storage, and superconducting magnet cooling
- Food Processing: Pasteurization heat exchangers, plate-and-frame coils, and refrigerated display cases
- Pharmaceutical & Biotech: Cold chain storage, vaccine refrigeration, and laboratory cryo-equipment
- Automotive & Transportation: Refrigerated truck trailers, rail car cooling systems, and marine refrigeration units
- Marine & Offshore: Subsea heat exchangers, ballast cooling systems, and shipboard refrigeration
6. Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System Certification
- ISO 14001:2015 — Environmental Management System Certification
- ASTM A269 / ASME SA-269 — Seamless and welded austenitic stainless steel tubing for chemical and heat-exchange equipment
- ASTM A213 / ASME SA-213 — Heat-exchanger and condenser tubing
- EN 10216-5 — European standard for seamless stainless steel tubes for heat exchangers
- GB/T 17897 — Chinese national standard for seamless stainless steel tubes for heat exchangers
- CE Marking — Conformity with European machinery and pressure equipment directives
- PED (Pressure Equipment Directive) 2014/68/EU — Compliance for pressure-containing applications
- Material Certificates: Mill test certificates (MTC) per EN 10204 Type 3.1 provided with every shipment
7. Unique Selling Points
- Research-Backed Frost Mitigation: Product design validated through experimental studies on evaporator frosting dynamics, delivering measurably lower frost accumulation rates and improved defrost efficiency
- Full Material Traceability: Every coil tube is traceable to its mill heat number with complete chemical and mechanical property documentation
- Customization Capability: Flexible manufacturing supports custom OD, wall thickness, coil geometry, surface finish, and end treatments to meet specific engineering requirements
- Cryogenic Performance: Maintains full mechanical integrity from −196°C to +400°C, enabling use in the most demanding thermal environments
- Extended Service Life: Superior corrosion and wear resistance reduces maintenance intervals and total cost of ownership (TCO) compared to carbon steel or aluminum alternatives
- Hygienic Design: Mirror-polished and electropolished variants suitable for food-grade and pharmaceutical applications meeting FDA and EHEDG guidelines
Wenzhou Jixing Metal Materials Co., Ltd. — Committed to delivering precision-engineered stainless steel coil tube solutions backed by rigorous experimental research, international quality standards, and tailored engineering support for thermal management applications worldwide.