Stainless Steel Evaporator Coil Tube (Coiltube) — HVAC & Refrigeration Grade
Product Overview
The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered tubing product specifically designed for use in evaporator and condenser heat exchanger assemblies within HVAC (Heating, Ventilation, and Air Conditioning), refrigeration, and industrial cooling systems. The coil tube is supplied in continuous spiral-wound coil form, enabling efficient fabrication of multi-circuit evaporator coil tubes that exhibit superior heat transfer and dehumidification performance under variable operating conditions such as fluctuating air-side wind speed and compressor frequency modulation.
Based on experimental research into the thermal-hydraulic characteristics of two-circuit evaporator coil tube configurations, these products are optimized for applications where dynamic thermal performance is critical — including inverter-driven air conditioning systems, heat pump units, chiller evaporators, and industrial process cooling loops.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, offering exceptional resistance to corrosion, oxidation, and chemical degradation in humid and aggressive environments. Key material properties include:
- Grade: SUS304 / SUS316 / SUS316L (ASTM A269 / ASTM B474 equivalent)
- Corrosion Resistance: Superior resistance to chloride-induced pitting and intergranular corrosion, particularly in 316/316L grades containing molybdenum (Mo)
- Mechanical Properties: Tensile strength ≥ 515 MPa; Yield strength ≥ 205 MPa; Elongation ≥ 40%
- Thermal Conductivity: 14.5–16.0 W/(m·K) at 20°C, providing reliable heat transfer performance
- Operating Temperature Range: −196°C to +870°C (SUS304); −196°C to +427°C (SUS316L)
- Hygienic Surface Finish: Ra ≤ 0.4 μm (electropolished option available), minimizing fouling and facilitating clean-in-place (CIP) protocols
Specifications
| Parameter | Specification | Standard / Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm / 4.0 mm / 6.0 mm / 8.0 mm / 9.52 mm (⅜") / 12.7 mm (½") / Custom | ASTM A269 / GB/T 12771 |
| Wall Thickness | 0.3 mm – 1.5 mm (tolerance ±0.02 mm) | ASTM A269 / EN 10217 |
| Coil Inner Diameter (CID) | 100 mm – 800 mm (customizable per customer requirement) | Manufacturer Specification |
| Coil Length per Spool | 15 m – 150 m (adjustable based on OD and wall thickness) | — |
| End Condition | Plain end / Beveled end / Soldered joint / Brazed joint | ASTM A240 |
| Surface Finish | 2B / BA (Bright Annealed) / Electropolished (EP) / Passivated | — |
| Pressure Rating | Up to 2.5 MPa (working); 3.75 MPa (hydrostatic test) | ASME B31.5 |
| Refrigerant Compatibility | R410A / R32 / R134a / R22 / CO₂ (R744) / NH₃ (ammonia) | ASHRAE Standard 34 |
| Manufacturing Process | Seamless (cold-drawn) / Welded (TIG / orbital) | — |
| Maximum Circuit Count | Up to 8 circuits per evaporator coil assembly | — |
Manufacturing Process
The production of high-quality stainless steel coil tubes follows a rigorous multi-stage manufacturing process:
- Raw Material Selection: High-purity stainless steel wire rod (billet) conforming to ASTM A276 or EN 10272-1 specifications is sourced from certified mills, with each heat accompanied by a mill test certificate (MTC) verifying chemical composition and mechanical properties.
- Wire Drawing & Annealing: The wire rod undergoes multi-pass cold drawing through tungsten carbide (WC) dies to achieve precise outer diameter and wall thickness tolerances. Intermediate annealing cycles are performed to relieve residual stresses and maintain ductility.
- Coil Winding: The drawn tube is spiral-wound onto precision mandrels using CNC-controlled winding equipment, ensuring uniform coil geometry, consistent pitch, and minimal residual deformation. This step is critical for maintaining predictable hydraulic resistance and heat transfer characteristics in evaporator coil tube assemblies.
- Welding (if applicable): For welded coil tube configurations, Tungsten Inert Gas (TIG) welding is employed with argon shielding gas to produce leak-tight, penetration-free joints. Weld quality is verified through visual inspection (VT) and, where required, radiographic testing (RT) per ASME Section IX.
- Heat Treatment & Passivation: Post-forming solution annealing (1050°C – 1150°C with rapid quench) restores full austenitic microstructure and maximizes corrosion resistance. Chemical passivation (citric acid or nitric acid treatment) removes surface iron contamination, forming a protective chromium oxide layer.
- Quality Inspection: Every production lot undergoes dimensional verification (OD, wall thickness, straightness), hydrostatic pressure testing, spectrometric chemical analysis, and surface quality assessment per ISO 9001:2015 protocols.
Applications
Stainless steel coil tubes from Wenzhou Jixing Metal Materials Co., Ltd are employed across a broad spectrum of thermal management systems:
- Residential & Commercial HVAC: Evaporator and condenser coil tubes in split air conditioners, multi-split systems (VRF/VRV), and unitary chillers, particularly where inverter-driven compressor frequency modulation creates variable heat transfer demands.
- Industrial Refrigeration: Plate-fin evaporator coil tubes in cold storage facilities, process cooling systems, and ammonia-based industrial refrigeration plants.
- Heat Pump Systems: Dual-circuit and multi-circuit evaporator coil tubes in air-to-water and air-to-air heat pumps operating under wide ambient temperature ranges.
- Food & Beverage Processing: Hygienic-grade coil tubes (316L electropolished) for CIP-compatible heat exchangers in dairy, brewing, and pharmaceutical processing lines.
- Marine & Offshore Applications: Corrosion-resistant coil tubes for shipboard HVAC and marine refrigeration systems exposed to high-chloride saltwater environments.
- Automotive & Transportation: Compact evaporator coil tubes for electric vehicle (EV) battery thermal management and cabin climate control systems.
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd maintains adherence to internationally recognized quality and safety standards:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control
- ISO 14001:2015 — Environmental Management System certification for sustainable manufacturing practices
- CE Marking — Conformity with European Union directives for pressure equipment and machinery
- EN 10204 3.1 — Third-party inspection certificates (Test Report) provided for all production lots
- ASME / PED 2014/68/EU — Compliance with pressure vessel and piping standards for high-pressure applications
- RoHS & REACH Compliance — Restriction of hazardous substances in all material compositions
- Third-Party Testing: Available upon request through accredited laboratories (SGS, Bureau Veritas, TÜV)
Unique Selling Points
Wenzhou Jixing Metal Materials Co., Ltd's stainless steel coil tubes are distinguished by the following competitive advantages:
- Variable-Frequency Optimized Design: Coil geometry is engineered to maintain high dehumidification efficiency and heat transfer coefficients across a wide range of air-side wind speeds and compressor operating frequencies, addressing the thermal performance challenges identified in experimental research on two-circuit evaporator coil tube systems.
- Multi-Circuit Flexibility: Customizable circuit configurations (2 to 8 circuits) allow OEMs to optimize refrigerant distribution, pressure drop, and superheat/subcooling characteristics for specific system designs.
- Ultra-Tight Tolerances: Wall thickness tolerance of ±0.02 mm ensures uniform heat transfer surface area and consistent hydraulic performance throughout the coil length.
- Extended Service Life: Stainless steel construction provides 2–3× the operational lifespan of traditional copper or aluminum coil tubes in corrosive or high-humidity environments, reducing total cost of ownership (TCO).
- Full Traceability: Each coil spool is serialized and traceable to its raw material heat number, manufacturing batch, and inspection records, supporting rigorous quality assurance and regulatory compliance requirements.