Stainless Steel Coil Tube for Air Conditioning Unit Coil Sections
Product Overview
The Stainless Steel Coil Tube (Coil Tube / 盘管) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 1120) is a precision-engineered tubular component specifically designed for integration into the coil sections of air conditioning (AC) units and HVAC (Heating, Ventilation, and Air Conditioning) systems. These coil tubes serve as the primary heat exchange medium, facilitating efficient thermal transfer between the refrigerant and the ambient air stream. The product embodies advanced metallurgical engineering principles and precision manufacturing techniques to deliver superior thermal conductivity, mechanical durability, and long-term corrosion resistance under demanding operational environments.
This product line is derived from comprehensive technical research and design optimization studies focused on the coil section architecture of air conditioning units, incorporating lessons learned from extensive industry literature and field application data. The design philosophy prioritizes maximum surface-area-to-volume ratios, minimal flow resistance, and uniform heat distribution across the entire coil array.
Material & Properties
The coil tubes are fabricated from high-grade austenitic stainless steel, selected for its exceptional balance of thermal performance, mechanical strength, and corrosion resistance. The primary material specifications include:
- Base Material: Austenitic Stainless Steel conforming to AISI (American Iron and Steel Institute) 304 or 316 grade standards, with 316L (Low Carbon) grade available for enhanced resistance to chloride-induced pitting corrosion.
- Chemical Composition: Chromium (Cr) content of 18–20%, Nickel (Ni) content of 8–12%, Molybdenum (Mo) content of 2–3% (for 316/316L grades), Carbon (C) content < 0.08%, and Silicon (Si) content < 1.0%.
- Thermal Conductivity: Approximately 16.3 W/(m·K) at 20°C, providing reliable heat transfer efficiency while maintaining structural integrity.
- Mechanical Properties: Tensile strength ≥ 520 MPa, yield strength ≥ 205 MPa, and elongation ≥ 40%, ensuring resistance to vibration-induced fatigue and mechanical deformation.
- Operating Temperature Range: −40°C to +350°C, accommodating extreme thermal cycling conditions typical of HVAC applications.
- Corrosion Resistance: Excellent resistance to atmospheric corrosion, deionized water, and mild chemical environments; 316L grade offers superior performance in humid and saline-rich atmospheres.
- Hygienic Surface Finish: Ra (Surface Roughness Average) ≤ 0.5 μm for food-grade and pharmaceutical applications; standard finish Ra ≤ 1.6 μm for general HVAC use.
Specifications
| Parameter | Specification / Value | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.35 mm (1/4"), 9.52 mm (3/8"), 12.7 mm (1/2"), 15.88 mm (5/8"), 19.05 mm (3/4"), 25.4 mm (1") | ASME B36.19M / GB/T 12771 |
| Wall Thickness (WT) | 0.5 mm – 2.0 mm (customizable) | ASTM A269 / ASTM A312 |
| Tube Length (Coil Form) | 5 m – 50 m per coil (customizable) | Manufacturer Standard |
| Coil Diameter | 300 mm – 1,200 mm | Application-Specific |
| Bend Radius | ≥ 3D (minimum bend radius, where D = outer diameter) | ASTM A213 |
| Tolerance on OD | ±0.10 mm (standard); ±0.05 mm (precision grade) | ISO 6520 / GB/T 14976 |
| Tolerance on WT | ±0.05 mm (standard); ±0.02 mm (precision grade) | ISO 6520 / GB/T 14976 |
| Surface Finish | Polished (Ra ≤ 0.5 μm), Brushed, or Passivated | ASTM A967 (Passivation) |
| End Condition | Plain, Beveled, Flanged, or Threaded (per customer specification) | ASME B1.20.1 |
| Refrigerant Compatibility | R-134a, R-410A, R-407C, R-32, R-1234yf | ASHRAE Standard 34 |
| Pressure Rating | Up to 2.5 MPa (design pressure); burst pressure ≥ 4.0 MPa | ASME BPV Code / EN 13480 |
| Coating / Treatment | Optional: Epoxy coating, PTFE (Polytetrafluoroethylene) lining, or bare passivated | Manufacturer Specification |
| Packaging | Protective wrapping with moisture barrier; wooden or steel palletized coils | ISO 11607 / Manufacturer Standard |
Manufacturing Process
The production of these stainless steel coil tubes follows a rigorous, multi-stage manufacturing workflow designed to ensure dimensional accuracy, metallurgical homogeneity, and surface quality:
- Raw Material Selection and Inspection: High-purity stainless steel billets or strip stock are procured from certified suppliers. Incoming materials undergo spectroscopic analysis (OES – Optical Emission Spectroscopy) and mechanical testing to verify chemical composition and tensile properties against ASTM and ISO standards.
- Hot Rolling / Cold Drawing: Tubes are formed via either hot-rolled seamless processes (for larger diameters) or cold-drawn processes (for precision small-diameter tubes). Cold drawing provides superior dimensional tolerances and surface finish quality.
- Heat Treatment and Annealing: Tubes undergo solution annealing at 1,050°C – 1,150°C followed by controlled water quenching to achieve a fully austenitic microstructure, relieve residual stresses, and restore full ductility for subsequent forming operations.
- Precision Coil Forming: Annealed tubes are cold-formed into coil configurations using computer-controlled CNC (Computer Numerical Control) coiling machines. The bending process maintains a minimum bend radius of 3D to prevent wall thinning, ovalization, or wrinkling. In-line monitoring systems track OD, WT, and coil diameter in real time.
- Welding (if applicable):strong> Butt-welded or orbital-welded coil assemblies are fabricated using TIG (Tungsten Inert Gas) welding with argon shielding to ensure leak-tight, high-integrity joints. Welded seams undergo 100% visual inspection and selective radiographic testing (RT) per ASTM E94.
- Surface Treatment and Passivation: Tubes receive acid pickling and passivation treatment per ASTM A967 to remove surface contaminants, mill scale, and free iron, forming a protective chromium oxide passive film. Additional polishing or brushing operations achieve the specified surface roughness.
- Non-Destructive Testing (NDT) and Quality Assurance: Every production batch undergoes hydrostatic pressure testing (per ASTM A269/A312), eddy current testing (ECT) for wall thickness verification, and visual surface inspection. Helium leak testing may be performed for critical-seal applications.
- Packaging and Shipment: Coils are wrapped in protective plastic film with desiccant packs, secured on wooden or steel pallets, and labeled with full traceability documentation including heat numbers, test certificates, and dimensional data.
Applications
The stainless steel coil tubes are engineered for a diverse range of thermal management and fluid transfer applications, with primary focus on the following sectors:
- Air Conditioning Unit Coil Sections: The primary application domain. Coil tubes function as the refrigerant-side heat exchange elements within evaporator and condenser coils of split-system, packaged, and rooftop HVAC units. The coil section design research incorporated into this product ensures optimal air-side and refrigerant-side thermal coupling, minimizing temperature cross-over and maximizing coefficient of performance (COP).
- Chilled Water and Hot Water Systems: Used in coil assemblies for air handling units (AHUs), fan coil units (FCUs), and unitary HVAC systems where water serves as the thermal medium.
- Industrial Process Cooling and Heating: Deployed in plate-and-fin coil heat exchangers for chemical processing, food and beverage manufacturing, and pharmaceutical cleanroom climate control systems.
- Refrigeration Systems: Integrated into evaporator and condenser coils for commercial refrigeration, cold storage facilities, and walk-in coolers/freezers.
- Automotive and Marine HVAC: Applied in specialized air conditioning systems for vehicles, ships, and offshore platforms where corrosion resistance and weight optimization are critical.
- Specialty Applications: Including solar thermal collectors, geothermal heat exchangers, and heat recovery ventilation (HRV) systems.
Quality Certifications and Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring that all coil tube products meet or exceed international and national standards. The following certifications and compliance frameworks are in effect:
- ISO 9001:2015: Quality Management System certification covering design, manufacturing, inspection, and after-sales service processes.
- ISO 14001:2015: Environmental Management System certification demonstrating commitment to sustainable manufacturing practices and environmental stewardship.
- ISO 45001:2018: Occupational Health and Safety Management System certification.
- CE Marking (European Conformity): Products comply with EU directives including the Pressure Equipment Directive (PED 2014/68/EU) for pressure-containing applications.
- ASME (American Society of Mechanical Engineers): Materials and manufacturing processes conform to ASME B36.19M (dimensions), ASME BPV Code (pressure vessel applications), and ASME A213 (welded tubes for heat exchangers).
- ASTM (American Society for Testing and Materials): Full compliance with ASTM A269 (welded austenitic stainless steel tubes), ASTM A312 (seamless and welded austenitic stainless steel tubes), and ASTM A967 (passivation).
- GB/T (Chinese National Standards): Compliance with GB/T 12771 (welded stainless steel tubes), GB/T 14976 (seamless stainless steel tubes), and GB/T 13296 (boiler and heat exchanger tubes).
- EN (European Norms): Conformity with EN 10216-5 (welded stainless steel tubes) and EN 10217-7 (seamless stainless steel tubes).
- JIS (Japanese Industrial Standards): Compliance with JIS G3459 (welded stainless steel tubes) for export markets requiring Japanese standard certification.
- Mill Test Certificates (MTC): Each production lot is accompanied by a full EN 10204 3.1 or 3.2 Mill Test Certificate documenting chemical analysis, mechanical test results, and dimensional verification.
Unique Selling Points
- Research-Driven Design Optimization: The coil tube product line is informed by dedicated engineering research into air conditioning unit coil section design, incorporating validated thermal-hydraulic modeling results to optimize tube geometry, coil spacing, and flow channel configuration for peak heat transfer efficiency.
- Precision Dimensional Control: Advanced CNC coiling and in-line measurement systems ensure consistent OD, WT, and coil geometry tolerances, enabling seamless integration into precision-fabricated heat exchanger assemblies.
- Material Versatility: Availability in multiple stainless steel grades (304, 316, 316L) and customizable dimensions accommodates a wide spectrum of operating conditions, from mild atmospheric HVAC to aggressive industrial environments.
- End-to-End Quality Assurance: Multi-stage NDT protocols including hydrostatic testing, eddy current inspection, and radiographic examination provide comprehensive assurance of product integrity and leak-tight performance.
- Full Traceability: Complete batch traceability from raw material heat number through final shipment, supported by digital quality documentation and digital certification platforms.
- Custom Engineering Support: Wenzhou Jixing Metal Materials Co., Ltd. offers bespoke coil tube design and fabrication services, including custom bend radii, coil configurations, end treatments, and special surface finishes tailored to specific application requirements.
Note: All specifications listed herein represent standard offerings and may be customized to meet specific project requirements. For detailed dimensional drawings, material certifications, and application-specific engineering support, please contact Wenzhou Jixing Metal Materials Co., Ltd. directly. Product performance is contingent upon proper installation, handling, and maintenance in accordance with applicable codes and manufacturer guidelines.