Stainless Steel Coil Tube for Fan Coil Unit Systems

Product Code: JX-1317 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd.

1. Product Overview

The Stainless Steel Coil Tube (also referred to as a Coil Tube or Coiltube) is a precision-engineered tubular component designed primarily for integration into Fan Coil Unit (FCU) systems within commercial and industrial air conditioning (HVAC) applications. This product is manufactured from high-grade austenitic stainless steel and is wound into a compact coil configuration to maximize heat transfer surface area within a constrained spatial envelope. The coil tube serves as the core heat exchange element in air conditioning and ventilation systems, facilitating efficient thermal energy transfer between circulating refrigerant or water and ambient air.

Wenzhou Jixing Metal Materials Co., Ltd. specializes in the production of stainless steel coil tubes that meet stringent international standards for dimensional accuracy, corrosion resistance, and mechanical integrity. The product is engineered to withstand the cyclic thermal stress and chemical exposure inherent in HVAC operational environments.

2. Material & Properties

2.1 Base Material Composition

2.2 Key Mechanical Properties

2.3 Thermal & Corrosion Properties

3. Specifications

Parameter Specification Standard / Tolerance
Outer Diameter (OD) 6.35 mm / 9.53 mm / 12.7 mm / 15.88 mm ±0.05 mm (ASME B36.19M)
Wall Thickness 0.4 mm – 1.5 mm ±10% of nominal
Coil Length 1 m – 12 m (customizable) ±50 mm
Coil Pitch (Wind Spacing) 12 mm – 25 mm ±0.5 mm
Number of Turns Up to 200 turns ±2 turns
Surface Finish Mirror Polish (Ra ≤ 0.2 μm) / Brushed / Matte ASTM A480
End Treatment Beveled / Flared / Threaded / Grooved ASME B1.20.1
Pressure Rating Up to 1.6 MPa (operating) / 3.2 MPa (test) EN 10216-5
Material Grade AISI 304 / AISI 316L / AISI 321 ASTM A213 / ASTM A269
Welding Quality Continuous weld / Butt weld / TIG welded ASTM A270

4. Manufacturing Process

  1. Material Selection & Inspection: Raw stainless steel wire rod or seamless tube stock is procured from certified mills and subjected to spectrographic analysis (OES) to verify chemical composition compliance with ASTM/EN standards.
  2. Cold Drawing: The tube stock is cold-drawn through precision tungsten carbide dies to achieve exact outer diameter and wall thickness tolerances, ensuring uniform cross-sectional geometry.
  3. Heat Treatment (Solution Annealing): Drawn tubing is solution-annealed at 1050°C ± 10°C followed by rapid water quenching to restore full austenitic microstructure, eliminate residual stresses, and maximize corrosion resistance.
  4. Coil Winding: The straightened tube is wound onto CNC-controlled coil-forming machines using programmable pitch and diameter parameters. This step defines the final helical geometry of the coil tube.
  5. Welding & Joining: Inlet and outlet connections are fabricated using Gas Tungsten Arc Welding (GTAW/TIG) with argon shielding to prevent oxidation. Weld seams undergo 100% visual inspection and 10% radiographic testing (RT).
  6. Surface Finishing: The coil tube undergoes mechanical polishing (electrolytic or mechanical) to achieve the specified surface roughness, critical for minimizing fluid friction and fouling in HVAC applications.
  7. Quality Control & Testing: Finished products undergo hydrostatic pressure testing (1.5× working pressure for 30 seconds), dimensional verification via coordinate measuring machine (CMM), and non-destructive testing (NDT) including dye penetrant inspection (DPI).

5. Applications

5.1 Primary Application: Fan Coil Unit (FCU) Systems

The stainless steel coil tube is the fundamental heat exchange component in Fan Coil Units used in modern air conditioning engineering. In these systems, conditioned water (chilled or hot) circulates through the coil tube while a fan draws ambient air across the coil surface, enabling precise temperature and humidity control within conditioned spaces.

5.2 Detailed Application Areas

5.3 Performance Advantages in HVAC Engineering

Studies in air conditioning engineering demonstrate that stainless steel coil tubes offer superior long-term thermal efficiency compared to copper or aluminum alternatives. The inherent corrosion resistance eliminates the need for chemical inhibitors in water-based systems, reducing maintenance costs by up to 40% over a 15-year operational lifecycle. Furthermore, the compact coil geometry provides a heat transfer coefficient (U-value) of 200–400 W/(m²·K), enabling high-capacity thermal exchange within minimal installation footprints.

6. Quality Certifications & Compliance

7. Unique Selling Points