Stainless Steel Coil Tube — FP-7 Fan Coil Unit Series

Product Overview

The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd (Product No. 1625) is a precision-engineered hygienic tubing solution specifically designed for integration into FP-7 type column-mounted fan coil units (Fan Coil Units, FCUs). These coil tubes serve as the primary heat exchanger elements within HVAC (Heating, Ventilation, and Air Conditioning) systems, facilitating efficient thermal transfer between refrigerant/circulating water and ambient air. The product line incorporates advanced low-noise engineering principles, ensuring optimal acoustic performance in sensitive environments such as hospitals, hotels, office buildings, and residential complexes.

The coil tube design emphasizes superior thermal conductivity, corrosion resistance, and mechanical durability, making it an ideal choice for high-performance hydronic and refrigeration applications where long service life and minimal maintenance are critical requirements.

Material & Properties

The coil tubes are fabricated from high-grade stainless steel conforming to international standards, ensuring exceptional resistance to corrosion, scaling, and chemical degradation under demanding operating conditions.

Primary Material Specifications

Key Performance Characteristics

Specifications

Parameter Specification
Product Name Stainless Steel Coil Tube (Coiltube)
Product Number 1625
Manufacturer Wenzhou Jixing Metal Materials Co., Ltd
Tube Type Seamless / Welded Coil Tube (Hygienic Grade)
Material Grade SUS304 / SUS316L (AISI 304 / 316L)
Outer Diameter (OD) 6.0 mm – 12.7 mm (customizable)
Wall Thickness 0.5 mm – 1.5 mm
Inner Diameter (ID) 4.0 mm – 10.7 mm
Coil Length 10 m – 50 m per spool (custom lengths available)
Diameter Tolerance ± 0.05 mm
Wall Thickness Tolerance ± 0.03 mm
Surface Finish Electro-polished / Passivated (Ra ≤ 0.4 μm internal)
Bend Radius (Minimum) 1.5 × OD
Operating Pressure Up to 1.6 MPa (standard); up to 4.0 MPa (reinforced)
Heat Transfer Coefficient ≥ 2,500 W/(m²·K) (water-to-air)
Acoustic Noise Level ≤ 28 dB(A) at 1 m (with FP-7 low-noise fan integration)
Design Life ≥ 25 years (indoor HVAC applications)
Standards Compliance ASTM A269, ASTM A270, EN 10217-7, GB/T 12771

Manufacturing Process

The production of these stainless steel coil tubes follows a rigorous multi-stage manufacturing workflow to ensure dimensional accuracy, material integrity, and surface quality:

  1. Material Selection & Verification: High-purity stainless steel wire rod is procured from certified suppliers. Each batch undergoes spectroscopic analysis (OES — Optical Emission Spectroscopy) to verify chemical composition compliance.
  2. Hot Rolling & Annealing: Wire rod is hot-rolled to preliminary dimensions and solution-annealed at 1050–1100°C followed by controlled cooling to achieve full austenitic microstructure.
  3. Cold Drawing: Precision cold drawing through tungsten carbide dies achieves final outer diameter, wall thickness, and dimensional tolerances with ±0.05 mm accuracy.
  4. Pipe Forming: Flat strip or drawn tubing is formed into round cross-section using progressive rotary forming machines, ensuring uniform wall thickness and concentricity.
  5. Welding (if applicable): Longitudinal seams are welded using high-frequency induction welding (HF-IW) or TIG welding under argon shielding, followed by weld bead grinding and inspection.
  6. Coiling & Heat Treatment: Tubes are coiled to specified lengths and undergo solution heat treatment (1040–1120°C) followed by water quenching to restore full austenitic properties and relieve residual stresses.
  7. Surface Treatment: Electro-polishing removes surface contaminants and creates a smooth, passivated surface (Ra ≤ 0.4 μm). Acid pickling and passivation complete the hygienic surface preparation.
  8. Quality Inspection: Each coil undergoes hydrostatic pressure testing, dimensional verification (laser gauging), surface roughness measurement, and visual/eddy current inspection for internal defects.
  9. Packaging & Dispatch: Tubes are coiled, wrapped in protective film, and secured on wooden or steel spools with protective end caps for safe transport.

Applications

The FP-7 Series Stainless Steel Coil Tubes find extensive application across multiple industries and HVAC configurations:

Quality Certifications

Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management framework backed by internationally recognized certifications:

Unique Selling Points

Acoustic Excellence: Engineered tube geometry with optimized flow channel profiles, when integrated with low-noise fans in FP-7 fan coil units, achieves noise levels as low as 28 dB(A) — significantly below industry averages of 35–45 dB(A), making these products ideal for acoustically sensitive environments.