Stainless Steel Coil Tube — Fan Coil Unit Application (Wenzhou Jixing Metal Materials)

Product Overview

The Stainless Steel Coil Tube (Coiltube) manufactured by Wenzhou Jixing Metal Materials Co., Ltd is a precision-engineered product specifically designed for use in fan coil units (风机盘管空调器), including the well-known "Penguin Brand" (企鹅牌) HVAC systems. These coil tubes serve as the primary heat exchange medium, transferring thermal energy between the circulating refrigerant or water circuit and the ambient air stream. The product is supplied in continuous coil form to facilitate efficient downstream manufacturing, minimizing waste and ensuring dimensional consistency throughout production runs.

As a critical component in commercial and residential air conditioning systems, the coil tube must meet stringent requirements for thermal conductivity, corrosion resistance, mechanical integrity, and long-term reliability under cyclic thermal stress conditions.

Material & Properties

The coil tube is fabricated from high-grade stainless steel conforming to international material standards. The selection of stainless steel over conventional copper or aluminum tubing offers distinct advantages in specific application environments, particularly where corrosion resistance, hygiene, and long service life are paramount.

Key Material Characteristics

Specifications

Parameter Specification Standard / Reference
Outer Diameter (OD) 3.0 mm – 12.7 mm (commonly 6.35 mm, 9.53 mm) ASTM A213 / ASME SA-213
Wall Thickness 0.3 mm – 1.0 mm (typical: 0.5 mm – 0.8 mm) ASTM A213 Type 304/316
OD Tolerance ±0.05 mm (precision grade); ±0.1 mm (standard grade) ISO 4414
Wall Thickness Tolerance ±10% of nominal ASTM A213
Coil Length Customizable; typical range 50 m – 500 m per coil Manufacturer specification
Coil Inner Diameter 200 mm – 600 mm (depending on tube OD and wall thickness) Manufacturer specification
End Condition Plain cut, or with protective caps to prevent contamination —
Surface Condition Interior and exterior pickled and passivated; free from scale, stains, and mechanical damage ASTM A380
Welding Quality Seamless or welded with full-penetration weld; 100% radiographic inspection available ASME BPV Code Section VIII
Heat Treatment Annealed and pickled (A&P condition) for maximum ductility and corrosion resistance ASTM A213
Hydrostatic Test Pressure Minimum 5.0 MPa for standard tubes; custom pressures available ASME SA-213
Temperature Range (Service) −196°C to +400°C (continuous); up to 870°C (intermittent) ASME BPV Code
Maximum Working Pressure Up to 10.0 MPa (design-dependent) ASME BPV Code Section VIII Div. 1
Application Standard ASHRAE 90.1; EN 14511; ISO 13380 —
Product Serial No. 1505 Internal catalog reference

Manufacturing Process

The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd follows a rigorously controlled multi-stage manufacturing process to ensure consistent quality and dimensional accuracy:

  1. Raw Material Selection & Inspection: Hot-rolled stainless steel strip is sourced from certified mills and subjected to incoming inspection for chemical composition (via optical emission spectrometry, OES), mechanical properties, and surface quality.
  2. Cold Rolling: The strip is cold-rolled to the target thickness with precise gauge control, achieving the required wall thickness with minimal thickness variation across the coil width.
  3. Pickle & Anneal (Pickling and Annealing): The cold-rolled strip is annealed at 1050–1150°C followed by acid pickling to remove oxide scale and restore full austenitic microstructure, ensuring optimal formability and corrosion resistance.
  4. Forming / Tube Making: The flat strip is fed through a series of precision rollers in a tube-making machine to form the tubular cross-section. For seamless tubes, the longitudinal seam is formed and welded using high-frequency induction welding (HF welding) or TIG welding with argon shielding gas.
  5. Weld Heat-Affected Zone (HAZ) Treatment: The HAZ is stabilized through post-weld annealing or solution treatment to prevent chromium carbide precipitation and intergranular corrosion susceptibility.
  6. Heat Exchanger Fin Attachment (if applicable): For fan coil unit-specific tubes, fins (laminated aluminum or copper) may be mechanically or brazed onto the tube OD to increase heat transfer surface area.
  7. Coiling: The finished tube is coiled to the specified inner diameter using a precision coiler, ensuring uniform coil formation without kinks, flattening, or surface damage.
  8. Quality Inspection: Each coil undergoes comprehensive inspection including visual examination, dimensional verification (OD, wall thickness, straightness), hydrostatic pressure testing, and non-destructive testing (NDT) — including eddy current testing (ECT) and ultrasonic testing (UT) — to detect internal and external defects.
  9. Passivation & Packaging: Final passivation treatment is applied to enhance the passive chromium oxide film. Coils are wrapped in protective film, placed in wooden or metal crates, and labeled with full traceability documentation.

Applications

The stainless steel coil tube from Wenzhou Jixing Metal Materials is primarily engineered for the following application domains:

1. Fan Coil Units (FCUs) — HVAC Systems

2. Heat Exchanger Manufacturing

3. Specialized Industrial Applications

Quality Certifications & Compliance

Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management system and holds the following certifications and compliances:

Unique Selling Points

Note: The product knowledge reference (Serial No. 1505) is associated with technical learning materials related to "Penguin Brand" fan coil unit systems. The specifications presented herein reflect the standard product configuration and may be customized upon request. All dimensional and material data should be verified against the specific purchase order and applicable engineering drawings for each project.