Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd.

1. Product Overview

The Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous-length tubular product supplied in coiled form. Unlike straight-length seamless or welded pipes, coil tubes are wound into a continuous helical configuration, enabling downstream processing with minimal cutting waste, reduced handling losses, and superior material utilization efficiency.

Coiltubes are widely recognized in the HVAC (Heating, Ventilation, and Air Conditioning), industrial heat exchange, fluid conveying, and specialized equipment manufacturing sectors. The continuous coiled geometry facilitates automated forming, bending, and crimping operations, making it an indispensable intermediate product in high-volume manufacturing environments. Research studies, including investigations into the impact of variable operating conditions on fan coil unit (FCU) performance, have demonstrated that the geometric consistency and thermal conductivity uniformity of stainless steel coil tubes directly influence the overall efficiency and reliability of heat exchange systems.

2. Material and Properties

Wenzhou Jixing Metal Materials Co., Ltd. offers Coiltubes fabricated from a range of austenitic and duplex stainless steel grades, selected to meet the rigorous demands of corrosive environments, high-temperature service, and hygienic applications.

2.1 Available Grades

2.2 Key Mechanical and Physical Properties (Typical Values for Grade 304)

2.3 Surface Finish Options

3. Specifications

Parameter Specification Standard Reference
Outer Diameter (OD) 6.00 mm – 159.00 mm (¼" – 6") ASTM A213 / EN 10216-5
Wall Thickness (WT) 0.50 mm – 6.00 mm (0.020" – 0.236") ASTM A213 / EN 10216-5
Coil Diameter 600 mm – 1,500 mm (24" – 60") Manufacturer Specification
Coil Length (per coil) 50 m – 500 m (164 ft – 1,640 ft), customizable Manufacturer Specification
OD Tolerance ± 0.05 mm to ± 0.15 mm (depending on diameter range) ASTM A213
Wall Thickness Tolerance ± 10% of nominal (minimum ± 0.05 mm) ASTM A213
Roundness ≤ 10% of wall thickness ASTM A213
Straightness (post-uncoiling) ≤ 2 mm per meter EN 10216-5
Material Grade 304, 304L, 316, 316L, 321, 347, 904L, 2205 (Duplex) ASTM A213 / ASTM A269
Manufacturing Method Seamless / Welded (ERW, FBW, Orbit) ASTM A213 / EN 10216-5
Surface Finish 2B, No. 4, Mirror (8K), Electropolished, Pickled & Passivated ASTM A480
Packaging Wooden pallet with stretch film, protective end caps, export-grade ISO 4126

4. Manufacturing Process

The production of Wenzhou Jixing Coiltubes follows a rigorously controlled multi-stage manufacturing process, ensuring dimensional accuracy, metallurgical integrity, and surface quality throughout the product lifecycle.

4.1 Process Flow

  1. Raw Material Procurement and Inspection: Stainless steel billets or strips are sourced from certified mills and subjected to incoming quality control (IQC), including spectroscopic analysis (OES / XRF) to verify chemical composition compliance with the specified grade.
  2. Hot Rolling or Hot Extrusion: Billets are heated to forging temperature (1,150–1,200°C) and hot-rolled or extruded into hollow sections, establishing the initial tubular geometry.
  3. Piercing and Sizing (Seamless Route): The hot-rolled blank is pierced using a mandrel or plug to create the internal bore, followed by rolling or sizing passes to achieve the target OD and wall thickness.
  4. Forming and Welding (Welded Route): Cold-rolled stainless steel strip is formed into a tubular profile using roll-forming mills, and the longitudinal seam is welded using Electric Resistance Welding (ERW), Flash Butt Welding (FBW), or Orbit welding techniques.
  5. Heat Treatment: The tube is solution-annealed at 1,010–1,120°C followed by rapid water quenching to dissolve carbides, restore full austenitic microstructure, and achieve the required mechanical properties and corrosion resistance.
  6. Pickling and Passivation: The annealed tube is immersed in a mixed acid solution (HNO₃ / HF) to remove oxide scale, followed by passivation in a nitric acid bath to form a protective chromium oxide (Cr₂O₃) passive film.
  7. Cold Drawing / Cold Sizing: For precision Coiltubes, the annealed tube undergoes cold drawing through a die and mandrel set to achieve tight dimensional tolerances (± 0.05 mm OD) and improved surface finish.
  8. Coiling: The finished tube is wound onto a large-diameter coil former using a tension-controlled winding system. The coil diameter and winding pattern are optimized to prevent deformation, kinking, or work hardening during the coiling process.
  9. Final Quality Inspection: Each coil undergoes comprehensive inspection including dimensional verification (OD, WT, roundness), hydrostatic pressure testing, surface visual inspection, and, where required, non-destructive testing (NDT) such as ultrasonic testing (UT) or eddy current testing (ECT).
  10. Packaging and Dispatch: Coils are wrapped in protective film, fitted with end caps, and secured on export-grade wooden pallets for safe transportation.

4.2 Process Advantages

5. Applications

Wenzhou Jixing Coiltubes serve a broad spectrum of industrial and commercial applications, leveraging the inherent advantages of stainless steel's corrosion resistance, hygienic properties, and thermal performance.

5.1 HVAC and Fan Coil Units (FCUs)

Coiltubes are the core heat exchange elements in fan coil units, air handlers, and chillers. Research into variable operating conditions has confirmed that the geometric precision and thermal conductivity of stainless steel coil tubes directly impact the heat transfer efficiency, pressure drop characteristics, and long-term reliability of FCU systems. Coiltubes enable the manufacture of compact, high-surface-area heat exchangers with optimized airflow and fluid distribution.

5.2 Additional Applications

6. Quality Certifications and Compliance

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

6.1 Management System Certifications

6.2 Product Standards Compliance

6.3 Testing and Inspection