Stainless Steel Coil Tube — Product Technical Specification

1. Product Overview

The Stainless Steel Coil Tube (hereinafter referred to as "Coil Tube") is a precision-engineered, continuous-length tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Unlike conventional straight-length seamless or welded pipes, Coil Tubes are produced in continuous helical coils, offering significant advantages in downstream processing efficiency, material utilization, and logistical flexibility. These products are designed for demanding applications in the chemical, petrochemical, pharmaceutical, food processing, and energy sectors where corrosion resistance, structural integrity, and dimensional accuracy are paramount.

Coil Tubes are fabricated through a combination of hot rolling, cold drawing, and cold rolling processes, resulting in products that exhibit superior mechanical properties, smooth surface finishes, and precise dimensional tolerances. The continuous coil configuration eliminates the need for butt welding during installation in many applications, thereby reducing potential failure points and improving system reliability.

2. Material & Properties

2.1 Base Alloy Grades

Coil Tubes are manufactured from a range of austenitic, ferritic, and duplex stainless steel grades in accordance with international standards including ASTM, AISI, EN, and GB specifications. Commonly available grades include:

2.2 Mechanical Properties

Property ASTM A213 TP304 ASTM A213 TP316L ASTM A213 TP321 Duplex 2205
Tensile Strength (MPa) ≥ 515 ≥ 485 ≥ 515 ≥ 550
Yield Strength (MPa, 0.2% Offset) ≥ 205 ≥ 170 ≥ 205 ≥ 450
Elongation (% in 50 mm) ≥ 40 ≥ 40 ≥ 40 ≥ 25
Density (g/cm³) 8.00 8.00 8.00 8.00
Thermal Conductivity (W/m·K, 100°C) 16.3 16.3 14.6 18.0
Maximum Service Temperature (°C) 870 870 925 350

2.3 Corrosion Resistance

Coil Tubes exhibit exceptional resistance to atmospheric, aqueous, and chemical corrosion environments. The passive chromium oxide (Cr₂O₃) film formed on the surface provides a self-healing protective barrier. In chloride-containing environments, grades such as 316L and Duplex 2205 demonstrate superior resistance to pitting corrosion (measured by Critical Pitting Temperature, CPT) and chloride stress corrosion cracking (SCC), making them suitable for marine, coastal, and aggressive chemical processing applications.

3. Specifications

Parameter Specification
Product Name Stainless Steel Coil Tube (Coil Tube)
Outer Diameter (OD) 6.00 mm – 108.00 mm
Wall Thickness (WT) 0.50 mm – 8.00 mm
Coil Length Customizable; typically 500 m – 3000 m per coil
Coil Weight Up to 10,000 kg per coil (standard); custom configurations available
Manufacturing Method Seamless (cold drawing / cold rolling) or Welded (TIG/ERW)
Surface Finish Pickled & Passivated, 2B, No. 4 Brushed, 6K, 8K Mirror, BA (Bright Annealed)
End Condition Plain, Beveled (GB/T 12574), Threaded, or Custom
Tolerance — OD ± 0.10 mm (cold drawn); ± 0.25 mm (hot rolled)
Tolerance — Wall Thickness ± 10% of nominal WT
Applicable Standards ASTM A213 / A269, EN 10216-5, GB/T 12771, JIS G3459
Available Grades 304, 304L, 316, 316L, 321, 310S, 347, 2205, 2507, 309S, 310
Heat Treatment Solution Annealing (1050°C – 1150°C), Stress Relief, Pickling & Passivation
Packaging Seaworthy export packaging; coil wrapped in kraft paper, PE film, and VCI (Volatile Corrosion Inhibitor) sheets; secured on wooden pallets or steel skids

4. Manufacturing Process

The production of high-quality Stainless Steel Coil Tubes involves a multi-stage manufacturing process designed to ensure dimensional accuracy, metallurgical homogeneity, and surface integrity:

  1. Slab Preparation and Hot Rolling — Stainless steel slabs are heated to temperatures between 1150°C and 1250°C and hot-rolled into hollow tubes (HAT — Hot Rolled and Cold Finished, or hot-rolled coils). This initial forming establishes the approximate dimensions of the final product.
  2. Piercing and Elongation — For seamless products, the hot-rolled slabs are pierced using a Mannesmann or plug piercing mill to create a hollow billet, which is then elongated to the desired dimensions.
  3. Cold Drawing / Cold Rolling (Cold Working) — The hot-rolled tubes are cold-drawn through a series of reducing dies or cold-rolled in a cold rolling mill to achieve precise final dimensions, improved surface finish, and enhanced mechanical properties. Cold working increases yield strength by 20%–40% through strain hardening.
  4. Intermediate Annealing — At critical deformation stages, the coil is annealed at 1050°C – 1150°C in a protective atmosphere (nitrogen or hydrogen) to relieve cold-work stresses, restore ductility, and prevent cracking during further processing.
  5. Pickling and Passivation — The coil is immersed in a mixed acid bath (typically HNO₃/HF or H₂SO₄/HNO₃) to remove mill scale and oxide layers, followed by passivation to regenerate the protective chromium oxide film.
  6. Surface Finishing — Depending on the application, the coil may undergo additional finishing such as mechanical polishing, electrolytic polishing, or brushing to achieve the required surface roughness (Ra values from 0.1 μm to 1.6 μm).
  7. Quality Inspection — Every coil undergoes comprehensive inspection including visual examination, dimensional measurement, hydrostatic testing, ultrasonic testing (UT), radiographic testing (RT), and chemical composition analysis (spectrometry).
  8. Coiling and Packaging — The finished tube is coiled on a dedicated coiling stand, ensuring uniform winding tension to prevent coil set and kinking. The coil is then packaged according to export or domestic delivery requirements.

5. Applications

Stainless Steel Coil Tubes find extensive use across a broad spectrum of industrial and commercial applications:

6. Quality Certifications

Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and holds the following certifications and compliance credentials:

7. Unique Selling Points

8. Technical Note: Coil Tube Performance in Thermal Cycling Applications

Research and field experience indicate that Stainless Steel Coil Tubes maintain excellent structural and workability performance under repeated thermal cycling conditions. The austenitic microstructure of grades such as 304 and 316L provides inherent thermal expansion compatibility, while the continuous coil geometry accommodates differential thermal expansion without inducing stress concentrations at weld joints. In applications involving concrete encasement or composite structural systems, the thermal expansion coefficient of stainless steel (approximately 17.3 × 10⁻⁶ /°C) is compatible with concrete (approximately 10–14 × 10⁻⁶ /°C), minimizing interfacial stress during temperature fluctuations. This thermal compatibility ensures long-term durability and prevents degradation of surrounding composite materials during thermal cycling events.

9. Ordering Information

For detailed quotations, technical consultations, and sample requests, customers are advised to specify the following parameters:

Wenzhou Jixing Metal Materials Co., Ltd. is committed to delivering high-quality, reliable, and cost-effective Stainless Steel Coil Tube solutions