Stainless Steel Coil Tube (Coil Pipe) — Product Technical Specification

1. Product Overview

The Stainless Steel Coil Tube (hereinafter referred to as "Coil Tube") is a continuous, helically wound tubular product manufactured from austenitic or duplex stainless steel strip. Unlike traditional straight seamless or welded pipes, coil tubes are produced in continuous coil form, enabling significant advantages in material utilization, downstream processing efficiency, and logistical flexibility. This product is engineered for demanding applications where corrosion resistance, mechanical integrity, and dimensional precision are critical.

Coil tubes are predominantly fabricated using the Automatic Welded (AW) process, with optional seamless variants available for high-pressure applications. The continuous coil configuration eliminates the need for cutting and straightening in many end-use scenarios, reducing material waste by up to 25% compared to straight-length pipe delivery.

2. Material & Properties

2.1 Material Grades

2.2 Key Material Properties

3. Specifications

Parameter Specification
Outer Diameter (OD) 6.0 mm – 159.0 mm (1/4" – 6")
Wall Thickness (WT) 0.3 mm – 6.0 mm (0.012" – 0.236")
Coil Width 150 mm – 600 mm (6" – 24")
Coil Length Up to 2000 m (6562 ft) per coil
Weld Type Single-pass AW / Multi-pass AW / Seamless
Surface Finish 2B, No. 1, BA (Bright Annealed), Pickled & Passivated, Mirror (Ra ≤ 0.2 μm)
Tolerance — OD ±0.1 mm (±0.004")
Tolerance — WT ±10% (standard); ±5% (tight tolerance available)
Applicable Standards ASTM A554, ASTM A213, ASTM A778, EN 10216-5, EN 10217-7, GB/T 12771, JIS G3459
End Condition Plain end, Beveled, Threaded, Flanged (custom)
Heat Treatment Annealed, Solution Treated, Stabilized, Stress Relieved
Coil Packaging Wooden reel / Steel reel with VCI (Vapor Corrosion Inhibitor) wrap

4. Manufacturing Process

4.1 Process Flow

  1. Strip Preparation: Cold-rolled stainless steel strip is inspected for surface quality, dimensional accuracy, and metallurgical homogeneity. Incoming material undergoes spectroscopic verification (PMI — Positive Material Identification) to confirm grade compliance.
  2. Edge Beveling: Strip edges are beveled to a precise angle (typically 45°) to facilitate uniform weld penetration and minimize weld defects.
  3. Coiling / Forming: The strip is fed through a series of forming rolls that progressively shape the flat strip into a tubular profile. Roller forming stations are precision-aligned to maintain dimensional consistency throughout the coil length.
  4. Welding: The formed tube is welded using a high-frequency induction (HFI) or gas metal arc welding (GMAW) process. Single-pass welding is standard for wall thicknesses below 3 mm; multi-pass welding is employed for thicker walls to achieve full penetration and optimal metallurgical properties.
  5. Post-Weld Heat Treatment: Welded tubes are solution-annealed at 1010–1150 °C followed by rapid quenching to restore full austenitic microstructure and maximize corrosion resistance. Stabilization annealing (850–880 °C) is applied for Ti-stabilized grades (321, 347).
  6. Pickling & Passivation: Tubes are acid-pickled (HNO₃/HF mixture) to remove oxide scale, followed by passivation treatment to establish a protective chromium oxide film on the surface.
  7. Dimensional Inspection: Automated optical measurement systems verify OD, wall thickness, and roundness at intervals of ≤ 10 m along the coil length.
  8. Coiling & Packaging: Finished tube is wound onto precision-machined reels and packaged with protective wrapping to prevent mechanical damage and corrosion during transit.

4.2 Advanced Manufacturing Capabilities

5. Applications

5.1 Primary Application Sectors

5.2 Coil-Specific Advantages in End-Use

6. Quality Certifications & Compliance

6.1 System Certifications

6.2 Product Compliance & Testing

6.3 Documentation Package

Each coil shipment is accompanied by a comprehensive quality documentation package including:

7. Unique Selling Points

Continuous Coil Advantage: The coil tube format delivers unmatched material efficiency and processing flexibility, making it the preferred choice for high-volume fabrication operations where straight-length pipe would result in excessive cutting waste and increased assembly labor.