Stainless Steel Coil Tube (Coiltube) — Product Technical Specification

1. Product Overview

The Stainless Steel Coil Tube (Coiltube) is a continuous, spirally wound tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is supplied in coil form, offering superior flexibility, ease of handling, and efficient downstream processing compared to straight-length pipe. The coil tube is designed for a wide range of industrial, commercial, and consumer applications where corrosion resistance, mechanical strength, and hygienic properties are critical.

Informed by the production benchmarks established by leading manufacturers such as Hailiang Group, which achieved a monthly copper coil tube output exceeding 1,100 metric tons, Wenzhou Jixing Metal Materials Co., Ltd. has adopted best-in-class manufacturing practices to ensure high-volume production capability, consistent quality, and competitive cost structures across the stainless steel coil tube product line.

2. Material & Properties

The stainless steel coil tube is fabricated from high-grade austenitic and duplex stainless steel grades, selected to meet or exceed international material specifications. Key material grades include:

2.1 Common Grades Available

Grade Designation UNS Number EN Equivalent Primary Alloying Elements Key Properties
304 / 304L S30400 / S30403 1.4301 / 1.4307 Cr 18–20%, Ni 8–10.5% Excellent general corrosion resistance, formability, weldability
316 / 316L S31600 / S31603 1.4401 / 1.4404 Cr 16–18%, Ni 10–14%, Mo 2–3% Superior chloride pitting and crevice corrosion resistance
321 S32100 1.4541 Cr 17–19%, Ni 9–12%, Ti High-temperature strength, resistance to intergranular corrosion
310S S31008 1.4845 Cr 24–26%, Ni 19–22% Outstanding oxidation resistance up to 1150°C
2205 (Duplex) S32205 1.4462 Cr 22–23%, Ni 4.5–6.5%, Mo 3–3.5%, N ~0.15% High yield strength (~450 MPa), excellent chloride SCC resistance
904L S39035 1.4539 Cr 19–21%, Ni 23–26%, Mo 4–5% Exceptional resistance to reducing and oxidizing acids

2.2 Mechanical Properties (Annealed Condition)

Property Grade 304/304L Grade 316/316L Grade 2205
Tensile Strength (MPa) ≥ 515 ≥ 515 ≥ 550
Yield Strength (MPa, 0.2% offset) ≥ 205 ≥ 205 ≥ 450
Elongation (% at break) ≥ 40 ≥ 40 ≥ 25
Hardness (HB max) 217 217 250
Density (g/cm³) 7.93 8.00 7.85

3. Specifications

3.1 Dimensional Parameters

Parameter Specification Range Tolerance Standard Reference
Outer Diameter (OD) 6.00 mm – 108.0 mm ±0.05 mm – ±0.15 mm (per OD range) ASTM A269 / A312
Wall Thickness (WT) 0.50 mm – 6.00 mm ±10% of nominal ASTM A269 / A312
Coil Length Up to 2,000 m per coil (typical) — Manufacturer specification
Coil ID (Inner Diameter of Coil) 152 mm / 203 mm / 305 mm ±3 mm Standard packaging specification
Coil Weight Up to 2,500 kg per coil — Manufacturer specification
End Condition Plain cut / Beveled / Threaded Per customer drawing Custom specification

3.2 Surface Finish Options

Finish Type Ra Value (μm) Application
Mill Finish (No. 1) — Industrial structural, mechanical components
Pickled & Passivated 0.5 – 1.0 General corrosion-resistant applications
Bright Annealed (BA) 0.2 – 0.4 Food processing, pharmaceutical, optical
Electropolished 0.05 – 0.2 Semiconductor, biotechnology, high-purity
Satinated / Brushed 0.4 – 1.6 Architectural, decorative, consumer products

4. Manufacturing Process

The stainless steel coil tube is produced through a meticulously controlled multi-stage manufacturing process, ensuring dimensional accuracy, metallurgical integrity, and surface quality throughout the product lifecycle.

  1. Raw Material Preparation:

    High-purity stainless steel strip (cold-rolled coil) is procured from certified mills and inspected for chemical composition, mechanical properties, and surface quality. Incoming material undergoes spectrometric verification (OES analysis) and dimensional gauging.

  2. Coiling & Slitting:

    The stainless steel coil is slit to precise strip widths corresponding to the target tube outer diameter. Precision slitting ensures uniform edge quality, eliminating burrs and defects that could propagate into the final tube.

  3. Tubular Forming (Cold Rolling):

    The slit strip is fed through a series of progressive forming rolls (roll-forming mill) that progressively bend the flat strip into a circular tube profile. The roll-forming process maintains continuous production without interruption, enabling high throughput rates.

  4. Welding (TIG / MIG):

    The formed tube is welded along the longitudinal seam using either Tungsten Inert Gas (TIG) welding or Metal Inert Gas (MIG) welding under a protective atmosphere of argon or helium. Back-purging is employed to prevent internal oxidation of the weld zone. Weld parameters are continuously monitored and recorded for traceability.

  5. Heat Treatment (Solution Annealing):

    The welded tube undergoes solution annealing at temperatures between 1010°C and 1150°C, followed by rapid quenching. This process dissolves carbide precipitates, restores full austenitic microstructure, and eliminates residual stresses introduced during forming and welding.

  6. Pickling & Passivation:

    Post-annealing, the tube is subjected to acid pickling (typically using a mixture of nitric and hydrofluoric acid) to remove the oxide scale formed during annealing. Passivation treatment with nitric acid solution establishes a stable chromium oxide passive film, enhancing corrosion resistance.

  7. Dimensional Calibration & Coiling:

    The finished tube passes through a calibrating mill to achieve precise final dimensions. The tube is then wound onto a coil former with controlled tension to produce a uniform, stable coil suitable for transport and downstream processing.

  8. Quality Inspection & Testing:

    Every coil undergoes comprehensive inspection including hydrostatic testing, dimensional gauging (OD, wall thickness, straightness), surface inspection (visual and automated), and chemical/spectrographic verification. Non-destructive testing (NDT) methods such as ultrasonic testing (UT) and eddy current testing (ECT) are applied as required.

  9. Packaging & Dispatch:

    Coils are wrapped with protective film or paper, secured with steel straps, and labeled with full traceability documentation including mill test certificates (MTC), heat numbers, and dimensional data.

5. Applications

The stainless steel coil tube is employed across a broad spectrum of industries due to its combination of corrosion resistance, mechanical performance, and processability:

6. Quality Certifications & Compliance

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