Stainless Steel Coil Tube (盘管 / Coiltube)
Product Overview
The Stainless Steel Coil Tube is a continuous-length tubular product supplied in coiled form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. Unlike traditional straight-length (定尺) pipe segments, coil tubes are wound into large-diameter coils during the final stage of production, enabling seamless downstream processing without the need for butt-welding multiple short segments. This format is particularly advantageous for automated forming, bending, and fabrication lines where material continuity is critical.
The coil tube product line encompasses a wide range of nominal diameters, wall thicknesses, and material grades, serving diverse industrial applications from automotive exhaust systems and heat exchangers to architectural ornamentation and chemical processing equipment. The coiled configuration minimizes material waste, reduces welding joints, and significantly improves production efficiency in high-volume manufacturing environments.
Key Advantage: The coil supply format eliminates the need for longitudinal butt welds between pipe segments, resulting in superior structural integrity, enhanced fluid-tight performance, and reduced labor costs during downstream fabrication.
Material & Properties
Common Material Grades
- 304 / 1.4301 (AISI 304): The most widely specified austenitic stainless steel, offering excellent corrosion resistance, formability, and weldability. Suitable for general-purpose applications in food processing, chemical, and architectural sectors.
- 304L / 1.4307 (AISI 304L): Low-carbon variant of 304 with carbon content ≤ 0.03%, designed to resist intergranular corrosion (IGC) during welding. Preferred for welded assemblies and heat-exposed components.
- 316 / 1.4401 (AISI 316): Molybdenum-enhanced austenitic grade with superior resistance to pitting and crevice corrosion, particularly in chloride-rich environments. Ideal for marine, pharmaceutical, and chemical processing applications.
- 316L / 1.4404 (AISI 316L): Low-carbon counterpart to 316, combining molybdenum-enhanced corrosion resistance with excellent post-weld performance.
- 321 / 1.4541 (AISI 321): Titanium-stabilized austenitic grade offering enhanced resistance to intergranular corrosion at elevated temperatures (450°C–850°C). Suitable for heat exchanger tubes and furnace components.
- 310S / 1.4845 (AISI 310S): High-nickel, high-chromium grade providing outstanding oxidation resistance and thermal stability up to 1100°C. Used in high-temperature industrial furnaces and heat treatment equipment.
- 2205 / 1.4462 (Duplex 2205): Duplex austenitic-ferritic stainless steel with approximately 22% Cr, 5% Ni, and 3% Mo. Offers yield strength roughly twice that of 304/316 with excellent chloride stress corrosion cracking (SCC) resistance.
Mechanical Properties (Typical Values for Annealed Condition)
| Property |
304 / 304L |
316 / 316L |
321 |
2205 Duplex |
| Tensile Strength (Rm, MPa) |
≥ 520 |
≥ 520 |
≥ 520 |
≥ 450 |
| Yield Strength (Rp0.2, MPa) |
≥ 205 |
≥ 205 |
≥ 205 |
≥ 450 |
| Elongation (A, %) |
≥ 40 |
≥ 40 |
≥ 40 |
≥ 15 |
| Hardness (HV) |
≤ 210 |
≤ 210 |
≤ 210 |
≤ 300 |
| Density (kg/m³) |
7930 |
8000 |
7900 |
7810 |
| Thermal Conductivity at 100°C (W/m·K) |
16.3 |
16.3 |
16.3 |
17.5 |
| Max. Service Temperature (°C) |
870 |
870 |
900 |
300 |
Chemical Composition (wt%, Maximum unless noted)
| Grade |
C |
Mn |
P |
S |
Si |
Cr |
Ni |
Mo |
Other |
| 304 |
≤ 0.08 |
≤ 2.0 |
≤ 0.045 |
≤ 0.03 |
≤ 1.0 |
18.0–20.0 |
8.0–10.5 |
— |
— |
| 304L |
≤ 0.03 |
≤ 2.0 |
≤ 0.045 |
≤ 0.03 |
≤ 1.0 |
18.0–20.0 |
8.0–12.0 |
— |
— |
| 316 |
≤ 0.08 |
≤ 2.0 |
≤ 0.045 |
≤ 0.03 |
≤ 1.0 |
16.0–18.0 |
10.0–14.0 |
2.0–3.0 |
— |
| 321 |
≤ 0.08 |
≤ 2.0 |
≤ 0.045 |
≤ 0.03 |
≤ 1.0 |
17.0–19.0 |
9.0–12.0 |
— |
Ti ≥ 5×C |
| 2205 |
≤ 0.03 |
≤ 2.0 |
≤ 0.030 |
≤ 0.02 |
≤ 1.0 |
22.0–23.0 |
4.5–6.5 |
2.5–3.5 |
N: 0.14–0.20 |
Specifications
| Parameter |
Specification |
| Product Name |
Stainless Steel Coil Tube (盘管) |
| Manufacturer |
Wenzhou Jixing Metal Materials Co., Ltd. |
| Supply Form |
Continuous coil (盘卷), wound on standard coil cores |
| Outer Diameter (OD) |
Φ3.0 mm – Φ60.0 mm (custom sizes available upon request) |
| Wall Thickness |
0.3 mm – 3.0 mm |
| Tolerance — OD |
±0.05 mm (precision grade); ±0.10 mm (commercial grade) |
| Tolerance — Wall Thickness |
±10% (commercial); ±5% (precision) |
| Coil Weight |
Typically 500 kg – 2,000 kg per coil (configurable) |
| Surface Finish |
No.1 (Industrial), 2B (Bright Annealed), BA (Bright Annealed), No.4 (Brushed), Mirror (8K) |
| Surface Roughness (Ra) |
2B: ≤ 0.4 µm; BA: ≤ 0.2 µm; Mirror: ≤ 0.05 µm |
| Heat Treatment Condition |
Full Annealed (Solution Annealed at 1050°C–1100°C followed by water quench) |
| Applicable Standards |
ASTM A554, ASTM A580, ASTM A778, EN 10217-7, GB/T 14976, JIS G3459 |
| Inspection |
100% Visual, Dimensional, Hydrostatic/Pneumatic Testing; Spectroscopic Composition Analysis; Ultrasonic Flaw Detection (UT) available |
| Packaging |
Wooden coil cradle with steel strapping, moisture-proof wrapping; seaworthy export packaging available |
Manufacturing Process
Process Flow Diagram (Summary)
- Raw Material Selection: High-purity stainless steel strip (cold-rolled coil) is sourced from certified mills, undergoing incoming inspection for chemical composition (via Optical Emission Spectrometry, OES) and mechanical properties.
- Strip Cutting & Slitting: The master coil is slit to the required width using precision slitting lines with razor-sharp blades, ensuring flat edges free of burrs and dimensional accuracy within ±0.05 mm.
- Pipe Forming (Seamless or Welded):
- Welded Route: The strip is formed into a tube shape via roll-forming or hydroforming dies, followed by longitudinal welding using Automatic Submerged Arc Welding (ASAW) or Tungsten Inert Gas (TIG/GTAW) welding under inert gas shielding (argon or argon-helium mixture) to prevent oxide formation.
- Seamless Route: Hot-rolled hollow bars undergo piercing and cold drawing/rolling to achieve the target OD and wall thickness, yielding a weld-free tube with superior pressure integrity.
- Weld Pass Finishing: For welded tubes, the longitudinal weld seam is ground and polished flush with the tube surface to eliminate stress concentrations and ensure uniform wall thickness across the seam.
- Solution Annealing: Tubes are heat-treated in a continuous annealing furnace at 1050°C–1100°C in a reducing atmosphere (endothermic gas or vacuum) to dissolve carbide precipitates, relieve residual stresses, and restore full austenitic microstructure. This is followed by rapid water quenching to lock in the solution-treated condition.
- Pickling & Passivation: Annealed tubes undergo acid pickling (HNO₃/HF mixed acid) to remove oxide scale, followed by passivation treatment to form a stable chromium oxide passive film (Cr₂O₃), enhancing long-term corrosion resistance.
- Precision Sizing & Calibration: The annealed tubes pass through sizing rolls or mandrel calibration stations to achieve final dimensional tolerances for OD and wall thickness.
- Quality Inspection:
- 100% visual inspection for surface defects (pinholes, scratches, oxide inclusions)
- Dimensional verification using laser diameter gauges and ultrasonic wall thickness gauges
- Hydrostatic or pneumatic pressure testing at 1.5×–2.0× the design pressure
- Non-Destructive Testing (NDT): Magnetic Particle Testing (MT) or Eddy Current Testing (ECT) for weld seam integrity
- Spectroscopic verification of chemical composition (OES)
- Coiling & Packaging: Tubes are wound onto coil cores of appropriate diameter using controlled tension winding systems to prevent deformation. Coils are protected with moisture-absorbent desiccant bags, wrapped in PE film or kraft paper, strapped with steel bands, and mounted on wooden or steel coil cradles for shipment.
Applications
Industrial & Process Engineering