Stainless Steel Coil Tube (Coiltube) — Wenzhou Jixing Metal Materials Co., Ltd.
Product Overview
The Stainless Steel Coil Tube (also known as Coil Tube or Coil Pipe) is a continuous-length hollow section of stainless steel wound into a helical coil configuration, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product Catalog No. 1016). This product category represents a critical intermediate and finished form in the stainless steel tube industry, serving as the foundational feedstock for downstream forming, cutting, and fabrication operations across a wide array of industrial sectors.
Unlike straight-length (cut-length) tubes, coil tubes are produced in continuous coils, enabling significantly higher material utilization rates, reduced waste from cut-off ends, and improved logistics efficiency. The coil format is particularly advantageous for high-volume manufacturing environments where tubes are subsequently processed into shorter segments or formed into specific geometries.
Unique Selling Points
- Continuous Production Capability: Coil tubes are manufactured in uninterrupted lengths, eliminating interpass seams and reducing production cycle times compared to discrete bar-fed processes.
- Superior Material Utilization: The coil format minimizes end-loss waste, achieving material utilization rates exceeding 95%, compared to 85–90% for straight-length tubes.
- Wide Grade Flexibility: Available in austenitic, ferritic, duplex, and precipitation-hardening stainless steel grades to meet diverse corrosion, mechanical, and temperature requirements.
- Consistent Dimensional Accuracy: Continuous rolling and cold-drawing processes ensure uniform wall thickness and outer diameter tolerances throughout the coil length.
- Customizable Surface Finishes: Ranges from mill finish (No. 1) to polished (BA, Mirror) surfaces, accommodating both functional and aesthetic requirements.
Material & Properties
Stainless steel coil tubes are primarily manufactured from austenitic stainless steels conforming to ASTM, EN, JIS, and GB standards. The following grades are commonly offered:
| Grade (ASTM / EN / GB) | Chemical Composition (Typical, wt%) | Mechanical Properties (Annealed) | Key Characteristics |
|---|---|---|---|
| 304 / 1.4301 / 06Cr19Ni10 | C ≤ 0.08, Cr 18–20, Ni 8–10.5 | Yield Strength: ≥ 205 MPa; Tensile Strength: 515–730 MPa; Elongation: ≥ 40% | Excellent general corrosion resistance; non-magnetic; high formability |
| 304L / 1.4307 / 022Cr19Ni10 | C ≤ 0.03, Cr 18–20, Ni 8–10.5 | Yield Strength: ≥ 170 MPa; Tensile Strength: 485–720 MPa; Elongation: ≥ 40% | Low-carbon variant for enhanced weldability; resistance to intergranular corrosion |
| 316 / 1.4401 / 06Cr17Ni12Mo2 | C ≤ 0.08, Cr 16–18, Ni 10–14, Mo 2–3 | Yield Strength: ≥ 205 MPa; Tensile Strength: 515–730 MPa; Elongation: ≥ 40% | Superior pitting and crevice corrosion resistance; suitable for chloride environments |
| 316L / 1.4404 / 022Cr17Ni12Mo2 | C ≤ 0.03, Cr 16–18, Ni 10–14, Mo 2–3 | Yield Strength: ≥ 170 MPa; Tensile Strength: 485–720 MPa; Elongation: ≥ 40% | Low-carbon 316 for welded applications; pharmaceutical and food-grade compliance |
| 321 / 1.4541 / 06Cr18Ni11Ti | C ≤ 0.10, Cr 17–19, Ni 9–12, Ti 5×C–0.70 | Yield Strength: ≥ 205 MPa; Tensile Strength: 515–730 MPa; Elongation: ≥ 40% | Titanium-stabilized; excellent resistance to intergranular corrosion at elevated temperatures |
| 310S / 1.4845 / 06Cr25Ni20 | C ≤ 0.08, Cr 24–26, Ni 19–22 | Yield Strength: ≥ 205 MPa; Tensile Strength: 515–690 MPa; Elongation: ≥ 40% | High-temperature oxidation resistance; suitable for furnace applications up to 1150°C |
| 430 / 1.4006 / 10Cr17 | C ≤ 0.12, Cr 16–18, Ni ≤ 0.60 | Yield Strength: ≥ 205 MPa; Tensile Strength: 450–620 MPa; Elongation: ≥ 25% | Ferritic grade; magnetic; cost-effective for atmospheric and mild chemical environments |
Key Physical Properties (Austenitic Grades, Annealed Condition):
- Density: 7.90–8.00 g/cm³
- Thermal Conductivity: 14–16 W/(m·K) at 20°C
- Thermal Expansion Coefficient: 16–18 × 10⁻⁶ /°C (20–100°C)
- Electrical Resistivity: 0.40–0.45 Ω·mm²/m at 20°C
- Melting Range: 1400–1450°C
- Maximum Service Temperature: 870°C (austenitic grades)
Specifications
| Parameter | Specification / Range |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product Catalog No. | 1016 |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. |
| Outer Diameter (OD) | Φ3.0 mm – Φ219.0 mm (custom sizes available upon request) |
| Wall Thickness (WT) | 0.15 mm – 6.00 mm |
| Coil Length | Typically 500 m – 3000 m per coil (continuous production up to 5000 m) |
| Coil Inner Diameter (ID) | 500 mm – 1500 mm (standard); up to 2000 mm upon request |
| OD Tolerance | ±0.05 mm (precision cold-drawn); ±0.10 mm (standard cold-drawn); ±0.5% (hot-rolled) |
| WT Tolerance | ±0.02 mm (precision cold-drawn); ±0.05 mm (standard cold-drawn); ±10% (hot-rolled) |
| Surface Finish | No. 1 (Mill Finish), 2B (Bright Annealed), BA (Bright Annealed), No. 4 (Brushed), HL (Hairline), Mirror (8K) |
| End Condition | Plain end, chamfered end, or beveled end (per customer specification) |
| Heat Treatment | Solution Annealed (1050–1150°C, water or air quenched); Stress Relieved |
| Applicable Standards | ASTM A213, ASTM A269, ASTM A554, ASTM A270, EN 10216-5, EN 10217-7, GB/T 12771, GB/T 21832, JIS G3459 |
| Material Grades | 201, 304, 304L, 316, 316L, 310S, 321, 347, 430, 904L, 2205 (Duplex), Custom Alloys |
| Production Method | ERW (Electric Resistance Welded), Laser Welded, Precision Cold-Drawn, Hot-Forged & Cold-Drawn |
| Packaging | Coiled on wooden or steel cores; wrapped in PE film and moisture-proof paper; outer steel strapping; palletized for container loading |
| Minimum Order Quantity (MOQ) | 1 coil (subject to grade and size availability) |
Manufacturing Process
The production of stainless steel coil tubes involves a multi-stage process combining metallurgical engineering principles with precision mechanical manufacturing. The following outlines the principal stages:
1. Raw Material Preparation
High-purity stainless steel slabs or hot-rolled coils are sourced from certified mills. Incoming materials undergo strict inspection for chemical composition (via Optical Emission Spectroscopy, OES), mechanical properties, and surface quality. Any material failing to meet the specified grade composition is rejected.
2. Hot Rolling / Hot Forging
For larger OD specifications, hot-rolled seamless tubes or hot-forged billets are produced at temperatures exceeding the austenitization range (1100–1250°C). The material is heated in induction or gas-fired furnaces and passed through rolling mills or upset-forging equipment to achieve approximate dimensions.
3. Pickling and Descaling
Hot-rolled tubes are subjected to acid pickling (hydrochloric acid / nitric acid mixture) or electrolytic pickling to remove the oxide scale formed during hot working. This step is critical for restoring corrosion resistance and enabling subsequent cold working.
4. Cold Drawing / Cold Rolling
The pickled tubes are cold-drawn through precision tungsten carbide (WC) dies or cold-rolled between grooved rolls. This process achieves:
- Dimensional accuracy within ±0.05 mm tolerance
- Improved surface finish (Ra ≤ 0.8 μm for precision grades)
- Work-hardening for enhanced mechanical properties (cold-worked condition)
- Continuous coil production via multi-pass drawing machines
5. Welding (for ERW / Laser Welded Tubes)
For welded coil tube production, cold-rolled stainless steel strip is fed through a roll-forming machine, shaped into a tube geometry, and joined along the longitudinal seam using either:
- ERW (Electric Resistance Welding): Induction heating with external electrode pressure welding; suitable for general-purpose applications.
- Laser Welding: High-power fiber laser beam welding with inert gas shielding; produces narrow, deep-penetration welds with minimal heat-affected zone (HAZ), ideal for high-purity and thin-wall applications.
6. Solution Annealing
Cold-worked or welded tubes undergo solution annealing in a protective atmosphere furnace (hydrogen-deoxidized nitrogen or vacuum) at temperatures of 1050–1150°C, followed by rapid quenching. This process:
- Recrystallizes the deformed microstructure
- Dissolves carbide precipitates (particularly in stabilized grades)
- Restores full ductility and corrosion resistance
- Eliminates residual stresses introduced during forming and welding
7. Surface Finishing
Post-annealing, tubes receive final surface treatment according to customer specification:
- 2B Finish: Cold-rolled and bright annealed; smooth, matte appearance
- BA (Bright Annealed): Annealed in a controlled atmosphere; highly reflective surface without pickling residue
- Mirror / 8K Finish: Multi-stage mechanical polishing and electrolytic polishing; Ra ≤ 0.1 μm
- Electrolytic Polishing: Removes surface micro-defects; enhances passive layer thickness for improved corrosion resistance
8. Quality Inspection & Testing
Each coil undergoes comprehensive inspection prior to dispatch:
- Chemical Analysis: OES spectroscopy for full compositional verification
- Mechanical Testing: Tensile testing (yield strength, tensile strength, elongation) per ASTM E8/E8M
- Hydrostatic / Pneumatic Testing: Internal pressure testing to verify weld integrity and wall soundness
- Dimensional Inspection: OD and WT measurement at regular intervals along the coil length
- Corrosion Testing: Salt spray testing (ASTM B117) and intergranular corrosion testing (ASTM A262 Practice E) for applicable grades
- Surface Inspection: Visual and eddy current (ET) testing for surface and near-surface defect detection
- Hardness Testing: Vickers or Rockwell hardness verification
9. Coiling and Packaging
Finished tubes are wound onto precision steel or wooden cores using hydraulic coiling equipment. The coils are wrapped in protective PE film, moisture-proof kraft paper, and secured with steel strapping bands. For export shipments, coils are palletized and containerized with desiccant packs to prevent moisture ingress during transit.
Applications
Stainless steel coil tubes find extensive application across multiple industrial sectors due to their combination of corrosion resistance, mechanical strength, hygienic properties, and aesthetic appeal:
1. Food and Beverage Industry
- Sanitary process piping for dairy, beer, and beverage production lines
- Heat exchanger tubes for pasteurization and sterilization systems
- CIP (Clean-in-Place) system tubing and fittings
- Milk processing equipment and food-grade conveyor components
2. Pharmaceutical Industry
- Bioreactor and fermentation vessel internal tubing
- WFI (Water for Injection) and PW (Purified Water) distribution piping