Stainless Steel Coil Tube (Coiltube)
Product Overview
Stainless steel coil tube (Coiltube) is a continuous, uncut length of precision-formed tubing wound into a compact helical coil configuration. Unlike discrete pipe segments, coil tubes are produced through continuous forming and drawing processes, resulting in seamless, joint-free products with uniform wall thickness and consistent mechanical properties along the entire length. This format offers significant advantages in terms of material utilization, reduced waste, and enhanced dimensional accuracy, making it an ideal choice for applications requiring long, uninterrupted tube runs.
Wenzhou Jixing Metal Materials Co., Ltd. specializes in the manufacture and supply of high-quality stainless steel coil tubes, leveraging advanced production technology and rigorous quality control systems to deliver products that meet international standards. The coil tube product line encompasses a wide range of diameters, wall thicknesses, and grades, catering to diverse industrial and commercial requirements.
Material & Properties
Stainless steel coil tubes are primarily fabricated from austenitic, ferritic, and duplex stainless steel grades, each offering distinct combinations of corrosion resistance, mechanical strength, and formability.
- Austenitic Grades: Including 304 (UNS S30408), 304L (UNS S30403), 316 (UNS S31608), and 316L (UNS S31603). These grades provide excellent corrosion resistance, high ductility, and superior weldability. The addition of molybdenum (Mo) in 316/316L enhances resistance to pitting and crevice corrosion in chloride-containing environments.
- Ferritic Grades: Including 430 (UNS S43000) and 409 (UNS S40900). These grades offer good resistance to stress corrosion cracking and oxidation at elevated temperatures, with lower alloy content reducing material costs.
- Duplex Grades: Including 2205 (UNS S32205) and 2507 (UNS S32750). These grades combine austenitic and ferritic microstructures, delivering roughly twice the yield strength of conventional austenitic grades while maintaining excellent corrosion resistance.
Key mechanical properties for standard austenitic coil tubes (e.g., Grade 304) include a minimum tensile strength of 515 MPa, a yield strength of 205 MPa, and elongation of at least 40%. Chemical composition adheres to ASTM, EN, and JIS standards, ensuring reliable performance in aggressive chemical, food, pharmaceutical, and marine environments.
Specifications
| Parameter | Specification Range |
|---|---|
| Outer Diameter (OD) | 3 mm – 102 mm (1/8" – 4") |
| Wall Thickness | 0.15 mm – 3.0 mm |
| Coil Length | Up to 200 m (custom lengths available) |
| Coil Inner Diameter | 300 mm – 1,500 mm |
| Applicable Grades | 304, 304L, 316, 316L, 310S, 321, 430, 409, 2205, 2507 |
| Surface Finish | No. 1 (Industrial), 2B (Bright Annealed), BA (Bright Annealed), Pickled & Passivated, Hairline, Mirror (8K) |
| Manufacturing Standard | ASTM A269, ASTM A213, EN 10217-7, ISO 13978, JIS G3447 |
| Temperature Range | −196°C to +870°C (grade-dependent) |
| Pressure Rating | Up to 32 MPa (PN32), grade- and dimension-dependent |
Manufacturing Process
The production of stainless steel coil tubes involves a sophisticated sequence of metallurgical and forming operations designed to ensure dimensional precision, surface integrity, and mechanical consistency.
- Slit and Form: Cold-rolled stainless steel strip is slit to the required width and then fed through precision roll-forming stations. The strip is gradually bent into a circular cross-section with controlled reduction ratios to minimize surface defects and maintain dimensional accuracy.
- Welding (for welded coil tube): The formed tube blank is passed through a high-frequency induction welding (HFW) system. Precise control of welding parameters—voltage, current, frequency, and roll pressure—ensures a homogeneous weld seam with minimal heat-affected zone (HAZ) distortion. Alternative welding methods include gas tungsten arc welding (GTAW) for higher-purity applications.
- Heat Treatment / Solution Annealing: Welded coil tubes undergo solution annealing at temperatures between 1,050°C and 1,150°C, followed by rapid cooling (water quench or air cool). This process dissolves carbides, restores full austenitic structure, and imparts maximum corrosion resistance and ductility.
- Pickling and Passivation: The annealed tube is pickled using a mixed acid solution (nitric acid and hydrofluoric acid) to remove oxide scale. Subsequent passivation with dilute nitric acid forms a protective chromium oxide layer (Cr₂O₃), enhancing long-term corrosion protection.
- Precision Drawing: For seamless coil tubes, the formed tube is drawn through tungsten carbide (WC) or polymer-lined dies to achieve tight dimensional tolerances, reduced wall thickness, and improved surface finish. Multi-draw processes may be employed for thin-wall, high-precision products.
- Coiling and Inspection: The finished tube is wound onto precision-wound coils with controlled tension to prevent ovality and deformation. Each coil undergoes comprehensive inspection including hydrostatic pressure testing, eddy current testing, visual examination, and dimensional verification.
Applications
Stainless steel coil tubes find extensive application across a broad spectrum of industries, owing to their combination of corrosion resistance, formability, and mechanical reliability:
- Food and Beverage Industry: Sanitary processing lines, pasteurization systems, brewing equipment, and dairy processing equipment where hygienic surface finishes (BA or mirror) and resistance to cleaning chemicals are critical.
- Pharmaceutical and Medical: Bioreactors, cleanroom piping, medical gas delivery systems, and instrumentation tubing requiring high purity and traceability.
- Automotive and Aerospace: Exhaust systems, fuel lines, brake lines, turbocharger components, and structural tubing where lightweight, corrosion-resistant materials are essential.
- Chemical Processing: Reactor piping, heat exchanger tubes, distillation columns, and chemical transfer lines exposed to aggressive acids, alkalis, and solvents.
- Oil and Gas: Downhole tubing, wellhead equipment, and offshore platform piping where resistance to sour gas (H₂S) and chloride-induced stress corrosion cracking is paramount.
- Construction and Architecture: Structural supports, handrails, decorative facades, and building components requiring durability and aesthetic appeal.
- Heat Exchangers and HVAC: Condenser tubes, evaporator coils, and refrigeration piping where thermal conductivity and corrosion resistance are key performance factors.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework to ensure that all stainless steel coil tube products meet or exceed international standards and customer specifications.
- ISO 9001:2015 — Quality Management System certification confirming systematic quality control from raw material procurement through final dispatch.
- ISO 14001:2015 — Environmental Management System certification demonstrating commitment to sustainable manufacturing practices and environmental stewardship.
- ISO 45001:2018 — Occupational Health and Safety Management System certification ensuring a safe production environment.
- EN 10204 3.1 — Material Test Certificates issued for each production batch, providing verified chemical composition, mechanical properties, and dimensional compliance data.
- ASTM / ASME Compliance — Products manufactured in accordance with ASTM A269 (A270) and ASME B36.19M standards for wrought austenitic stainless steel tubing.
- Mill Test Reports (MTR) — Comprehensive traceability documentation for every coil, including heat number, mill analysis, mechanical test results, and non-destructive testing (NDT) reports.
- Third-Party Inspection — Available upon request: SGS, Bureau Veritas, or TÜV inspection and certification for export orders and critical applications.
Unique Selling Points
- Seamless Continuity: Coil tube format eliminates field-welding joints, reducing potential failure points and installation labor costs while maintaining uniform wall thickness throughout the entire length.
- Superior Surface Quality: Advanced cold-drawing and surface treatment processes deliver exceptionally smooth inner and outer surfaces, critical for sanitary and precision applications.
- Wide Grade Availability: Full range of austenitic, ferritic, and duplex grades available from stock, enabling rapid response to diverse project requirements.
- Custom Fabrication: Capability to produce coil tubes to custom dimensions, surface finishes, and cut lengths, tailored to specific customer specifications and project drawings.
- Cost Efficiency: Continuous coil production maximizes material utilization, minimizing trim waste and reducing overall project material costs compared to discrete pipe segments.
- Full Traceability: Every coil is traceable to its mill heat number, enabling complete supply chain transparency and regulatory compliance in regulated industries.