Extrusion & Cold-Drawn Seamless Stainless Steel Coil Tube (Coiltube) for Small-to-Medium Bore Precision Applications
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. offers premium-grade seamless stainless steel coil tubes manufactured through a combined extrusion and cold-drawing process. This advanced manufacturing approach delivers superior surface finish quality and dimensional accuracy that significantly outperforms conventional hot-rolled piercing methods. Designed specifically for small-to-medium bore applications, these seamless coil tubes serve as parent stock for downstream coiling operations and are ideal where tight tolerances, smooth internal and external surfaces, and high mechanical integrity are critical.
Key Advantage: The extrusion-plus-cold-drawing process eliminates the surface defects, scale, and roughness commonly associated with hot-rolled piercing, resulting in a tube product that requires minimal or no secondary finishing before use.
Material & Properties
These seamless coil tubes are available in a comprehensive range of austenitic, ferritic, and duplex stainless steel grades, each offering distinct combinations of corrosion resistance, mechanical strength, and formability.
- Austenitic Grades: 304 (1.4301), 304L (1.4307), 316 (1.4401), 316L (1.4404), 321 (1.4541), 310S (1.4845) — excellent corrosion resistance, good weldability, and high ductility.
- Ferritic Grades: 430 (1.4006), 444 (1.4521) — improved resistance to chloride stress corrosion cracking and intergranular corrosion.
- Duplex Grades: 2205 (1.4462), 2507 (1.4410) — high yield strength (≥450 MPa) combined with outstanding pitting and crevice corrosion resistance.
- Surface Finishes: 2B, BA (Bright Annealed), No.4 Brushed, No.8 Mirror Polish — available to specification.
- Typical Tensile Strength: 520–800 MPa depending on grade and condition.
- Yield Strength (0.2% offset): 205–550 MPa depending on grade and condition.
- Elongation at Break: ≥30% (annealed condition), ensuring excellent cold-forming capability for coiling operations.
Specifications
| Parameter | Specification / Range |
|---|---|
| Outer Diameter (OD) | 6.00 – 108.00 mm (0.24 – 4.25 in) |
| Wall Thickness | 0.50 – 6.00 mm (0.020 – 0.236 in) |
| OD Tolerance | ±0.05 – ±0.20 mm (per ASTM A213 / EN 10216-5) |
| Wall Thickness Tolerance | ±10% of nominal (or ±0.05 mm minimum, whichever is greater) |
| Coil Length | 6,000 – 20,000 mm (20 – 66 ft) per coil |
| Coil Inner Diameter | 200 – 500 mm (7.9 – 19.7 in) |
| Coil Outer Diameter | ≤ 1,000 mm (≤ 39.4 in) |
| Material Grades | 304, 304L, 316, 316L, 321, 310S, 430, 444, 2205, 2507 |
| Surface Condition | 2B, BA, No.4, No.8 (custom finishes available) |
| Manufacturing Process | Extrusion + Cold Drawing |
| Standards | ASTM A213 / A269, EN 10216-5, ISO 13905, GB/T 12771 |
| Heat Treatment | Solution Annealed (1050–1150°C water quench) |
| Packaging | Wooden crate or steel banding with moisture-proof wrapping |
Manufacturing Process
The extrusion-plus-cold-drawing manufacturing methodology employed by Wenzhou Jixing Metal Materials Co., Ltd. is a multi-stage precision process that ensures exceptional quality at every step:
- Raw Material Selection: High-purity stainless steel billets or slabs are sourced from certified suppliers with full chemical composition traceability (mill certificates available).
- Hot Extrusion: The billets are heated to 1100–1200°C (2012–2192°F) and extruded through a calibrated die set to produce seamless hollow tubes. This step establishes the initial geometry while maintaining metallurgical integrity.
- Pickle & Descale: Extruded tubes undergo acid pickling (typically HNO₃/HF blend) and mechanical descaling to remove all oxide scale, ensuring a clean substrate for subsequent cold working.
- Cold Drawing: The pickled tubes are drawn through precision-drawn tungsten carbide or hardened steel dies, progressively reducing wall thickness and OD to final dimensions. This cold working step:
- Refines grain structure for superior mechanical properties
- Achieves tight dimensional tolerances (±0.05 mm achievable)
- Produces a smooth, defect-free surface finish
- Enhances straightness and roundness of the tube profile
- Intermediate Annealing: Where multiple drawing passes are required, intermediate solution annealing (1050–1150°C, water quench) relieves work hardening and restores ductility for continued deformation.
- Final Annealing & Pickling: A final solution anneal followed by acid pickling and passivation ensures optimal corrosion resistance and a uniform, clean surface.
- Non-Destructive Testing: 100% eddy current testing (ECT) and hydrostatic pressure testing are performed to detect internal and external defects.
- Coiling: Qualified tubes are coiled to specified lengths and coil diameters using automated coiling equipment to prevent surface damage and maintain dimensional stability.
Unique Selling Points
- Superior Surface Quality: The extrusion + cold-drawing process eliminates the surface roughness, scale, and inclusions inherent to hot-rolled piercing, delivering a near-finish surface that reduces or eliminates downstream machining costs.
- High Dimensional Accuracy: Tight OD and wall thickness tolerances (as tight as ±0.05 mm) ensure consistent performance in precision applications and reduce material waste during fabrication.
- Optimized for Small-to-Medium Bore Coiling: Specifically engineered as parent stock for seamless coil tube production in the 6–108 mm OD range, offering unmatched flexibility for downstream coiling operations.
- Excellent Mechanical Properties: Cold-drawing work hardens the tube walls, providing enhanced tensile and yield strength without sacrificing corrosion resistance.
- Full Traceability: Every coil is accompanied by mill test certificates (MTC) conforming to EN 10204 Type 3.1, with full heat-number traceability.
- Customization Capability: Non-standard dimensions, special surface finishes, and tailored coil configurations are available upon request.
Applications
The combination of superior surface finish, precise dimensions, and reliable mechanical properties makes these extrusion-and-cold-drawn seamless stainless steel coil tubes suitable for a wide range of demanding industrial applications:
- Heat Exchangers & Condensers: Coil tubes used in shell-and-tube heat exchangers, air coolers, and refrigeration systems where smooth internal surfaces maximize heat transfer efficiency and minimize fouling.
- Automotive Industry: Exhaust system components, turbocharger tubes, fuel injection lines, and high-temperature exhaust manifolds requiring corrosion resistance and thermal stability.
- Food & Beverage Processing: Sanitary-grade piping, brewing equipment, dairy processing lines, and pharmaceutical manufacturing where hygienic surface finishes and compliance with FDA/3-A standards are essential.
- Chemical & Petrochemical Processing: Reactor internals, distillation columns, heat exchanger bundles, and process piping handling aggressive chemical media.
- Medical Devices: Endoscope tubing, implant-grade components, and surgical instrument shafts requiring biocompatibility and precision tolerances.
- Energy & Power Generation: Boiler tubes, superheater elements, and turbine components operating under high-temperature and high-pressure conditions.
- Oil & Gas: Subsea flow lines, wellhead components, and downhole tools in sour service environments.
- Architecture & Decoration: Precision-formed architectural railings, elevator components, and decorative elements where surface aesthetics are paramount.
Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains rigorous quality management systems and adheres to internationally recognized standards to ensure consistent product performance:
- ISO 9001:2015 — Quality Management System certification covering all manufacturing and quality assurance processes.
- ISO 14001:2015 — Environmental Management System ensuring sustainable and responsible manufacturing practices.
- ISO/IEC 17025 — Laboratory accreditation for in-house testing and measurement capabilities.
- EN 10204 Type 3.1 — Inspection certificates issued by a designated quality assurance representative for each heat/coil.
- Product Standards: ASTM A213 / A269, EN 10216-5, ISO 13905, GB/T 12771, JIS G3459.
- Testing Protocols: 100% eddy current inspection, hydrostatic pressure testing (per ASTM A213), chemical analysis (spectrometry), mechanical testing (tensile, hardness, impact), and dimensional verification.
- Third-Party Inspection: Available upon request — SGS, Bureau Veritas, or TÜV inspection services can be arranged at the mill.
Supplier Commitment: Every coil of seamless stainless steel tube produced by Wenzhou Jixing Metal Materials Co., Ltd. is backed by comprehensive traceability, rigorous in-process quality controls, and full compliance with applicable international standards — ensuring reliable performance in the most demanding industrial environments.