Stainless Steel Coil Tube — Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (product code: 1650) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a continuous-length tubular product formed through precision cold-drawing and coiling processes. Unlike discrete pipe sections, coil tubes are supplied in continuous helical form, enabling high-efficiency downstream processing including cutting, forming, and welding without the need for butt-joining. This product is engineered for applications demanding superior corrosion resistance, hygienic surface finish, and dimensional consistency across extended lengths.
Coil tubes represent a critical intermediate product in the stainless steel value chain, serving as feedstock for tube mills, food processing equipment fabricators, pharmaceutical engineering firms, and automotive exhaust system manufacturers. The continuous coil format eliminates longitudinal seams inherent in welded pipe, offering enhanced structural integrity and uniform wall thickness distribution.
2. Material Composition & Mechanical Properties
Wenzhou Jixing Metal Materials Co., Ltd. produces coil tubes in a range of austenitic, duplex, and ferritic stainless steel grades conforming to ASTM, EN, and GB standards. The primary grades include:
- ASTM A269 / A213 Type 304 (UNS S30400): General-purpose austenitic grade with excellent corrosion resistance and formability.
- ASTM A269 / A213 Type 316L (UNS S31603): Low-carbon variant with molybdenum addition for superior resistance to pitting and crevice corrosion.
- ASTM A790 Duplex 2205 (UNS S32205): High-strength duplex grade combining austenitic and ferritic microstructures for enhanced yield strength and resistance to chloride-induced stress corrosion cracking (SCC).
- ASTM A240 Type 430 (UNS S43000): Ferritic grade offering good atmospheric corrosion resistance at reduced cost.
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HBW) | Cr Equivalent (%) | Mo (%) |
|---|---|---|---|---|---|---|
| 304 / 304L | ≥515 | ≥205 | ≥40 | ≤180 | 18.0–20.0 | — |
| 316 / 316L | ≥515 | ≥205 | ≥40 | ≤180 | 16.0–18.0 | 2.0–3.0 |
| 2205 Duplex | ≥450–800 | ≥450 | ≥25 | ≤310 | 21.0–23.0 | 2.5–3.5 |
| 430 Ferritic | ≥450 | ≥205 | ≥25 | ≤200 | 16.0–18.0 | — |
3. Technical Specifications
| Parameter | Specification / Range | Standard Reference |
|---|---|---|
| Outside Diameter (OD) | Φ6.0 mm – Φ168.3 mm | ASTM A269 / A213; EN 10216-5 |
| Wall Thickness (WT) | 0.5 mm – 10.0 mm | ASTM A269; ISO 15492 |
| OD Tolerance | ±0.15 mm (OD ≤ 50 mm); ±0.20% (OD > 50 mm) | ASTM A269 |
| Wall Thickness Tolerance | ±10% of nominal | ASTM A269 |
| Coil Inner Diameter (ID) | Φ500 mm – Φ1200 mm | Manufacturer specification |
| Coil Length (Continuous) | 200 m – 2,000 m per coil | Manufacturer specification |
| Surface Finish | No. 1 Annealed; 2B; BA (Bright Annealed); 2D; Electropolished | ASTM A480; EN 10088 |
| End Condition | Plain cut; Beveled; Threaded; Flanged | Per customer requirement |
| Maximum Straight Length (Post-Uncoiling) | Up to 12,000 mm | ASTM A269 |
| Packaging | Wooden crate / Steel banding with moisture-proof wrapping | ISO 4126 |
4. Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorously controlled multi-stage process designed to ensure metallurgical homogeneity, dimensional accuracy, and surface integrity:
- Hot-Rolled Strip Production: Ingot casting (VIM/ESR for premium grades) → Hot rolling into flat strip → Pickling and annealing (continuous annealing line at 1,050–1,150°C) → Descaling.
- Cold Reduction: Multi-stand cold rolling to reduce strip thickness to target coil tube wall thickness with controlled reduction ratios (≤30% per pass) to prevent work hardening.
- Forming & Welding (ERW/ODW): Strip is fed into a forming die set, shaped into a tubular cross-section, and joined via Electromagnetic Resistance Welding (ERW) or Orbital Direct Welding (ODW) with in-line weld inspection.
- Weld Heat-Affected Zone (HAZ) Removal: Internal and external grinding to remove the weld HAZ, achieving seamless-equivalent metallurgical properties (for high-integrity applications).
- Intermediate Annealing: Solution annealing at 1,000–1,100°C followed by controlled cooling to achieve full austenitic structure and eliminate residual stresses.
- Final Sizing & Coiling: Precision sizing through multi-roller trains → Surface finishing (polishing or pickling) → Coiling onto steel mandrels with controlled wrap tension.
- Non-Destructive Testing (NDT): Eddy current testing (ECT) for wall thickness and longitudinal defect detection; ultrasonic testing (UT) for transverse defects; hydrostatic or pneumatic pressure testing.
Key Process Advantage: The coil format enables continuous processing without interruptions for butt-welding of discrete pipe sections, reducing energy consumption by approximately 25–35% compared to discrete pipe manufacturing and eliminating weld-induced anisotropy at longitudinal joints.
5. Applications
- Food & Beverage Processing: Hygienic-grade tubing for milk processing lines, brewing systems, and CIP (Clean-In-Place) circuits (304L/316L, electropolished surface, Ra ≤ 0.4 μm).
- Pharmaceutical & Biotechnology: Sterilizable process tubing for bioreactors, chromatography systems, and aseptic filling lines (316L, passivated finish).
- Automotive Exhaust Systems: Catalytic converter inlet/outlet piping and exhaust manifold feedstock (321, 409, or 310S grades for elevated-temperature service).
- Chemical & Petrochemical Processing: Heat exchanger tubing, reactor internals, and corrosion-resistant piping (2205 Duplex, 904L, or Alloy 625 for aggressive media).
- Architectural & Decorative: Handrail systems, elevator cab cladding, and structural elements requiring both aesthetic finish and structural performance.
- Heat Exchanger Manufacturing: Coil tubes serve as pre-formed feedstock for tube mills producing U-tubes, hairpin tubes, and plate-fin heat exchanger elements.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring traceability and compliance with international standards:
- ISO 9001:2015 — Quality Management System certification covering all production operations.
- ISO 14001:2015 — Environmental Management System certification.
- EN 10204 3.1 / 3.2 Certificates — Third-party inspection and material certification available upon request.
- ASTM / ASME Compliance: Products manufactured and tested per ASTM A269, A213, A790, and ASME B31.3/B31.5 code requirements.
- EN 10216-5 / EN 10217-7 — European standard conformity for welded stainless steel tubes.
- GB/T 12771 / GB/T 20878 — Chinese national standard compliance for cold-rolled stainless steel seamless and welded tubes.
- Mill Test Reports (MTR): Each coil lot accompanied by chemical composition analysis (spectrometric), mechanical test results, and dimensional verification data.
- Food Safety Compliance: 3-A Sanitary Standards and FDA 21 CFR 178.301 compliance for food-contact applications.
7. Unique Selling Points
- Continuous Length Advantage: Single coils up to 2,000 meters eliminate field welding, reducing installation time and leak points by up to 80% in process piping applications.
- Metallographic Uniformity: Continuous annealing and controlled coiling ensure consistent grain structure (ASTM E112 grain size 6–8) throughout the entire coil length, unlike discrete pipe sections which may exhibit end-to-end variation.
- Custom Coil Configuration: Flexible coil inner diameter, wrap direction, and end preparation to accommodate specific downstream equipment requirements.
- Integrated Value-Added Services: In-house capabilities for post-coiling processing including laser cutting, mandrel bending, orbital welding, and surface treatment under one roof.
- Full Traceability: Heat-number-based traceability from raw material ingot through final coil delivery, enabling recall management and qualification support for critical applications.
8. Storage & Handling Recommendations
Caution: Coil tubes should be stored indoors or under covered racks to prevent exposure to atmospheric moisture, which may cause surface staining or white rust. Contact with carbon steel must be avoided to prevent iron contamination and subsequent pitting corrosion. Coils should be handled with dedicated coil carriers or C-hooks to prevent deformation of the tube cross-section.
Wenzhou Jixing Metal Materials Co., Ltd. remains committed to delivering stainless steel coil tube products that meet the most demanding international specifications, supported by rigorous metallurgical quality assurance and responsive technical service.