Stainless Steel Coil Tube — Precision Tolerance & Standard-Compliant Coiled Tubing Solutions
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. (Product Code: 207) manufactures and supplies high-performance stainless steel coil tubes engineered for demanding industrial applications. Coiled tubing, also referred to as coil tube, is produced in continuous lengths wound onto standard reels, offering superior material utilization, reduced waste, and seamless integration into high-volume fabrication lines. Every coil tube produced by Wenzhou Jixing is governed by clearly defined dimensional tolerances, standard references, and quality grades — eliminating the ambiguity that commonly leads to delivery disputes in the global stainless steel tube market.
Unlike conventional cut-length tubes, coil tubes are formed continuously through cold-rolling or cold-drawing processes, resulting in excellent mechanical consistency along the entire coil length. This makes them particularly suitable for applications requiring uniform wall thickness, precise outer diameter control, and high surface finish integrity over extended runs.
Unique Selling Points
- Explicit Standard & Tolerance Grade Declaration: Every order contract specifies the exact international standard number (e.g., ASTM A213, EN 10216-5, GB/T 14976) and the corresponding dimensional tolerance class (e.g., EN 10216-5 Class T2, ASTM Close Tolerance). This eliminates the "default widest tolerance" ambiguity that is the number-one source of delivery disputes in the stainless steel coil tube industry.
- Multi-Standard Compliance: Products are manufactured to simultaneously meet ASTM, EN, ISO, and GB standards, providing procurement flexibility for international buyers.
- Continuous Production Integrity: Full-length mechanical property consistency achieved through continuous cold-forming processes, ensuring no localized weakness points along the coil.
- Comprehensive Traceability: Each coil is assigned a unique heat number and batch traceability code, enabling full material provenance verification from raw steel mill to end delivery.
- Custom Tolerance Options: Beyond standard tolerance classes, Wenzhou Jixing offers custom tolerance agreements for precision-critical applications, with agreed tolerances contractually locked before production begins.
Material & Properties
Available Grades
Stainless steel coil tubes are available in a comprehensive range of austenitic, duplex, and ferritic grades to suit diverse corrosion, mechanical, and thermal performance requirements:
- Austenitic Grades: 304 (UNS S30400), 304L (UNS S30403), 316 (UNS S31600), 316L (UNS S31603), 321 (UNS S32100), 310S (UNS S31008)
- Super-Austenitic Grades: 904L (UNS N08904), 254 SMO (UNS S31254)
- Duplex Grades: 2205 (UNS S31803/S32205), 2507 (UNS S32750/S32760)
- Ferritic Grades: 430 (UNS S43000), 446 (UNS S44600)
Mechanical Properties (Typical — Annealed Condition)
| Grade | Tensile Strength (MPa) | Yield Strength (MPa, 0.2% offset) | Elongation (%) | Hardness (HBW max) |
|---|---|---|---|---|
| 304 / 304L | ≥ 515 (≥ 75 ksi) | ≥ 205 (≥ 30 ksi) | ≥ 40 | ≤ 217 |
| 316 / 316L | ≥ 515 (≥ 75 ksi) | ≥ 205 (≥ 30 ksi) | ≥ 40 | ≤ 217 |
| 321 | ≥ 515 (≥ 75 ksi) | ≥ 205 (≥ 30 ksi) | ≥ 40 | ≤ 217 |
| 310S | ≥ 515 (≥ 75 ksi) | ≥ 205 (≥ 30 ksi) | ≥ 40 | ≤ 217 |
| 2205 Duplex | ≥ 550 (≥ 80 ksi) | ≥ 450 (≥ 65 ksi) | ≥ 15 | ≤ 352 |
| 2507 Super Duplex | ≥ 620 (≥ 90 ksi) | ≥ 550 (≥ 80 ksi) | ≥ 15 | ≤ 352 |
Corrosion Resistance
Coil tubes in grades 304L and 316L exhibit excellent resistance to atmospheric corrosion, mild acids, and alkaline environments. The addition of molybdenum in 316/316L provides superior pitting and crevice corrosion resistance in chloride-containing environments. Super-austenitic grades such as 904L and 254 SMO deliver outstanding resistance to oxidizing acids, sulfuric acid, and mixed-acid environments. Duplex grades (2205, 2507) combine high strength with exceptional chloride stress corrosion cracking resistance, making them ideal for aggressive offshore and chemical processing applications.
Temperature Performance
Standard austenitic coil tubes (304, 316) maintain structural integrity from cryogenic temperatures (−196 °C / −321 °F) up to 870 °C (1,598 °F). Grade 310S extends the upper service temperature to 1,150 °C (2,094 °F). Duplex grades are recommended for service temperatures up to 300 °C (572 °F) to prevent phase transformation.
Specifications
Dimensional Specifications
| Parameter | Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.00 mm – 168.00 mm (0.24 in – 6.62 in) | ASTM A213 / EN 10216-5 / GB/T 14976 |
| Wall Thickness | 0.50 mm – 6.00 mm (0.020 in – 0.236 in) | ASTM A213 / EN 10216-5 |
| Coil Length per Reel | 50 m – 500 m (164 ft – 1,640 ft) | Per customer specification |
| Reel Inner Diameter | 200 mm / 300 mm / 500 mm (7.87 in / 11.81 in / 19.69 in) | Per customer specification |
| Reel Outer Diameter (max) | ≤ 1,200 mm (≤ 47.24 in) | Per shipping standard |
| Coil Weight (typical) | 500 kg – 3,000 kg (1,100 lb – 6,614 lb) | Per reel configuration |
| End Condition | Cut ends, beveled ends, or plain ends | Per customer specification |
Dimensional Tolerance Classes
Critical Note: In the absence of a specified tolerance class in the purchase order or contract, the default tolerance is the widest permissible class under the referenced standard. This is the single highest-risk factor for delivery disputes. Wenzhou Jixing requires all buyers to explicitly declare the tolerance class at the order stage.
| Tolerance Class | OD Tolerance | Wall Thickness Tolerance | Applicable Standard | Typical Application |
|---|---|---|---|---|
| EN 10216-5 Class T2 | ± 0.10 mm (± 0.004 in) | ± 10% (min. ± 0.05 mm) | EN 10216-5 | General engineering, structural |
| EN 10216-5 Class T3 | ± 0.15 mm (± 0.006 in) | ± 10% (min. ± 0.05 mm) | EN 10216-5 | Standard industrial use |
| EN 10216-5 Class T4 | ± 0.20 mm (± 0.008 in) | ± 10% (min. ± 0.05 mm) | EN 10216-5 | Non-critical applications |
| EN 10216-5 Class T5 | ± 0.30 mm (± 0.012 in) | ± 10% (min. ± 0.05 mm) | EN 10216-5 | Economic / non-precision |
| ASTM Close Tolerance | ± 0.10 mm (± 0.004 in) | ± 0.10 mm (± 0.004 in) | ASTM A213 / ASME B36.19M | High-precision instrumentation, heat exchangers |
| Custom Tolerance | Per contract agreement | Per contract agreement | Contractually defined | Critical applications, OEM specifications |
Surface Finish Options
| Finish Type | Ra Value (μm) | Description |
|---|---|---|
| Pickled & Annealed (P&A) | 0.8 – 1.6 | Standard mill finish; smooth, non-directional surface |
| Pickled & Passivated (P&Pass) | 0.6 – 1.2 | Enhanced corrosion resistance through passive film formation |
| Mechanically Polished | 0.2 – 0.8 | Smooth, bright finish for hygienic and cosmetic applications |
| Electropolished | 0.1 – 0.4 | Ultra-smooth, chemically pure surface for pharmaceutical and food-grade use |
Manufacturing Process
The production of stainless steel coil tubes at Wenzhou Jixing follows a rigorous, multi-stage manufacturing sequence designed to ensure dimensional precision, metallurgical integrity, and surface quality:
- Raw Material Selection & Inspection: Cold-rolled stainless steel strip is sourced from certified mills (e.g., Outokumpu, Aperam, Tsingshan, POSCO). Each incoming batch undergoes chemical composition analysis (spectrometry), mechanical testing, and visual inspection for surface defects. Material certificates (EN 10204 3.1) are verified prior to acceptance.
- Strip Preparation: The cold-rolled strip is uncoiled, leveled, and slit to the required width and thickness. Surface cleanliness is ensured through degreasing and pickling to remove any mill scale or oxidation residues.
- Coil Forming (Tube Making): The prepared strip is fed through a series of progressive rollers in a tube mill that progressively form the flat strip into a circular cross-section. The forming sequence is calibrated to minimize residual stresses and maintain uniform wall thickness.
- Welding (for welded coil tubes): For welded variants, the formed tube is welded using either resistance welding (ERW), gas tungsten arc welding (GTAW/TIG), or orbital welding. Weld parameters are precisely controlled and continuously monitored to ensure full penetration and minimal heat-affected zone distortion.
- Heat Treatment / Annealing: Welded tubes undergo solution annealing in a protective atmosphere (argon or endothermic gas) at temperatures between 1,050 °C and 1,150 °C (1,922 °F – 2,094 °F), followed by controlled cooling. This restores full austenitic microstructure, relieves residual stresses, and maximizes corrosion resistance.
- Pickling & Passivation: Annealed tubes are subjected to acid pickling (HNO₃/HF blend or H₂SO₄) to remove heat-treatment scale, followed by nit