Stainless Steel Coil Tube (Coil Tubing) — Wenzhou Jixing Metal Materials Co., Ltd.
1. Product Overview
The Stainless Steel Coil Tube (Coil Tubing) manufactured by Wenzhou Jixing Metal Materials Co., Ltd. is a precision-engineered continuous-length tubular product formed into a helical coil configuration. Unlike conventional straight-length seamless or welded tubes, coil tubes are produced in a continuous winding format, offering significant advantages in material utilization, handling logistics, and downstream processing efficiency. This product is engineered for demanding industrial applications requiring high corrosion resistance, mechanical integrity, and dimensional consistency across extended production runs.
Coil tubing is particularly advantageous in applications where long, uninterrupted lengths of tubing are required without butt-weld joints, thereby minimizing points of potential failure and enhancing system reliability. The helical coil form factor reduces storage footprint and facilitates automated feeding into downstream forming, cutting, and assembly operations.
2. Material & Properties
2.1 Available Grades
- 304 (UNS S30400 / 1.4301): Austenitic stainless steel with excellent general corrosion resistance; widely used in food processing, chemical, and architectural applications.
- 316 (UNS S31600 / 1.4401): Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion, particularly in chloride-containing environments.
- 316L (UNS S31603 / 1.4404): Low-carbon variant of 316L suitable for welding applications requiring resistance to intergranular corrosion.
- 321 (UNS S32100 / 1.4541): Titanium-stabilized austenitic grade designed for high-temperature service (up to 870°C / 1600°F) with resistance to sensitization.
- 310S (UNS S31008 / 1.4845): High-temperature austenitic grade with exceptional oxidation resistance up to 1150°C (2100°F).
2.2 Mechanical Properties (Typical — Annealed Condition)
| Property | Grade 304 | Grade 316 | Grade 321 | Grade 310S |
|---|---|---|---|---|
| Tensile Strength (MPa) | ≥ 515 | ≥ 515 | ≥ 515 | ≥ 515 |
| Yield Strength (0.2% Proof, MPa) | ≥ 205 | ≥ 205 | ≥ 205 | ≥ 205 |
| Elongation (% at Break) | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 |
| Hardness (HBW Max) | 217 | 217 | 217 | 217 |
| Density (g/cm³) | 7.93 | 8.00 | 7.93 | 8.03 |
| Thermal Conductivity (W/m·K, 100°C) | 16.3 | 14.6 | 16.3 | 24.0 |
| Maximum Service Temperature (°C) | 870 | 870 | 870 | 1150 |
2.3 Surface Finish Options
- 2B Finish: Cold-rolled and annealed; matte, uniform appearance; suitable for general industrial use.
- No. 4 Brushed: Fine linear grain pattern; aesthetic finish for visible applications.
- Mirror (8K): High-polish reflective surface; requires precision grinding and polishing.
- Pickled & Passivated: Chemical surface treatment removing scale and forming a protective chromium oxide layer.
3. Technical Specifications
| Parameter | Specification Range | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 3.0 mm – 219.1 mm (1/8" – 8") | ASTM A554 / A269 / GB/T 12771 |
| Wall Thickness (WT) | 0.3 mm – 6.0 mm (0.012" – 0.236") | ASTM A554 / A269 / GB/T 12771 |
| OD Tolerance | ±0.05 mm (OD ≤ 10 mm); ±0.10 mm (OD > 10 mm) | ASTM A554 |
| Wall Thickness Tolerance | ±10% (WT ≤ 1.0 mm); ±0.05 mm (WT > 1.0 mm) | ASTM A554 |
| Coil Length | 100 m – 3,000 m (continuous run) | — |
| Coil Diameter | 300 mm – 1,200 mm (configurable) | — |
| Coil Weight | Up to 2,000 kg per coil (grade-dependent) | — |
| End Condition | Open ends; beveled ends; capped ends (upon request) | — |
| Welding Type | Autogenous TIG Weld (for welded coil tube) | ASTM A554 |
| Weld Seam Condition | Smooth, flush, or slightly raised; ground flat (optional) | — |
| Heat Treatment | Full Anneal at 1010°C – 1120°C; solution anneal (310S) | ASTM A554 / A269 |
| Passivation | ASTM A967 citric acid or nitric acid passivation | ASTM A967 |
4. Manufacturing Process
The production of high-quality stainless steel coil tubing follows a rigorously controlled multi-stage process ensuring dimensional accuracy, metallurgical integrity, and surface quality:
- Hot-Rolled Coil Production: Continuous casting of stainless steel billets followed by hot rolling to produce intermediate coil stock with nominal dimensions.
- Pickling & Descaling: Hot acid pickling (HNO₃/HF blend) removes oxide scale formed during hot rolling, restoring the base metal surface.
- Cold Reduction (Cold Rolling): Multi-stand cold rolling reduces the coil to final OD and wall thickness specifications. Cold working induces beneficial strain hardening and tightens dimensional tolerances.
- Forming & Welding (for Welded Coil Tube): The flat coil strip is formed into a tubular shape via roll-forming dies and joined by continuous autogenous Tungsten Inert Gas (TIG) welding. Weld parameters are precisely controlled to ensure uniform penetration and minimal heat-affected zone (HAZ).
- Intermediate Annealing: Periodic solution annealing during cold reduction relieves accumulated cold work stress, restores ductility, and prevents cracking during subsequent forming operations.
- Final Annealing & Pickling: Full solution annealing at grade-specific temperatures (typically 1010°C – 1120°C for 300-series austenitic grades) followed by rapid cooling (air or water quench) ensures a fully austenitic, stress-free microstructure. Subsequent acid pickling removes any residual oxide.
- Surface Finishing: Final surface treatment (2B, brushed, mirror polish, or matte) is applied according to customer specification.
- Passivation: Chemical passivation per ASTM A967 establishes a stable chromium oxide passive film, enhancing corrosion resistance.
- Quality Inspection: Comprehensive non-destructive testing (NDT) including eddy current inspection (ECI), ultrasonic testing (UT), and visual inspection of the weld seam. Dimensional verification via laser gauging and micrometry.
- Coiling & Packaging: Finished tubing is coiled to specified diameter with protective interlayer wrapping, end-capping, and moisture-barrier packaging for shipment.
5. Applications
Stainless steel coil tubing from Wenzhou Jixing Metal Materials Co., Ltd. serves a diverse range of industrial sectors:
- Food & Beverage Industry: Hygienic process piping, CIP (Clean-In-Place) systems, brewing equipment, and dairy processing lines (304/316L grades).
- Pharmaceutical Manufacturing: GMP-compliant process tubing, autoclave assemblies, and sanitary fittings requiring high purity and corrosion resistance.
- Heat Exchangers & HVAC: Tubular heat exchanger bundles, condenser tubes, evaporator coils, and refrigeration circuits exploiting the coil form for compact heat transfer surface area.
- Automotive & Aerospace: Fuel lines, exhaust system components, hydraulic lines, and structural tubing requiring high strength-to-weight ratios.
- Chemical Processing: Corrosive fluid transport, reactor internals, and distillation column tubing (316/316L grades for chloride resistance).
- Medical Devices: Endoscopic tubing, implantable stents, and surgical instrument shafts requiring biocompatibility and precision dimensions.
- Construction & Architecture: Structural bracing, decorative elements, handrail systems, and elevator guide rails.
- Marine & Offshore: Ballast system tubing, seawater piping, and underwater equipment housings.
6. Quality Certifications & Standards Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system ensuring product conformance to international standards:
| Certification / Standard | Scope of Application |
|---|---|
| ISO 9001:2015 | Quality Management System — all manufacturing operations |
| ISO 14001:2015 | Environmental Management System |
| ISO 45001:2018 | Occupational Health & Safety Management |
| EN 10204 3.1 | Material Test Certificates — third-party verified |
| ASTM A554 | Standard Specification for Cold-Rolled or Cold-Drawn Stainless Steel Seamless, Welded, and Heavy-Walled Tube |
| ASTM A269 | Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing |
| ASTM A967 | Standard Practice for Chemical Passivation of Stainless Steel Parts |
| GB/T 12771 | Chinese National Standard for Welded Stainless Steel Tubes for General Purposes |
| GB/T 13296 | Chinese National Standard for Seamless Stainless Steel Tubes for Heat Exchangers and Heat Sinks |
| 3-A Sanitary Standards | Dairy and Food Processing Equipment Hygiene Certification |
| CE Marking (PED 2014/68/EU) | Pressure Equipment Directive compliance for pressure-containing applications |
7. Unique Selling Points
- Extended Continuous Length: Coil format enables production runs up to 3,000 meters without butt-w