Stainless Steel Coil Tube — Continuous Coiled Tubing Product
Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd | Catalog Reference No.: 1125
1. Product Overview
The Stainless Steel Coil Tube (盘管, Coiltube) is a continuously wound, seamless or welded tubular product manufactured in long coil form, designed for applications requiring uninterrupted lengths of stainless steel piping without the need for on-site welding or joining. Unlike conventional straight-length stainless steel pipes, coil tubes are supplied in large-diameter coils that can be uncoiled and laid directly into service, significantly reducing installation time, labor costs, and joint-related failure points.
This product category is particularly critical in pipeline conveyor systems, hydraulic transmission lines, chemical processing plants, and structural applications where the integrity of a continuous, leak-free tube is paramount. The coil tube form factor enables rapid deployment in linear infrastructure projects such as slurry transport pipelines, mining conveyor systems, and automated material handling lines.
2. Material Composition & Mechanical Properties
The Stainless Steel Coil Tube is available in a range of austenitic and duplex stainless steel grades, selected to meet the specific corrosion, mechanical, and thermal requirements of the end application.
2.1 Commonly Available Grades
- AISI 304 (UNS S30400) — General-purpose austenitic stainless steel with excellent corrosion resistance and formability. Suitable for non-aggressive chemical environments and food-grade applications.
- AISI 304L (UNS S30403) — Low-carbon variant of 304, optimized for welding applications where sensitization resistance is required.
- AISI 316 (UNS S31600) — Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion in chlorinated environments.
- AISI 316L (UNS S31603) — Low-carbon 316 variant, providing enhanced weldability and resistance to intergranular corrosion.
- AISI 321 (UNS S32100) — Titanium-stabilized grade suitable for elevated temperature applications (up to 870°C continuous service).
- 2205 Duplex (UNS S31803) — Austenitic-ferritic duplex steel offering approximately twice the yield strength of 300-series austenitics, with excellent resistance to chloride stress corrosion cracking (Cl-SCC).
2.2 Typical Mechanical Properties (AISI 304, Annealed Condition)
| Property | Specification | Standard Reference |
|---|---|---|
| Tensile Strength (UTS) | ≥ 515 MPa (≥ 75 ksi) | ASTM A213 / ASTM A269 |
| Yield Strength (0.2% offset) | ≥ 205 MPa (≥ 30 ksi) | ASTM A213 / ASTM A269 |
| Elongation (in 50 mm / 2 in.) | ≥ 40% | ASTM A213 / ASTM A269 |
| Hardness (Rockwell B) | ≤ 92 HRB | ASTM A213 / ASTM A269 |
| Density | 8.0 g/cm³ | — |
| Thermal Conductivity (at 100°C) | 16.3 W/(m·K) | ASTM E153 |
| Modulus of Elasticity | 193 GPa (28 × 10⁶ psi) | ASME BPVC Section II |
2.3 Chemical Composition Requirements (AISI 304, wt.%)
| Element | Maximum / Minimum | Standard Reference |
|---|---|---|
| Carbon (C) | ≤ 0.08 | ASTM A213 |
| Chromium (Cr) | 18.0 – 20.0 | ASTM A213 |
| Nickel (Ni) | 8.0 – 10.5 | ASTM A213 |
| Manganese (Mn) | ≤ 2.0 | ASTM A213 |
| Silicon (Si) | ≤ 0.75 | ASTM A213 |
| Phosphorus (P) | ≤ 0.045 | ASTM A213 |
| Sulfur (S) | ≤ 0.030 | ASTM A213 |
3. Dimensional Specifications
3.1 Outer Diameter & Wall Thickness Ranges
| Parameter | Range | Units |
|---|---|---|
| Outer Diameter (OD) | 3.0 – 168.3 | mm (1/8" – 6") |
| Wall Thickness (WT) | 0.30 – 6.35 | mm (0.012" – 1/4") |
| Coil Length per Spool | 30 – 200 | meters (customizable) |
| Coil Inner Diameter (ID) | 300 – 1200 | mm (adjustable per logistics requirement) |
| OD Tolerance | ± 0.1 mm (± 0.004") | mm |
| WT Tolerance | ± 0.05 mm (± 0.002") | mm |
| Roundness | ≤ 0.5% of OD | — |
3.2 Surface Finish Options
- Pickled & Passivated (P&P) — Standard mill finish with a smooth, matte silver-gray appearance. Provides baseline corrosion resistance.
- Ba & Pe (Bright Annealed & Pickled) — Enhanced surface finish with improved aesthetic quality and slightly enhanced corrosion resistance. Common for visible or food-contact applications.
- Electrolytic Polished — Mirror finish (Ra ≤ 0.4 μm) achieved through electrochemical dissolution. Critical for pharmaceutical, semiconductor, and hygienic processing applications.
- Brushed Finish — Uniform directional grain pattern for decorative and architectural uses.
3.3 Applicable Standards & Specifications
- ASTM A213 — Standard Specification for Stainless Steel Tubing, Seamless, Cold-Drawn or Cold-Rolled, for High-Pressure Boiler and Heat Exchanger Tubing
- ASTM A269 — Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service
- ASTM A270 — Standard Specification for Welded Austenitic Stainless Steel Tubing for Chemical and Other Severely Corrosive Services
- EN 10216-5 — Seamless Stainless Steel Tubes for Pressure Purposes — Technical Delivery Conditions
- ISO 3506 — Fasteners Made of Stainless Steel (reference for mechanical property classification)
- JIS G3459 — Seamless Stainless Steel Tubes for General Use (Japanese Industrial Standard)
4. Manufacturing Process
The production of Stainless Steel Coil Tube at Wenzhou Jixing Metal Materials Co., Ltd. follows a rigorously controlled multi-stage process, ensuring dimensional accuracy, metallurgical integrity, and surface quality consistent with international standards.
4.1 Process Flow
- Raw Material Selection & Inbound Inspection — Hot-rolled stainless steel strip or seamless tube blanks are sourced from certified mills. Each lot undergoes spectrographic analysis (optical emission spectrometry, OES) to verify chemical composition compliance with the specified grade.
- Slitting & Leveling — Coiled strip is slit to the required width and leveled to eliminate coiling stresses, ensuring uniform feed into the forming station.
- Forming (Cold-Rolling or Cold-Drawing) —
- Welded Coil Tube: The leveled strip is fed through a series of progressive roll-forming stations that incrementally shape the flat strip into a circular cross-section. The formed tube passes through a TIG (Tungsten Inert Gas) welding station where the longitudinal seam is fused under a shielded argon atmosphere to prevent oxidation.
- Seamless Coil Tube: Pre-formed seamless billets are cold-drawn through calibrated dies to achieve the target OD and WT, preserving the metallurgical homogeneity of the material.
- Weld Seam Treatment (Welded Products Only) — The weld seam is mechanically polished and/or chemically passivated to eliminate residual weld stress and restore the protective chromium oxide layer across the entire inner surface.
- Heat Treatment (Annealing) — Tubes are subjected to controlled annealing (typically 1050–1150°C for austenitic grades) followed by rapid air or water quenching. This relieves cold-work hardening, restores full ductility, and stabilizes the austenitic microstructure.
- Pickling & Passivation — Tubes are immersed in a mixed acid bath (nitric acid / hydrofluoric acid blend) to remove scale, discoloration, and surface contaminants. A final passivation step (dilute nitric acid or citric acid) promotes the formation of a stable, self-healing Cr₂O₃ passive film on the surface.
- Dimensional Inspection & Non-Destructive Testing (NDT) —
- OD & WT: Measured at multiple points along each coil using ultrasonic thickness gauges and laser micrometers.
- Eddy Current Testing (ECT): Detects internal and surface defects (pores, cracks, inclusions) along the full length of the tube at high speed.
- Visual Inspection: Automated camera systems scan the tube surface for scratches, dents, or discoloration.
- Hydrostatic Testing: Tubes are pressurized to 1.5× the maximum design pressure for a specified dwell time to verify pressure integrity and absence of leaks.
- Coiling & Packaging — The finished tube is wound onto a steel or wooden coil core at a controlled tension to prevent springback or deformation. Coils are wrapped in moisture-proof plastic film, strapped with steel banding, and labeled with a full material traceability tag (heat number, grade, dimensions, inspection certificate reference).
5. Applications
5.1 Primary Application Domains
- Pipeline Conveyor Systems — The coil tube form is ideal for slurry transport pipelines in mining, mineral processing, and dredging operations, where continuous lengths eliminate the risk of joint leakage and reduce maintenance intervals. The dynamic analysis of traction steel wire ropes in series coil pipeline conveyors (as referenced in the associated technical literature) underscores the importance of tube dimensional consistency and mechanical properties in ensuring reliable conveyor performance.
- Chemical & Petrochemical Processing — Used for reactor feed lines, heat exchanger bundles, distillation column internals, and process piping in environments containing chlorides, sulfides, and organic acids. Grades 316L and 2205 Duplex are preferred for aggressive chemical service.
- Food & Beverage Processing — Hygienic-grade coil tubes (electrolytic polished finish, Ra ≤ 0.4 μm) are employed in CIP (Clean-in-Place) systems, pasteurization lines, and transfer piping for dairy, brewing, and pharmaceutical applications.
- Automotive & Exhaust Systems — High-temperature resistant grades (321, 310) are used for catalytic converter housings, exhaust manifolds, and EGR (Exhaust Gas Recirculation) piping.
- Structural & Architectural Applications — Coil tube is used for handrails, balustrades, decorative facades, and structural bracing in modern architecture, where the continuous coil form allows for complex curved geometries without fabrication joints.
- Medical & Laboratory Equipment — Used in autoclaves, dialysis equipment, surgical instrument tubing, and laboratory gas delivery lines, where biocompatibility and sterilizability are mandatory.
- Energy & Power Generation — Heat exchanger tubes in boilers, condensers, and cooling towers; feedwater lines in nuclear power plants (stabilized grades such as 321H and 347H).
5.2 Value Proposition in Pipeline Conveyor Systems
In series coil pipeline conveyor systems, the coil tube serves as the primary conveying medium for bulk materials (slurry, granular solids, viscous fluids). The traction steel wire rope that drives the conveyor must be dynamically matched to the tube's weight, stiffness, and frictional characteristics. Wenzhou Jixing's coil tubes are manufactured with tight dimensional tolerances (± 0.1 mm OD, ± 0.05 mm WT) and consistent mechanical properties, ensuring predictable friction coefficients and uniform load distribution across the conveyor system. This consistency is critical for the dynamic analysis and optimization of wire rope tension, preventing premature fatigue failure and ensuring operational safety.
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications and complies with the following standards:
6.1 Management System Certifications
- ISO 9001:2015 — Quality Management Systems (QMS) certification
- ISO 14001:2015 — Environmental Management Systems (EMS) certification
- ISO 45001:2018 — Occupational Health and Safety Management Systems (OHSMS) certification
6.2 Product & Industry Certifications
- EN 10204 Type 3.1 — Inspection Certificate stating conformity with the order requirements, issued by a designated authority (e.g., Bureau Veritas, SGS, TÜV)
- ASME "S" Stamp