Stainless Steel Coil Tube (Coiltube) — Technical Specification
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered tubular product supplied in continuous coiled form, manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is specifically designed for applications requiring flexible, continuous-length tubing with superior corrosion resistance, mechanical integrity, and dimensional accuracy. The coil configuration enables efficient downstream processing, including cutting, bending, forming, and welding without the need for joint splicing, thereby minimizing material waste and ensuring structural continuity.
Research and simulation studies—particularly those involving Discrete Element Method (DEM) analysis and Multi-Attribute Evaluation (MAE) frameworks—have been conducted to characterize the behavior of coiled tubing systems in bulk material handling and conveying applications. These studies provide empirical validation for the product's performance under complex loading and deformation conditions.
2. Material & Properties
The Coil Tube is fabricated from high-grade austenitic and/or duplex stainless steels, conforming to international standards including ASTM A213, ASTM A312, EN 10216-5, and GB/T 12771. The material selection ensures exceptional resistance to oxidation, pitting, crevice corrosion, and chloride-induced degradation across a wide temperature and pressure range.
2.1 Common Grade Designations
- 304 (UNS S30400) — General-purpose corrosion resistance; optimal for food-grade and chemical processing environments.
- 316 (UNS S31600) — Enhanced molybdenum content for superior resistance to chlorides and marine environments.
- 321 (UNS S32100) — Titanium-stabilized for elevated-temperature service up to 870°C.
- 316L (UNS S31603) — Low-carbon variant for improved weldability and resistance to intergranular corrosion.
- 904L (UNS N08904) — High-alloy austenitic grade for aggressive chemical environments.
2.2 Key Mechanical Properties
- Tensile Strength (UTS): 515–720 MPa (grade-dependent)
- Yield Strength (0.2% Offset): 205–310 MPa
- Elongation at Break: ≥30% (minimum)
- Hardness: ≤217 HB (annealed condition)
- Thermal Conductivity: 16.3 W/(m·K) at 100°C
- Thermal Expansion Coefficient: 16–18 × 10⁻⁶ /°C (20–100°C)
3. Specifications
| Parameter | Specification | Standard Reference |
|---|---|---|
| Outer Diameter (OD) | 6.0 mm – 168.3 mm | ASTM A312 / EN 10216-5 |
| Wall Thickness | 0.5 mm – 6.0 mm | ASTM A312 |
| Coil Length | Up to 1,000 m per coil (standard); custom lengths available | Manufacturer Specification |
| Coil Inner Diameter (ID) | 300 mm – 600 mm | Manufacturer Specification | Surface Finish | Mirror polished (Ra ≤ 0.4 μm), Electropolished (Ra ≤ 0.1 μm), 2B finish, or Hairline finish | ASTM A269 / EN 10204 |
| Dimensional Tolerance (OD) | ±0.1 mm (precision); ±0.3 mm (standard) | ASTM A312 / ASME B36.19M |
| Dimensional Tolerance (Wall) | ±10% of nominal wall thickness | ASTM A312 |
| Welding Method | Automatic TIG (Gas Tungsten Arc) welding with full internal/external weld pass | ISO 15493 / ASME B31.3 |
| Heat Treatment | Solution annealing at 1050°C – 1150°C followed by rapid water quench | ASTM A312 |
| Pressure Rating | Up to 40 MPa (PN40) at 20°C, depending on OD and wall thickness | ASME B31.3 / EN 12379 |
| Temperature Range | −196°C to +870°C (grade-dependent) | ASTM A312 |
| End Treatment | Plain ends, beveled ends, threaded ends, or custom fittings | Manufacturer Specification |
4. Manufacturing Process
The production of Stainless Steel Coil Tube follows a rigorously controlled multi-stage process to ensure dimensional precision, metallurgical integrity, and surface quality:
- Raw Material Selection: Hot-rolled stainless steel strip is procured from certified mills with full Chemical Composition (CC) and Mechanical Properties (MP) documentation.
- Strip Cleaning & Degreasing: Surface contaminants are removed via alkaline washing and pickling to ensure a clean substrate for forming.
- Forming & Welding: The strip is formed into a tubular shape using a roll-forming or mandrel-die process, followed by high-precision automatic TIG welding with inert gas shielding (Argon) on both internal and external weld surfaces.
- Weld Annealing: The welded tube undergoes solution heat treatment to homogenize the weld zone microstructure, restoring full mechanical properties and corrosion resistance.
- Pickling & Passivation: The tube is immersed in a mixed acid bath (HNO₃/HF) to remove the oxide scale, followed by nitric acid passivation to establish a protective chromium oxide layer.
- Surface Finishing: Depending on the application, the tube may undergo mechanical polishing, electropolishing, or chemical polishing to achieve the specified surface roughness.
- Coiling: The finished tube is coiled onto a steel spool at controlled tension to prevent deformation, denting, or kinking during storage and transport.
- Quality Inspection: Each coil undergoes 100% visual inspection, dimensional verification (caliper and ultrasonic thickness gauge), hydrostatic or pneumatic pressure testing, and weld inspection (dye penetrant or eddy current testing).
5. Applications
The versatility of Stainless Steel Coil Tube makes it suitable for a broad spectrum of industrial applications:
- Petrochemical & Refinery: Process piping, heat exchanger tubes, and fluid transport lines in high-corrosion environments.
- Food & Beverage Processing: Hygienic-grade tubing for milk, dairy, beer, and pharmaceutical production lines (electropolished finish).
- Oil & Gas: Subsea pipelines, wellhead tubing, and offshore platform piping systems.
- Automotive Industry: Exhaust systems, fuel lines, and hydraulic brake lines.
- Medical Equipment: Surgical instrument tubing, endoscope sheaths, and dialysis machine components.
- Bulk Material Conveying: As validated by Discrete Element Method (DEM) simulations and Multi-Attribute Evaluation (MAE) studies, coiled stainless steel tubing is integral to disk pipeline scraper conveyor systems, where it provides durable, low-friction channels for bulk solid material transport.
- Structural & Architectural: Decorative railings, guardrails, and structural framing elements.
- Heat Exchangers & Boilers: High-temperature service tubing for steam generators and condensers.
6. Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications:
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System certification
- ISO 45001:2018 — Occupational Health and Safety Management System certification
- EN 10204 3.1 / 3.2 — Certificate of Conformity and Third-Party Inspection certification
- ASTM / ASME Material Certification — Full material traceability documentation
- CE Marking — European Conformity for pressure equipment (PED 2014/68/EU)
- NSF / FDA Compliance — Food-contact material certification for hygienic applications
- Pressure Vessel Inspection — Third-party inspection by accredited bodies (TÜV, Lloyd's, DNV)
Each shipment is accompanied by a Mill Test Certificate (MTC) detailing chemical composition, mechanical properties, heat treatment records, and non-destructive testing (NDT) results, ensuring full traceability from raw material to finished product.
7. Unique Selling Points
- Continuous Length Advantage: Coil configuration eliminates butt welds, reducing failure points and enabling seamless integration into automated manufacturing lines.
- Simulation-Validated Performance: Product behavior in conveying and transport applications is backed by Discrete Element Method (DEM) simulation data and Multi-Attribute Evaluation (MAE) analysis, providing quantifiable performance metrics for engineering design.
- Full Customization: OD, wall thickness, coil length, surface finish, and end treatments are all configurable to meet project-specific requirements.
- Superior Corrosion Resistance: Available in grades ranging from 304 to 904L, covering virtually all industrial corrosion scenarios.
- Hygienic-Grade Capability: Electropolished surfaces with Ra ≤ 0.1 μm meet the most stringent sanitary requirements in pharmaceutical and food processing industries.
- Full Traceability: Every coil is individually heat-numbered with complete documentation from raw material mill to final inspection.
Note: This technical specification is intended for engineering reference and procurement evaluation purposes. For project-specific material selection and dimensional requirements, please contact Wenzhou Jixing Metal Materials Co., Ltd. directly to obtain customized quotations and certified test documentation.