Stainless Steel Coil Tube — Technical Product Specification
Product Code: No. 391 | Manufacturer: Wenzhou Jixing Metal Materials Co., Ltd. | Category: Literature Study / Technical Reference
1. Product Overview
The Stainless Steel Coil Tube (盘管) is a continuous-length tubular product formed by rolling or drawing stainless steel into a spiral coil configuration. Unlike straight seamless or welded pipes, coil tubes are supplied in large-diameter coils, enabling high-efficiency downstream processing through continuous forming, cutting, and welding operations. This product is designed for applications requiring flexible deployment, compact storage, and streamlined manufacturing workflows.
Wenzhou Jixing Metal Materials Co., Ltd. supplies precision-engineered stainless steel coil tubes that conform to international material standards and undergo rigorous quality verification in accordance with recognized testing protocols, including the Room Temperature Tensile Test Method for Metal Coil Tubes (金属盘管的室温拉伸试验方法), which establishes standardized procedures for evaluating mechanical performance under ambient conditions.
2. Material & Properties
Coil tubes are manufactured from austenitic, ferritic, and duplex stainless steel grades, selected according to the corrosion resistance, mechanical strength, and temperature tolerance requirements of the intended application.
2.1 Common Material Grades
- 304 / 304L (UNS S30400 / S30403): General-purpose austenitic grade with excellent corrosion resistance and formability; widely used in food processing, chemical, and architectural applications.
- 316 / 316L (UNS S31600 / S31603): Molybdenum-enhanced austenitic grade offering superior resistance to pitting and crevice corrosion, particularly in chloride-containing environments.
- 321 / 347 (UNS S32100 / S34700): Stabilized austenitic grades suitable for elevated-temperature service where sensitization resistance is critical.
- 430 / 409 (UNS S43000 / S40900): Ferritic grades offering cost-effective corrosion resistance for moderate environmental conditions.
- 2205 Duplex (UNS S31803): High-strength duplex stainless steel combining austenitic and ferritic microstructures for enhanced yield strength and improved chloride stress corrosion cracking resistance.
2.2 Mechanical Properties (Typical Values at Room Temperature)
| Property | Test Standard | 304 / 304L | 316 / 316L | 2205 Duplex |
|---|---|---|---|---|
| Tensile Strength (Rm) | GB/T 228.1 / ASTM E8 | ≥ 520 MPa | ≥ 515 MPa | ≥ 550 MPa |
| Yield Strength (Rp0.2) | GB/T 228.1 / ASTM E8 | ≥ 205 MPa | ≥ 170 MPa | ≥ 450 MPa |
| Elongation (A50) | GB/T 228.1 / ASTM E8 | ≥ 40% | ≥ 40% | ≥ 25% |
| Hardness (HV) | GB/T 1817 / ASTM E92 | ≤ 210 | ≤ 210 | ≤ 330 |
| Density (ρ) | — | 7.93 g/cm³ | 7.98 g/cm³ | 7.81 g/cm³ |
2.3 Chemical Composition (Typical, wt%)
| Element | 304 / 304L | 316 / 316L | 2205 Duplex |
|---|---|---|---|
| C | ≤ 0.08 / ≤ 0.03 | ≤ 0.08 / ≤ 0.03 | ≤ 0.03 |
| Cr | 18.0 – 20.0 | 16.0 – 18.0 | 22.0 – 23.0 |
| Ni | 8.0 – 10.5 | 10.0 – 14.0 | 4.5 – 6.5 |
| Mo | — | 2.0 – 3.0 | 3.0 – 3.5 |
| N | — | — | 0.14 – 0.20 |
| Mn | ≤ 2.0 | ≤ 2.0 | ≤ 1.5 |
| Si | ≤ 1.0 | ≤ 1.0 | ≤ 1.0 |
3. Specifications
| Parameter | Specification |
|---|---|
| Outer Diameter (OD) | 6.0 mm – 114.3 mm (1/4" – 4½") |
| Wall Thickness | 0.3 mm – 6.0 mm |
| Coil Length (Continuous) | 100 m – 3,000 m (customizable) |
| Coil Diameter (Outer) | 500 mm – 1,200 mm |
| Coil Core Diameter | 150 mm – 300 mm |
| Tolerance on OD | ±0.05 mm – ±0.10 mm (per GB/T 14976 / ASTM A269) |
| Tolerance on Wall Thickness | ±10% of nominal (or ±0.02 mm, whichever is greater) |
| Surface Finish | Pickled & Passivated (P&P), Bright Annealed, Polished (2B, No. 4, Mirror) |
| End Condition | Flat cut, beveled, or threaded (per customer requirement) |
| Packaging | Wooden pallet with moisture-proof wrapping; protective coil cradle |
| Applicable Standards | GB/T 14976, GB/T 12771, ASTM A269, ASTM A213, EN 10216-5, ISO 7736 |
4. Manufacturing Process
The production of stainless steel coil tubes involves a multi-stage process designed to ensure dimensional accuracy, metallurgical integrity, and surface quality:
- Hot-Rolled Billet Preparation: High-purity stainless steel ingots are cast via Vacuum Arc Remelting (VAR) or Electro-Slag Remelting (ESR) to minimize inclusions and ensure homogeneous chemistry.
- Hot Rolling & Annealing: Billets are hot-rolled into hollow tube blanks and subsequently annealed to relieve residual stresses and refine grain structure.
- Pickling & Descaling: The tube blanks are subjected to acid pickling (typically HNO₃/HF blend) to remove oxide scale and form a passive chromium oxide layer.
- Tube Drawing / Cold Reduction: The hot-rolled blanks are cold-drawn through precision dies to achieve the target outer diameter, wall thickness, and roundness. This step is critical for dimensional accuracy and surface finish.
- Intermediate Annealing: Periodic annealing at 1,050°C – 1,150°C in a protective atmosphere (high-purity nitrogen or argon) restores ductility during multi-pass cold working.
- Coiling & Straightening: The finished tube is wound onto a precision coil former under controlled tension to prevent deformation or kinking. A final straightening pass ensures the coil exhibits uniform curvature.
- Final Passivation & Surface Treatment: A final passivation treatment enhances the passive film, improving long-term corrosion resistance.
- Quality Inspection & Testing: Each coil undergoes non-destructive testing (eddy current, ultrasonic, or dye penetrant inspection) and destructive mechanical testing per the applicable standard.
4.1 Room Temperature Tensile Testing Protocol
In accordance with the Room Temperature Tensile Test Method for Metal Coil Tubes, mechanical verification is performed as follows:
- Specimen Preparation: Test specimens are cut longitudinally from the coil tube, with gauge length of 5d₀ (for thin-walled tubes) or 50 mm (for thicker sections), conforming to GB/T 228.1 and ASTM E8.
- Test Conditions: Testing is conducted at ambient temperature (10°C – 35°C) in a calibrated universal testing machine (UTM) with crosshead speed controlled per the standard's strain-rate provisions.
- Measured Parameters: Proportional limit, yield strength (Rp0.2), tensile strength (Rm), elongation (A), and reduction of area (Z).
- Acceptance Criteria: All measured values must meet or exceed the minimum requirements specified in the product standard for the applicable grade.
- Coil-Specific Considerations: Due to the residual bending stresses inherent in coiled configuration, specimens are drawn from the coil and allowed to relax for a minimum of 4 hours before testing to ensure representative results.
5. Applications
Stainless steel coil tubes are employed across a broad spectrum of industrial and commercial sectors due to their combination of corrosion resistance, mechanical performance, and processing flexibility:
5.1 Chemical & Petrochemical Industry
- Process piping for aggressive chemical transfer systems
- Heat exchanger tubing and reactor internals
- Catalytic converter housings and emission control systems
5.2 Food & Beverage Processing
- Hygienic process piping (3-A / EHEDG compliant configurations)
- Beverage dispensing systems and brewing equipment
- Dairy processing lines and pharmaceutical-grade fluid transfer
5.3 Oil & Gas
- Downhole tubing and completion strings (duplex grades)
- Wellhead manifolds and pressure vessels
- Subsea umbilicals and flexible pipeline components
5.4 Automotive & Transportation
- Exhaust system components and turbocharger manifolds
- Hydrogen fuel cell system piping and balance-of-plant tubing
- Brake lines and high-pressure fuel injectors
5.5 Architecture & Construction
- Structural railings, handrails, and decorative elements
- Building façade systems and curtain wall profiles
- Water supply and fire suppression piping
5.6 Medical & Laboratory Equipment
- Surgical instrument tubing and medical gas lines
- Analytical instrument fluidic pathways
- Autoclave-resistant components for sterilization equipment
6. Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management system and holds the following certifications and compliances:
| Certification / Standard | Description |
|---|---|
| ISO 9001:2015 | Quality Management System certification ensuring consistent product quality and customer satisfaction. |
| ISO 14001:2015 | Environmental Management System certification demonstrating commitment to sustainable manufacturing practices. |
| ISO/IEC 17025 | Testing laboratory accreditation for in-house mechanical, chemical, and dimensional testing capabilities. |
| EN 10204 Type 3.1 | Material test certificates issued by an authorized inspection body, providing third-party verification of product conformity. |
| CE Marking (PED 2014/68/EU) | Compliance with the European Pressure Equipment Directive for components used in pressure systems. |
| NACE MR0175 / ISO 15156 | Qualification for use in sour service (H₂S-containing environments) in the oil and gas industry. |
| NSF / ANSI 61 | Drinking water system component certification for food-grade applications. |
7. Unique Selling Points
- Continuous-Length Supply: Coiled configuration eliminates the need for butt-welding short pipe segments, reducing labor costs, minimizing leak points, and improving system integrity.
- Precision Dimensional Control: Advanced cold-drawing technology and real-time coil tension monitoring ensure tight tolerances on OD and wall thickness throughout the entire coil length.
- Comprehensive Testing Protocol: Every coil undergoes room temperature tensile testing per the standardized Room Temperature Tensile Test Method for Metal Coil Tubes, ensuring mechanical properties are verified with coil-specific specimen preparation and relaxation protocols.
- Wide Grade & Specification Range: Product availability spans austenitic, ferritic, and duplex stainless steel grades across multiple international standards, enabling single-source procurement for diverse project requirements.
- Custom Coiling Configuration: Coil diameter, core size, and length are customizable to match downstream processing equipment, optimizing material utilization and reducing waste.
- Full Traceability: Each coil is tagged with heat number, grade, dimensions, and test results, enabling complete material traceability from raw steel mill to final installation.
8. Technical Reference
Primary Testing Standard: 《金属盘管的室温拉伸试验方法》 — Room Temperature Tensile Test Method for Metal Coil Tubes. This standard defines specimen geometry, test apparatus calibration, loading rates, and