Stainless Steel Coil Tube with Metallographic & Eddy Current Verification — Wenzhou Jixing Metal Materials
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 210) offers a premium-grade stainless steel coil tube designed for demanding industrial applications where material integrity and authenticity are paramount. This product line addresses a critical market challenge: the visual similarity between welded and seamless stainless steel coil tubes, which has historically allowed fraudulent substitution in procurement chains. Through rigorous quality verification protocols — including metallographic examination of the weld zone and eddy current (ET) signal comparison — Jixing ensures that every coil tube delivered meets the exact specification ordered, whether welded or seamless.
The coil tube is supplied in continuous coil form, enabling efficient downstream processing, minimal waste, and high throughput in manufacturing operations. Available in a range of austenitic, ferritic, and duplex stainless steel grades, the product serves sectors from chemical processing to oil and gas infrastructure.
Material & Properties
Available Grades
- Austenitic: 304, 304L, 316, 316L, 321, 347
- Ferritic: 430, 444
- Super-Austenitic: 904L, 254 SMO, Alloy C-276
Mechanical & Physical Properties (Typical for Grade 316L)
- Tensile Strength: ≥ 485 MPa (≥ 70 ksi)
- Yield Strength (0.2% offset): ≥ 205 MPa (≥ 30 ksi)
- Elongation: ≥ 40%
- Density: 8.0 g/cm³ (0.29 lb/in³)
- Thermal Conductivity: 16.3 W/(m·K) at 100°C (300°F)
- Corrosion Resistance: Excellent resistance to pitting, crevice, and intergranular corrosion
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Product No. | 210 |
| Manufacturing Method | Welded (ERW) / Seamless — Verified via Metallography & Eddy Current |
| Outer Diameter | 3.0 – 219.1 mm (0.12 – 8.63 in) |
| Wall Thickness | 0.3 – 6.0 mm (0.012 – 0.236 in) |
| Coil Inner Diameter | 150 – 600 mm (5.9 – 23.6 in) |
| Coil Weight | Up to 2,500 kg (5,512 lb) per coil |
| Surface Finish | Bright Annealed (BA), 2B, Pickled & Passivated, or Custom |
| Applicable Standards | ASTM A213, ASTM A269, EN 10216-5, GB/T 14976 |
| Weld Seam | Single-pass or double-pass TIG — fully verified |
| Tolerance (OD) | ±0.05 mm to ±0.5 mm (±0.002 – ±0.020 in) depending on size |
| Verification Methods | Metallographic Microstructure Examination; Eddy Current (ET) Signal Comparison |
Manufacturing Process
- Coil Forming: Cold-rolled stainless steel strip is precision-fed through forming rolls to produce a continuous tubular blank with tight dimensional control.
- Welding: The tube blank is joined using high-frequency resistance welding (ERW) or transverse argon arc welding (TIG), producing a homogeneous weld seam with minimal heat-affected zone.
- Heat Treatment: Tubes undergo solution annealing at 1050–1150°C (1922–2092°F) followed by rapid water quenching to achieve the desired microstructure and corrosion resistance.
- Sizing & Coiling: Tubes pass through a sizing stand to finalize outer diameter and wall thickness, then are wound into coils on precision coilers.
- Surface Treatment: Bright annealing or pickling and passivation is applied according to customer specification.
- Quality Verification: Every coil undergoes mandatory metallographic examination and eddy current testing to confirm product authenticity and structural integrity.
Quality Verification — Unique Selling Point
"When appearance is highly similar, metallographic and eddy current verification is the only reliable method to distinguish welded from seamless coil tube."
This represents the core differentiator of Jixing's Product No. 210. In industrial procurement, the visual distinction between welded and seamless stainless steel coil tubes is often negligible, creating significant risk of unauthorized substitution. Jixing's verification protocol includes:
- Metallographic Examination: Cross-sectional samples from the weld zone are etched and examined under optical microscopy (50×–500×) to identify weld line microstructure, grain boundary morphology, and heat-affected zone characteristics unique to the welded process.
- Eddy Current (ET) Signal Comparison: Non-destructive eddy current testing generates characteristic signal signatures at the weld seam location. Seamless tubes produce uniform signal profiles, while welded tubes exhibit detectable anomalies at the weld line — providing a rapid, non-destructive authentication method.
- Full Traceability: Each coil is accompanied by a verification report documenting the test method, results, and certification of conformity.
This dual-verification approach ensures that customers receive precisely the product type they specified — eliminating procurement risk and protecting downstream applications from material substitution failures.
Applications
- Chemical Processing: Heat exchangers, reactor tubing, and process piping where corrosion resistance and material authenticity are critical
- Oil & Gas: Downhole tubing, wellhead components, and separation equipment
- Food & Pharmaceutical: Hygienic process tubing requiring verified sanitary-grade materials
- Power Generation: Boiler tubes, condenser tubes, and heat transfer components
- Marine & Offshore: Seawater cooling systems and desalination equipment
- Automotive & Aerospace: Precision tubing for fluid systems and structural components
Quality Certifications & Compliance
- ISO 9001:2015 Quality Management System Certified
- ISO 14001 Environmental Management System Certified
- ISO/IEC 17025 Laboratory Competence (Metallographic & NDT Testing)
- EN 10204 Type 3.1 Inspection Certificates available
- Mill Test Reports (MTR) with full chemical and mechanical analysis
- NDT Testing per ASTM E309 (Eddy Current) and ASTM E1051 (Metallography)
- Compliant with PED 2014/68/EU for pressure equipment applications
- Third-party inspection available (SGS, Bureau Veritas, TUV)
Why Choose Wenzhou Jixing Metal Materials
- Eliminates Procurement Risk: The industry-leading metallographic and eddy current verification system guarantees that customers receive exactly what they ordered — no unauthorized substitution.
- Full Traceability: Every coil carries complete documentation from raw material to final delivery, including verification reports.
- Wide Grade Availability: From standard austenitic to super-austenitic alloys, covering the full spectrum of stainless steel applications.
- Flexible Sizing: Comprehensive range of OD and wall thickness to accommodate custom engineering requirements.
- Cost-Efficient Coil Form: Continuous coil supply reduces cutting losses and maximizes material utilization in downstream fabrication.
- Global Supply Capability: Export-oriented manufacturing with international standard compliance and competitive lead times.