Stainless Steel Coil Tube — TOFD & Phased Array NDT Certified
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. manufactures high-grade stainless steel coil tubes (coiltubes) engineered for demanding industrial applications across energy, chemical processing, pharmaceutical, and food-grade sectors. These coil tubes are supplied in continuous wound coils, offering superior material utilization, reduced waste, and streamlined downstream forming and fabrication workflows.
What distinguishes this product line is the advanced non-destructive testing (NDT) protocol employed throughout production. Wenzhou Jixing integrates Time of Flight Diffraction (TOFD) and Phased Array Ultrasonic Testing (PAUT) as primary inspection methods — representing the industry's leading-edge approach to defect detection and quantification for tubular products.
Key Unique Selling Points
- Digital Imaging Superiority: TOFD and Phased Array produce high-resolution digital images of internal tube geometry, enabling far more accurate defect quantification than conventional methods.
- Defect Characterization Precision: Provides precise measurement of defect size, orientation, and depth — critical for safety-critical and pressure-vessel applications.
- Industry-Leading Inspection: TOFD/Phased Array is the recognized successor to radiographic testing (RT) for high-end projects, eliminating radiation hazards while delivering superior data fidelity.
- Full Digital Traceability: All inspection data is digitally archived, supporting complete quality traceability from raw material to finished coil.
- Reduced False Indications: Compared to conventional ultrasonic testing (UT), phased array reduces false call rates significantly, improving throughput and confidence.
Material & Properties
Coil tubes are available in a comprehensive range of stainless steel grades to suit diverse service environments:
- Austenitic Grades: 304, 304L, 316, 316L, 321, 347
- Duplex Grades: 2205, 2507
- Super Duplex: S32750
- Custom Grades: Available upon request for specialized applications
Typical mechanical properties (annealed condition) include:
- Tensile Strength: ≥ 520 MPa (75,400 psi) for austenitic grades
- Yield Strength: ≥ 205 MPa (29,700 psi)
- Elongation: ≥ 40%
- Corrosion Resistance: Excellent resistance to pitting, crevice, and intergranular corrosion
- Temperature Range: Operational from cryogenic temperatures up to 870°C (1,598°F)
Specifications
| Parameter | Specification |
|---|---|
| Product Name | Stainless Steel Coil Tube (Coiltube) |
| Outer Diameter (OD) | 6.0 mm (0.236 in) – 102.0 mm (4.016 in) |
| Wall Thickness | 0.5 mm (0.020 in) – 6.0 mm (0.236 in) |
| Coil Length | Up to 2,000 m (6,562 ft) per coil |
| Surface Finish | Pickled & Passivated (P&P), Bright Annealed, Matte |
| Manufacturing Standard | ASTM A213, ASTM A269, EN 10216-5, GB/T 14976 |
| Seam Type | Welded (ERW) or Seamless |
| NDT Method | TOFD (EN 1714), Phased Array UT (EN ISO 13588) |
| Defect Acceptance Criteria | ASME BPV Section V, EN 1714, per customer specification |
| Coil Packaging | Wooden reel or steel frame with moisture-proof wrapping |
| Weight per Coil | Up to 5,000 kg (11,023 lbs) |
Manufacturing Process
The production of Wenzhou Jixing coil tubes follows a tightly controlled, multi-stage manufacturing process:
- Raw Material Selection: Certified stainless steel strip from approved mills, verified for chemical composition and mechanical properties.
- Slitting & Edge Preparation: Precision slitting to specified width with deburring and edge quality inspection.
- Forming & Welding: High-frequency resistance welding (ERW) with precise heat input control to minimize heat-affected zone distortion.
- Heat Treatment: Full solution annealing in protective atmosphere to achieve required microstructure and corrosion resistance.
- Pickling & Passivation: Removal of oxide scale followed by chemical passivation to establish a protective chromium oxide layer.
- Coiling: Controlled coiling to maintain dimensional accuracy and prevent surface damage.
- Non-Destructive Testing (NDT): Comprehensive inspection using TOFD and Phased Array ultrasonic methods (detailed below).
- Final Dimensional & Visual Inspection: Verification of OD, wall thickness, and surface quality against specification tolerances.
- Packaging & Dispatch: Protective wrapping, moisture control, and secure coil packaging for transport.
Non-Destructive Testing — TOFD & Phased Array
Wenzhou Jixing employs TOFD and Phased Array ultrasonic testing as its primary volumetric inspection methods for coil tubes, positioning the company at the forefront of quality assurance in the tubular products industry.
TOFD (Time of Flight Diffraction)
- Principle: Measures the time of flight of ultrasonic diffractions from defect tips to precisely determine defect height.
- Advantage: Provides highly accurate defect sizing independent of defect orientation or reflectivity.
- Standard: Performed in accordance with EN 1714 and ASME BPV Section V, Article 4.
Phased Array Ultrasonic Testing (PAUT)
- Principle: Uses multi-element transducer arrays with electronic beam steering and focusing to generate sectorial scan images.
- Advantage: Produces real-time digital images of the tube wall, enabling comprehensive visualization of weld geometry and internal discontinuities.
- Standard: Performed in accordance with EN ISO 13588 and ASME BPV Section V, Article 4.
Why TOFD/Phased Array Over Radiographic Testing (RT)?
| Criteria | Radiographic Testing (RT) | TOFD / Phased Array |
|---|---|---|
| Defect Quantification | Approximate sizing | Precise, digital quantification |
| Imaging Type | 2D projection (analog or digital) | 3D sectorial scan with digital imaging |
| Radiation Hazard | Yes — requires shielding & access control | No — no ionizing radiation |
| Data Retention | Requires film or DR storage | Full digital dataset with automated reporting |
| Orientation Sensitivity | May miss non-planar defects | Orientations-independent with proper probe setup |
| Industry Trend | Declining in high-end applications | Preferred for critical projects |
"TOFD and Phased Array represent the clear industry trajectory for replacing radiographic testing in high-integrity applications. Their digital imaging capability provides defect quantification accuracy that is unmatched by conventional methods." — Industry Best Practice
Applications
- Oil & Gas: Downhole tubing, heat exchangers, subsea piping systems
- Power Generation: Boiler tubes, supercritical steam lines, condenser tubes
- Chemical & Petrochemical: Reactor internals, heat exchanger bundles, process piping
- Pharmaceutical & Biotech: Hygienic process tubing, CIP/SIP systems
- Food & Beverage: Sanitary processing lines, brewing equipment
- Marine & Offshore: Seawater systems, desalination plants, ballast water treatment
- Automotive: Exhaust system tubing, turbocharger components
- Heat Exchanger Manufacturing: Coil tubes ideal for U-tube and hairpin bending applications
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive quality management framework:
- ISO 9001:2015 — Quality Management System
- ISO 14001:2015 — Environmental Management System
- EN 10204 3.1 — Third-party material certification available
- EN 1714 — TOFD testing qualification
- EN ISO 13588 — Phased Array testing qualification
- ASME BPV Section V — NDT personnel qualification (Level II & Level III)
- API Q1 / API Q2 — Quality system certification for oil & gas products
- PED (EU 2014/68/EU) — Pressure Equipment Directive compliance
- Mill Test Certificates (MTC) — Provided with every shipment
Ordering & Customization
Wenzhou Jixing offers full customization support including:
- Custom OD and wall thickness combinations
- Special grade alloys and heat-treated conditions
- Tailored NDT protocols per customer or project specification
- Special surface finishes and end treatments
- Coil dimensions optimized for customer's downstream equipment
For detailed technical inquiries, quotation requests, or sample evaluation, contact Wenzhou Jixing Metal Materials Co., Ltd. directly. Our engineering team is available to assist with specification matching, NDT protocol development, and application engineering support.