Stainless Steel Coil Tube with Radiographic Testing (RT) Quality Assurance
Product Overview
Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 94) offers premium-grade stainless steel coil tubes manufactured to the highest industry standards and subjected to rigorous non-destructive testing (NDT) protocols. This product line is distinguished by its comprehensive radiographic testing (RT) program, which employs both X-ray and gamma-ray film or digital imaging techniques to ensure exceptional weld integrity and structural reliability. The coil tube format provides superior flexibility in downstream processing, making it ideal for applications demanding precision, corrosion resistance, and verified material quality.
Unlike standard coil tube offerings, this product incorporates an arbitration-grade quality assurance system where volumetric defect detection — including porosity, slag inclusions, and other internal discontinuities — is performed with the highest possible sensitivity. This ensures that every coil tube delivered meets the most stringent acceptance criteria required by critical industries.
Material & Properties
The stainless steel coil tubes are manufactured from high-quality austenitic and duplex stainless steel grades, offering excellent mechanical properties, corrosion resistance, and formability. Key material characteristics include:
- Corrosion Resistance: Superior resistance to pitting, crevice, and intergranular corrosion across a wide range of chemical environments
- Mechanical Strength: High tensile strength and yield strength suitable for pressure-containing applications
- Formability: Excellent cold-forming and bending characteristics, enabling complex geometries without cracking
- Weldability: Compatible with all standard welding processes including TIG, MIG, and resistance welding
- Temperature Performance: Maintains mechanical integrity from cryogenic temperatures up to 870°C (1,600°F)
- Hygienic Surface: Available in sanitary finishes (Ra ≤ 0.5 μm) suitable for food-grade and pharmaceutical applications
Specifications
| Parameter | Specification | Standard |
|---|---|---|
| Material Grades | 304, 304L, 316, 316L, 321, 347, 904L, 2205, 2507 | ASTM A554 / EN 10217-7 |
| Outer Diameter | 3.00 – 219.00 mm (0.12" – 8.62") | ASTM B534 / EN 10217 |
| Wall Thickness | 0.30 – 12.00 mm (0.012" – 0.472") | ASTM B534 / EN 10217 |
| Coil Length | 20 – 100 m (66 – 328 ft) per coil | — |
| Surface Finish | 2B, BA, No. 4, No. 8, Electropolished (Ra ≤ 0.25 μm) | ASTM A478 |
| Tolerance — OD | ±0.05 mm to ±0.50 mm (per EN 10217 Class 1 or 2) | EN 10217-7 |
| Tolerance — Wall Thickness | ±10% of nominal (Class 1) / ±15% (Class 2) | EN 10217-7 |
| End Form | Plain, Beveled, Threaded, or Custom | — |
| Weld Type | Longitudinal welded (ERW / TIG) or Seamless | ASTM A554 / ASTM A213 |
| Coil Core | 50.8 mm (2"), 101.6 mm (4"), or 203.2 mm (8") | — |
| Heat Treatment | Solution Annealed, Pickled & Passivated | ASTM A999 |
Manufacturing Process
- Raw Material Selection: Only certified stainless steel strip or hot-rolled coil from approved mills is procured, with full material traceability and chemical composition verification via spectroscopic analysis.
- Coil Winding / Forming: Precision cold-forming or ERW (Electric Resistance Welding) processes shape the strip into tube geometry with controlled dimensional tolerances.
- Welding (if applicable): TIG or ERW welding is performed with inert gas shielding to ensure clean, oxidation-free welds. Weld parameters are monitored in real-time for process consistency.
- Heat Treatment: Tubes undergo solution annealing at 1050–1150°C (1,922–2,092°F) followed by controlled cooling to achieve uniform microstructure and maximum corrosion resistance.
- Pickling & Passivation: Acid pickling removes oxide scale, followed by passivation treatment to establish a protective chromium oxide layer on the surface.
- Surface Finishing: Mechanical or electrochemical polishing achieves the required surface roughness specifications.
- Dimensional Inspection: Automated gauging verifies OD, wall thickness, and roundness throughout the coil length.
- Radiographic Testing (RT) — See Quality Assurance section below.
- Final Coiling & Packaging: Tubes are coiled on appropriate cores, wrapped in protective material, and labeled with full traceability documentation.
Quality Assurance: Radiographic Testing (RT) Program
NDT Classification: Radiographic Testing (RT)
Wenzhou Jixing Metal Materials employs X-ray and gamma-ray film or digital radiographic imaging as a primary quality assurance method for weld verification. This represents the company's commitment to delivering products with verified internal integrity.
Capabilities and Performance
- High Volumetric Defect Detection: The RT program achieves exceptionally high detection rates for volumetric defects including porosity (gas voids), slag inclusions, and internal voids — the most critical defect types affecting structural integrity and pressure containment.
- Weld Quality Arbitration: RT serves as the definitive arbitration method for weld quality disputes, providing objective, permanent records of internal weld condition that cannot be contested.
- Full-Penetration Verification: Both X-ray and gamma-ray sources can verify complete weld fusion and penetration, ensuring no lack-of-fusion or incomplete penetration defects exist.
- Permanent Documentation: Film-based and digital imaging records provide permanent, auditable proof of weld quality for regulatory compliance and traceability.
Testing Parameters
| RT Parameter | Specification |
|---|---|
| Imaging Method | X-ray film, gamma-ray film, or digital radiography (CR/DR) |
| Energy Source | X-ray tube (40–300 kVp) / Iridium-192 or Cobalt-60 gamma source |
| Image Quality Indicator (IQI) | Wire or step-wedge per ASTM E1019 / EN ISO 17636 |
| Acceptance Criteria | ASTM E94 / EN ISO 17636-2 (Type B1 or B2 quality level) |
| Sampling Rate | 100% for critical applications; 10–100% for standard orders |
| Defect Types Detected | Porosity, slag inclusions, lack of fusion, incomplete penetration, internal cracks |
| Reporting | Detailed radiographic reports with film/digital images, density measurements, and pass/fail disposition |
Advantages of RT-Based Quality Assurance
Industry-recognized arbitration standard: Radiographic testing is universally accepted as the gold standard for weld quality arbitration. When disputes arise regarding weld integrity, RT provides the most objective and irrefutable evidence of internal weld condition. This gives end-users absolute confidence in product reliability.
While RT is recognized as a higher-cost and slower inspection method compared to surface NDT techniques (such as magnetic particle or dye penetrant testing), Wenzhou Jixing Metal Materials considers this investment essential for delivering products suitable for safety-critical and regulated applications. The comprehensive defect detection capability of RT — particularly its unmatched sensitivity to volumetric discontinuities — directly translates to reduced failure risk in service.
Applications
The combination of premium material quality and RT-verified weld integrity makes this stainless steel coil tube suitable for demanding applications across multiple industries:
- Oil & Gas: Downhole tubing, wellhead components, pipeline connectors, and subsea equipment where weld integrity is critical for pressure containment
- Chemical Processing: Reactor internals, heat exchanger tubes, piping systems handling aggressive chemical media
- Food & Beverage: Hygienic processing lines, brewing equipment, dairy processing systems (sanitary finish options)
- Pharmaceutical: CIP/SIP-compatible piping, bioreactor components, and high-purity transfer lines
- Petrochemical: Distillation columns, vapor recovery systems, and high-temperature process piping
- Power Generation: Boiler tubes, heat exchangers, and superheater components
- Medical Devices: Instrument tubing, surgical equipment housings, and implant-grade components
- Marine & Offshore: Seawater cooling systems, ballast piping, and offshore platform structures
Quality Certifications & Compliance
Wenzhou Jixing Metal Materials Co., Ltd. maintains a comprehensive certification portfolio ensuring full regulatory compliance and customer confidence:
- ISO 9001:2015 — Quality Management System certification ensuring consistent product quality and process control
- ISO 3834 — Welding quality requirements (Part 2: Comprehensive certification)
- EN 10204 3.1 — Third-party inspection certificates available upon request
- NACE MR0175 / ISO 15156 — Compliance for sour service applications (H₂S environments)
- ASME Stamp (where applicable) — For pressure-containing component applications
- Mill Test Certificates (MTC) — Full chemical and mechanical analysis documentation for every heat
- NDT Personnel Certification — RT operators certified to ASNT SNT-TC-1A Level II or ISO 9712 Level II
- Material Traceability — Full heat-number traceability from mill origin through final delivery
Unique Selling Points
- Arbitration-Grade Quality Assurance: Every critical weld is verified through radiographic testing — the universally accepted arbitration standard for weld quality — providing customers with irrefutable proof of product integrity.
- Superior Volumetric Defect Detection: RT's exceptional sensitivity to porosity, slag inclusions, and other internal defects ensures that only structurally sound tubing reaches the customer.
- Full Traceability: Complete documentation chain from raw material through RT inspection to final delivery supports regulatory audits and quality investigations.
- Flexible Coil Format: The coil configuration enables efficient downstream processing with minimal waste, while maintaining the dimensional precision of individually cut tubes.
- Multi-Grade Availability: Broad material selection from standard austenitic grades to high-performance super-austenitic and duplex steels accommodates the most demanding service conditions.
Wenzhou Jixing Metal Materials Co., Ltd. is committed to delivering stainless steel coil tube products that combine proven material performance with the highest level of quality assurance. The integration of radiographic testing into the standard quality program reflects a philosophy that in critical applications, thoroughness in inspection is never an unnecessary cost — it is the foundation of reliability and safety.