Stainless Steel Coil Tube (Coiltube) — Nuclear-Grade Seismic-Resilient Product
1. Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered, continuously wound tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product Reference No. 801). This product is specifically designed for demanding industrial applications, with particular emphasis on nuclear power plant (NPP) auxiliary systems where seismic resilience and long-term structural integrity are critical safety requirements. The coil tube configuration offers superior flexibility, efficient material utilization, and simplified installation compared to straight-length pipe sections, making it an ideal solution for heat exchange, ventilation, and fluid transport systems within nuclear containment environments.
Based on research and development informed by seismic qualification testing of nuclear-grade fan coil tube prototypes, this product line demonstrates validated performance under simulated seismic loading conditions consistent with international nuclear safety standards.
2. Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its exceptional corrosion resistance, mechanical ductility, and non-magnetic properties essential for nuclear service.
- Material Grades: AISI 304 (UNS S30400), AISI 316 (UNS S31600), and AISI 321 (UNS S32100)
- Key Mechanical Properties: Tensile strength ≥ 515 MPa (304 grade), elongation ≥ 40%, yield strength ≥ 205 MPa
- Corrosion Resistance: Excellent resistance to intergranular corrosion, pitting, and stress corrosion cracking (SCC) in high-temperature and high-humidity environments
- Temperature Range: Operating temperature from −196 °C to +870 °C (304 grade)
- Surface Finish: Electropolished or passivated, surface roughness Ra ≤ 0.4 μm
- Non-Magnetic: Magnetic permeability ≤ 1.05 (after cold working)
3. Specifications
| Parameter | Specification |
|---|---|
| Product Category | Stainless Steel Coil Tube (盘管 / Coiltube) |
| Reference Number | 801 |
| Outer Diameter (OD) | Φ6.0 mm – Φ50.8 mm (customizable) |
| Wall Thickness | 0.5 mm – 3.0 mm |
| Coil Length | 5 m – 200 m per coil |
| Coil Diameter | 500 mm – 2000 mm (adjustable per application) |
| Material Standard | ASTM A213 / ASTM A269 / GB/T 12771 |
| Manufacturing Standard | EN 10217-7 / ASME B31.3 / IEC 60895 |
| Seismic Qualification | Compliant with IEEE 344 / GB 19905 (nuclear seismic design) |
| Surface Treatment | Electropolished / Pickled & Passivated |
| Packaging | Wooden crate with moisture-proof wrapping; coil secured with steel bands |
| Traceability | Full heat-number traceability with mill test certificates (MTC) |
4. Manufacturing Process
- Raw Material Selection & Inspection: Stainless steel strip or tube blanks are sourced from certified mills with full chemical and mechanical analysis. Incoming material undergoes ultrasonic testing (UT) and visual inspection for defects.
- Forming & Welding: Cold-rolled stainless steel strip is precision-formed into tubular geometry via high-frequency induction welding (HF-W) or orbital TIG welding (GTAW), ensuring uniform weld bead quality and metallurgical integrity.
- Heat Treatment & Annealing: Solution annealing at 1050–1150 °C followed by rapid cooling to restore full austenitic structure, relieve residual stresses, and ensure maximum corrosion resistance.
- Coiling: The finished tube is wound into a continuous coil using CNC-controlled coiling equipment, maintaining consistent curvature radius and preventing kinking or ovality.
- Surface Finishing: Electropolishing or acid pickling and passivation to achieve a clean, contamination-free surface suitable for nuclear-grade service.
- Quality Assurance & Testing: Each coil undergoes dimensional inspection (OD, wall thickness, ovality), hydrostatic pressure testing (per ASTM A213), and spectral analysis (PMI) for material verification.
- Seismic Qualification Testing: Prototype assemblies incorporating the coil tube are subjected to seismic qualification tests simulating Safe Shutdown Earthquake (SSE) conditions, validating structural integrity under dynamic loading per IEEE 344 methodology.
5. Applications
- Nuclear Power Plant (NPP) Systems: Auxiliary ventilation ducting, HVAC coil assemblies, emergency cooling system piping, and containment atmosphere monitoring conduits
- Industrial Heat Exchangers: Compact heat exchanger coils for process cooling, condensation, and evaporator applications
- Chemical & Petrochemical Industry: Corrosive fluid transport, reactor cooling loops, and distillation column internals
- Pharmaceutical & Food Processing: Sanitary-grade fluid conveying, CIP (Clean-in-Place) compatible tubing systems
- Oil & Gas: Subsea umbilicals, wellhead instrumentation tubing, and offshore platform piping
- Power Generation (Conventional): Boiler feedwater systems, steam generator support structures, and turbine cooling circuits
6. Quality Certifications & Compliance
- ISO 9001:2015 — Quality Management System certification
- ISO 14001:2015 — Environmental Management System
- Nuclear Quality Assurance (NQA-1): Compliance with U.S. Nuclear Regulatory Commission (NRC) Quality Assurance requirements for nuclear facility components
- ASME "U" Stamp: Authorization for pressure-containing equipment fabrication
- EN 10204 3.1 Certificate: Material Test Reports issued by qualified third-party inspectors
- IEEE 344 Compliance: Seismic qualification testing methodology validated for nuclear-grade components
- GB 19905: Chinese national standard for seismic design of nuclear power plants
7. Unique Selling Points
Seismic-Validated Performance: This coil tube product line is uniquely backed by empirical seismic qualification test data from nuclear power plant fan coil prototype studies, providing demonstrated structural resilience under extreme dynamic loading — a critical differentiator for safety-of-life nuclear applications.
- End-to-End Traceability: Every coil is traceable to its mill heat number with complete documentation chain from raw material to final delivery.
- Nuclear-Grade Manufacturing Discipline: Production processes adhere to NQA-1 quality assurance principles, ensuring documented control at every stage.
- Design Flexibility: Customizable OD, wall thickness, and coil dimensions allow seamless integration into diverse system architectures without compromising material integrity.
- Superior Corrosion & Fatigue Resistance: The austenitic stainless steel matrix combined with controlled manufacturing ensures long service life in aggressive nuclear coolant and ventilation environments.
- Efficient Installation: The coiled configuration reduces field welding and fitting requirements, minimizing installation time and potential leak points in containment-boundary systems.
8. Conclusion
The Wenzhou Jixing Metal Materials Co., Ltd. Stainless Steel Coil Tube (Product No. 801) represents a high-integrity, nuclear-grade tubular solution validated through rigorous seismic qualification testing. Its combination of superior material properties, precision manufacturing, and comprehensive quality assurance makes it a reliable choice for critical infrastructure applications where failure tolerance is zero and regulatory compliance is non-negotiable.