Stainless Steel Spiral Coil Tube — HTR-10 Steam Generator Grade
Product Overview
The Stainless Steel Spiral Coil Tube (Coiltube) is a precision-engineered tubular component designed specifically for high-temperature nuclear reactor applications, including the HTR-10 (High Temperature Reactor-10) pebble-bed modular reactor system. This product is manufactured by Wenzhou Jixing Metal Materials Co., Ltd and represents a critical heat-transfer element within the steam generator assembly of Generation IV nuclear reactor technology.
The spiral coil tube configuration enables superior heat exchange efficiency while maintaining structural integrity under extreme thermal cycling, neutron irradiation, and mechanical vibration conditions. The coiltube geometry provides a compact heat-transfer surface area while facilitating uniform coolant flow distribution across the generator channels.
Material & Properties
The coil tube is fabricated from austenitic stainless steel grades selected for exceptional resistance to oxidation, corrosion, and radiation-induced degradation in high-temperature helium environments.
- Base Material: AISI 304 / 316L austenitic stainless steel, or nickel-enhanced variants (e.g., Alloy 690, Alloy 800HT) depending on service temperature requirements.
- Operating Temperature Range: Up to 750°C (1,382°F) sustained; transient tolerance to 850°C (1,562°F).
- Corrosion Resistance: Excellent resistance to high-temperature oxidation in helium atmosphere; resistant to steam corrosion and intergranular attack.
- Creep Strength: Maintains tensile strength and elongation properties under prolonged high-temperature stress exposure.
- Neutron Irradiation Tolerance: Designed to resist radiation-induced swelling and embrittlement over design life cycles exceeding 60 years.
- Thermal Conductivity: Optimized for efficient radial heat transfer from primary helium coolant to secondary water/steam circuit.
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Outer Diameter (OD) | 14.0 – 22.0 | mm |
| Wall Thickness | 1.0 – 2.5 | mm |
| Coil Diameter (Helix Pitch) | 120 – 250 | mm |
| Coil Length (Uncoiled) | 3,000 – 15,000 | mm |
| Surface Finish (Inner) | ≤ 0.4 Ra (mirror polished) | — |
| Surface Finish (Outer) | ≤ 1.6 Ra (electropolished) | — |
| Acceptable Helix Deviation | ± 0.15 | mm |
| Maximum Allowable Pressure (Design) | 15.0 | MPa |
| Design Service Life | ≥ 60 | Years |
| Heat Treatment | Solution annealed at 1050°C, water quenched | — |
| Dimensional Tolerance (OD) | ± 0.05 | mm |
| Dimensional Tolerance (Wall) | ± 0.03 | mm |
Manufacturing Process
The production of HTR-10 grade spiral coil tubes follows a rigorously controlled multi-stage manufacturing sequence to ensure dimensional accuracy, metallurgical homogeneity, and freedom from manufacturing defects:
- Raw Material Selection & Inspection: Certified austenitic stainless steel bar stock undergoes 100% chemical composition analysis, ultrasonic flaw detection (UT), and grain boundary structure verification.
- Tube Forming: Seamless tubing is produced via hot-rolling or cold-piercing methods, followed by cold drawing to achieve precise inner and outer diameters.
- Coiling / Helix Forming: The straight tube is formed into a spiral coil geometry using CNC-controlled helix winding machines. The forming process employs controlled bending with precise die geometry to prevent wall thinning, ovality, or residual stress concentration.
- Stress Relief Annealing: Post-forming annealing at 850–950°C in a protective atmosphere eliminates residual bending stresses and stabilizes the microstructure.
- Surface Treatment: Internal and external surfaces are polished to specified roughness grades through mechanical polishing followed by electrochemical polishing (ECP) to remove surface contamination and enhance corrosion resistance.
- End Preparation & Welding: Tube ends are prepared for butt-welding or socket-welding connections to steam generator header assemblies. Welding is performed using Orbital Automatic TIG (Gas Tungsten Arc) welding with helium shielding.
- Final Inspection & Testing: Each coil tube assembly undergoes hydrostatic pressure testing, eddy current inspection (ECI), radiographic examination (RT), and dimensional verification prior to shipment.
Applications
The HTR-10 Steam Generator Spiral Coil Tube serves as a primary heat exchanger component in the following applications:
- High Temperature Gas-Cooled Reactors (HTGR): Integral steam generators in pebble-bed modular reactors (e.g., HTR-10, THTR-10, HTR-PM).
- Generation IV Nuclear Power Plants: Advanced reactor designs requiring high-temperature, high-reliability heat transfer components.
- Nuclear Fuel Reprocessing Facilities: Heat exchangers in reprocessing plant secondary circuits.
- High-Performance Industrial Heat Exchangers: Compact spiral coil heat exchangers for chemical processing, petrochemical, and aerospace thermal management systems.
- Vibration Analysis & Structural Integrity Research: The coil tube geometry is a subject of dynamic analysis for vibration mode identification, natural frequency determination, and stability assessment under flow-induced vibration (FIV) conditions.
Unique Selling Points
- Optimized Spiral Geometry: The helical coil design maximizes heat transfer surface area per unit volume while minimizing pressure drop, achieving thermal efficiency exceeding 95% in steam generator channels.
- Proven Nuclear-Grade Reliability: Manufactured to meet ASME BPV Section III (Nuclear Power Plant Components) and RCC-M (French Nuclear Code) requirements, with full traceability documentation.
- Vibration Resistance: The coil tube configuration has been validated through finite element analysis (FEA) and experimental modal analysis for resistance to flow-induced vibration in high-velocity helium streams.
- Full Lifecycle Quality Assurance: End-to-end quality control from raw material certification through final product acceptance testing, with complete non-destructive examination (NDE) records.
Quality Certifications
Wenzhou Jixing Metal Materials Co., Ltd maintains a comprehensive quality management and nuclear-grade certification portfolio:
- ISO 9001:2015 — Quality Management Systems
- ISO 3834-2 — Welding Quality Requirements for Steel Products
- ASME "U" Stamp — National Board Registration for Pressure Vessel Components
- ASME "N" Stamp — Nuclear Pressure Vessel and Piping Components
- EN 1090 — Execution of Steel Structures (where applicable)
- IAEA INFCIRC/225 — Nuclear Material Safeguards Compliance
- HAF Certificate (China) — Nuclear Safety Administration of China Manufacturing License
- 100% NDE Coverage: Ultrasonic Testing (UT), Radiographic Testing (RT), Eddy Current Testing (ET), and Dye Penetrant Testing (PT) performed per ASTM E164, ASTM E1417, and relevant nuclear industry codes.
Note: The HTR-10 steam generator spiral coil tube represents a critical safety-related component in Generation IV nuclear reactor technology. All manufacturing, inspection, and testing procedures are conducted under a Nuclear Quality Assurance (NQA-1) program to ensure compliance with international nuclear safety standards and regulatory requirements.