Customized High-Temperature Slotted Nut for Steam Turbine
The High-Temperature Slotted Nut is a specialized locking fastener designed to complement the turbine's high-temperature stud bolts, particularly in critical flanged connections subject to extreme heat and vibration. This nut is engineered to ensure a secure, precisely controlled preload and features an inherent mechanical locking capability that is essential for maintaining joint integrity and preventing catastrophic failure.
1. Product Functions
1.1 Precise Tightening and Adjustment
The internal thread of the nut achieves a precision grade of 6H, manufactured via advanced cold rolling or grinding processes to ensure a smooth thread surface (Ra ≤ 0.8 μm) and minimal fit clearance with mating bolts. This high precision enables uniform transfer of pre-tightening force across the thread interface, eliminating localized stress caused by uneven force distribution and enhancing the stability of turbine core connections (e.g., rotor-flange joints). The external slotted structure is engineered with a 0.05mm tolerance for slot width and depth, compatible with custom slotted wrenches featuring anti-slip tooth profiles. This design allows torque control accuracy within ±3%, critical for meeting the strict pre-tightening requirements of turbine components operating at high speeds (up to 15,000 rpm).
1.2 Anti-Loosening and Locking
The slotted configuration is fully compatible with standard anti-loosening components, including stainless steel split pins (ASTM A480) and high-temperature locking washers (Inconel 718). After tightening the nut to the specified torque (typically 80-120 N·m for turbine applications), inserting a split pin through the nut slot and corresponding bolt hole forms a mechanical interlock. This structure effectively resists loosening caused by high-frequency vibration (10-500 Hz) and extreme thermal shock (temperature fluctuations of -40℃ to 650℃). Test data shows that after 1,000 thermal cycles and 2,000 hours of vibration testing, the nut’s loosening displacement remains below 0.02mm, far exceeding industry standards for turbine reliability.
1.3 Adaptation to Thermal Deformation
The slotted nut's overall structure is optimized using finite element analysis software to simulate thermal stress distribution under turbine operating conditions (continuous service temperature up to 600℃). The nut is fabricated from A286 high-temperature alloy, whose thermal expansion coefficient is matched with the mating bolts and flange materials. This material compatibility reduces thermal stress concentration at the nut-bolt interface by over 40%, preventing thread deformation or seizure caused by temperature differences. Additionally, the nut's root adopts a circular arc transition design , lowering the stress concentration factor to ≤1.2 and extending the service life of connected components by 2-3 times compared to conventional nuts. At 600℃, the nut retains over 80% of its room-temperature tensile strength, ensuring long-term mechanical stability in high-temperature environments.
2. Drawing-Based Processing
Drawing-Based Processing: Manufacture strictly per customer-provided drawings, complying with dimensional tolerances, surface finish requirements, and material specifications. Key processes include CNC turning, thread grinding, slot milling, and heat treatment. Post-processing inspection covers thread precision, slot geometry, and mechanical properties.
This high-temperature slotted nut is tailored for gas/steam turbine hot-end components. Its core advantages—precision torque control, anti-loosening reliability, and thermal deformation resistance—ensure seamless adaptation to extreme turbine. Convert design requirements into physical products with 100% drawing compliance, supporting turbine efficiency and maintenance cycle optimization.
