S-91211A233 3/4"-10 x 4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Thread-Locking Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 psi ensures reliable performance under extreme loads, preventing fastener failure in demanding applications.
• Vibration-resistant nylon patch provides secure locking from -55° to 250° F, maintaining clamp load and assembly integrity in high-stress environments.
• High hardness (Rockwell C33) offers superior wear resistance and durability, extending the screw's service life in abrasive conditions.
• Zinc yellow-chromate plating delivers excellent corrosion protection, safeguarding the fastener against rust and environmental degradation.
• Coarse UNC threading enables faster installation and reduced cross-threading risk, improving assembly efficiency and reliability.
• External hex drive design allows for high-torque application with standard tools, ensuring tight and secure fastening.
• Partial threading provides an unthreaded shank for precise clamping and shear strength in structural connections.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to solve critical fastening challenges in heavy machinery, construction, and automotive assemblies where vibration loosening and high tensile loads are common. The nylon patch thread locker eliminates the need for separate locking washers or adhesives, providing consistent resistance to dynamic forces across a wide temperature range from -55° to 250° F. Manufactured from zinc yellow-chromate plated steel, it offers superior corrosion protection for outdoor and harsh environment applications. The 3/4"-10 UNC coarse thread configuration ensures rapid installation in thick materials while maintaining Class 2A thread fit precision for reliable engagement. These characteristics make it ideal for structural connections, equipment frames, and high-stress industrial applications requiring 150,000 psi tensile strength and vibration-resistant performance.

Specification Summary & Compliance

This fastener features Class 2A thread fit tolerance for consistent engagement and meets ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. The UNC coarse thread with 3/4"-10 sizing follows standardized threading protocols. Manufacturing complies with industry standards for Grade 8 strength classification, ensuring 150,000 psi minimum tensile strength and Rockwell C33 hardness. The zinc yellow-chromate plating provides RoHS and REACH compliant corrosion protection for environmental safety.