S-91286A348 1/2"-13 x 4 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With a 150,000 psi tensile rating, this screw withstands extreme loads and vibrations, reducing the risk of fastener failure in demanding applications.
• Superior Corrosion Resistance – The zinc-flake coating provides long-lasting protection against rust and environmental degradation, extending service life in harsh industrial settings.
• High Hardness for Durability – Rockwell C33 hardness ensures the screw maintains its shape and thread integrity under high torque and repeated use.
• Reliable Thread Engagement – Partially threaded design with UNC coarse threads offers quick assembly and secure holding power, minimizing cross-threading risks.
• Heavy-Duty Grade 8 Certification – Meets stringent Grade 8 standards, guaranteeing consistent performance for critical structural and machinery fastening.
• Easy Installation with External Hex Drive – The 3/4" hex head allows for high-torque application using standard tools, speeding up assembly and maintenance.
• Broad Regulatory Compliance – Conforms to ASME B18.2.1, SAE J429, RoHS 3, and REACH, ensuring safety and environmental standards are met for global supply chains.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, this Grade 8 hex head screw delivers reliable performance where high strength and corrosion resistance are critical. The steel material combined with zinc-flake coating effectively combats moisture, chemicals, and UV exposure, making it ideal for construction equipment, automotive assemblies, and machinery frames. Its UNC coarse thread and Class 2A thread fit ensure easy alignment and robust clamping force, reducing installation time and preventing loosening under dynamic loads. By specifying this partially threaded fastener, engineers achieve precise load distribution and vibration resistance, enhancing the longevity and safety of bolted joints in structural and mechanical systems.

Specification Summary & Compliance

This screw features a 1/2"-13 UNC coarse thread with Class 2A tolerance for consistent fit and performance. It complies with ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring adherence to environmental and safety regulations.