S-91247A459 5/8"-18 x 8 1/2" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With 120,000 psi tensile strength, this screw reliably handles high-stress applications, reducing the risk of fastener failure in demanding environments.
• Superior Corrosion Resistance – The zinc plating provides a durable protective layer, extending service life and maintaining performance in humid or outdoor settings.
• Precise Thread Engagement – UNF fine threading and Class 2A fit ensure tight, secure fastening with minimal vibration loosening, ideal for machinery and structural assemblies.
• High-Grade Material Durability – Made from Grade 5 steel with Rockwell C25 hardness, it offers excellent wear resistance and long-term reliability under heavy loads.
• Optimized for Industrial Use – The external hex drive and hex head design allow for easy installation with standard tools, speeding up assembly in maintenance and production lines.
• Regulatory Compliance Assurance – Meets ASME B18.2.1 and SAE J429 standards, plus RoHS 3 and REACH compliance, ensuring safety and environmental responsibility in global supply chains.
• Versatile Partial Threading – The partially threaded shank provides strong clamping force where needed, making it suitable for a range of bolting and fastening configurations.

Professional Applications & Engineering Value

This 5/8"-18 UNF hex head screw is engineered to address common industrial challenges such as vibration-induced loosening and corrosion in heavy-duty applications. Constructed from Grade 5 steel with a zinc-plated finish, it combats environmental wear while maintaining structural integrity. The fine UNF threading and Class 2A thread fit deliver precise alignment and secure fastening, critical in machinery, construction, and automotive assemblies where reliability is paramount. Its external hex drive facilitates quick installation with common tools, reducing downtime. Ideal for use in equipment frames, structural supports, and industrial machinery, this screw ensures long-term performance by mitigating fatigue and corrosion risks, supported by compliance with ASME B18.2.1 and other industry standards.

Specification Summary & Compliance

This fastener adheres to precise dimensional tolerances, including a Class 2A thread fit for consistent engagement and UNF fine thread standards to ensure compatibility. It meets ASME B18.2.1 and SAE J429 specifications for quality and performance, and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and material restrictions adherence.