S-91257A821 5/8"-11 x 7 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 150,000 psi tensile strength and Rockwell C33 hardness for reliable performance in high-stress applications
• Superior corrosion resistance through zinc yellow-chromate plating that protects against harsh industrial environments
• Optimized thread engagement with 5/8"-11 UNC coarse threads providing faster installation and enhanced vibration resistance
• Secure torque transmission via external hex drive design that prevents tool slippage during high-torque applications
• Precision manufacturing ensuring Class 2A thread fit for consistent performance and easy assembly
• Partial threading design offering concentrated thread engagement where maximum holding power is required
• Industry compliance assurance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed quality and reliability

Professional Applications & Engineering Value

This Grade 8 heavy-duty hex head screw delivers exceptional engineering value through its high-strength steel construction and zinc yellow-chromate plating, specifically designed to address critical industrial fastening challenges. The 5/8"-11 UNC coarse thread configuration ensures rapid installation while maintaining superior clamping force in heavy machinery, structural steel connections, and equipment assembly applications. The partially threaded design concentrates stress distribution at critical engagement points, preventing thread stripping in high-vibration environments. With 150,000 psi tensile strength and Rockwell C33 hardness, these external hex drive screws provide reliable performance in construction, manufacturing, and automotive applications where failure is not an option. The corrosion-resistant finish extends service life in demanding conditions, making these industrial strength screws ideal for permanent installations requiring long-term reliability.

Specification Summary & Compliance

This heavy-duty hex head screw features precise Class 2A thread fit with 5/8"-11 UNC coarse threads and partial threading extending to a minimum of 1 3/4". Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and mechanical properties. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, guaranteeing safe use across various industrial sectors while maintaining the highest quality standards for professional applications.