S-91257A224 7/8"-9 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 for reliable performance in high-stress applications
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh environments
• Optimized thread engagement through 7/8"-9 UNC coarse thread design ensuring secure fastening and vibration resistance
• Enhanced installation efficiency with external hex drive and hex head design allowing for high-torque application
• Precise thread compatibility with Class 2A thread fit ensuring consistent mating with standard nuts and components
• Robust material performance featuring Grade 8 steel with Rockwell C33 hardness for maximum durability
• Regulatory compliance assurance meeting industry standards for safety and environmental requirements

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers exceptional engineering value for heavy-duty industrial applications where reliability is paramount. The partially threaded 7/8"-9 UNC coarse thread configuration provides optimal stress distribution while preventing thread damage during installation. Manufactured from high-strength steel with zinc yellow-chromate plating, this fastener effectively combats corrosion in demanding environments including construction equipment, machinery assembly, and structural applications. The external hex drive design facilitates high-torque installation with standard tools, while the 7 1/2" length accommodates thick material sections. This combination of material strength, corrosion protection, and precise threading addresses critical challenges in industrial fastening, including vibration loosening, environmental degradation, and mechanical failure under extreme loads.

Specification Summary & Compliance

This 7/8"-9 UNC hex head screw maintains Class 2A thread fit tolerance for consistent mating with standard components. The fastener complies with ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and mechanical properties. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) standards, confirming the absence of restricted substances. The partially threaded design with 2 1/4" minimum thread length provides optimal unthreaded shank for shear applications while maintaining full thread engagement in standard thickness materials.