S-91257A923 7/8"-9 x 5 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 withstands harsh industrial environments
• Optimized thread engagement with UNC coarse threading and Class 2A fit ensuring secure fastening and vibration resistance
• Heavy-duty construction meeting Grade 8 specifications for maximum durability in demanding applications
• Easy installation and removal with external hex drive design providing superior torque transmission
• Versatile partial threading allowing for both clamping force and adjustment flexibility in assembly
• Regulatory compliance assurance with RoHS 3 and REACH standards for environmental and safety requirements

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers exceptional engineering value for heavy machinery, structural steel connections, and industrial equipment where failure is not an option. The 7/8"-9 UNC coarse thread configuration provides superior resistance to vibration loosening while maintaining easy assembly in field conditions. The zinc yellow-chromate plating creates a robust barrier against corrosion, significantly extending service life in outdoor or chemically aggressive environments. With partial threading and 5 1/2" length, this fastener offers optimal grip range for thick material assemblies while the external hex drive ensures maximum torque application without stripping. These industrial fasteners solve critical challenges in construction, mining equipment, and heavy vehicle manufacturing where 150,000 PSI tensile strength prevents catastrophic joint failure under extreme loads.

Specification Summary & Compliance

This hex head screw features precise Class 2A thread fit tolerances with 7/8"-9 UNC coarse threading and 2" minimum thread length. 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, making it suitable for global industrial applications requiring strict chemical substance control.