S-91247A506 7/8"-14 x 3 1/4" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 120,000 psi tensile strength for reliable performance in demanding applications
• Superior corrosion resistance through zinc plating, extending service life in harsh industrial environments
• Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
• Optimized torque transmission via external hex drive and 1 5/16" head width for easy installation with standard tools
• Controlled thread engagement through partial threading design, preventing over-tightening in specific assembly scenarios
• Consistent mechanical properties with Rockwell C25 hardness, maintaining dimensional stability under stress
• Regulatory compliance assurance meeting ASME B18.2.1 and SAE J429 standards for quality and interoperability

Professional Applications & Engineering Value

This Grade 5 hex head screw delivers critical engineering solutions for heavy machinery, structural assemblies, and industrial equipment where high tensile strength and vibration resistance are paramount. The 7/8"-14 UNF fine thread configuration provides superior clamping force distribution compared to coarse threads, while the partial threading design allows for precise unthreaded shank placement in shear-critical applications. The zinc plated steel construction offers sacrificial corrosion protection, making these external hex drive fasteners ideal for outdoor equipment, agricultural machinery, and construction applications where environmental exposure is a concern. The combination of Rockwell C25 hardness and standardized dimensions ensures consistent performance across multiple connection points in complex assemblies.

Specification Summary & Compliance

Manufactured to precise Class 2A thread fit tolerances with UNF (Unified National Fine) thread form and right-hand thread direction. This fastener complies with ASME B18.2.1 dimensional specifications and SAE J429 Grade 5 mechanical requirements. The product meets RoHS 3 (2015/863/EU) compliance for hazardous substance restrictions and REACH (EC 1907/2006) regulations for chemical safety. Critical dimensions include 3 1/4" length, 2" minimum thread length, and 1 5/16" head width with 35/64" head height for standardized tool compatibility.