S-91247A361 1/2"-20 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 Grade 5 steel construction and 120,000 psi tensile strength for reliable performance in high-stress applications
• Superior corrosion protection through zinc plating, extending service life in demanding industrial environments
• Precise thread engagement with UNF fine threading and Class 2A fit ensuring vibration resistance and secure fastening
• Optimized torque transmission via external hex drive and 3/4" head width for easy installation with standard tools
• Controlled thread engagement through partial threading design, preventing over-tightening in critical assemblies
• Enhanced durability with Rockwell C25 hardness maintaining structural integrity under repeated stress
• Regulatory compliance assurance meeting ASME B18.2.1 and SAE J429 standards for quality and safety

Professional Applications & Engineering Value

This Grade 5 steel hex head screw delivers critical engineering solutions for industrial assembly challenges where vibration resistance and structural integrity are paramount. The UNF fine threading (1/2"-20) provides superior holding power in machinery, automotive components, and structural frameworks, while the zinc plated finish combats environmental degradation in manufacturing facilities and outdoor applications. With partial threading and Class 2A thread fit, engineers achieve precise clamp load control without compromising joint strength. The external hex drive and substantial head dimensions facilitate high-torque installation in confined spaces, making this fastener ideal for heavy equipment maintenance, construction projects, and production line assemblies where reliability cannot be compromised.

Specification Summary & Compliance

Manufactured to exacting Class 2A thread tolerance standards with UNF (Unified National Fine) thread form ensuring precise fitment. Complies with ASME B18.2.1 dimensional specifications and SAE J429 material standards for Grade 5 fasteners. Meets environmental regulations including RoHS 3 (2015/863/EU) compliance and REACH (EC 1907/2006) requirements for hazardous substance restrictions. The 3 1/4" length with 1 1/4" minimum thread length provides optimal engagement for various material thicknesses while maintaining structural integrity.