S-91247A494 3/4"-16 x 8 1/2" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Superior tensile strength of 120,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Enhanced corrosion resistance from zinc plating extends service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 2A thread fit with UNF fine threading provides secure, vibration-resistant connections for critical assemblies.
• High hardness rating (Rockwell C25) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Partially threaded design allows for controlled clamping force and easier alignment in structural applications.
• External hex drive with a 1 1/8" head width enables high-torque installation using standard tools, speeding up assembly processes.
• Compliance with major standards including ASME B18.2.1 and SAE J429 ensures consistent quality and interoperability in regulated industries.

Professional Applications & Engineering Value

This Grade 5 steel hex head screw is engineered to address common industrial challenges such as joint loosening under dynamic loads and environmental degradation. The 3/4"-16 UNF fine thread configuration delivers superior clamping force distribution, making it ideal for heavy machinery, structural steel connections, and automotive assemblies where vibration resistance is critical. The zinc-plated finish provides a sacrificial layer that significantly slows corrosion in humid or chemically exposed settings, reducing downtime and replacement costs. With its partial threading, the fastener allows unthreaded shank sections to bear shear loads directly, preventing thread damage during installation and ensuring long-term reliability in construction equipment and industrial manufacturing applications.

Specification Summary & Compliance

This 8 1/2" hex head screw features precise Class 2A thread fit with 3/4"-16 UNF fine threads and a minimum thread length of 2". Manufactured to ASME B18.2.1 and SAE J429 Grade 5 specifications, it meets rigorous dimensional and mechanical requirements. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material traceability for global industrial supply chains.