S-91247A480 3/4"-16 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 Tensile Strength – With 120,000 psi tensile strength and Grade 5 classification, this screw provides reliable holding power for demanding structural and machinery applications.
• Superior Corrosion Resistance – The zinc plating finish offers enhanced protection against rust and environmental degradation, extending service life in harsh industrial settings.
• Precision Thread Fit – Class 2A thread fit ensures smooth assembly and secure fastening, reducing the risk of cross-threading and improving installation efficiency.
• Optimized for Heavy-Duty Use – Rockwell C25 hardness and partially threaded design deliver excellent shear strength and vibration resistance in high-stress environments.
• Industry-Standard Compliance – Manufactured to ASME B18.2.1 and SAE J429 specifications, guaranteeing consistent quality, dimensional accuracy, and interchangeability.
• Secure External Hex Drive – The 1 1/8" wide hex head allows for high-torque application with standard tools, ensuring tight, dependable fastening in confined spaces.
• Fine Thread Advantage – 3/4"-16 UNF fine threading provides increased engagement and better resistance to loosening under dynamic loads compared to coarse threads.

Professional Applications & Engineering Value

This Grade 5 hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive assemblies where vibration resistance and load-bearing capacity are paramount. The partially threaded design concentrates strength along the shank, preventing failure at stress points, while the zinc plating defends against corrosion in outdoor or humid conditions. Its 3/4"-16 UNF fine thread and Class 2A fit ensure precise alignment and reduced galling, making it ideal for high-torque applications in equipment frames, engine components, and structural steel connections. By combining 120,000 psi tensile strength with standardized external hex drive compatibility, this fastener simplifies maintenance and upgrades across industrial platforms.

Specification Summary & Compliance

This hex head screw meets ASME B18.2.1 and SAE J429 standards, with Class 2A thread fit for consistent dimensional accuracy. It is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring adherence to environmental and safety regulations. Key specifications include a 3 1/4" length, 1 3/4" minimum thread length, and Rockwell C25 hardness, providing reliable performance in regulated industrial applications.