S-91283A256 1 1/4"-7 x 5 1/2" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 100,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Grade 5 steel construction with Rockwell C19 hardness provides superior durability and resistance to wear, extending service life in industrial environments.
• 1 1/4"-7 UNC coarse threading offers faster installation and better resistance to vibration loosening compared to fine threads.
• Partially threaded design allows for precise clamping force control, ideal for applications where specific unthreaded grip length is required.
• External hex drive with 1 7/8" head width enables high-torque installation using standard tools, improving assembly efficiency.
• Class 2A thread fit ensures consistent, reliable engagement with nuts and tapped holes while maintaining easy assembly.
• Compliance with RoHS 3 and REACH regulations guarantees environmental safety and unrestricted use in regulated markets.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 5 hex head screws deliver critical performance where structural integrity is paramount. The steel construction combined with 100,000 psi tensile strength provides exceptional resistance to dynamic loads and fatigue, making them ideal for machinery assembly, structural frameworks, and equipment manufacturing. The 1 1/4"-7 UNC coarse thread configuration ensures rapid installation in thick materials while maintaining vibration resistance, significantly reducing maintenance cycles. With partial threading and precise Class 2A thread fit, these screws offer optimized clamp load distribution, preventing joint relaxation in high-vibration environments. Their compliance with ASME B18.2.1 and SAE J429 standards guarantees interchangeability and reliability in OEM and MRO applications across various industries.

Specification Summary & Compliance

This hex head screw features a 1 1/4"-7 UNC coarse thread with Class 2A thread fit ensuring standard-compliant dimensional accuracy. Manufacturing adheres to ASME B18.2.1 and SAE J429 specifications for Grade 5 fasteners. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming environmental safety and unrestricted industrial use.