S-91263A187 5/16"-24 x 1 1/4" ASME B18.3 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated alloy steel construction for extended service life in demanding environments
• Exceptional load-bearing capability with 120,000 psi tensile strength to withstand high-stress applications
• Precise thread engagement with Class 3A fine thread fit ensuring vibration resistance and secure fastening
• Optimized flush mounting with 82° countersink angle and standard flat head profile for seamless surface integration
• Enhanced installation efficiency with hex drive design providing superior torque transmission and slip resistance
• Full-threaded reliability offering maximum grip length and uniform stress distribution along the entire fastener
• Regulatory compliance assurance meeting ASME B18.3 specifications and environmental standards including RoHS 3 and REACH

Professional Applications & Engineering Value

These zinc-plated alloy steel flat head screws deliver critical performance advantages for precision industrial assemblies. The Class 3A thread fit with UNF fine threading provides exceptional vibration resistance in machinery, automotive, and aerospace applications where loosening under dynamic loads is a primary concern. The 82° countersink angle ensures perfect flush mounting in precision-machined components, eliminating protrusions that could interfere with moving parts or aesthetic requirements. With 120,000 psi tensile strength and Rockwell C32 hardness, these fully threaded fasteners maintain structural integrity under extreme mechanical stress while the hex drive configuration prevents tool slippage during high-torque installation. The zinc plating offers sacrificial protection against corrosion, making these screws ideal for both indoor industrial equipment and outdoor applications exposed to environmental elements.

Specification Summary & Compliance

This 5/16"-24 UNF flat head screw features precision Class 3A thread fit with fine thread spacing for superior engagement. Manufacturing complies with ASME B18.3 specifications ensuring dimensional accuracy and performance reliability. The product meets RoHS 3 (2015/863/EU) compliance for restricted substance control and REACH (EC 1907/2006) regulations for chemical safety. With a length of 1-1/4" and fully threaded design, these screws maintain consistent mechanical properties throughout their entire length for uniform load distribution in critical assemblies.