S-91253A331 5/16"-24 x 1/2" ASME B18.3 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 130,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Precise Class 3A thread fit provides superior engagement and vibration resistance, minimizing loosening in critical assemblies.
• Durable black-oxide finish on alloy steel offers enhanced corrosion resistance and a professional appearance for long-term use.
• Fully threaded design allows for maximum grip and holding power along the entire length, ideal for securing components of varying thicknesses.
• Standard 82° countersink angle enables a flush, low-profile installation, improving aerodynamics and safety in assembled products.
• Hex drive (3/16") facilitates easy installation and removal with standard tools, speeding up assembly and maintenance processes.
• Compliance with ASME B18.3 and ASTM F835 guarantees consistent quality and interchangeability, ensuring compatibility with industry-standard components.

Professional Applications & Engineering Value

This 5/16"-24 UNF flat head socket cap screw is engineered to address common industrial challenges such as vibration-induced loosening and corrosion in harsh environments. The black-oxide alloy steel construction, combined with a fine thread and Class 3A fit, delivers superior clamp load retention and fatigue resistance, making it ideal for precision machinery, automotive assemblies, and electronic enclosures. The fully threaded right-hand design ensures uniform stress distribution, while the 82° countersink angle allows for seamless integration into tapered holes, reducing protrusion and enhancing structural integrity. By meeting rigorous standards, this screw provides reliable performance in applications requiring high strength and durability.

Specification Summary & Compliance

This fastener features a 5/16"-24 UNF thread with a Class 3A tolerance for precise fit, and is manufactured from alloy steel with a tensile strength of 130,000 psi and Rockwell C39 hardness. It complies with ASME B18.3 and ASTM F835 specifications, ensuring dimensional accuracy and performance. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting environmental and safety regulations for industrial use.