S-91253A580 5/16"-18 x 5/8" 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 in high-stress applications, reducing the risk of fastener failure.
• Corrosion-resistant Black-Oxide finish on alloy steel enhances durability and longevity in harsh industrial environments.
• Class 3A thread fit provides superior thread engagement and vibration resistance for secure, long-lasting assemblies.
• Fully threaded design offers maximum grip and holding power along the entire screw length.
• 82° countersink angle allows for a flush, professional finish that minimizes protrusion and improves safety.
• Hex drive (3/16") enables high-torque installation with common tools, speeding up assembly processes.
• Compliance with ASME B18.3, ASTM F835, RoHS 3, and REACH guarantees consistent quality and environmental safety for global supply chains.

Professional Applications & Engineering Value

These 5/16"-18 UNC flat head screws are engineered to address critical challenges in industrial assembly, where vibration loosening and material fatigue are common concerns. The Black-Oxide alloy steel construction, combined with a Class 3A thread fit, ensures excellent resistance to wear and environmental factors, making them ideal for machinery, automotive, and heavy equipment applications. The coarse thread spacing and fully threaded design provide rapid installation and superior clamping force, reducing maintenance needs. With a 130,000 psi tensile strength and Rockwell C39 hardness, they deliver reliable performance in demanding conditions, while the 82° countersink promotes a smooth surface finish, essential for aesthetic and safety-critical assemblies.

Specification Summary & Compliance

This screw features a 5/16"-18 UNC thread with Class 3A fit for precise thread engagement and dimensional accuracy per ASME B18.3 standards. It is manufactured from alloy steel with a Black-Oxide surface treatment, ensuring compliance with ASTM F835 for mechanical properties. The product meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for environmentally conscious and international industrial markets.