S-91771A125 5-40 x 5/16" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with passivated 18-8 stainless steel construction, ideal for harsh environments and long-term reliability.
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness, ensuring secure, vibration-resistant fastening.
• Precise flush installation thanks to the standard 82° countersink angle and flat head design, providing a smooth, professional finish.
• Effortless installation and removal with the No. 2 Phillips drive, reducing tool slippage and assembly time.
• Reliable thread engagement with UNC coarse threads and Class 2A fit, offering consistent performance and easy alignment.
• Full threading along the 5/16" length maximizes grip and load distribution in various material thicknesses.
• Compliance with major industry standards including ASME B18.6.3, RoHS 3, and REACH, ensuring safety and environmental responsibility.

Professional Applications & Engineering Value

These 5-40 UNC flat head screws are engineered to address common industrial challenges, such as corrosion-induced failure and inconsistent fastening in demanding applications. Made from passivated 18-8 stainless steel, they provide excellent resistance to moisture, chemicals, and oxidation, extending service life in machinery, electronics, and outdoor equipment. The fully threaded design and Class 2A thread fit ensure tight, reliable connections that withstand vibrations and dynamic loads. With an 82° countersink angle and Phillips drive, installation is quick and secure, minimizing the risk of head stripping and improving assembly efficiency in automated or manual settings. Ideal for use in aerospace, automotive, and construction industries, these screws deliver consistent performance where precision and durability are critical.

Specification Summary & Compliance

This product adheres to precise dimensional standards, including a Class 2A thread fit for consistent engagement and UNC coarse threads per inch system requirements. It meets ASME B18.6.3 specifications for mechanical and dimensional integrity, ensuring reliable performance in industrial assemblies. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of hazardous substances and supporting environmental and workplace safety.