S-93791A421 5/16"-18 x 3/4" ASME B18.3 Stainless Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and black-oxide passivated finish, ideal for harsh industrial environments.
• Exceptional tensile strength rated at 70,000 psi, ensuring reliable performance under high-stress applications.
• Precise Class 3A thread fit with UNC coarse threading for secure, vibration-resistant fastening and easy installation.
• Optimized flush mounting thanks to the standard 82° countersink angle and flat head design, providing a smooth surface finish.
• Enhanced durability with Rockwell B55 hardness, offering excellent wear resistance and long service life.
• Efficient hex drive (3/16") for quick, tool-friendly installation and removal, reducing assembly time.
• Full compliance with ASME B18.3, RoHS 3, and REACH standards, ensuring safety and regulatory adherence.

Professional Applications & Engineering Value

This 5/16"-18 x 3/4" flat head screw is engineered to address critical challenges in industrial and mechanical assemblies. The 18-8 stainless steel material, combined with a black-oxide passivated finish, provides outstanding resistance to corrosion and oxidation, making it suitable for outdoor, marine, or chemically exposed settings. The UNC coarse thread and Class 3A fit ensure tight, reliable connections that resist loosening under vibration—common in machinery, automotive, and construction applications. Its fully threaded design and 82° countersink angle allow for flush installation, minimizing protrusion and improving aerodynamics or safety in enclosed systems. These features make it a top choice for heavy-duty fastening where strength, precision, and environmental durability are paramount.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including UNC thread with Class 3A fit for high accuracy and a coarse thread spacing for robust engagement. It meets ASME B18.3 specifications for consistency and reliability. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring it is free from hazardous substances and safe for various industrial uses.