S-91781A581 5/16"-18 x 3/4" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish, ideal for harsh or humid environments
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for reliable performance under high stress
• Optimized for flush mounting thanks to the standard 82° countersink angle and flat head design, providing a smooth, secure surface finish
• Quick and efficient installation with coarse UNC thread spacing and fully threaded design for faster driving and superior holding power
• Precise, reliable thread engagement ensured by Class 2A thread fit, reducing cross-threading risks in repetitive assembly
• Broad compatibility with standard slotted drive tools, offering straightforward installation and removal in various settings
• Long-term operational reliability backed by compliance with ASME B18.6.3, RoHS 3, and REACH, ensuring safety and environmental responsibility

Professional Applications & Engineering Value

This 18-8 stainless steel flat head screw is engineered to address common industrial challenges such as material degradation and fastener failure in demanding conditions. The passivated finish significantly enhances its corrosion resistance, making it suitable for applications in marine, chemical processing, and outdoor equipment where moisture and corrosive agents are prevalent. Its fully threaded UNC coarse spacing design ensures rapid, secure fastening in materials like metal, plastic, and wood, reducing installation time while maintaining high tensile strength and durability. The flat head with 82° countersink allows for a flush fit, minimizing protrusion and improving safety in machinery, enclosures, and structural assemblies. These features collectively provide long-term reliability and reduce maintenance needs in industrial fastening applications.

Specification Summary & Compliance

This screw adheres to Class 2A thread fit for consistent dimensional accuracy and smooth assembly. It conforms to UNC coarse thread standards with a 5/16"-18 thread size and right-hand threading. Manufacturing and quality are governed by ASME B18.6.3 specifications, ensuring uniformity and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its safety and environmental suitability for global industrial use.