S-91263A181 5/16"-18 x 3 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc plating that protects against rust in demanding industrial environments
• Exceptional tensile strength of 130,000 psi ensures reliable performance in high-stress applications
• Precise Class 3A thread fit provides superior engagement and vibration resistance in critical assemblies
• Optimized flat head design with 82° countersink angle creates flush surfaces for streamlined installations
• Enhanced driving efficiency with 3/16" hex drive that prevents cam-out and ensures secure fastening
• Partial threading configuration allows for precise clamping force control in varied material thicknesses
• Full regulatory compliance with RoHS 3 and REACH standards for global industrial applications

Professional Applications & Engineering Value

This 5/16"-18 UNC flat head screw delivers exceptional engineering value through its zinc-plated alloy steel construction and Class 3A thread precision. The combination of 130,000 psi tensile strength and Rockwell C39 hardness ensures reliable performance in heavy-duty applications where vibration resistance and structural integrity are critical. The partial threading design allows for optimal clamp load distribution, making it ideal for machinery assembly, equipment manufacturing, and structural frameworks. The 82° countersink angle provides seamless flush mounting in industrial applications requiring aerodynamic or smooth surface profiles. Engineered to meet ASME B18.3 and ASTM F835 specifications, this coarse thread screw offers superior holding power in both metal and composite materials.

Specification Summary & Compliance

This flat head screw features precise Class 3A thread fit with 5/16"-18 UNC coarse threading and maintains dimensional accuracy per ASME B18.3 manufacturing standards. The product demonstrates full compliance with ASTM F835 specifications for mechanical properties and surface treatments. Environmental and safety regulations are met through RoHS 3 (2015/863/EU) compliance and REACH (EC 1907/2006) compliance, ensuring suitability for global industrial markets and restricted substance management.