S-91253A589 5/16"-18 x 1 3/4" ASME B18.3 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength (130,000 PSI) ensures reliable performance in high-stress industrial applications
• Superior corrosion resistance from Black-Oxide coating extends service life in demanding environments
• Precision Class 3A thread fit provides secure, vibration-resistant connections with minimal backlash
• 82° countersink angle design allows for flush mounting and clean aesthetic finishes
• Heavy-duty alloy steel construction with Rockwell C39 hardness maintains structural integrity under load
• Hex drive compatibility (3/16") enables efficient installation with standard tools
• Full threading coverage ensures maximum engagement strength along the entire fastener length

Professional Applications & Engineering Value

These 5/16"-18 UNC flat head screws deliver critical engineering solutions where high tensile strength and corrosion resistance are paramount. The Black-Oxide Alloy Steel construction combined with Class 3A thread fit addresses common industrial challenges including vibration loosening, material fatigue, and environmental degradation. Ideal for machinery assembly, structural frameworks, and heavy equipment manufacturing, these fully threaded screws with coarse UNC threading provide rapid installation and superior holding power. The 82° countersink angle ensures seamless integration into precision components while maintaining structural integrity under extreme operational stresses.

Specification Summary & Compliance

Manufactured to exacting ASME B18.3 and ASTM F835 specifications with Class 3A thread fit tolerance. Features 5/16"-18 UNC coarse threading with right-hand orientation and standard flat head profile. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Dimensional accuracy maintained with 1 3/4" length, 0.656" head diameter, and 3/16" hex drive configuration.