S-91263A166 1/4"-20 x 1 1/8" ASME B18.3 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc plating, extending service life in demanding industrial environments
• Exceptional tensile strength of 120,000 PSI ensures reliable performance under high-stress applications
• Precise Class 3A thread fit provides secure, vibration-resistant connections for critical assemblies
• 82° countersink angle design allows for flush mounting in various materials without protrusion
• Hex drive compatibility (5/32") enables quick installation and high torque application with standard tools
• Full threading along 1-1/8" length offers maximum grip strength and adjustment flexibility
• Rockwell C32 hardness rating maintains structural integrity and prevents thread deformation

Professional Applications & Engineering Value

These zinc-plated alloy steel flat head screws with 1/4"-20 UNC coarse threading deliver exceptional engineering value across industrial applications. The combination of Class 3A thread fit and 120,000 PSI tensile strength addresses critical vibration loosening concerns in machinery, automotive, and construction assemblies. The 82° countersink angle ensures seamless flush mounting in metal fabrication and woodworking projects, while the hex drive design provides superior torque transmission compared to standard slotted drives. Engineered for heavy-duty fastening requirements, these screws maintain dimensional stability under load, making them ideal for structural applications where reliability cannot be compromised.

Specification Summary & Compliance

Manufactured to exacting ASME B18.3 standards with Class 3A thread tolerances for precision fit. Features UNC coarse thread profile with right-hand threading and fully threaded 1-1/8" length. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global industrial markets.