S-91253A313 1/4"-28 x 1 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating, extending service life in demanding industrial environments
• Exceptional tensile strength (130,000 PSI) prevents stripping and failure under high-stress applications
• Precision Class 3A thread fit ensures secure fastening with minimal vibration loosening in critical assemblies
• 82° countersink angle design provides flush mounting for streamlined surfaces and improved aerodynamics
• Fully threaded shank maximizes grip length and load distribution across the entire fastener
• Hex drive compatibility (5/32") enables high-torque installation with standard industrial tools
• Regulatory compliance meets ASME B18.3, ASTM F835, RoHS 3 and REACH standards for global supply chain integration

Professional Applications & Engineering Value

These 1/4"-28 UNF flat head screws with black-oxide alloy steel construction address critical engineering challenges in precision manufacturing and heavy-duty equipment. The fine thread spacing and Class 3A thread fit provide vibration-resistant fastening for machinery components, while the 82° countersink angle enables seamless integration in aerospace and automotive applications where surface discontinuity is unacceptable. The fully threaded design ensures uniform stress distribution across the entire length, preventing localized failure points in structural assemblies. With 130,000 PSI tensile strength and Rockwell C39 hardness, these screws maintain integrity in high-load scenarios where standard fasteners would deform or fail prematurely.

Specification Summary & Compliance

Manufactured to ASME B18.3 and ASTM F835 specifications with precision Class 3A thread fit and UNF fine threading. Full compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Standard 82° countersink angle and right-hand thread direction ensure compatibility with industrial fastening systems worldwide.