S-91274A244 5/16"-18 x 1" ASME B18.3, ASTM A574, ASTM B117 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the zinc-flake coating protects against harsh industrial environments, extending service life.
• Precise Class 3A thread fit guarantees secure, vibration-resistant assemblies with minimal risk of loosening.
• High hardness (Rockwell C37) provides excellent wear resistance, maintaining thread integrity through repeated use.
• 1/4" hex drive design allows for easy installation and removal with standard tools, improving assembly efficiency.
• Full threading offers consistent clamping force along the entire length, enhancing joint stability.
• Compliance with ASME B18.3 and ASTM A574 ensures dimensional accuracy and material quality for dependable engineering use.

Professional Applications & Engineering Value

This 5/16"-18 UNC Socket Head Cap Screw is engineered for demanding industrial applications where reliability is critical. The zinc-flake-coated alloy steel construction provides outstanding corrosion resistance, making it ideal for machinery, automotive assemblies, and outdoor equipment exposed to moisture or chemicals. The Class 3A thread fit and coarse thread spacing ensure quick, secure fastening in high-vibration environments, reducing maintenance needs. With a 1/4" hex drive and fully threaded design, it simplifies installation in confined spaces while delivering consistent clamping force. These features address common engineering challenges like fastener fatigue, corrosion-induced failure, and assembly time, offering a robust solution for heavy-duty cap screws in precision-driven sectors.

Specification Summary & Compliance

This screw adheres to Class 3A thread fit per UNC standards, ensuring tight tolerances for precision assemblies. It meets ASME B18.3 for dimensional consistency and ASTM A574 for material integrity, with a length of 1" and coarse thread spacing. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), it supports environmentally responsible sourcing and use in regulated industries.