S-91274A256 5/16"-18 x 1 3/4" 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 zinc-flake coating extends service life in harsh environments, minimizing maintenance and replacement costs.
• Precise Class 3A thread fit provides secure, vibration-resistant connections, enhancing assembly integrity and safety.
• High hardness rating (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Partially threaded design allows for optimal clamping force distribution, preventing joint loosening in dynamic applications.
• Standard hex drive compatibility with 1/4" tools enables quick installation and removal, improving maintenance efficiency.
• Compliance with major industry standards including ASME B18.3 and ASTM A574 guarantees consistent quality and interoperability.

Professional Applications & Engineering Value

This 5/16"-18 UNC Socket Head Cap Screw delivers critical engineering advantages in demanding industrial settings. The zinc-flake-coated alloy steel construction provides superior protection against corrosion and chemical exposure, making it ideal for outdoor equipment, automotive assemblies, and machinery subjected to harsh operating conditions. The coarse UNC thread design ensures rapid installation and reliable performance in materials where fine threads might strip or fail. With its partially threaded configuration, this fastener offers precise clamping control in applications requiring specific unthreaded shank sections, such as precision machinery and structural frameworks. The combination of 170,000 psi tensile strength and Rockwell C37 hardness addresses common failure points in heavy-duty applications, providing engineers with a dependable solution for high-vibration environments where joint integrity is paramount.

Specification Summary & Compliance

This socket head cap screw features precise Class 3A thread fit with 5/16"-18 UNC coarse threads and a minimum thread length of 1 1/8". Manufactured to ASME B18.3 and ASTM A574 specifications, it ensures dimensional accuracy and mechanical consistency. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, meeting environmental and safety standards for industrial use worldwide.