S-91274A276 5/16"-18 x 3" 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 under high-stress conditions, reducing the risk of fastener failure.
• Superior corrosion resistance from the zinc-flake coating extends service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides secure, vibration-resistant assemblies, enhancing joint integrity and reducing loosening over time.
• Partially threaded design allows for controlled clamping force and easier alignment in applications requiring specific grip lengths.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity during repeated installation and removal.
• 1/4" hex drive compatibility enables efficient torque application with standard tools, speeding up assembly and disassembly processes.
• Compliance with major standards including ASME B18.3 and ASTM A574 ensures consistent quality and interoperability in regulated industries.

Professional Applications & Engineering Value

This 5/16"-18 UNC Socket Head Cap Screw is engineered for demanding applications where mechanical reliability and corrosion resistance are critical. The zinc-flake-coated alloy steel construction provides a robust barrier against environmental factors, making it ideal for machinery, automotive assemblies, and outdoor equipment exposed to moisture or chemicals. The coarse UNC thread and Class 3A fit deliver superior holding power in high-vibration settings, such as heavy-duty manufacturing or construction, while the partially threaded rod type allows precise load distribution. By integrating high tensile strength and standardized dimensions, this fastener minimizes assembly errors and enhances long-term performance in industrial cap screw applications, reducing downtime and maintenance costs.

Specification Summary & Compliance

This socket head cap screw features a 5/16"-18 UNC coarse thread with Class 3A thread fit for precise tolerances, and a minimum thread length of 1 1/8". It is manufactured in accordance with ASME B18.3 and ASTM A574 specifications, ensuring dimensional accuracy and material consistency. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting environmentally responsible and safe usage in global markets.