S-91274A288 5/16"-18 x 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 with zinc-flake coating protects against harsh industrial environments, extending service life and reducing maintenance needs.
• High hardness rating (Rockwell C37) provides excellent wear resistance, maintaining dimensional stability under heavy loads.
• Precise Class 3A thread fit delivers secure engagement and vibration resistance in critical assemblies.
• Partially threaded design allows for optimal clamping force distribution while minimizing thread damage during installation.
• Standard hex drive compatibility with 1/4" drive size enables efficient installation using common industrial tools.
• Comprehensive regulatory compliance including RoHS 3 and REACH ensures environmental responsibility and global market acceptance.

Professional Applications & Engineering Value

This zinc-flake-coated socket head cap screw delivers critical engineering advantages in demanding applications where corrosion resistance and high strength are paramount. The alloy steel construction with Rockwell C37 hardness maintains structural integrity in heavy machinery, automotive assemblies, and industrial equipment subjected to constant vibration and dynamic loads. The 5/16"-18 UNC coarse thread configuration provides rapid installation and superior holding power in softer materials or where frequent disassembly isn't required. The zinc-flake coating offers exceptional protection against chemical exposure and atmospheric corrosion, making these socket head cap screws ideal for outdoor equipment, marine applications, and manufacturing environments where moisture and contaminants are present. The partially threaded design concentrates clamping force precisely where needed, preventing joint loosening while protecting thread integrity.

Specification Summary & Compliance

This socket head cap screw features Class 3A thread fit for precision engagement and meets ASME B18.3 dimensional specifications. Manufactured from alloy steel per ASTM A574 with corrosion resistance verified per ASTM B117 testing standards. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and regulatory acceptance for industrial applications worldwide.