S-90344A118 5/16"-18 x 3/4" ASME B18.3, ASTM A574 Socket Head Screws with Flat Washer

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 black-oxide finish on both the alloy steel screw and washer, extending service life in demanding environments.
• Precise Class 3A thread fit guarantees secure, vibration-resistant connections with minimal backlash in assembly operations.
• Integrated flat washer distributes load evenly, preventing surface damage and maintaining joint integrity under heavy loads.
• Hex socket drive design allows for high-torque installation with standard tools, facilitating efficient assembly and disassembly.
• Full threading provides consistent engagement along the entire length, offering flexibility in adjustment and clamping force.
• Compliance with ASME B18.3 and environmental standards ensures dimensional accuracy and safe use in regulated industries.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, this black-oxide alloy steel socket head cap screw with a flat washer addresses critical challenges in machinery assembly, automotive systems, and construction equipment. The UNC coarse thread with Class 3A fit ensures rapid installation and robust performance in high-vibration environments, reducing maintenance downtime. Combined with a Rockwell C39 hardness and 170,000 psi tensile strength, it resists shear and tensile forces effectively. The hex drive enables precise torque application, while the integrated washer minimizes stress concentration, making it ideal for applications requiring reliable fastening solutions that meet ASME B18.3 specifications for consistency and safety.

Specification Summary & Compliance

This socket head cap screw features a 5/16"-18 UNC thread with Class 3A tolerance for precise fit, coarse thread spacing, and right-hand direction. Manufactured to ASME B18.3 standards, it ensures dimensional accuracy and interoperability. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, it is free from hazardous substances, supporting sustainable industrial practices. The assembly includes a black-oxide steel flat washer for enhanced performance in inch-system applications.