S-91247A557 1/4"-20 x 3 3/4" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• High tensile strength of 120,000 psi ensures reliable performance in demanding applications, reducing the risk of fastener failure under load
• Zinc plating provides corrosion resistance, extending service life in various environmental conditions and reducing maintenance requirements
• Grade 5 classification guarantees consistent mechanical properties and load-bearing capacity for structural applications
• External hex drive design allows for high torque application and secure installation with standard tools
• Class 2A thread fit ensures easy assembly while maintaining proper engagement for vibration resistance
• Partially threaded shank provides optimal clamping force distribution and prevents joint loosening
• Coarse UNC threading enables faster installation and better performance in softer materials

Professional Applications & Engineering Value

This Grade 5 hex head screw delivers exceptional engineering value through its zinc plated steel construction and UNC coarse threading, specifically designed to address common industrial challenges. The combination of 120,000 psi tensile strength and Rockwell C25 hardness provides reliable performance in heavy-duty applications where vibration resistance and structural integrity are critical. The external hex drive configuration ensures maximum torque transfer during installation, preventing stripping while the partially threaded design concentrates clamping force precisely where needed. These industrial fasteners are engineered to maintain joint integrity in construction equipment, machinery assemblies, and structural frameworks where consistent performance under dynamic loads is essential. The coarse thread pitch particularly benefits applications involving softer materials or where rapid assembly is required without compromising holding power.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerances per UNC standards with 1/4"-20 thread size and 3 3/4" length. Manufacturing complies with ASME B18.2.1 specifications and SAE J429 Grade 5 requirements. The product is certified RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring environmental regulatory adherence for international industrial applications.