S-91286A375 1/2"-20 x 2 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capacity: Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior Corrosion Protection: Zinc-flake coating provides excellent resistance to rust and environmental degradation, extending service life in harsh industrial conditions.
• Precision Thread Engagement: UNF fine threading and Class 2A fit offer secure, vibration-resistant fastening with reduced likelihood of loosening under dynamic loads.
• Optimized Strength-to-Weight Ratio: Partially threaded design with 1 1/4" minimum thread length concentrates strength where needed while minimizing overall weight.
• Enhanced Installation Efficiency: External hex drive and 3/4" head width allow for high-torque application using standard tools, speeding up assembly processes.
• Consistent Hardness Performance: Rockwell C33 hardness rating maintains structural integrity under repeated stress, preventing deformation during installation and use.
• Regulatory Compliance Assurance: Meets ASME B18.2.1 and SAE J429 specifications, plus RoHS 3 and REACH compliance for global market acceptance.

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions where high tensile strength and corrosion resistance are paramount. The zinc-flake coated steel construction specifically addresses industrial challenges in automotive, heavy machinery, and structural applications where exposure to moisture, chemicals, and constant vibration would compromise ordinary fasteners. The UNF fine threading provides superior clamping force distribution compared to coarse threads, making it ideal for precision equipment and assemblies requiring minimal clearance. With partial threading optimizing the strength-to-length ratio, engineers can specify this fastener for connections where full threading isn't necessary, reducing material costs while maintaining 150,000 psi tensile strength in critical load-bearing sections. The external hex drive design ensures compatibility with standard industrial tools for efficient installation in confined spaces.

Specification Summary & Compliance

This 1/2"-20 hex head screw features Class 2A thread fit per UNF standards with precise dimensional compliance to ASME B18.2.1 and SAE J429 specifications. The manufacturing process adheres to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance requirements, ensuring environmental responsibility and global market acceptability. With Rockwell C33 hardness and 150,000 psi tensile strength verification, this fastener meets rigorous industrial standards for heavy-duty applications.