S-91286A345 1/2"-13 x 4 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the zinc-flake coating extends service life in harsh industrial environments, minimizing maintenance needs.
• High hardness (Rockwell C33) provides excellent wear resistance, maintaining thread integrity and drive engagement over repeated use.
• Coarse UNC threading with Class 2A fit allows for quick assembly and secure fastening, improving installation efficiency and joint stability.
• Partial threading design offers optimal grip and clamping force distribution, enhancing structural integrity in heavy-duty assemblies.
• External hex drive enables easy installation and removal with standard tools, streamlining maintenance and reducing downtime.
• Compliance with major standards including ASME B18.2.1 and SAE J429 ensures consistent quality and interoperability in professional applications.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive assemblies where vibration, high loads, and environmental exposure are common. The zinc-flake coated steel provides a robust barrier against corrosion, significantly extending fastener lifespan in outdoor or chemically aggressive settings. With a coarse UNC thread and Class 2A fit, it ensures rapid, secure fastening even in applications with slight misalignments, reducing assembly time and improving reliability. The partial threading concentrates clamping force effectively, preventing joint loosening under dynamic stresses. Ideal for structural frames, equipment mounts, and high-torque connections, this screw delivers consistent performance backed by 150,000 psi tensile strength and rigorous manufacturing standards.

Specification Summary & Compliance

This fastener features precise Class 2A thread fit and adheres to UNC thread standards with a 1/2"-13 size. It meets ASME B18.2.1 and SAE J429 specifications for dimensional accuracy and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and regulatory acceptance in global markets.