S-91257A963 1"-8 x 4 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum load-bearing capacity with Grade 8 classification and 150,000 psi tensile strength for critical structural applications
• Superior corrosion protection through zinc yellow-chromate plating that withstands harsh industrial environments
• Optimized thread engagement with 1"-8 UNC coarse threads providing faster assembly and vibration resistance
• Precise mechanical fit ensured by Class 2A thread tolerance for consistent performance in high-stress applications
• Enhanced durability from Rockwell C33 hardness that maintains structural integrity under extreme conditions
• Secure torque transmission via external hex drive design that prevents tool slippage during installation
• Reduced material stress through partial threading that concentrates strength where needed most

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver exceptional engineering value for heavy machinery, structural steel connections, and industrial equipment where failure is not an option. The 1"-8 UNC coarse thread configuration ensures rapid installation while maintaining superior clamping force in thick materials and structural components. The zinc yellow-chromate plating provides a robust barrier against corrosion in demanding environments, from manufacturing facilities to outdoor construction applications. With partial threading that optimizes stress distribution and 150,000 psi tensile strength, these fasteners solve critical challenges in load-bearing assemblies where vibration resistance and long-term reliability are paramount. The combination of external hex drive and precise Class 2A thread fit guarantees consistent performance in high-torque applications across industrial maintenance, heavy equipment manufacturing, and infrastructure projects.

Specification Summary & Compliance

Manufactured to exacting ASME B18.2.1 specifications with Class 2A thread fit tolerance for precision engagement. These Grade 8 hex head screws feature 1"-8 UNC coarse threads with partial threading and comply with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards. The fasteners maintain dimensional accuracy per industrial standards with 4 1/2" length and 1 1/2" head width for consistent performance in professional applications.