S-91257A964 1"-8 x 4 3/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 150,000 psi tensile strength for critical structural applications
• Superior corrosion resistance through zinc yellow-chromate plating, extending service life in harsh environments
• Optimized thread engagement with UNC coarse threading and partial threading design for faster assembly and reduced weight
• Reliable mechanical performance backed by Grade 8 classification and Rockwell C33 hardness for consistent durability
• Industry-standard compatibility with Class 2A thread fit ensuring proper mating with standard nuts and components
• Secure installation facilitated by external hex drive design providing positive torque transmission
• Proven engineering compliance meeting ASME B18.2.1 and SAE J429 specifications for quality assurance

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical performance where high tensile strength and reliability are non-negotiable. The 1"-8 UNC coarse thread configuration provides superior resistance to vibration loosening while enabling rapid assembly in heavy machinery, structural steel connections, and industrial equipment. The zinc yellow-chromate plating creates a protective barrier against oxidation and chemical exposure, significantly extending service life in manufacturing plants, construction sites, and outdoor applications. The partially threaded design concentrates strength where needed most while reducing overall weight, making it ideal for flange connections, bracket mounting, and machinery assemblies requiring precise clamping force. Engineered to withstand extreme mechanical stress, this heavy-duty fastener ensures structural integrity in the most demanding industrial environments.

Specification Summary & Compliance

This hex head screw features precise Class 2A thread fit tolerances with 1"-8 UNC coarse threading and minimum 2 1/4" thread length. Manufactured from high-strength steel with Rockwell C33 hardness and 150,000 psi tensile strength, it complies with ASME B18.2.1 and SAE J429 Grade 8 specifications. The zinc yellow-chromate plating provides corrosion protection while maintaining dimensional stability. With 4 3/4" overall length and external hex drive configuration, this fastener meets industrial standards for heavy-duty applications requiring reliable mechanical performance and corrosion resistance.