S-91257A946 7/8"-14 x 6 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capability with 150,000 psi tensile strength for reliable performance in demanding applications
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh environments
• Precision threading with Class 2A fit and UNF fine thread profile ensures secure, vibration-resistant connections
• Optimized strength-to-weight ratio through Grade 8 steel construction and Rockwell C33 hardness rating
• Enhanced installation efficiency with external hex drive design and 1 5/16" head width for superior torque application
• Versatile partial threading allows for both clamping force and adjustment flexibility in assembled components
• Regulatory compliance assurance meeting ASME B18.2.1, SAE J429, RoHS 3, and REACH standards for global industrial use

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions for heavy machinery, structural assemblies, and industrial equipment where high tensile strength and vibration resistance are paramount. The 7/8"-14 UNF fine thread configuration with Class 2A thread fit provides superior engagement in tapped holes, reducing the risk of stripping while maintaining precise alignment. The partially threaded design creates an optimal balance between clamping force in the unthreaded shank section and adjustability in the threaded portion. Zinc yellow-chromate plating on steel construction offers exceptional corrosion protection, making these hex head screws ideal for outdoor equipment, automotive assemblies, and manufacturing systems exposed to environmental challenges. The external hex drive facilitates high-torque installation without cam-out concerns, significantly improving assembly efficiency in industrial maintenance and production environments.

Specification Summary & Compliance

This heavy-duty fastener features precise Class 2A thread fit tolerances with 7/8"-14 UNF fine threading and partial threading extending 2 1/4" minimum. Manufactured to exacting ASME B18.2.1 and SAE J429 specifications for dimensional consistency and performance reliability. The Grade 8 classification ensures 150,000 psi tensile strength and Rockwell C33 hardness for maximum durability. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, making these screws suitable for global industrial distribution and use in regulated industries.