S-91257A943 7/8"-14 x 5 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 capability with 150,000 psi tensile strength for critical high-stress applications
• Superior corrosion resistance through zinc yellow-chromate plating that withstands harsh industrial environments
• Enhanced durability from Rockwell C33 hardness and Grade 8 classification for long service life
• Precise thread engagement with Class 2A fit and 7/8"-14 UNF fine threads for vibration-resistant connections
• Optimized installation efficiency featuring external hex drive and 1 5/16" head width for secure tool engagement
• Reliable partial threading providing both threaded and unthreaded sections for specific clamping requirements
• Comprehensive regulatory compliance meeting ASME B18.2.1, SAE J429, RoHS 3, and REACH standards

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers exceptional engineering value in demanding industrial environments where failure is not an option. The zinc yellow-chromate plated steel construction provides superior corrosion protection while maintaining the 150,000 psi tensile strength required for structural applications, heavy machinery, and construction equipment. The 7/8"-14 UNF fine thread configuration ensures secure fastening in vibration-prone applications, while the Class 2A thread fit guarantees precise installation without compromising joint integrity. The partially threaded design allows for optimal load distribution, making it ideal for applications requiring both clamping force and shear strength. These heavy-duty hex screws solve critical fastening challenges in manufacturing, automotive, and industrial assembly where reliability and compliance with ASME B18.2.1 and SAE J429 standards are paramount.

Specification Summary & Compliance

This fastener maintains Class 2A thread fit tolerance for precise installation and features 7/8"-14 UNF fine threads with right-hand direction. Manufacturing complies with ASME B18.2.1 specifications where identified under SAE J429 standards. The product is fully RoHS 3 (2015/863/EU) compliant and meets REACH (EC 1907/2006) requirements current as of January 17, 2023. Dimensions include 5½" length with 2" minimum thread length, 37/64" head height, and 1 5/16" head width for standardized tool compatibility.