S-91257A919 7/8"-9 x 4 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength and durability with Grade 8 classification, 150,000 psi tensile strength, and Rockwell C33 hardness for reliable performance in high-stress applications
• Superior corrosion resistance provided by zinc yellow-chromate plating, extending service life in harsh industrial environments
• Optimal thread engagement with UNC coarse threading and Class 2A thread fit ensuring secure fastening and vibration resistance
• Enhanced installation efficiency through external hex drive design and 1 5/16" head width for easy tool access and high torque application
• Versatile partial threading design allowing for precise clamping force distribution across the 2" minimum threaded section
• Heavy-duty construction with 4 1/2" length and 7/8" diameter providing substantial load-bearing capacity for structural applications
• Regulatory compliance assurance meeting ASME B18.2.1 and SAE J429 standards while being RoHS 3 and REACH compliant

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers exceptional engineering value through its high-strength steel construction and zinc yellow-chromate plating, specifically designed to address critical industrial challenges. The 7/8"-9 UNC coarse thread configuration provides superior resistance to vibration loosening in heavy machinery, construction equipment, and structural assemblies. The partial threading design ensures optimal stress distribution, preventing material deformation in high-load applications. With 150,000 psi tensile strength and Rockwell C33 hardness, this fastener maintains integrity under extreme mechanical stress while the corrosion-resistant plating protects against environmental degradation in outdoor or chemically aggressive settings. The external hex drive and substantial head dimensions facilitate efficient installation in confined spaces, reducing assembly time and labor costs.

Specification Summary & Compliance

This heavy-duty hex head screw features precise Class 2A thread fit tolerance with 7/8"-9 UNC coarse threading and right-hand thread direction. Manufacturing complies with ASME B18.2.1 and SAE J429 specifications, ensuring dimensional accuracy and performance reliability. The fastener is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting current environmental regulations for industrial components. With 4 1/2" length and 2" minimum thread length, the screw maintains strict quality control standards throughout production.