S-91257A791 9/16"-18 x 3 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel Hex Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Maximum load-bearing capacity with 150,000 psi tensile strength for critical structural applications
- Superior corrosion protection through zinc yellow-chromate plating in harsh industrial environments
- Precise torque transmission with external hex drive design and 13/16" head width
- Enhanced thread engagement through UNF fine threading and Class 2A fit for vibration resistance
- Exceptional durability backed by Rockwell C33 hardness and Grade 8 certification
- Reliable partial threading allowing for optimal clamp load distribution
- Industry compliance assurance meeting ASME B18.2.1 and SAE J429 standards
Professional Applications & Engineering Value
This Grade 8 hex head screw delivers exceptional performance in demanding industrial settings where failure is not an option. The 9/16"-18 UNF fine threading provides superior resistance to vibrational loosening compared to coarse threads, while the zinc yellow-chromate plating creates a robust barrier against corrosion in outdoor or chemically aggressive environments. With 150,000 psi tensile strength and Rockwell C33 hardness, this fastener maintains structural integrity under extreme loads, making it ideal for heavy machinery, construction equipment, and automotive assemblies. The external hex drive and substantial 13/16" head width ensure secure tool engagement during installation, reducing the risk of stripping and ensuring consistent clamping force in critical joints.
Specification Summary & Compliance
This 3 1/2" length hex head screw features precise Class 2A thread fit tolerances and UNF fine threading manufactured to ASME B18.2.1 and SAE J429 specifications. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global markets. With partial threading extending to a minimum of 1 3/8" and manufactured from high-strength steel, this screw meets the rigorous demands of industrial applications requiring reliable, high-performance fastening solutions.
