S-91286A138 1/4"-28 x 1 1/4" 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
- Exceptional load-bearing capacity with 150,000 psi tensile strength for reliable performance in high-stress applications
- Superior corrosion protection through zinc-flake coating that extends service life in harsh environments
- Precise thread engagement with Class 2A UNF fine threads ensuring secure, vibration-resistant connections
- Optimized drive efficiency featuring external hex design for high-torque installation with standard tools
- Grade 8 certification guaranteeing consistent mechanical properties and Rockwell C33 hardness
- Partial threading design providing enhanced grip length where full thread engagement isn't required
- Regulatory compliance meeting ASME, SAE, RoHS 3 and REACH standards for global industrial acceptance
Professional Applications & Engineering Value
Engineered for heavy-duty industrial applications, these Grade 8 hex head screws deliver critical performance where fastener failure is not an option. The 1/4"-28 UNF fine thread configuration provides superior resistance to vibrational loosening in machinery, construction equipment, and automotive assemblies. The zinc-flake coating offers exceptional corrosion protection, significantly outperforming conventional zinc plating in harsh environments. With partial threading and 1-1/4" length, these fasteners optimize clamping force distribution while the external hex drive enables high-torque installation without stripping. The combination of 150,000 psi tensile strength and Rockwell C33 hardness ensures these screws maintain integrity under extreme mechanical stress, making them ideal for structural connections, heavy machinery, and critical infrastructure projects.
Specification Summary & Compliance
Manufactured to precise Class 2A thread fit tolerances with UNF (Unified National Fine) thread form ensuring consistent engagement. Complies with ASME B18.2.1 dimensional standards and SAE J429 mechanical requirements for Grade 8 fasteners. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features 1/4"-28 thread size with 3/4" minimum thread length and 1-1/4" overall length for standardized industrial applications.
