S-91257A118 5/16"-18 x 5 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 demanding applications
- Superior corrosion resistance through zinc yellow-chromate plating that protects against harsh environmental conditions
- Optimized torque transmission with external hex drive design for secure installation and removal
- Enhanced durability with Rockwell C33 hardness that maintains structural integrity under heavy stress
- Precise thread engagement with Class 2A thread fit ensuring consistent fastening performance
- Reduced cross-threading risk with UNC coarse threads that facilitate easier alignment and installation
- Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed quality and reliability
Professional Applications & Engineering Value
These Grade 8 hex head screws deliver exceptional engineering value in heavy-duty industrial applications where failure is not an option. The steel construction with Rockwell C33 hardness provides the necessary structural integrity for machinery assembly, construction frameworks, and equipment manufacturing. The zinc yellow-chromate plating offers superior protection against corrosion in challenging environments, extending service life in outdoor applications or high-moisture conditions. The 5/16"-18 UNC coarse threading ensures rapid installation while minimizing cross-threading risks, and the partial threading design provides optimal clamping force distribution. These industrial fasteners solve critical challenges in applications requiring high tensile strength and reliable performance under extreme mechanical stress.
Specification Summary & Compliance
This Grade 8 hex head screw features precise Class 2A thread fit with 5/16"-18 UNC coarse threads and partial threading extending to a minimum of 7/8". The fastener maintains dimensional accuracy per ASME B18.2.1 specifications and meets SAE J429 standards for material quality and performance. With a total length of 5-1/4" and external hex drive configuration, these screws deliver consistent performance in industrial applications requiring high-strength fastening solutions.
