S-91257A552 1/4"-20 x 2 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 capability with Grade 8 strength rating and 150,000 psi tensile strength for critical heavy-duty applications
- Superior corrosion protection through zinc yellow-chromate plating that withstands harsh industrial environments
- Optimized torque transmission with external hex drive design and 7/16" head width for secure installation
- Reliable coarse thread engagement with UNC 1/4"-20 threading that resists vibration loosening
- Precision thread fit meeting Class 2A specifications for consistent assembly performance
- Enhanced durability with Rockwell C33 hardness that maintains integrity under repeated stress
- Versatile partial threading allowing for both clamping and alignment functions in structural applications
Professional Applications & Engineering Value
These Grade 8 hex head screws deliver exceptional engineering value in demanding industrial environments where failure is not an option. The zinc yellow-chromate plated steel construction provides superior corrosion resistance for outdoor equipment, machinery, and structural assemblies exposed to moisture and chemicals. The 1/4"-20 UNC coarse thread design ensures rapid installation and maintains grip strength in vibrating applications, while the partial threading allows for precise clamping force distribution. With 150,000 psi tensile strength and Rockwell C33 hardness, these fasteners prevent stripping and deformation under extreme loads, making them ideal for heavy machinery, construction equipment, and automotive applications where reliability is paramount.
Specification Summary & Compliance
This 2-1/2" hex head screw features precision Class 2A thread fit with 1/4"-20 UNC coarse threads and 3/4" minimum thread length. Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, ensuring dimensional accuracy and performance consistency. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, making it suitable for global industrial applications requiring strict regulatory adherence.
