S-91257A778 9/16"-12 x 6 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
- Exceptional load-bearing capacity with 150,000 PSI tensile strength for critical structural applications
- Superior corrosion resistance through zinc yellow-chromate plating that withstands harsh industrial environments
- Optimized thread engagement with UNC coarse threading for faster assembly and reduced cross-threading risk
- Reliable mechanical performance backed by Grade 8 certification and Rockwell C33 hardness rating
- Secure external hex drive design for high-torque installation using standard tools
- Precision thread fit with Class 2A tolerance ensuring consistent mating with nuts and tapped holes
- Strategic partial threading providing maximum grip length where needed while reducing weight
Professional Applications & Engineering Value
Engineered for heavy-duty industrial applications, this Grade 8 hex head screw delivers exceptional performance in demanding environments. The 9/16"-12 UNC coarse thread configuration ensures rapid installation in structural steel, heavy machinery, and construction equipment, while the zinc yellow-chromate plating provides superior protection against corrosion in outdoor or chemically aggressive settings. The partially threaded design concentrates strength where needed most, making it ideal for high-strength bolting applications requiring precise clamp load distribution. With its 150,000 PSI tensile strength and external hex drive, this fastener withstands extreme vibration and dynamic loads in industrial machinery, transportation equipment, and structural frameworks.
Specification Summary & Compliance
This Grade 8 hex head screw features precise Class 2A thread fit with 9/16"-12 UNC coarse threading and meets ASME B18.2.1 and SAE J429 specifications. The inch-system fastener maintains dimensional accuracy with a 6 1/2" length and 1 5/8" minimum thread length. Manufactured from high-strength steel with Rockwell C33 hardness, it complies with industry standards for heavy-duty fastening applications and meets relevant environmental regulations for industrial use.
