S-91257A651 3/8"-16 x 4 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
- Maximum load-bearing capacity with 150,000 psi tensile strength for critical heavy-duty applications
- Superior corrosion resistance through zinc yellow-chromate plating, extending service life in harsh environments
- Enhanced durability with Rockwell C33 hardness to withstand high-stress conditions without deformation
- Reliable thread engagement with Class 2A fit UNC coarse threads for secure fastening and vibration resistance
- Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for quality assurance
- Optimized partial threading providing both gripping strength and clearance where needed
- Easy installation and removal with external hex drive design for standard tool compatibility
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 protection for outdoor equipment, machinery, and structural applications exposed to moisture and chemicals. The 3/8"-16 UNC coarse thread configuration ensures rapid assembly and reliable performance in high-vibration settings, while the partial threading design offers optimal clamp load distribution. With 150,000 psi tensile strength and Rockwell C33 hardness, these fasteners prevent stripping and maintain integrity under extreme loads, making them ideal for construction equipment, automotive assemblies, and heavy machinery where safety and reliability are paramount.
Specification Summary & Compliance
Manufactured to precise dimensional standards with Class 2A thread fit tolerance for consistent performance. Complies with ASME B18.2.1 and SAE J429 specifications governing dimensional requirements and mechanical properties. Features 3/8"-16 UNC coarse threads with right-hand direction and 1" minimum thread length on a 4-1/4" overall length. The zinc yellow-chromate plating meets industry standards for corrosion protection while maintaining the fastener's high-strength characteristics.
