S-91257A141 3/8"-24 x 4 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

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 resistance through zinc yellow-chromate plating, extending service life in harsh environments
• Precise thread engagement with Class 2A UNF fine threads ensuring secure fastening and vibration resistance
• Optimal strength-to-weight ratio from Grade 8 steel construction with Rockwell C33 hardness
• Enhanced torque transmission via external hex drive design for easy installation with standard tools
• Reduced material stress concentration through partial threading design for improved fatigue resistance
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed quality

Professional Applications & Engineering Value

These Grade 8 hex head screws deliver critical performance where failure is not an option. The combination of 150,000 psi tensile strength and Rockwell C33 hardness provides exceptional resistance to elongation and shear forces in heavy machinery, structural steel connections, and industrial equipment. The zinc yellow-chromate plating creates a protective barrier against corrosive elements in manufacturing facilities, outdoor installations, and marine-adjacent applications. The 3/8"-24 UNF fine thread configuration offers superior resistance to vibrational loosening compared to coarse threads, while the partial threading design concentrates strength where needed most. These industrial-grade heavy-duty fasteners are engineered to maintain integrity under extreme mechanical stress and environmental challenges.

Specification Summary & Compliance

Manufactured to exacting standards with Class 2A thread fit tolerance for precise engagement and consistent performance. Complies with ASME B18.2.1 dimensional specifications and SAE J429 material requirements for Grade 8 fasteners. Features right-hand UNF fine thread (3/8"-24) with minimum 1" thread length on a 4 1/4" overall length. The external hex drive (9/16" width, 1/4" height) ensures compatibility with standard industrial tools. Meets industry standards for heavy-duty applications requiring reliable steel fasteners with documented performance characteristics.