S-91257A633 3/8"-16 x 2 1/4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Maximum Load-Bearing Capability – Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in high-stress industrial environments.
• Superior Corrosion Resistance – Zinc yellow-chromate plating provides long-lasting protection against rust and environmental degradation.
• Optimized Thread Engagement – UNC coarse thread design and Class 2A thread fit enable quick assembly and secure fastening in various materials.
• Enhanced Durability – Rockwell C33 hardness and steel construction deliver exceptional wear resistance and longevity.
• Easy Installation & Removal – External hex drive and 9/16" head width allow for standard wrench access and high torque application.
• Versatile Partial Threading – Combines strong clamping force with unthreaded shank stability for demanding structural applications.
• Regulatory Compliance Assurance – Meets ASME B18.2.1, SAE J429, RoHS 3, and REACH standards for quality and environmental safety.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 8 hex head screws address critical challenges in machinery assembly, structural steel connections, and automotive components. The 3/8"-16 UNC coarse thread provides excellent grip in both metal and composite materials, while the zinc yellow-chromate plating significantly extends service life in corrosive environments. The partially threaded design ensures optimal stress distribution, preventing loosening under vibration and dynamic loads. With 150,000 psi tensile strength and Rockwell C33 hardness, these fasteners maintain integrity in high-torque applications where failure is not an option, making them ideal for construction equipment, industrial machinery, and transportation systems requiring ASME B18.2.1 compliance.

Specification Summary & Compliance

This 2-1/4" hex head screw features precise Class 2A thread fit with 3/8"-16 UNC coarse threading and minimum 1" thread length. Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, it ensures dimensional accuracy and mechanical performance. The fastener is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, guaranteeing safe use across global industrial markets.