S-91257A505 1/2"-20 x 12" 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 industrial environments
• Precise thread engagement with Class 2A thread fit ensuring consistent fastening and vibration resistance
• Optimized torque transmission via external hex drive and 3/4" head width for secure installation with standard tools
• Enhanced durability from Rockwell C33 hardness maintaining structural integrity under repeated stress
• Versatile partial threading allowing both secure clamping and adjustable positioning in assembly applications
• Industry-standard compliance meeting ASME B18.2.1 and SAE J429 specifications for guaranteed interoperability

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, this Grade 8 hex head screw addresses critical challenges in machinery assembly, structural steel connections, and equipment manufacturing. The 1/2"-20 UNF fine threading provides superior resistance to vibrational loosening while maintaining higher tensile strength compared to coarse threads. The zinc yellow-chromate plating creates a protective barrier against oxidation and chemical exposure, significantly extending maintenance intervals in demanding environments. With partial threading along its 12" length, this fastener enables precise clamping force distribution while allowing unthreaded sections to function as precision guides or alignment pins. The combination of 150,000 psi tensile strength and Rockwell C33 hardness ensures reliable performance in applications subject to dynamic loads and impact forces, from construction equipment to industrial processing machinery.

Specification Summary & Compliance

This 12" hex head screw features precise Class 2A thread fit with 1/2"-20 UNF fine thread spacing and right-hand threading. Manufactured to ASME B18.2.1 and SAE J429 standards, ensuring dimensional accuracy and mechanical properties. The zinc yellow-chromate plating provides corrosion protection while maintaining compliance with industrial fastener specifications. The Grade 8 classification guarantees consistent performance with documented 150,000 psi tensile strength and Rockwell C33 hardness verification.