S-91257A649 3/8"-16 x 6 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 psi ensures reliable performance in the most demanding heavy-duty applications, reducing the risk of fastener failure.
• Superior corrosion resistance provided by the zinc yellow-chromate plating extends the fastener's service life in harsh or outdoor environments.
• High hardness rating (Rockwell C33) offers excellent wear resistance and durability, maintaining thread integrity under high stress.
• Coarse UNC threads allow for faster installation and better performance in materials where fine threads might strip or fail.
• Partially threaded design provides an unthreaded shank for enhanced shear strength and precise clamping in structural connections.
• Class 2A thread fit ensures consistent, easy assembly while maintaining secure fastening, improving installation efficiency.
• External hex drive and hex head design offers high torque capability and easy access for standard tools, speeding up assembly and disassembly.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to solve critical challenges in heavy-duty industrial applications, such as construction, machinery assembly, and structural frameworks. The steel material combined with a zinc yellow-chromate plating provides a robust barrier against corrosion, addressing the common issue of fastener degradation in exposed or chemically aggressive environments. The 3/8"-16 UNC coarse thread and partial threading deliver optimal grip and clamping force, preventing loosening under vibration and dynamic loads. With a 6 1/2" length and external hex drive, it ensures easy installation and reliable performance in high-stress connections, making it a go-to solution for engineers requiring ASME B18.2.1 and SAE J429 compliance for safety and reliability.

Specification Summary & Compliance

This fastener adheres to precise dimensional standards, including a Class 2A thread fit for consistent assembly and UNC coarse thread specifications. It meets ASME B18.2.1 and SAE J429 standards, ensuring compatibility and performance in regulated industrial applications. The product complies with common industry requirements for material and manufacturing quality, supporting reliable use in construction and machinery.