S-91257A654 3/8"-16 x 9" 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 under extreme loads, reducing the risk of fastener failure in critical assemblies.
• Superior corrosion resistance from zinc yellow-chromate plating extends service life in harsh environments, minimizing maintenance and replacement costs.
• High hardness rating (Rockwell C33) provides excellent wear resistance, maintaining thread integrity through repeated installations and vibrations.
• Precise Class 2A thread fit with UNC coarse threading enables faster installation and secure holding power in a wide range of materials.
• Partially threaded design allows for controlled clamping force distribution, ideal for applications requiring precise joint compression.
• Heavy-duty Grade 8 certification guarantees consistent quality and mechanical properties for demanding industrial applications.
• External hex drive compatibility with standard 9/16" wrench sizes ensures easy installation and removal with common industrial tools.

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 8 hex head screws deliver critical performance where structural integrity is paramount. The combination of 150,000 psi tensile strength and Rockwell C33 hardness makes them ideal for construction equipment, automotive frames, and machinery assemblies subjected to high stress and vibration. The zinc yellow-chromate plating provides essential corrosion protection in outdoor or chemically aggressive environments, while the UNC coarse threads and partial threading design prevent loosening under dynamic loads. These steel fasteners solve common engineering challenges by offering predictable failure margins, consistent torque-tension relationships, and compliance with industry standards for reliable bolted connections in critical structural applications.

Specification Summary & Compliance

Manufactured to ASME B18.2.1 and SAE J429 Grade 8 specifications, these screws feature Class 2A thread fit tolerances for consistent engagement. The 3/8"-16 UNC coarse thread pattern ensures compatibility with standard components, while the 9" length with 1 1/4" minimum thread length provides optimal fastening capability. The zinc yellow-chromate finish meets industry standards for corrosion resistance, and the external hex drive design (9/16" head width) accommodates standard wrenching tools. These fasteners comply with relevant industrial specifications for dimensional accuracy and mechanical properties required in critical assembly applications.