S-91211A145 5/16"-18 x 2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Thread-Locking Hex Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with nylon patch thread locker that maintains secure fastening in temperatures from -55° to 250°F
• Exceptional strength and durability with Grade 8 classification, 150,000 psi tensile strength, and Rockwell C33 hardness for heavy-duty applications
• Superior corrosion protection through zinc yellow-chromate plating that extends service life in demanding environments
• Reliable installation and removal with external hex drive and standard 1/2" head width for common tool compatibility
• Optimized thread engagement with Class 2A thread fit and UNC coarse threading for faster assembly and reduced cross-threading risk
• Versatile partial threading design allowing precise clamping force distribution across the 2" length
• Industry-standard compliance ensuring interchangeability and performance reliability per ASME B18.2.1 and SAE J429 specifications

Professional Applications & Engineering Value

Engineered for demanding industrial environments, these Grade 8 hex head screws with nylon patch thread locker provide critical vibration resistance in machinery, automotive assemblies, and structural applications. The zinc yellow-chromate plated steel construction offers superior corrosion protection where environmental factors threaten fastener integrity. With 150,000 psi tensile strength and Rockwell C33 hardness, these 5/16"-18 UNC coarse thread fasteners maintain clamp load under extreme stress conditions. The partially threaded design ensures optimal load distribution while the external hex drive enables high-torque installation in confined spaces. These industrial fasteners solve common challenges of joint relaxation, thermal cycling, and mechanical shock in heavy equipment and manufacturing systems.

Specification Summary & Compliance

These hex head screws feature Class 2A thread fit tolerance with UNC coarse threading (5/16"-18) and comply with ASME B18.2.1 and SAE J429 specifications. The Grade 8 classification ensures mechanical properties including 150,000 psi tensile strength and Rockwell C33 hardness. Manufacturing follows standardized dimensions with 2" length, 7/8" minimum thread length, and right-hand thread direction. The zinc yellow-chromate plating provides corrosion resistance while meeting industry standards for heavy-duty industrial fasteners.