S-91286A174 5/16"-18 x 3 1/2" 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 protection through zinc-flake coating, extending service life in harsh industrial environments
• Optimized thread engagement with UNC coarse threading and Class 2A fit ensuring secure fastening and vibration resistance
• Enhanced driving efficiency with external hex drive design providing maximum torque transfer during installation
• Consistent mechanical properties maintained through Rockwell C33 hardness and Grade 8 certification
• Reduced cross-threading risk with partially threaded design allowing easier alignment in deep-hole applications
• Regulatory compliance assurance meeting ASME B18.2.1, SAE J429, RoHS 3, and REACH standards for global acceptance

Professional Applications & Engineering Value

Engineered for heavy-duty industrial applications, these Grade 8 steel hex head screws deliver exceptional performance where reliability is critical. The zinc-flake coated surface provides superior corrosion resistance, making them ideal for outdoor equipment, machinery assembly, and structural frameworks exposed to environmental elements. The UNC coarse thread configuration ensures rapid installation and secure fastening in materials where fine threads might strip or fail. With partial threading and external hex drive, these screws offer precise clamping force control while accommodating thermal expansion in metal-to-metal connections. The combination of 150,000 PSI tensile strength and Rockwell C33 hardness provides the durability needed for vibration-prone applications, from construction equipment to automotive assemblies, ensuring long-term joint integrity without premature failure.

Specification Summary & Compliance

This 5/16"-18 x 3 1/2" hex head screw features Class 2A thread fit tolerance for consistent engagement and UNC coarse thread spacing (18 TPI) per standardized specifications. Manufacturing complies with ASME B18.2.1 dimensional requirements and SAE J429 Grade 8 material standards. The product is fully compliant with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations concerning chemical substances, ensuring environmental responsibility and global market acceptance.