S-90058A581 5/16"-18 x 3/4" Tamper-Resistant Tri-Groove-Drive Steel Round Head Screws

Key Features & Benefits at a Glance

• Enhanced corrosion resistance with zinc-plated steel construction for extended service life in harsh environments
• Superior holding power achieved through Class 3A thread fit ensuring precise, vibration-resistant connections
• Optimized drive engagement with Tri-Groove design providing excellent torque transmission and reduced cam-out risk
• Maximum thread engagement from fully threaded design for consistent clamping force across the entire fastener length
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell C28 hardness for heavy-duty applications
• Reliable coarse threading (UNC) enabling quick installation and superior performance in softer materials
• Streamlined installation with rounded head profile that minimizes snagging and provides a finished appearance

Professional Applications & Engineering Value

Engineered for demanding industrial fastening applications, these zinc-plated steel screws deliver exceptional performance where reliability is critical. The Class 3A UNC thread fit provides precise tolerances that prevent loosening under vibration, making them ideal for machinery, equipment assembly, and structural applications. The Tri-Groove drive system offers superior torque transfer compared to conventional drives, reducing installation time and tool wear. With 80,000 psi tensile strength and full threading, these rounded head screws maintain consistent clamping force in high-stress environments, while the zinc plating provides essential corrosion protection for extended service life in manufacturing, construction, and maintenance operations.

Specification Summary & Compliance

This 5/16"-18 x 3/4" screw features UNC coarse threading with precision Class 3A fit tolerances, ensuring consistent performance across industrial applications. Manufactured from high-strength steel with zinc plating for corrosion resistance, the fastener meets industry standards for inch system fasteners and is suitable for applications requiring Rockwell C28 hardness and 80,000 psi tensile strength. The Tri-Groove drive (No. 20 size) provides reliable engagement, while the fully threaded design maximizes fastening efficiency. Compliant with industry specifications for heavy-duty mechanical fasteners.