S-94688A313 1/4"-20 x 1 1/2" ASME B18.2.1 Square Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength with 150,000 psi rating for reliable performance in high-stress applications
• Superior corrosion resistance provided by zinc yellow-chromate plating for extended service life in harsh environments
• Precision thread engagement with Unified Standard Class 3A fit ensuring secure fastening and vibration resistance
• Optimized drive efficiency through external square head design for maximum torque application and reduced stripping
• Industry-standard compliance with ASME B18.2.1 specifications guaranteeing consistent quality and interchangeability
• Enhanced grip performance from UNC coarse thread design that resists loosening under dynamic loads
• Full-threaded construction providing maximum holding power across the entire 1-1/2" length

Professional Applications & Engineering Value

This SAE Grade 8 square head screw delivers exceptional engineering value in demanding industrial environments where failure is not an option. The 150,000 psi tensile strength makes it ideal for heavy machinery, structural assemblies, and equipment subjected to extreme vibrational forces. The zinc yellow-chromate plating provides superior corrosion protection, significantly extending service life in outdoor applications or humid conditions. The external square drive design allows for higher torque application compared to standard hex heads, reducing the risk of stripping during installation in confined spaces. With its UNC coarse thread and Class 3A thread fit, this fastener maintains secure connections in materials where fine threads might fail, making it particularly valuable for construction equipment, agricultural machinery, and industrial maintenance applications requiring dependable, long-lasting fastening solutions.

Specification Summary & Compliance

This high-performance square head screw features precise 1/4"-20 UNC coarse threads with Unified Standard Class 3A tolerance for optimal fit and function. The fastener is manufactured to meet ASME B18.2.1 specifications, ensuring dimensional accuracy and industrial-grade reliability. With SAE Grade 8 classification and 150,000 psi tensile strength, it exceeds standard requirements for high-strength applications. The zinc yellow-chromate plating provides RoHS-compliant corrosion protection while maintaining the screw's mechanical properties. The fully threaded design and right-hand thread direction follow industry standards for compatibility with existing equipment and tooling.