S-90517A511 1/4"-20 x 1/2" ASME B18.3 Tamper-Resistant Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized hex drive design to prevent unauthorized access in sensitive applications
• Superior corrosion resistance through 18-8 stainless steel construction and passivated surface treatment
• Exceptional mechanical strength with 70,000 psi tensile strength and Rockwell B55 hardness for demanding environments
• Precision thread engagement with Class 3A fit and UNC coarse threading for reliable fastening performance
• Complete flush mounting capability with standard 82° countersink angle and flat head profile
• Full regulatory compliance meeting ASME B18.3 standards and environmental regulations including RoHS 3 and REACH
• Optimized drive efficiency with 5/32" tamper-resistant hex drive for secure installation and removal

Professional Applications & Engineering Value

This 1/4"-20 UNC flat head tamper-resistant hex screw delivers critical security and durability for industrial applications where unauthorized tampering poses significant risks. The 18-8 stainless steel construction combined with passivated finish provides exceptional resistance to corrosion and chemical exposure, making it ideal for harsh environments including outdoor installations, manufacturing equipment, and public infrastructure. The tamper-resistant hex drive design ensures that only authorized personnel with specialized tools can access the fastener, while the Class 3A thread fit and coarse thread spacing guarantee secure engagement in various materials. These security screws are engineered to maintain integrity under vibration and load, with fully threaded design distributing stress evenly along the entire fastener length for enhanced reliability in critical assemblies.

Specification Summary & Compliance

This fastener features precision 1/4"-20 UNC threading with Class 3A thread fit for superior dimensional accuracy and engagement. Manufacturing complies with ASME B18.3 specifications, ensuring consistent quality and performance. The product meets RoHS 3 (2015/863/EU) compliance for restricted substances and REACH (EC 1907/2006) regulations regarding chemical safety. Additional specifications include standard 82° countersink angle, right-hand thread direction, and fully threaded design for maximum fastening capability across the entire screw length.