S-90484A540 1/4"-20 x 3/4" ASME B18.3, ASTM F835 Tamper-Resistant Hex-Drive Steel Button Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized hex drive design to prevent unauthorized access in secure environments
• Superior corrosion protection through black-oxide surface treatment for extended service life in demanding conditions
• Exceptional load-bearing capacity with 130,000 psi tensile strength and Rockwell C39 hardness for heavy-duty applications
• Precise Class 3A thread fit ensuring reliable engagement and vibration resistance in mechanical assemblies
• Optimized installation efficiency with coarse UNC threading for faster driving and reduced cross-threading risks
• Full regulatory compliance meeting ASME B18.3 manufacturing standards and international environmental regulations
• Versatile rounded button head profile providing a finished appearance while minimizing snagging hazards

Professional Applications & Engineering Value

Engineered for critical security applications, these black-oxide alloy steel screws deliver exceptional performance in industrial machinery, public infrastructure, and electronic enclosures where tampering prevention is paramount. The tamper-resistant hex drive combined with Class 3A UNC coarse threading ensures secure fastening while resisting removal attempts. The fully threaded design maximizes grip length distribution, while the rounded button head provides clean aesthetics without sharp edges. With 130,000 psi tensile strength, these fasteners maintain integrity under substantial vibrational loads and mechanical stress, making them ideal for heavy-duty industrial applications requiring both security and reliability.

Specification Summary & Compliance

Manufactured to precision Class 3A thread tolerances with 1/4"-20 UNC coarse threading and right-hand orientation. Fully compliant with ASME B18.3 specifications (ASTM F835) for dimensional accuracy and mechanical properties. Meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental compliance standards, ensuring safe use in regulated industries. The black-oxide alloy steel construction provides consistent performance across the 3/4" fully threaded length with maintained Rockwell C39 hardness throughout the fastener.