S-90484A557 5/16"-18 x 1" ASME B18.3, ASTM F835 Tamper-Resistant Hex-Drive Steel Button Head Screws

Key Features & Benefits at a Glance

• Superior tamper resistance with a specialized hex drive that deters unauthorized access in secure environments.
• Exceptional tensile strength of 130,000 psi ensures reliable performance under high-stress and heavy-duty conditions.
• Enhanced durability and corrosion resistance from the black-oxide finish on alloy steel, extending service life in harsh industrial settings.
• Precise, secure fastening with Class 3A thread fit, providing tighter tolerances and reduced risk of loosening in vibration-prone applications.
• Optimized for quick installation using a coarse UNC thread and fully threaded design, allowing for faster assembly and strong holding power.
• High hardness rating (Rockwell C39) maintains thread integrity and drive features, resisting wear and deformation over repeated use.
• Low-profile rounded button head offers a smooth finish that minimizes snagging and provides a clean, professional appearance.

Professional Applications & Engineering Value

Engineered for demanding industrial and commercial applications, this 5/16"-18 UNC Rounded Head Screw delivers critical performance where reliability is non-negotiable. The black-oxide alloy steel construction provides a robust barrier against corrosion, making it ideal for machinery, automotive assemblies, and outdoor equipment exposed to moisture and chemicals. Its tamper-resistant hex drive is essential in public infrastructure, security panels, and access control systems, preventing tampering without sacrificing installation efficiency. The coarse thread and Class 3A thread fit ensure rapid, vibration-resistant fastening in metals and engineered plastics, reducing assembly time while maintaining joint integrity under dynamic loads. This combination of material strength, precise threading, and specialized drive addresses common failure points—such as stripping, corrosion, and unauthorized removal—providing long-term value in heavy-duty fastening scenarios.

Specification Summary & Compliance

This screw adheres to UNC coarse thread standards with a Class 3A thread fit for high precision. It is manufactured in accordance with ASME B18.3 specifications and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), ensuring it meets stringent environmental and safety regulations for industrial use.