S-91870A775 1/4"-20 x 1/2" ASME B18.3 Tamper-Resistant Torx Plus Steel Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced Security: Tamper-resistant Torx Plus IPR27 drive prevents unauthorized removal, ideal for public or high-security installations.
• Superior Corrosion Resistance: Black oxide finish provides durable protection against rust, extending service life in harsh industrial environments.
• Exceptional Mechanical Strength: 160,000 psi tensile strength and Rockwell C38 hardness ensure reliable performance under heavy loads and stress.
• Precision Fit & Easy Installation: Class 2A thread fit and coarse UNC threading enable quick, accurate assembly with reduced cross-threading risk.
• Optimized Head Design: Undercut flat head with 82° countersink angle allows for a flush, low-profile finish that minimizes snagging and improves aesthetics.
• Full Thread Engagement: Fully threaded design maximizes grip and load distribution across the entire fastener length.
• Regulatory Compliance: Meets ASME B18.3 specifications and is RoHS 3 & REACH compliant, ensuring safety and environmental standards are upheld.

Professional Applications & Engineering Value

This 1/4-20 UNC alloy steel flat head screw is engineered to address critical challenges in industrial assembly and security-focused applications. The tamper-resistant Torx Plus drive (IPR27 size) deters vandalism and unauthorized access, making it ideal for public infrastructure, machinery guards, and electronic enclosures. Its black oxide finish significantly enhances corrosion resistance, which is vital for outdoor or humid environments. The undercut flat head design ensures a seamless, flush mount that reduces protrusion risks and improves aerodynamic or aesthetic profiles. Combined with 160,000 psi tensile strength and full threading, this screw provides robust, reliable fastening for heavy-duty equipment, automotive components, and structural frameworks where vibration resistance and long-term durability are paramount.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including Class 2A thread fit for consistent engagement and UNC coarse threads (1/4"-20) that facilitate rapid installation. Manufacturing and quality are governed by ASME B18.3 specifications, ensuring uniformity and reliability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and safe for various industrial and commercial uses.