S-90517A515 1/4"-20 x 1 1/4" ASME B18.3 Tamper-Resistant Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized hex drive requiring matching security bits, preventing unauthorized access in sensitive installations.
• Superior corrosion resistance from 18-8 stainless steel construction with passivated finish, ensuring long-term reliability in harsh environments.
• High-strength performance delivering 70,000 psi tensile strength and Rockwell B55 hardness for demanding industrial applications.
• Precision Class 3A thread fit providing secure, vibration-resistant fastening with consistent engagement in UNC coarse threads.
• Optimized flush mounting with standard 82° countersink angle and flat head design for smooth surface finishing.
• Partial threading design allowing superior clamping force distribution across connected materials.
• Full regulatory compliance meeting ASME B18.3 specifications and environmental standards including RoHS 3 and REACH.

Professional Applications & Engineering Value

These 1/4-20 UNC flat head tamper-resistant hex screws address critical security and durability challenges in industrial fastening. The 18-8 stainless steel construction with passivated finish provides exceptional resistance to corrosion and chemical exposure, making them ideal for outdoor equipment, marine applications, and harsh manufacturing environments. The tamper-resistant hex drive (5/32") specifically counters unauthorized tampering in public infrastructure, electrical enclosures, and security systems. With 70000 psi tensile strength and Class 3A thread fit, these screws maintain clamping force under vibration and dynamic loads, while the 82° countersink angle ensures flush mounting in precision assemblies. Their partial threading design prevents joint loosening in structural applications where shear strength is paramount.

Specification Summary & Compliance

Manufactured to ASME B18.3 specifications with Class 3A thread fit for precision UNC coarse threading (1/4"-20). Features include 1" minimum thread length, 1-1/4" overall length, and standardized 82° flat head profile. Full compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across regulated industries.