S-91870A140 4-40 x 1/2" ASME B18.3 Tamper-Resistant Torx Stainless Steel Flat Head Screws

Key Features & Benefits at a Glance

• Enhanced tamper resistance with specialized T8 Torx drive that deters unauthorized access while providing secure installation
• Superior corrosion protection through 18-8 stainless steel construction and passivated surface treatment for extended service life
• Reliable thread engagement with 4-40 UNC coarse threading and Class 2A fit ensuring consistent performance in vibration-prone applications
• High-strength performance delivering 70,000 psi tensile strength and Rockwell B70 hardness for demanding industrial environments
• Flush mounting capability with standard 82° countersink angle flat head design for smooth surface finishes
• Full regulatory compliance meeting ASME B18.3 specifications and environmental standards including RoHS 3 and REACH
• Complete threading coverage along the entire 1/2" length for maximum grip and holding power

Professional Applications & Engineering Value

These 4-40 UNC tamper-resistant Torx flat head screws provide critical security solutions for industrial applications where unauthorized access prevention is paramount. The combination of 18-8 stainless steel material and passivated finish creates exceptional resistance to corrosion and chemical exposure, making them ideal for harsh environments including outdoor equipment, marine applications, and chemical processing facilities. The T8 tamper-resistant drive system ensures that critical assemblies remain secure while maintaining the installation advantages of Torx drive technology. With 70000 psi tensile strength and Rockwell B70 hardness, these fasteners maintain integrity under stress and vibration, preventing loosening in machinery, electronic enclosures, and public infrastructure applications where reliability is non-negotiable.

Specification Summary & Compliance

Manufactured to precise dimensional standards with Class 2A thread fit and 4-40 UNC coarse threading for reliable engagement. These security screws feature a standard 82° countersink angle and fully threaded 1/2" length design. Compliance includes ASME B18.3 specifications for dimensional accuracy and mechanical properties, along with environmental regulations including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance, ensuring they meet current industry standards for safety and environmental responsibility.