S-90517A120 4-40 x 3/8" 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 tools, preventing unauthorized access in sensitive applications
• Superior corrosion resistance through 18-8 stainless steel construction and passivated surface treatment for extended service life
• High-strength performance delivering 70,000 psi tensile strength and Rockwell B55 hardness for demanding industrial environments
• Precise thread engagement with Class 3A thread fit ensuring reliable fastening and vibration resistance in critical assemblies
• Optimal flush mounting featuring standard 82° countersink angle for seamless integration with mating surfaces
• Full-threaded design providing maximum grip length and load distribution across the entire fastener length
• Regulatory compliance meeting ASME B18.3 specifications while adhering to RoHS 3 and REACH environmental standards

Professional Applications & Engineering Value

Engineered for security-critical applications, these 4-40 UNC flat head screws with tamper-resistant hex drive address the growing need for protected assemblies in public infrastructure, electronic enclosures, and industrial equipment. The 18-8 stainless steel composition combined with passivated finish creates a robust barrier against corrosive environments, significantly extending maintenance intervals in harsh operating conditions. The Class 3A thread fit ensures precise mating with corresponding components, reducing the risk of loosening under vibration while maintaining 70,000 psi tensile strength for high-stress applications. The 82° countersink angle facilitates flush installation, eliminating protrusions that could compromise safety or aesthetics in finished products.

Specification Summary & Compliance

This 4-40 UNC threaded security screw features Class 3A thread fit precision and coarse thread spacing for optimal engagement. Manufacturing conforms to ASME B18.3 standards for dimensional accuracy and performance reliability. The product maintains full compliance with RoHS 3 (2015/863/EU) restrictions on hazardous substances and REACH (EC 1907/2006) regulations for chemical safety, ensuring environmental responsibility in industrial supply chains.