S-91870A777 1/4"-20 x 1" ASME B18.3 Tamper-Resistant Torx Plus Steel Flat Head Screws

Key Features & Benefits at a Glance

• Superior tamper resistance with Torx Plus IPR30 drive for enhanced security in public or restricted-access applications
• Exceptional tensile strength rated at 160,000 psi ensures reliable performance under heavy loads and vibration
• Enhanced corrosion protection from black oxide finish, extending service life in demanding industrial environments
• Precision Class 3A thread fit provides superior engagement and consistent clamping force in critical assemblies
• Optimized countersinking with 82° flat head profile creates flush surfaces while distributing load effectively
• Full threading design allows maximum adjustment flexibility and uniform stress distribution along entire length
• Certified material integrity with Rockwell C38 hardness balancing durability with machinability

Professional Applications & Engineering Value

These alloy steel flat head screws with 1/4-20 UNC coarse threading deliver critical solutions for industrial equipment, machinery, and security installations where vibration resistance and unauthorized access prevention are paramount. The tamper-resistant Torx Plus drive system specifically addresses maintenance security concerns in public infrastructure, transportation, and manufacturing facilities. Engineered with black oxide surface treatment, these fasteners maintain integrity in moderately corrosive environments while the Class 3A thread fit ensures precise assembly in high-vibration applications. The combination of 160,000 psi tensile strength and fully threaded design provides exceptional load distribution, making them ideal for heavy-duty fastening in construction equipment, automotive assemblies, and industrial machinery where reliability cannot be compromised.

Specification Summary & Compliance

Manufactured to exacting ASME B18.3 specifications with Class 3A thread fit ensuring precision tolerance for demanding applications. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. Features standard 82° countersink angle compatible with common chamfered holes. The UNC coarse thread provides optimal performance in most materials while the right-hand thread direction follows industry standards for compatibility with existing tooling and assemblies.