S-91266A250 10-32 x 3/8" ASTM F835 Alloy Steel Thread-Locking Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with permanent nylon patch ensures reliable fastening in high-stress environments, preventing loosening under dynamic loads.
• Exceptional corrosion protection from black-oxide coating on alloy steel, extending service life in demanding industrial conditions.
• High tensile strength of 130,000 psi and Rockwell C39 hardness provide superior load-bearing capacity and resistance to shear forces.
• Precise Class 3A thread fit with UNF fine threading enables secure engagement and reduced risk of cross-threading in critical assemblies.
• Wide temperature tolerance from -65° to 250°F allows consistent performance in extreme thermal cycling applications.
• 82° countersink flat head design with hex drive ensures flush mounting and easy installation with standard tools, minimizing protrusion.
• Full compliance with ASTM F835, RoHS 3, and REACH guarantees material safety and meets rigorous industrial and environmental standards.

Professional Applications & Engineering Value

This 10-32 UNF flat head screw is engineered to address critical challenges in machinery, automotive, and aerospace assemblies where vibration-induced loosening and thermal stability are concerns. The nylon patch locking mechanism chemically bonds with mating threads, creating a permanent seal that outperforms mechanical lock washers. Manufactured from black-oxide alloy steel, it resists oxidation and galling while maintaining 130,000 psi tensile strength under sustained loads. The fine UNF threading and Class 3A fit provide tighter tolerances for precision equipment, reducing maintenance downtime. Ideal for securing engine components, electronic enclosures, and structural frames exposed to temperature fluctuations from -65° to 250°F.

Specification Summary & Compliance

This fastener adheres to Class 3A thread fit per UNF standards, ensuring precise engagement with 10-32 fine threading. Manufacturing follows ASTM F835 specifications for dimensional consistency and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances. The 82° countersink angle and fully threaded design meet industry requirements for flush-mounted applications in regulated environments.