S-91266A629 3/8"-16 x 1 3/4" ASTM F835 Alloy Steel Thread-Locking Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant secure fastening with nylon patch thread locker that maintains integrity across a wide temperature range (-65° to 250°F)
• Exceptional load-bearing capacity thanks to 130,000 psi tensile strength and Rockwell C39 hardness for demanding industrial applications
• Precise thread engagement with Class 3A thread fit ensuring reliable installation and reduced risk of cross-threading
• Superior corrosion protection from black-oxide coating on alloy steel, extending service life in harsh environments
• Optimized flush mounting with standard 82° countersink angle and flat head design for smooth surface finishes
• High-torque installation capability through 7/32" hex drive that prevents stripping during assembly
• Full-threaded design providing maximum grip length and uniform stress distribution along the entire fastener

Professional Applications & Engineering Value

These 3/8"-16 UNC flat head screws deliver critical performance advantages for industrial assembly where vibration resistance and structural integrity are paramount. The black-oxide alloy steel construction combined with Class 3A thread fit ensures precise alignment and durable fastening in heavy machinery, automotive systems, and construction equipment. The integrated nylon patch thread locking technology effectively prevents loosening under dynamic loads, while the coarse UNC threading facilitates quicker installation in structural steel and other demanding materials. The 82° countersink angle creates seamless flush mounting in predrilled applications, making these hex drive screws ideal for applications requiring both aesthetic cleanliness and mechanical reliability.

Specification Summary & Compliance

Manufactured to exacting Class 3A thread fit tolerances with UNC coarse threading (3/8"-16) and full threading along the 1 3/4" length. These screws conform to ASTM F835 specifications for mechanical properties and are fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The black-oxide surface treatment provides additional corrosion protection while maintaining dimensional accuracy across all critical parameters including head diameter (0.781"), drive size (7/32"), and thread diameter (0.375").