S-91266A583 5/16"-18 x 1" ASTM F835 Alloy Steel Thread-Locking Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant performance with permanent nylon patch locking that maintains secure connections in demanding applications
• Exceptional strength and durability from alloy steel construction with 130,000 psi tensile strength and Rockwell C39 hardness
• Reliable temperature tolerance with thread locker effectiveness maintained from -65° to 250°F for diverse operating environments
• Precision threading with Class 3A fit and UNC coarse threads ensuring consistent engagement and reduced cross-threading risk
• Corrosion protection through black-oxide surface treatment extending service life in industrial conditions
• Easy installation with standard 82° flat head profile and 3/16" hex drive for efficient assembly operations
• Full thread coverage along the 1" length provides maximum grip strength and load distribution

Professional Applications & Engineering Value

These 5/16"-18 UNC flat head screws with nylon patch locking technology deliver critical vibration resistance in machinery, automotive, and heavy equipment applications where loosening under dynamic loads poses significant failure risks. The black-oxide alloy steel construction combines high tensile strength with corrosion resistance, while the Class 3A thread fit ensures precise engagement in tapped holes. The standard flat head profile with 82° countersink angle provides flush mounting in precision assemblies, and the coarse thread design offers superior performance in softer materials and high-vibration environments. Engineered to maintain locking capability across extreme temperature ranges, these fasteners solve reliability challenges in industrial maintenance and manufacturing operations.

Specification Summary & Compliance

Manufactured to exacting Class 3A thread fit tolerances with UNC coarse threading (18 TPI) and full threading along the 1" length. These screws conform to ASTM F835 specifications for mechanical properties and performance. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations ensures suitability for global industrial applications. The black-oxide surface treatment provides additional corrosion protection while maintaining dimensional accuracy per industry standards.