S-99891A110 5/16"-18 Hex Nuts

Key Features & Benefits at a Glance

• Exceptional tensile strength from Grade 8 classification, ensuring reliable performance in high-stress industrial environments.
• Superior corrosion resistance with zinc yellow-chromate plating, extending service life in harsh or outdoor conditions.
• Secure left-hand thread engagement for specialized applications where reverse rotation prevents loosening under vibration.
• Precise Class 2B thread fit for smooth assembly and consistent clamping force without cross-threading risks.
• Coarse UNC threading enabling faster installation and reduced susceptibility to debris clogging in rugged settings.
• Standard external hex drive design for easy wrench access and high torque application with common tools.
• Durable steel construction providing long-term reliability and resistance to wear in repetitive use scenarios.

Professional Applications & Engineering Value

This Grade 8 hex nut with left-hand thread direction addresses critical challenges in machinery, automotive, and construction sectors where standard right-hand threads may unscrew under counter-rotational forces. The zinc yellow-chromate plated steel material combats oxidation and chemical exposure, ideal for outdoor equipment or humid environments. Its coarse UNC thread profile ensures rapid installation in high-volume assembly lines while maintaining grip strength. Engineers specify this heavy-duty hex nut for rotating shafts, mixer blades, or press fittings where reverse-thread mechanics enhance safety. The Class 2B thread fit guarantees compatibility with matching 5/16"-18 UNC bolts, minimizing play and vibration-induced failures in dynamic load applications.

Specification Summary & Compliance

Manufactured to UNC coarse thread standards with Class 2B thread fit tolerances for consistent engagement. Dimensions include 5/16"-18 thread size, 1/2" width across flats, and 17/64" height. Complies with ASME B18.2.2 for hex nut specifications and Grade 8 strength requirements (approximately 150 ksi minimum tensile strength). Surface treatment meets RoHS and REACH environmental directives for hazardous substance restrictions.