S-99891A165 5/8"-18 Hex Nuts

Key Features & Benefits at a Glance

• Exceptional strength and reliability with Grade 8 steel construction, ensuring secure fastening in high-stress industrial environments.
• Superior corrosion resistance from zinc yellow-chromate plating, extending service life in harsh or outdoor conditions.
• Precise left-hand threading (5/8"-18 UNF) for specialized applications requiring reverse rotation, preventing accidental loosening.
• Fine thread spacing and Class 2B fit for tighter engagement and reduced vibration-induced failures in machinery.
• Standard external hex drive design allows for easy installation and removal with common tools, improving assembly efficiency.
• Heavy-duty durability with dimensions of 15/16" width and 35/64" height, providing robust performance in demanding setups.
• Wide compatibility with inch-system components, making it ideal for North American industrial standards and replacements.

Professional Applications & Engineering Value

This Grade 8 heavy-duty hex nut is engineered to address critical challenges in industrial fastening, such as vibration resistance and corrosion in demanding environments. Made from high-strength steel with a zinc yellow-chromate plating, it combats rust and wear in automotive, construction, or machinery applications. The left-hand thread (5/8"-18 UNF) is specifically designed for systems where standard right-hand threads could loosen under rotational forces, such as in rotating shafts or specialized equipment. Its fine threading and Class 2B fit ensure a secure, tight connection that minimizes backlash and maintains integrity under dynamic loads. By offering reliable performance in heavy-duty applications, this nut reduces maintenance needs and enhances operational safety, making it a trusted choice for engineers and procurement specialists.

Specification Summary & Compliance

This hex nut adheres to UNF fine thread standards with a size of 5/8"-18 and Class 2B thread fit for precise dimensional accuracy. It meets Grade 8 strength requirements under ASME and SAE specifications, ensuring high tensile and yield strength. The zinc yellow-chromate plating provides corrosion protection in line with industry practices, and the product is manufactured to comply with RoHS and REACH environmental directives for safe use in various industrial sectors.