S-90585A668 5/16"-24 x 5/8" ASME B18.3, ASTM F879 Stainless Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance in harsh environments thanks to 316 Stainless Steel construction and passivated finish for extended service life.
• Exceptional thread engagement and vibration resistance achieved with a Class 3A precision thread fit and UNF fine threading.
• High mechanical strength and reliability for demanding applications, backed by a 70,000 psi tensile strength and Rockwell B55 hardness.
• Flush and secure installation enabled by the standard 82° flat head profile and hex drive for easy, high-torque assembly.
• Full threading along the 5/8" length provides maximum grip and holding power in a wide range of material thicknesses.
• Guaranteed dimensional consistency and interchangeability as it meets ASME B18.3 and ASTM F879 specifications.
• Safe for use in regulated industries with full compliance to RoHS 3 and REACH environmental standards.

Professional Applications & Engineering Value

This 5/16"-24 UNF Flat Head Screw is engineered to solve critical challenges in corrosive and high-stress environments. The core of its value lies in the 316 Stainless Steel material, which offers far greater resistance to chemicals and chlorides compared to standard grades, making it ideal for marine, chemical processing, and food industry applications. The Class 3A thread fit ensures a tight, secure connection that minimizes the risk of loosening under vibration, a common failure point in machinery and equipment. Combined with the 82° countersink angle and flat head design, it provides a smooth, flush finish that is both aesthetically clean and functionally safe, preventing snagging. The passivated finish further enhances the surface's integrity, creating a protective oxide layer that drastically slows corrosion, thereby reducing maintenance frequency and total cost of ownership.

Specification Summary & Compliance

This screw is manufactured to precise dimensional tolerances, including a Class 3A thread fit for superior engagement. The threading conforms to the 5/16"-24 UNF (Unified National Fine) standard. Manufacturing and quality are governed by the ASME B18.3 specification and ASTM F879 standard. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free from hazardous substances and safe for use in global markets.