S-91781A599 5/16"-18 x 4" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 Stainless Steel construction and passivated finish, ensuring long-term reliability in harsh environments
• Exceptional mechanical strength delivering 80,000 psi tensile strength and Rockwell B80 hardness for heavy-duty fastening applications
• Precision thread engagement with Class 2A fit and UNC coarse threads providing secure, vibration-resistant connections
• Optimized flush mounting featuring standard 82° countersink angle for seamless surface integration
• Enhanced installation control through slotted drive design and partially threaded shank for precise placement
• Regulatory compliance assurance meeting ASME B18.6.3 standards and environmental regulations including RoHS 3 and REACH
• Versatile industrial application with 4" length and right-hand threading suitable for various assembly requirements

Professional Applications & Engineering Value

This 5/16"-18 UNC flat head slotted screw delivers critical engineering advantages in demanding industrial environments. The 18-8 Stainless Steel composition combined with passivated finish provides exceptional resistance to corrosion and chemical exposure, making it ideal for marine, food processing, and outdoor applications where moisture resistance is paramount. The partially threaded design allows for precise clamping force distribution, while the 82° countersink angle ensures flush mounting in standardized recesses. With 80,000 psi tensile strength and Rockwell B80 hardness, this fastener maintains structural integrity under significant mechanical stress, preventing joint failure in machinery, equipment assembly, and structural frameworks. The coarse UNC thread pattern facilitates quick installation and superior holding power in various materials.

Specification Summary & Compliance

This 4" flat head screw features precise Class 2A thread fit with 5/16"-18 UNC coarse threading and right-hand direction. Manufacturing specifications strictly adhere to ASME B18.6.3 standards for dimensional accuracy and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across various industries. The partially threaded configuration provides optimal engagement while maintaining specified tensile strength and hardness characteristics throughout the fastener's service life.