S-91771A597 5/16"-18 x 3 1/2" ASME B18.6.3 Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with passivated 18-8 stainless steel construction for extended service life in harsh environments
• Exceptional tensile strength rated at 80,000 psi for reliable performance in demanding industrial applications
• Precision thread engagement with UNC coarse threads and Class 2A fit ensuring secure fastening and vibration resistance
• Optimized flush mounting featuring standard 82° countersink angle for seamless surface integration
• Enhanced drive stability with Phillips No. 4 drive design providing secure torque transmission
• Industry compliance assurance meeting ASME B18.6.3 specifications and environmental regulations
• Versatile partial threading allowing for both clamping and alignment functions in assembly operations

Professional Applications & Engineering Value

These 5/16"-18 UNC flat head screws deliver critical engineering advantages through their passivated 18-8 stainless steel composition and precision manufacturing. The corrosion-resistant properties make them ideal for marine, chemical processing, and outdoor applications where environmental exposure compromises fastener integrity. The partially threaded design provides optimal grip length while allowing unthreaded shank sections to function as precision alignment pins. With 80000 psi tensile strength and Rockwell B80 hardness, these industrial flat head screws maintain structural integrity under dynamic loads and vibration, preventing joint failure in machinery, equipment frames, and structural assemblies. The standardized 82° countersink angle ensures flush mounting in conforming recesses, eliminating protrusions that could interfere with moving components or create safety hazards.

Specification Summary & Compliance

Manufactured to exacting dimensional standards with Class 2A thread fit and UNC coarse thread spacing for reliable engagement. These flat head screws comply with ASME B18.6.3 mechanical and dimensional specifications, ensuring interchangeability and performance predictability. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) requirements, confirming the absence of restricted substances. The 3 1/2" length with 1 1/2" minimum thread length provides versatile fastening capability across various material thicknesses while maintaining structural reliability.