S-91771A585 5/16"-18 x 1 1/4" 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, ideal for harsh industrial environments
• Exceptional tensile strength of 80,000 psi ensures reliable performance under heavy loads and vibration
• Precise Class 2A thread fit provides smooth installation and secure fastening in coarse UNC threading applications
• Optimized Phillips No. 4 drive design delivers efficient torque transfer and reduced cam-out during installation
• Standard 82° countersink angle allows for flush mounting in various materials and applications
• Full threading along the 1-1/4" length maximizes grip strength and load distribution across the entire fastener
• Rockwell B80 hardness rating maintains structural integrity and prevents deformation under stress

Professional Applications & Engineering Value

These 5/16"-18 UNC flat head screws deliver critical engineering solutions where corrosion resistance and high tensile strength are paramount. The passivated 18-8 stainless steel construction provides excellent protection against rust and chemical exposure, making them ideal for marine equipment, food processing machinery, and outdoor industrial applications. The combination of fully threaded coarse UNC threading with Class 2A tolerance ensures rapid installation and secure fastening in metal assemblies, wood constructions, and composite materials. The standard 82° countersink angle and flat head profile create seamless, flush surfaces that eliminate protrusions in precision assemblies. These Phillips drive screws with No. 4 drive size offer reliable torque transmission while the 80000 psi tensile strength guarantees long-term performance in vibration-prone environments.

Specification Summary & Compliance

Manufactured to exacting ASME B18.6.3 specifications, these flat head screws feature Class 2A thread fit with 5/16"-18 UNC coarse threading and maintain dimensional accuracy throughout the 1-1/4" length. The fasteners are fully compliant with RoHS 3 (2015/863/EU) regulations and meet REACH (EC 1907/2006) requirements for hazardous substances, ensuring environmental responsibility and workplace safety. The mechanical properties include Rockwell B80 hardness and 80,000 psi tensile strength, providing reliable performance across industrial applications while maintaining consistent quality standards.