S-91771A638 3/8"-16 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, ensuring long-term reliability in harsh environments.
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for demanding, high-stress applications.
• Precise, reliable fastening due to Class 2A thread fit and UNC coarse threading, providing secure engagement and vibration resistance.
• Optimized for flush mounting with a standard 82° countersink angle and flat head design, ideal for applications requiring a smooth surface finish.
• Efficient installation with Phillips #4 drive, allowing for quick and secure torque application during assembly.
• Versatile partial threading on a 3 1/2" length offers flexibility for clamping and adjustment in various assembly setups.
• Full regulatory compliance with ASME B18.6.3, RoHS 3, and REACH, ensuring safety and environmental standards are met.

Professional Applications & Engineering Value

Engineered for demanding industrial applications, these 3/8"-16 UNC flat head screws provide a robust solution where corrosion resistance and structural integrity are critical. The passivated 18-8 stainless steel material effectively combats oxidation and chemical exposure, making these screws ideal for machinery, marine equipment, and outdoor structures. The partially threaded design and coarse UNC thread enhance grip and reduce the risk of loosening under dynamic loads, while the flat head with 82° countersink ensures a seamless fit, preventing protrusion and improving aerodynamic or aesthetic surfaces. This combination addresses common engineering challenges like material degradation, vibration-induced failure, and installation efficiency, delivering long-term performance in heavy-duty fastening scenarios.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including Class 2A thread fit for consistent accuracy and UNC coarse thread specifications. Manufacturing follows ASME B18.6.3 guidelines, ensuring reliability in mechanical assemblies. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and safe for various industrial uses.