S-91771A543 1/4"-20 x 1 1/8" 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 industrial environments.
• Exceptional mechanical strength with 80,000 psi tensile strength and Rockwell B80 hardness for heavy-duty applications.
• Precise, reliable fastening achieved through Class 2A thread fit and fully threaded design for consistent engagement and vibration resistance.
• Efficient installation and flush finish with standard 82° countersink angle and No. 3 Phillips drive for secure, low-profile assembly.
• Broad industry compatibility using 1/4"-20 UNC coarse threads and right-hand direction for versatile use across equipment and machinery.
• Regulatory peace of mind with full compliance to ASME B18.6.3, RoHS 3, and REACH standards for safe, quality-assured procurement.

Professional Applications & Engineering Value

Engineered for demanding environments, these 1/4"-20 UNC flat head screws address critical industrial challenges such as material fatigue and chemical exposure. The passivated 18-8 stainless steel provides excellent resistance to oxidation and corrosive agents, extending service life in applications like machinery assembly, electrical enclosures, and outdoor structures. The fully threaded design and Class 2A thread fit ensure uniform load distribution and minimize loosening under vibration, while the standard 82° countersink allows for a smooth, flush surface—ideal for aesthetic or safety-critical assemblies. With a No. 3 Phillips drive, installation is straightforward, reducing labor time without compromising on the 80,000 psi tensile strength required for high-stress connections.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 2A thread fit for precise dimensional accuracy as per ASME B18.6.3 specifications. Manufacturing adheres to strict standards, including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance, ensuring environmental safety and material integrity. The fully threaded design, 82° countersink angle, and right-hand thread direction are maintained to support reliable performance in industrial fastening systems.