S-91771A559 1/4"-28 x 3/4" 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 environments and long-term reliability.
• High tensile strength of 80,000 psi ensures secure fastening under significant mechanical stress and vibration.
• Precision Class 2A thread fit provides smooth assembly and consistent engagement, reducing installation time and risk of cross-threading.
• 82° countersink angle and flat head design allows for a flush, clean finish in countersunk holes, minimizing protrusion and snagging.
• Phillips No. 3 drive offers efficient torque transfer and widespread tool compatibility for streamlined installation.
• Full threading along the 3/4" length maximizes grip and load distribution across the entire fastened joint.
• Compliance with ASME B18.6.3, RoHS 3, and REACH guarantees adherence to industry standards and environmental safety regulations.

Professional Applications & Engineering Value

This 1/4"-28 UNF flat head screw is engineered to address critical challenges in industrial assembly, where corrosion resistance, high tensile strength, and precise fit are paramount. The passivated 18-8 stainless steel material combats rust and chemical exposure, making it suitable for applications in marine, chemical processing, and outdoor equipment. The UNF fine thread and Class 2A fit ensure tight, reliable fastening in dynamic or high-vibration environments, such as machinery, automotive components, and electronic enclosures. The flat head with 82° countersink provides a seamless surface finish, essential for aerodynamic or safety-critical designs where protrusions are unacceptable. By integrating these features, this screw delivers long-term durability and performance, reducing maintenance needs and downtime in demanding industrial applications.

Specification Summary & Compliance

This screw features a 1/4"-28 UNF fine thread with Class 2A thread fit for precise dimensional accuracy and easy assembly. It is manufactured in accordance with ASME B18.6.3 specifications, ensuring consistent quality and interoperability. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) confirms that it is free from hazardous substances, meeting environmental and safety standards for global industrial use.