S-91781A552 1/4"-20 x 2 1/2" ASME B18.6.3 Stainless Steel Slotted Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction and passivated finish for extended service life in harsh environments.
• High mechanical strength offering 80,000 psi tensile strength and Rockwell B80 hardness for reliable performance under heavy loads.
• Precise and secure fastening ensured by the Class 2A thread fit and UNC coarse thread profile, reducing the risk of cross-threading.
• Flush mounting capability with a standard flat head and 82° countersink angle for a smooth, unobtrusive finish in assembled products.
• Optimized for industrial use with partial threading providing strong grip where needed and compliance with ASME B18.6.3 standards.
• Easy installation and maintenance using a standard slotted drive, compatible with common tools for efficient assembly and disassembly.
• Environmentally compliant design meeting RoHS 3 and REACH regulations, ensuring safety and sustainability in global supply chains.

Professional Applications & Engineering Value

This 1/4-20 UNC Flat Head Screw is engineered to address common industrial challenges such as vibration loosening and material fatigue. The 18-8 Stainless Steel material, enhanced by a passivated finish, provides excellent resistance to oxidation and chemical exposure, making it ideal for applications in machinery, marine hardware, and food processing equipment where moisture and contaminants are present. The partially threaded design concentrates the clamping force, preventing joint failure in dynamic loads. With a coarse thread spacing and Class 2A fit, it ensures quick assembly and reliable performance in heavy-duty flat head screw applications, reducing downtime and maintenance costs for engineers and procurement specialists.

Specification Summary & Compliance

This screw features precise dimensional accuracy with a Class 2A thread fit and UNC thread type, adhering to ASME B18.6.3 manufacturing specifications. It complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material sustainability. The design includes standard inch measurements, a right-hand thread direction, and a countersink angle of 82° for consistent performance in industrial assemblies.