S-98070A143 4-40 x 3/4" Sealing Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Superior sealing performance with Buna-N rubber O-rings rated for pressures up to 1500 psi and temperatures from -40° to 225° F, preventing leaks in demanding environments.
• Excellent corrosion resistance thanks to 18-8 stainless steel construction and passivated finish, ensuring long-term durability in harsh conditions.
• Reliable thread engagement with Class 2A fit and UNC coarse threads, providing secure fastening and easy installation in various materials.
• Flush mounting capability featuring an undercut flat head design that sits seamlessly in countersunk holes for a smooth surface finish.
• Wide industrial compliance meeting RoHS 3 and REACH regulations, making them suitable for global supply chains and sensitive applications.
• High tensile strength of 70,000 psi, offering robust mechanical performance for critical assemblies.
• Convenient drive system with Phillips No. 1 drive, enabling efficient installation with common tools.

Professional Applications & Engineering Value

These 4-40 UNC flat head screws are engineered to address critical sealing challenges in industrial settings. The combination of 18-8 stainless steel and a passivated finish provides exceptional resistance to corrosion, extending service life in moist or chemical-exposed environments. The integrated Buna-N rubber O-ring ensures reliable sealing against fluids and gases up to 1500 psi, making these screws ideal for hydraulic systems, pneumatic equipment, and machinery requiring pressure integrity. The undercut flat head design allows for a flush fit, reducing protrusion risks and improving aesthetics in assembled products. Fully threaded with coarse UNC threads, they offer quick installation and strong holding power in metals and plastics, streamlining maintenance and reducing downtime in manufacturing, automotive, and electronics applications.

Specification Summary & Compliance

This screw features a 4-40 UNC thread size with Class 2A thread fit for precise dimensional accuracy and reliable performance. It is fully threaded and includes a 100° countersink angle for proper head seating. The product complies with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and suitability for industrial use without hazardous substances.