S-98070A137 4-40 x 1/4" Sealing Stainless Steel Phillips Flat Head Screws

Key Features & Benefits at a Glance

• Reliable Sealing Performance: Integrated Buna-N rubber O-ring creates a dependable seal, preventing leaks in applications with pressures up to 1500 psi.
• Superior Corrosion Resistance: Constructed from 18-8 Stainless Steel with a passivated finish, offering excellent protection against rust and degradation in harsh environments.
• High Tensile Strength: With a tensile strength of 70,000 psi, this screw ensures a secure and durable fastening solution for demanding applications.
• Wide Temperature Tolerance: The Buna-N O-ring maintains its sealing integrity across a broad temperature range from -40° to 225° F.
• Precision Thread Fit: Features a Class 2A UNC coarse thread for easy installation and a reliable, consistent fit.
• Flush, Secure Installation: The undercut flat head design allows the screw to sit flush with the surface, providing a clean finish and improved performance.
• Compliant for Global Use: Meets RoHS 3 and REACH regulations, ensuring the screw is suitable for various international industrial markets.

Professional Applications & Engineering Value

This 4-40 UNC Flat Head Phillips Screw is engineered to solve critical sealing challenges in industrial assemblies. The combination of 18-8 Stainless Steel and a passivated finish provides robust corrosion resistance, making it ideal for use in moist or chemically aggressive environments. The integrated Buna-N rubber O-ring is the key to its sealing capability, effectively containing fluids and gases in systems operating up to 1500 psi. Its undercut flat head profile ensures a flush mount, which is crucial in applications where protrusions are not permissible. Commonly used in pneumatic systems, fluid power components, and electronic enclosures, this screw delivers reliable performance where pressure integrity and environmental sealing are paramount.

Specification Summary & Compliance

This screw adheres to the UNC coarse thread standard with a precision Class 2A thread fit for consistent assembly. The threading is fully threaded for maximum grip. It is manufactured to be RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, confirming its suitability for regulated industrial applications. The specified countersink angle is 100° for proper head seating.