S-95198A278 4-40 x 3/4" ASME B18.3, DIN 912, ISO 4762 Sealing Socket Head Screws

Key Features & Benefits at a Glance

• Superior sealing performance with integrated Buna-N rubber O-ring, effectively preventing leaks in high-pressure applications up to 1500 psi.
• Excellent corrosion resistance from 18-8 stainless steel construction, ensuring long-term reliability in harsh or humid industrial environments.
• Precise thread engagement with Class 3A fit, providing secure, vibration-resistant fastening and reducing the risk of loosening.
• High tensile strength of 100,000 psi and Rockwell B85 hardness, offering exceptional durability and load-bearing capacity for demanding applications.
• Wide temperature tolerance from -40° to 225°F, maintaining sealing integrity and mechanical performance across varied operating conditions.
• Hex socket drive design allows for easy installation and high torque application in confined spaces, minimizing assembly time.
• Full threading ensures consistent clamping force along the entire 3/4" length, ideal for components requiring uniform pressure distribution.

Professional Applications & Engineering Value

This 4-40 UNC thread socket head cap screw is engineered to address critical sealing and mechanical fastening challenges in industrial settings. The combination of 18-8 stainless steel and a Buna-N rubber O-ring provides a reliable seal against fluids and gases, making it ideal for hydraulic systems, pneumatic equipment, and machinery exposed to variable pressures. The coarse UNC thread and Class 3A fit ensure quick assembly and secure retention, reducing maintenance needs in vibration-prone applications like automotive assemblies, pump housings, and valve systems. Its hex drive socket head facilitates installation in tight spaces, enhancing efficiency while maintaining a high-strength connection that withstands operational stresses up to 1500 psi.

Specification Summary & Compliance

This screw features a 4-40 UNC coarse thread with Class 3A precision fit for accurate engagement, and is fully threaded for consistent performance. It complies with ASME B18.3, DIN 912, and ISO 4762 standards, ensuring dimensional accuracy and interchangeability. The product is also RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting environmental and safety regulations for industrial use.