S-91997A225 1/4"-20 x 3/4" ASME B18.3 Sealing Tamper-Resistant Torx Stainless Steel Button 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 thanks to 18-8 Stainless Steel construction and passivated finish, ensuring long-term reliability in harsh environments.
• Enhanced tamper resistance with Torx T27 drive, providing added security against unauthorized access while allowing for high torque application.
• Precise thread engagement with Class 3A UNC coarse threads, delivering superior holding power and vibration resistance in demanding assemblies.
• Wide temperature compatibility from -40° to 225°F, maintaining seal integrity and mechanical properties across extreme operating conditions.
• Optimized head design with rounded button profile, offering a clean aesthetic while minimizing snagging in tight spaces.
• Full regulatory compliance with ASME B18.3 standards and environmental regulations including RoHS 3 and REACH.

Professional Applications & Engineering Value

This rounded head Torx sealing screw delivers exceptional engineering value in applications where fluid containment and environmental protection are critical. The combination of 18-8 Stainless Steel material with passivated finish provides outstanding corrosion resistance, while the integrated Buna-N rubber O-ring creates a reliable seal against moisture, gases, and contaminants. The tamper-resistant Torx T27 drive ensures security in public-access equipment while allowing for higher torque transmission compared to standard drives. With Class 3A thread fit and UNC coarse threading, this fastener maintains precise engagement in vibration-prone assemblies, making it ideal for industrial machinery, fluid handling systems, outdoor enclosures, and automotive applications where both security and sealing performance are paramount.

Specification Summary & Compliance

This 1/4"-20 x 3/4" rounded head screw features Class 3A thread fit with UNC coarse threading and full threading along the entire shank length. The fastener meets ASME B18.3 specifications for dimensional accuracy and is manufactured from 18-8 Stainless Steel with Rockwell B70 hardness and 70,000 psi tensile strength. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations ensures safe use across various industries and applications.