S-91997A223 1/4"-20 x 1/2" ASME B18.3 Sealing Tamper-Resistant Torx Stainless Steel Button Head Screws

Key Features & Benefits at a Glance

• Superior tamper resistance with T27 Torx drive to prevent unauthorized access in public or high-security environments.
• Reliable sealing performance using a Buna-N rubber O-ring that withstands pressures up to 1500 psi and temperatures from -40° to 225°F, preventing leaks in critical applications.
• Exceptional corrosion resistance from 18-8 Stainless Steel with passivated finish, ensuring long-term durability in harsh or outdoor conditions.
• High tensile strength of 70,000 psi for secure fastening under mechanical stress, reducing the risk of failure in demanding assemblies.
• Precise Class 3A thread fit with UNC coarse threading for easy installation and consistent engagement, minimizing cross-threading and rework.
• Low-profile rounded button head design that provides a smooth finish, reducing snagging and improving safety in compact spaces.
• Compliance with industry standards including ASME B18.3, RoHS 3, and REACH, ensuring material safety and interchangeability in regulated sectors.

Professional Applications & Engineering Value

This 1/4"-20 x 1/2" rounded head tamper-resistant Torx screw is engineered to address common industrial challenges such as fluid leakage, tampering, and environmental degradation. The combination of 18-8 Stainless Steel and a passivated finish offers robust resistance to rust and chemicals, making it ideal for outdoor machinery, marine equipment, or chemical processing plants. The integrated Buna-N rubber O-ring creates a dependable seal in high-pressure systems up to 1500 psi, commonly used in hydraulic assemblies, pneumatic controls, and fluid transfer systems. With its T27 tamper-resistant Torx drive, it secures enclosures in public infrastructure, transportation, or electronics where unauthorized access must be prevented. The Class 3A thread fit and UNC coarse thread ensure quick, reliable installation, reducing assembly time and maintenance costs in automated or manual production lines.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 3A precision fit for accurate threading and secure hold. It is manufactured in compliance with ASME B18.3 specifications for dimensional consistency and performance. The product is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, adhering to environmental and safety regulations for hazardous substance restrictions. Additional attributes include a maximum hole diameter of 0.265" and full threading for uniform load distribution.