S-91997A222 1/4"-20 x 3/8" ASME B18.3 Sealing Tamper-Resistant Torx Stainless Steel Button Head Screws

Key Features & Benefits at a Glance

• Tamper-resistant T27 drive prevents unauthorized access, enhancing security in public or controlled environments.
• Buna-N rubber O-ring seal provides reliable leak-proof performance up to 1500 psi, ideal for high-pressure fluid systems.
• 18-8 stainless steel with passivated finish offers superior corrosion resistance and durability in harsh industrial conditions.
• Class 3A thread fit ensures precise, secure fastening with minimal risk of loosening under vibration.
• Wide temperature tolerance (-40° to 225°F) maintains sealing integrity and mechanical strength in extreme environments.
• 70,000 psi tensile strength delivers high load-bearing capacity for demanding structural applications.
• ASME B18.3 compliance and RoHS/REACH adherence guarantees consistent quality and environmental safety standards.

Professional Applications & Engineering Value

This rounded head tamper-resistant Torx screw is engineered to address critical challenges in industrial assembly, where security, sealing, and corrosion resistance are paramount. The 18-8 stainless steel construction, combined with a passivated finish, resists oxidation and chemical exposure, extending service life in outdoor or corrosive settings. The integrated Buna-N rubber O-ring creates a robust seal against fluids and gases, making it ideal for high-pressure applications such as hydraulic systems, machinery enclosures, and plumbing fixtures. The T27 tamper-resistant drive deters vandalism and unauthorized disassembly in public infrastructure, transportation, or security equipment. With UNC coarse threads and Class 3A fit, it ensures quick installation and reliable hold in metal or composite materials, reducing maintenance downtime and enhancing operational safety.

Specification Summary & Compliance

This screw features a 1/4"-20 UNC coarse thread with Class 3A fit for high precision and strength. It is fully threaded for consistent engagement and manufactured in compliance with ASME B18.3 specifications. The product meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring it is free from hazardous substances. Dimensions include a head diameter of 0.437", length of 3/8", and is designed for a maximum hole diameter of 0.265".