S-98164A521 1/4"-28 x 1/2" ASME B18.3, ASTM F879 Stainless Steel Button Head Hex-Drive Screws
Stainless Steel Button Head Hex-Drive Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Superior corrosion resistance with 316 Stainless Steel construction and passivated finish, ideal for harsh chemical and marine environments
- Exceptional thread precision with Class 3A fit and UNF fine threading ensures reliable, vibration-resistant connections in critical assemblies
- High mechanical strength offering 70,000 psi tensile strength and Rockwell B55 hardness for durable performance under heavy loads
- Secure, slip-resistant installation via 5/32" hex drive combined with a rounded button head design for flush, low-profile fastening
- Full thread engagement across the entire 1/2" length provides maximum grip and uniform stress distribution
- Compliance with industry standards including ASME B18.3, ensuring dimensional accuracy and interchangeability
- Environmental and regulatory safety with RoHS 3 and REACH compliance, suitable for regulated industries
Professional Applications & Engineering Value
Engineered for demanding industrial settings, these 1/4"-28 UNF rounded head screws deliver critical reliability where failure is not an option. The 316 Stainless Steel material, enhanced by a passivated finish, provides outstanding resistance to chlorides, acids, and oxidation, making them perfect for chemical processing, marine equipment, and food-grade machinery. The Class 3A thread fit and fine threading prevent loosening under vibration, a common issue in automotive and aerospace assemblies. With a hex drive and rounded button head, installation is straightforward and results in a smooth surface, reducing snag risks in moving parts. These screws are designed to maintain integrity in high-stress applications, from precision instruments to heavy-duty enclosures.
Specification Summary & Compliance
This screw adheres to ASME B18.3 dimensional standards with a Class 3A thread fit for precise, tight-tolerance assemblies. It features a UNF fine thread (1/4"-28) and is fully threaded for consistent performance. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), it meets environmental regulations, ensuring safe use across global markets.
