S-91355A085 5/16"-18 x 1/2" ASME B18.3, ASTM F835 Steel Flanged Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional corrosion resistance with black-oxide coating, extending service life in harsh industrial environments
• High tensile strength of 120,000 psi ensures reliable performance under heavy loads and vibration
• Precision Class 3A thread fit provides superior engagement and reduces cross-threading risks
• Flanged button head design eliminates need for separate washers while distributing clamp force evenly
• Hex drive compatibility allows for high-torque installation with standard 3/16" tools
• Coarse UNC threading enables faster assembly and better performance in softer materials
• Full threading along 1/2" length offers maximum adjustability and holding power

Professional Applications & Engineering Value

Engineered for demanding industrial applications, this black-oxide alloy steel screw combines Rockwell C39 hardness with 120,000 psi tensile strength to withstand extreme mechanical stress. The flanged rounded head design provides superior bearing surface without requiring additional washers, while the coarse UNC threading ensures rapid installation in machinery, structural frameworks, and heavy equipment. The hex drive system delivers secure torque transmission during assembly, preventing tool slippage in high-vibration environments. Ideal for automotive assemblies, construction equipment, and manufacturing systems where Class 3A thread precision and corrosion resistance are critical for long-term reliability.

Specification Summary & Compliance

Manufactured to ASME B18.3 specifications with Class 3A thread fit for precision engagement. Features 5/16"-18 UNC coarse threads and 1/2" fully threaded length with 0.688" flange diameter. Fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global industrial markets.