S-90550A820 5/16"-18 x 5/8" ASME B18.3, ASTM F879, MIL-DTL-18240 Venting Stainless Steel Hex-Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with 18-8 stainless steel construction, ideal for harsh industrial environments
• Enhanced torque transmission through hex drive design for secure, reliable fastening
• Precise thread engagement with Class 3A thread fit ensuring tight, vibration-resistant connections
• Optimized pressure equalization via vented feature preventing pressure buildup in critical assemblies
• Streamlined installation with 82° countersink angle allowing flush mounting in various materials
• Robust compliance meeting ASME B18.3, ASTM F879, and MIL-DTL-18240 specifications for quality assurance
• Environmental safety through RoHS 3 and REACH compliance for sustainable operations

Professional Applications & Engineering Value

This 5/16"-18 UNC flat head screw delivers exceptional engineering value for demanding industrial applications where corrosion resistance and mechanical reliability are paramount. The 18-8 stainless steel construction provides excellent durability against moisture, chemicals, and temperature variations, making it ideal for marine, chemical processing, and outdoor equipment. The hex drive design ensures maximum torque application without cam-out, while the fully threaded coarse UNC configuration offers rapid installation and superior holding power in metals, plastics, and composite materials. The vented feature addresses pressure differential issues in sealed assemblies, preventing fluid or air lock during fastening operations. With Class 3A thread fit precision, these screws maintain consistent clamping force in high-vibration environments common in machinery, transportation, and structural applications.

Specification Summary & Compliance

This flat head screw maintains Class 3A thread fit tolerance for precision threading applications with 5/16"-18 UNC coarse thread specification. Manufacturing complies with ASME B18.3, ASTM F879, and MIL-DTL-18240 standards ensuring dimensional accuracy and performance reliability. Environmental compliance includes RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming restriction of hazardous substances for workplace and environmental safety.