S-90403A846 5/16"-18 x 1 1/2" ASME B18.13 Steel Pan Head Phillips Screws with Internal-Tooth Lock Washer

Key Features & Benefits at a Glance

• Superior vibration resistance with integrated internal-tooth lock washer that prevents loosening under dynamic loads
• Enhanced corrosion protection through zinc-plated steel construction for extended service life in harsh environments
• Optimized drive engagement with Phillips No. 4 drive for efficient installation and reduced cam-out risk
• Maximum thread engagement through full threading along the 1-1/2" length for superior holding power
• Reliable performance under stress with 60,000 psi tensile strength and Rockwell B69 hardness rating
• Industry-standard compatibility with 5/16"-18 UNC coarse threads meeting Class 2A fit requirements
• Secure regulatory compliance meeting ASME B18.13 specifications and environmental standards including RoHS 3 and REACH

Professional Applications & Engineering Value

These zinc-plated steel screws with internal-tooth lock washers provide critical vibration resistance in demanding applications where secure fastening is paramount. The 5/16"-18 UNC coarse thread configuration ensures rapid installation and reliable performance in construction, industrial machinery, and heavy equipment assemblies. The combination of 60,000 psi tensile strength and Rockwell B69 hardness delivers exceptional durability against shear forces and mechanical stress. The Phillips pan head design with integrated washer creates a flush mounting surface while the zinc plating offers corrosion protection for outdoor or high-moisture environments. These fully threaded screws maintain consistent clamping force across the entire engagement length, making them ideal for applications requiring maximum thread contact and vibration dampening in structural connections and mechanical assemblies.

Specification Summary & Compliance

This 5/16"-18 x 1-1/2" screw features precision UNC coarse threads with Class 2A fit tolerance for consistent engagement and assembly efficiency. Manufactured to ASME B18.13 specifications with complete compliance to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards. The fastener system includes an integrated internal-tooth lock washer (0.61" OD, 0.034" thickness) manufactured from zinc-plated steel, ensuring uniform quality and performance across all components.