S-90403A845 5/16"-18 x 1" 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 maintains tight clamping force under dynamic loads
• Enhanced corrosion protection through zinc-plated steel construction for extended service life in harsh environments
• High tensile strength of 60,000 psi ensures reliable performance in demanding applications requiring heavy-duty fastening
• Quick installation and removal with Phillips No. 4 drive design that provides efficient torque transfer
• Secure thread engagement through Class 2A thread fit and UNC coarse threading for optimal assembly precision
• Rockwell B69 hardness rating delivers exceptional durability and resistance to deformation under stress
• Comprehensive regulatory compliance meets ASME B18.13 standards and environmental regulations for global acceptance

Professional Applications & Engineering Value

These zinc-plated steel rounded head screws with internal-tooth lock washers provide critical vibration-resistant fastening solutions for industrial equipment, machinery assembly, and automotive components. The UNC coarse thread configuration ensures rapid installation while maintaining Class 2A thread fit precision for consistent clamping force. The Phillips No. 4 drive offers practical torque application in confined spaces, while the integrated locking mechanism prevents loosening from operational vibrations. With 60,000 psi tensile strength and Rockwell B69 hardness, these fully threaded screws deliver reliable performance in high-stress applications where fastener failure is not an option, making them ideal for manufacturing, construction, and maintenance operations requiring dependable, long-term fastening solutions.

Specification Summary & Compliance

This 5/16"-18 x 1" rounded head screw features UNC coarse threading with Class 2A thread fit tolerance for precise engagement. Manufactured to ASME B18.13 specifications with fully threaded design and right-hand thread direction. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe use across global markets. The integrated internal-tooth lock washer (0.61" OD, 0.034" thickness) provides permanent vibration resistance without requiring additional components.