S-91247A556 1/4"-20 x 3 1/2" ASME B18.2.1, SAE J429 Medium-Strength Grade 5 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional load-bearing capacity with 120,000 psi tensile strength for reliable performance in heavy-duty applications
• Superior corrosion resistance provided by zinc plating, extending service life in harsh industrial environments
• Optimized thread engagement through UNC coarse threading and Class 2A fit ensures secure fastening and vibration resistance
• Enhanced driving efficiency with external hex drive design allowing high torque application and easy installation
• Grade 5 strength certification guarantees consistent mechanical properties and Rockwell C25 hardness for durable performance
• Versatile partial threading design provides both threaded and unthreaded sections for flexible application requirements
• Regulatory compliance assurance meeting ASME B18.2.1, RoHS 3, and REACH standards for quality and environmental safety

Professional Applications & Engineering Value

These Grade 5 hex head screws deliver critical engineering value through their zinc plated steel construction and UNC coarse thread design, specifically engineered to address common industrial fastening challenges. The combination of 120,000 psi tensile strength and Rockwell C25 hardness ensures reliable performance in structural applications where vibration resistance and load capacity are paramount. The partially threaded configuration allows for both clamping force distribution and shear resistance, making these industrial screws ideal for construction equipment, machinery assembly, and structural frameworks. The external hex drive facilitates high-torque installation while the zinc plating provides essential corrosion protection in demanding environments, significantly reducing maintenance requirements and extending service intervals.

Specification Summary & Compliance

This fastener maintains precise Class 2A thread fit tolerances with 1/4"-20 UNC coarse threading and 3-1/2" length with 3/4" minimum thread length. Manufactured in compliance with ASME B18.2.1 specifications SAE J429, ensuring dimensional accuracy and mechanical performance. The product is certified RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant (01/17/2023 233 SVHC), meeting international environmental and safety standards for industrial applications.