S-91286A131 1/4"-20 x 4" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 150,000 psi ensures reliable performance under extreme loads, preventing fastener failure in critical applications.
• Superior corrosion resistance from the zinc-flake coating extends service life, reducing maintenance and replacement costs in harsh environments.
• High hardness (Rockwell C33) provides excellent wear resistance, maintaining thread integrity and drive features through repeated use.
• Coarse UNC threading allows for quicker installation and better performance in materials where fine threads might strip or cross-thread.
• Partial threading design offers optimal clamping force distribution, ideal for applications requiring precise grip length and vibration resistance.
• External hex drive enables high torque application with standard tools, ensuring secure fastening and easy maintenance.
• Compliance with major standards including ASME B18.2.1 and SAE J429 guarantees consistent quality and interchangeability in industrial assemblies.

Professional Applications & Engineering Value

Engineered for demanding environments, this Grade 8 hex head screw combines high-strength steel construction with a zinc-flake coating to address common industrial challenges like vibration loosening and corrosive wear. The 1/4"-20 UNC coarse thread ensures rapid assembly in soft materials or where debris accumulation is a concern, while the partial threading provides superior clamp load control in structural applications. Ideal for heavy machinery, automotive frames, and construction equipment, this fastener delivers reliable performance where tensile strength and corrosion resistance are critical to operational safety and longevity.

Specification Summary & Compliance

This 4" hex head screw features precise Class 2A thread fit and UNC coarse threading per ASME B18.2.1 specifications. Manufactured to meet SAE J429 Grade 8 requirements, it ensures consistent dimensional accuracy and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and regulatory adherence for global industrial use.