S-91211A124 1/4"-20 x 2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Thread-Locking Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capability with 150,000 psi tensile strength and Grade 8 classification, ensuring reliable performance in high-stress environments.
• Vibration-Resistant Locking via the integrated nylon patch, maintaining secure fastening across a wide temperature range from -55° to 250°F without loosening.
• Superior Corrosion Protection from zinc yellow-chromate plating, extending service life in harsh industrial conditions.
• Optimized Thread Engagement with UNC coarse threading and Class 2A fit, enabling quick assembly and reduced cross-threading risks.
• Enhanced Durability backed by Rockwell C33 hardness, providing excellent wear resistance and long-term fastener integrity.
• Secure External Hex Drive allows for high-torque installation using standard tools, ensuring tight connections in confined spaces.
• Versatile Partial Threading design offers flexibility for applications requiring both clamped and unthreaded shaft sections.

Professional Applications & Engineering Value

Engineered for demanding industrial settings, this Grade 8 hex head screw combines high-strength zinc yellow-chromate plated steel with a nylon patch thread locker to address critical vibration-induced loosening in machinery, automotive assemblies, and structural frameworks. The 1/4"-20 UNC coarse thread and partial threading facilitate rapid alignment and secure clamping in heavy-duty applications, minimizing downtime. Its external hex drive ensures compatibility with common wrenches, streamlining maintenance and installation processes while the robust 150,000 psi tensile strength withstands dynamic loads, making it ideal for construction, manufacturing, and equipment repair where reliability is paramount.

Specification Summary & Compliance

This fastener adheres to ASME B18.2.1 standards with a Class 2A thread fit for precise dimensional accuracy. It is manufactured to meet SAE J429 Grade 8 requirements and is REACH (EC 1907/2006) compliant, ensuring environmental and safety regulations are satisfied. The specifications include a right-hand UNC coarse thread, 2" length, and partial threading with a minimum thread length of 3/4", providing consistent performance and interoperability in regulated industries.