S-91211A131 1/4"-20 x 3" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Thread-Locking Hex Head Screws
High-Strength Grade 8 Steel Thread-Locking Hex Head Screws
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Basic Information
Head Parameters
Dimensions
Thread Parameters
Tip & Drive Parameters
Material & Strength
Temperature & Environment
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Key Features & Benefits at a Glance
- Vibration-resistant locking with nylon patch thread locker prevents loosening under dynamic loads, ensuring long-term joint integrity
- Exceptional tensile strength of 150,000 psi provides reliable performance in heavy-duty applications and high-stress environments
- Superior corrosion protection through zinc yellow-chromate plating extends service life in demanding industrial conditions
- Wide temperature tolerance from -55° to 250°F maintains locking performance across extreme operating environments
- Precision thread fit with Class 2A tolerance ensures smooth installation and consistent engagement with mating components
- High-strength Grade 8 rating with Rockwell C33 hardness delivers exceptional durability and load-bearing capacity
- Optimized partial threading provides maximum grip length while allowing for precise clamping force distribution
Professional Applications & Engineering Value
These Grade 8 hex head screws with nylon patch thread locking address critical vibration-induced loosening challenges in heavy machinery, construction equipment, and industrial assemblies. The zinc yellow-chromate plated steel construction provides superior corrosion resistance in harsh environments, while the UNC coarse thread design ensures rapid installation and reliable performance in structural applications. The combination of 150,000 psi tensile strength and Rockwell C33 hardness makes these external hex drive fasteners ideal for high-stress applications where joint integrity is paramount. The partially threaded design allows for optimal clamp load distribution, making them particularly valuable in automotive, manufacturing, and infrastructure projects requiring vibration-resistant fastening solutions.
Specification Summary & Compliance
Manufactured to precise Class 2A thread fit tolerances with UNC coarse thread specifications (1/4"-20). These hex head screws comply with ASME B18.2.1 standards and SAE J429 Grade 8 requirements, ensuring consistent quality and performance. The fasteners are REACH compliant (EC 1907/2006) and feature a nylon patch thread locker rated for temperatures from -55° to 250°F. The 3" length with 3/4" minimum thread length provides optimal engagement for various application requirements.
