S-91211A148 5/16"-18 x 2 1/2" 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
- Exceptional load-bearing capability with Grade 8 classification and 150,000 psi tensile strength for reliable performance in high-stress applications.
- Superior vibration resistance provided by the Nylon Patch thread locker, maintaining secure fastening from -55° to 250°F in dynamic environments.
- Enhanced corrosion protection through zinc yellow-chromate plating, extending service life in harsh industrial conditions.
- Optimized assembly efficiency with UNC coarse threading and Class 2A thread fit for quick installation and reduced cross-threading risks.
- Robust mechanical durability ensured by Rockwell C33 hardness and partial threading design for concentrated strength where needed.
- Secure torque transmission via the external hex drive and 1/2" head width, allowing for high tightening forces with standard tools.
- Industry-standard compliance with ASME B18.2.1 and SAE J429 specifications, guaranteeing interchangeability and reliability.
Professional Applications & Engineering Value
Engineered for demanding industrial applications, these Grade 8 hex head screws address critical challenges in machinery, construction, and automotive assemblies. The zinc yellow-chromate plated steel construction provides excellent resistance to corrosion, while the Nylon Patch thread locker ensures permanent fastening under extreme vibration and temperature fluctuations (-55° to 250°F). With UNC coarse threading and partial threading, these screws offer superior grip in softer materials and reduce weight without compromising the 150,000 psi tensile strength. Ideal for heavy-duty frames, equipment mounts, and structural connections, they deliver long-term reliability and minimize maintenance downtime in high-stress environments.
Specification Summary & Compliance
This fastener meets Class 2A thread fit tolerances for consistent engagement and is manufactured in accordance with ASME B18.2.1 and SAE J429 standards. It features UNC coarse threads (5/16"-18) with a minimum thread length of 7/8" and is compliant with RoHS and REACH environmental regulations, ensuring safe and sustainable use across global industrial sectors.
