S-91286A442 5/8"-18 x 2 1/2" ASME B18.2.1, SAE J429 High-Strength Grade 8 Steel Hex Head Screws
High-Strength Grade 8 Steel 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 capacity with 150,000 psi tensile strength and Grade 8 classification, ideal for high-stress industrial assemblies.
- Superior corrosion resistance from the zinc-flake coating, extending service life in harsh or outdoor environments.
- Reliable fine-thread engagement with 5/8"-18 UNF threads and Class 2A fit, ensuring vibration resistance and secure fastening.
- Optimized for high-torque applications featuring an external hex drive and hex head design for easy installation with standard tools.
- Enhanced durability backed by Rockwell C33 hardness, providing excellent wear resistance and reduced risk of stripping.
- Versatile partial threading allowing for unthreaded shank sections to bear shear loads effectively in structural connections.
- Compliance with major industry standards including ASME B18.2.1 and SAE J429, guaranteeing consistent quality and performance.
Professional Applications & Engineering Value
This Grade 8 steel hex head screw is engineered to address critical challenges in heavy machinery, construction, and automotive sectors where high tensile strength and corrosion resistance are paramount. The zinc-flake coating provides a robust barrier against moisture and chemicals, reducing maintenance needs in aggressive environments. With its 5/8"-18 UNF fine thread and Class 2A thread fit, it ensures precise, vibration-resistant connections in dynamic load applications. The partially threaded design allows the unthreaded portion to act as a dowel, resisting shear forces and improving joint integrity. These features make it a reliable choice for bolting flanges, structural frames, and equipment requiring long-term durability and compliance with rigorous industrial standards.
Specification Summary & Compliance
This screw adheres to Class 2A thread tolerance for consistent fit and is manufactured per UNF thread standards. It meets ASME B18.2.1 and SAE J429 specifications, ensuring dimensional accuracy and mechanical properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting safe and sustainable industrial use.
