S-91257A742 1/2"-13 x 9" 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 in the most demanding heavy-duty applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the zinc yellow-chromate plating extends service life, even in harsh or outdoor industrial environments.
• High hardness rating (Rockwell C33) provides excellent wear resistance and maintains thread integrity under high stress and vibration.
• Coarse UNC threads and Class 2A thread fit enable faster, easier installation and a secure hold in a wide range of materials.
• External hex drive design allows for high torque application with standard tools, ensuring tight and efficient fastening.
• Partial threading offers an unthreaded shank for added shear strength, ideal for applications where precise clamping is critical.
• Compliance with major standards including ASME B18.2.1 guarantees consistent quality, dimensional accuracy, and interchangeability.

Professional Applications & Engineering Value

This Grade 8 hex head screw is engineered to solve critical challenges in heavy machinery, construction, and structural assemblies where failure is not an option. The steel material and Grade 8 classification deliver a robust combination of 150,000 psi tensile strength and Rockwell C33 hardness, preventing stripping and deformation under extreme loads. The zinc yellow-chromate finish provides a durable barrier against rust and corrosion, making it suitable for outdoor or chemically aggressive environments. With its 1/2"-13 UNC coarse thread and partial threading, it ensures rapid installation and superior resistance to vibrational loosening, reducing maintenance needs and enhancing the longevity of your equipment and structures.

Specification Summary & Compliance

This fastener adheres to precise dimensional and performance criteria, including a Class 2A thread fit for consistent assembly and a 9" length with a minimum thread length of 1 1/2". It conforms to ASME B18.2.1 and SAE J429 specifications, ensuring reliability and interchangeability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free of hazardous substances and safe for use in regulated markets.