S-91670A720 1/2"-13 x 2" ASTM A574 Left-Hand Threaded Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 PSI ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in critical applications.
• Left-hand thread design provides secure fastening in applications where right-hand rotation could cause loosening, ideal for specific machinery and rotating equipment.
• Black-oxide coating on alloy steel offers superior corrosion resistance and a durable, non-reflective finish for extended service life in harsh environments.
• Class 3A thread fit delivers precise, tight tolerances for superior engagement and vibration resistance, minimizing the need for re-tightening.
• 3/8" hex drive socket head allows for high-torque installation with standard tools, facilitating quick and secure assembly in confined spaces.
• Full compliance with ASTM A574, RoHS 3, and REACH ensures material consistency, environmental safety, and suitability for regulated industrial sectors.
• Coarse UNC threading enables faster installation and better performance in materials where fine threads might strip or fail.

Professional Applications & Engineering Value

This left-hand thread socket head cap screw is engineered to address specific industrial challenges where reverse-threading is essential to prevent unintentional loosening due to rotational forces. Constructed from black-oxide alloy steel, it combines high Rockwell C37 hardness with a 170,000 PSI tensile strength, making it ideal for heavy-duty machinery, automotive assemblies, and high-vibration equipment. The UNC coarse thread and Class 3A fit ensure secure fastening in softer materials or applications requiring rapid assembly, while the hex socket drive allows for efficient torque application in space-constrained environments. Its robust design and compliant standards make it a reliable choice for engineers seeking durability and performance in demanding industrial fastening scenarios.

Specification Summary & Compliance

This screw adheres to precise dimensional standards, including Class 3A thread fit for tight tolerances and UNC coarse threading with a 1/2"-13 thread size. It meets ASTM A574 specifications for alloy steel socket head cap screws, ensuring material and manufacturing consistency. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its suitability for use in environments with strict environmental and safety requirements.