S-91205A583 5/16"-18 x 1" ASME B18.3, ASTM A574 Alloy Steel Thread-Locking Socket Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking: Integrated nylon patch thread locker prevents loosening under dynamic loads, maintaining clamp force in temperatures from -70° to 250°F.
• Exceptional strength-to-weight ratio: Alloy steel construction with 170,000 psi tensile strength handles extreme mechanical stresses without failure.
• Precision thread engagement: Class 3A UNC coarse threads ensure accurate, secure mating with components, reducing cross-threading risks.
• Corrosion-resistant surface: Black-oxide coating provides durable protection against rust and wear in harsh industrial environments.
• High-torque installation capability: Standard socket head with 1/4" hex drive allows for concentrated force application without stripping.
• Full thread coverage: 1" fully threaded design enables adjustable positioning and uniform load distribution along the entire fastener length.
• Industry-standard compliance: Manufactured to ASME B18.3 and ASTM A574 specifications for guaranteed interchangeability and performance.

Professional Applications & Engineering Value

Engineered for demanding assembly applications, these black-oxide alloy steel socket head cap screws deliver critical vibration resistance through their nylon patch thread locking technology. The Class 3A UNC coarse threads provide rapid installation in production environments while maintaining precise tolerances for high-strength joints. With Rockwell C37 hardness and 170,000 psi tensile strength, they prevent shear failure in heavy machinery, automotive subsystems, and industrial equipment subjected to cyclic loading. The combination of corrosion-resistant black-oxide finish and temperature-stable locking patch (-70° to 250°F) ensures long-term reliability in outdoor, chemical exposure, or thermal cycling applications where maintenance access is limited.

Specification Summary & Compliance

This 5/16"-18 x 1" socket head cap screw features precision Class 3A thread fit with UNC coarse threading and complete compliance with ASME B18.3 dimensional standards and ASTM A574 material specifications. The fastener meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring suitability for global industrial supply chains. Manufacturing controls maintain consistent 0.3125" thread diameter and fully threaded configuration for reliable performance in critical assemblies.