SAE J429 Grade 5 Hex Bolts ASME B18.2.1

SAE Grade 5 hex bolts, also known as Grade 5 hex head bolts, are inch-series externally threaded fasteners specified to SAE J429 for mechanical and material requirements, with dimensional requirements covered by ASME B18.2.1. Their six-sided heads accept standard wrenches or sockets, while the threaded shanks accommodate the fastening requirements of different joint configurations.

The Grade 5 designation identifies a specific mechanical property grade. These bolts are marked with three radial lines on the head for visual grade identification. Minimum tensile strength depends on nominal diameter: 120 ksi for sizes from 1/4 inch through 1 inch, and 105 ksi for sizes over 1 inch through 1-1/2 inches. This distinction matters when verifying specifications for larger diameters.

Grade 5 hex bolts are used in machinery, vehicle equipment, agricultural machinery, maintenance assemblies, and general mechanical applications where inch-series fasteners are specified. They should not be confused with hex cap screws, which are a separate product type covered by ASME B18.2.1 and have different dimensional tolerances.

Selection requires confirmation of nominal diameter, UNC or UNF thread series, bolt length, thread length, and compatibility with the mating nut or tapped component. SAE J429 and ASME B18.2.1 serve different purposes: the former establishes mechanical and material requirements, while the latter defines dimensional requirements.