SAE J429 Grade 2 Hex Bolts ASME B18.2.1

SAE J429 Grade 2 hex bolts, also called SAE Grade 2 hex-head bolts, are inch-series steel fasteners used to form bolted joints where the Grade 2 strength level is appropriate. Their six-sided heads allow tightening with a wrench or socket, while the threaded shank engages a matching nut or tapped hole.

The two standards serve different purposes: SAE J429 specifies material and mechanical requirements for externally threaded fasteners, while ASME B18.2.1 defines dimensional requirements for inch-series hex bolts, including head and body dimensions and thread-length provisions. Compliance with one does not replace compliance with the other.

Grade 2 bolts are a lower-strength option within the SAE J429 grade system. They are commonly used in general equipment, maintenance, machinery and automotive-related assemblies where the design does not call for a higher-strength fastener. The specified mechanical properties vary by nominal diameter, and the Grade 2 requirements for smaller diameters are subject to bolt-length limits. Confirm diameter, length, thread series and required strength against the applicable standard and joint design before selection.

Grade 2 bolts do not use the radial grade lines found on higher-strength SAE J429 grades; a manufacturer identification mark may still appear on the head.