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Frequently asked questions

Short, plain-language answers to the questions that come up most. Where an answer depends on a published value, confirm it against the standard before relying on it.

On SAE J429 inch fasteners they identify the grade: no marks is Grade 2, three radial lines is Grade 5, and six radial lines is Grade 8.

SAE J429 grades are the common commercial designations (Grade 2/5/8). ASTM specs like A449 and A354 define similar strength levels but under a structural standard, which is what many engineering prints and codes call out. A449 is roughly Grade 5-class; A354 Grade BD is roughly Grade 8-class.

Not exactly. A hex cap screw is held to tighter body and head tolerances and has a washer face under the head. The terms get used interchangeably in the field, but the dimensional standard treats them differently.

No. Higher grades are stronger but harder and less ductile. In joints that see fatigue, shock, or need some give, a higher grade isn't automatically better — match the grade to what the joint actually needs.

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