What Is “Unknown” Grade Hardware?

“Unknown” grade hardware refers to fasteners—such as bolts, studs, or nuts—that do not have identifiable markings or documentation to confirm their material grade or strength. In oil and gas and industrial settings, this typically happens when bolts arrive unmarked, come from unlabeled boxes, or lose their identification during handling and storage.

How It Happens

In many cases, technicians encounter unknown-grade hardware when supply chain controls fail or when leftover fasteners get mixed together. For example, bolts may arrive without head markings, packaging may lack certification labels, or storage bins may lose traceability information over time.