A certified document from the steel mill or fastener maker listing heat number, chemical composition and mechanical test results for a lot of material. For fasteners, buyers also expect a lot test report or certificate of conformance tying the parts to the heat and to proof, hardness and coating tests. Without the paper, a critical fastener is just steel of unknown pedigree.
Customer won't take the flange studs without mill certs matching the heat numbers stamped on the ends.
Also heard as
- MTR
- material test report
- cert
Related terms
Head marking
The grade symbols and maker's mark stamped on a bolt head, the main clue to its strength once it leaves the box.
B7
The chromium-molybdenum alloy stud grade that is the default for pipe flange and pressure vessel bolting.
Head burst
A split on the edge of a cold-headed bolt head, caused by metal being stretched past its ductility.
Hardware-store grade
Dismissive term for unmarked, soft, zinc-plated bolts of unknown origin with no certified strength.