Traceability is what lets the question “what covers this joint?” be answered in one step instead of a hunt through folders.
It runs both ways: forward, from a material certificate to every joint it went into; and backward, from a weld to the heat, the consumable, the welder’s qualification and the NDT report.
When any link is retyped rather than shared, that is exactly where the chain breaks — usually at the moment an auditor is looking.
Why it matters
If a heat is later found out of specification, traceability is the difference between recalling the specific joints that used it and re-examining the whole job.