Mill test reports: what to collect, and how to match them to heat numbers
Short answer
A mill test report is the mill's certified record of what a specific heat of steel actually is: its chemistry, its mechanical properties, the specification it was produced to, and where it was melted and manufactured.
The file is only useful if each report ties to material that is physically on your job. That link is the heat number, and it has to be captured at receiving, not reconstructed months later from a pile of paperwork.
What the report actually contains
A usable report identifies the producing mill, the heat or lot number, the governing ASTM specification and grade, the chemical analysis, the mechanical test results, and on most work the country of melt and manufacture.
A packing list is not a mill test report. A supplier letter stating that material meets a specification is not a mill test report. Inspectors ask for the mill's own certified document.
Why heat number matching is the whole exercise
Steel is identified by heat. The report certifies a heat, and the material carries that heat identification. If the reports in your file do not correspond to the heats that showed up on the truck, you have a stack of paper that certifies someone else's steel.
This surfaces at the worst possible time. A special inspector on site asks for the cert covering a specific piece, and there is no clean answer because nobody recorded what arrived.
Collect at receiving, not at closeout
The cheapest moment to get a report is when the material arrives and the supplier still has an open transaction with you. Months later, at a different service center, with different staff, it is a favour.
- State the material test report requirement on the purchase order, not in a follow-up email.
- Capture heat numbers off the tags and the packing list at receiving.
- Reconcile reports against heats received while the delivery is fresh, and chase gaps immediately.
- Note shortages and damage at delivery, when the claim is still good.
Domestic material requirements
Where a contract carries domestic sourcing provisions, the melt-and-manufacture information on the report is the evidence. Requirements differ substantially between federally funded work and state or local public work, and between programs, so the governing requirement comes from the contract rather than from a general rule.
Verify it at order. Discovering at inspection that the material does not qualify is a replacement, not a paperwork problem.
Common questions
What is a mill test report?
A certified document from the producing mill recording the chemical composition, mechanical properties, governing ASTM specification, and heat or lot identification of a specific heat of steel. It is also called an MTR or a certified mill test report.
Why do mill test reports need to match heat numbers?
Steel is identified by heat number. A report certifies a specific heat, and the material carries that identification. If the reports on file do not correspond to the heats actually delivered, the documentation does not cover the steel installed on the job.
When should mill test reports be collected?
At receiving, with the material test report requirement stated on the purchase order. Collecting at closeout means chasing suppliers on a transaction they have already closed.
This is part of Material procurement. If you would rather not run it yourself, that is the scope it falls under.
Requirements come from the contract. The governing specification, the awarding agency, and the jurisdiction decide what applies on a given project. Confirm against the contract documents before relying on it.
Send one package and see what it costs.
Fixed price, quoted before anything starts. Nothing ongoing.