Also called mill certificate, material test report, heat certificate, CMTR
What is a mill test report?
The mill’s certificate of what a batch of material actually is: chemistry, mechanical properties and heat number.
What else it is called
- Other names
- mill certificate, material test report, heat certificate, CMTR
- In French
- certificat de conformité matériau
Related entries
Understanding mill test report
A certificate issued by the producing mill for a specific heat or cast of material, stating its chemical composition and its mechanical test results - yield, tensile, elongation, and impact values where they are required. It is the document that lets you prove the steel in a finished weldment is the steel the drawing called for.
The heat number is the part that matters. It appears on the certificate, is marked on the plate or bar, and gets transferred onto the parts cut from it, which is how a finished assembly can be traced back to a melt years later. Plants lose this at the cutting table: an unmarked offcut returned to the rack is material with no provenance, and on certified work that means scrap.
The distinction between a mill certificate and a distributor’s certificate of conformance matters in Canadian structural and pressure work, where a buyer asking for a mill test report means the mill’s own document and will reject a transcription of it.
In practice
Transcribing values off these by hand is one of the better uses of document reading software in a plant - photograph the certificate, pull the chemistry and the heat number, check them against what the order required.
Frequently asked
How long do we have to keep mill test reports?
Longer than you expect, and the driver is the customer contract rather than a general rule. Pressure, nuclear, defence and structural work commonly require retention for the life of the asset. Absent a stated requirement, treat the longest of your customer agreements as the floor.
Is a certificate of conformance the same thing?
No. A certificate of conformance is a statement by a supplier that what they sent meets the order. A mill test report is the melting mill’s own test data for an identified heat. On certified work the two are not interchangeable, and substituting one is a common cause of rejected submittals.