How to read a mill test certificate.
A buyer-side guide to EN 10204 3.1 / MTC / MTR information for industrial fasteners, studs, nuts and project bolting.
Trace the material.
Then check the results.
The exact certificate layout varies by mill and manufacturer. The important point is that the product, heat/lot and reported test results can be tied back to the supplied material.
Training example — not a real material certificate
Heat: H26-1048 · Lot: L-72
Purchaser / PO / item
Confirm customer, PO, item description, size, quantity and any project reference match the order.
CHECK AGAINST PO / STANDARDProduct standard & grade
Look for the material / mechanical specification: for example ASTM A193 B7, ASTM A194 2H, ISO 898-1 Class 8.8, or the project-defined grade.
CHECK AGAINST PO / STANDARDHeat / melt / lot number
This is the traceability key. The physical product identification, packing label or batch record should link to the heat/lot shown on the certificate.
CHECK AGAINST PO / STANDARDChemical composition
Review reported C, Mn, P, S, Cr, Mo, Ni and other elements against the governing material specification and grade.
CHECK AGAINST PO / STANDARDMechanical properties
Check tensile strength, yield/proof strength, elongation, reduction of area, hardness and impact tests where the grade/service requires them.
CHECK AGAINST PO / STANDARDHeat treatment
For quenched-and-tempered grades, confirm the certificate states the applicable heat-treatment route and that results are for the certified heat/lot.
CHECK AGAINST PO / STANDARDDimensions / threads
Dimensional acceptance may be on a separate inspection report. Verify size, pitch/thread series, tolerance class and product standard where required.
CHECK AGAINST PO / STANDARDCoating / finish
HDG, zinc-flake, PTFE/Xylan-type or other finish may have a separate coating certificate. Check coating specification, thickness and lot link where required.
CHECK AGAINST PO / STANDARDInspection / test method
Confirm applicable test methods, third-party inspection references and any purchaser-specific hold/witness points.
CHECK AGAINST PO / STANDARDCertification & sign-off
A 3.1 certificate should identify the manufacturer and authorized inspection representative. Check date, certificate number and revision.
CHECK AGAINST PO / STANDARDCommon red flags
- Certificate grade does not match the PO or product marking.
- Heat/lot on the certificate cannot be tied to the supplied packing or item.
- Required mechanical or impact tests are missing.
- Values are reported without units, test method or acceptance reference.
- Coating certificate is present but not traceable to the fastener batch.
- Certificate has been edited, cropped or retyped without a controlled issuer reference.
MTC vs COC
A Certificate of Conformity normally declares that supplied goods conform to the stated order/specification. An MTC/MTR reports material or test results. They serve different purposes and one should not automatically be treated as a substitute for the other.
For a quotation, tell BIS the required certificate level and inspection documents at enquiry stage so the documentation route is included in the supply plan.