How to Read a Mill Test Report (MTR)

The most important document in a shipping file is the material certificate. It is usually filed and forgotten, yet checking a few lines prevents problems in the field.

What the document contains

• Manufacturer and order data: maker, order number, product description
• Standard: material standard (such as ASTM A105) and dimensional standard (such as ASME B16.5)
• Heat number: must match the stamp on the part
• Chemical analysis: carbon, manganese, sulphur, phosphorus and alloying elements
• Mechanical values: yield, tensile, elongation, hardness and Charpy impact results where required
• Heat treatment: normalising, quench and temper or solution annealing record
• Inspection: dimensional and visual inspection, and NDT where required
• Approval: the maker's quality department signature, plus an independent inspector on 3.2 documents

Lines worth checking

1. Does the heat number match? The stamp on the part and the number on the document must agree. 2. Are the standard and grade correct? If the order was A350 LF2 and the document says A105, the part is not fit for low temperature service. 3. Is the carbon equivalent within limits? This matters on parts that will be welded. 4. Is hardness within the sour service limit? Critical on work under NACE MR0175. 5. Is impact testing reported? Low temperature service needs the test temperature and energy values on the document. 6. Is there a heat treatment record? Inspection looks for this on heavy wall, high class parts.

3.1 versus 3.2

A 3.1 certificate carries the approval of the manufacturer's own quality department. A 3.2 document adds an independent inspection body or customer representative. 3.2 usually extends lead time, so the required level must be clear at the order stage.

What belongs in the document file

Material certificate, packing list, dimensional inspection report, PMI report where requested and NDT records. This file is defined at order stage, not on site.

Stating the certificate level on your enquiry makes price and lead time right the first time: enquiry form.

FAQ

Is an MTR the same as a declaration of conformity?
No. A declaration states compliance with a standard, while an MTR contains actual test results and the heat number.

What if the heat number does not match?
The document does not belong to that part, and it is rejected on projects requiring traceability.

Does a PMI report replace the certificate?
No. PMI only confirms alloy composition; mechanical values and heat treatment records come from the certificate.