Common MTC red flags and inconsistencies

A mill test certificate can look professional and still contain inconsistencies. MTC review should therefore be more than checking whether the grade name appears somewhere on the page.

The purpose of a first-pass audit is to confirm that the document tells a coherent story from manufacturer → heat → product → tests → acceptance.

1. Product identity does not match the order

Check:

• product form;
• dimensions;
• quantity/weight where shown;
• grade;
• product standard;
• delivery condition;
• heat/lot number.

A certificate for “S355J2” is not automatically acceptable when the PO says S355J2+N, S355J2H, S355MLO or another related but different designation.

2. Standard and grade combination looks impossible or unusual

A common red flag is a grade designation that does not belong to the cited product standard or edition.

Examples of questions to ask:

• Does this standard actually contain this grade?
• Was the grade valid in the edition shown?
• Is the product form covered by that standard?
• Is the delivery condition permitted?

Do not assume the certificate is wrong immediately — but investigate.

3. Heat number is missing or inconsistent

The MTC heat number should align with:

• material marking;
• tags;
• packing list where applicable;
• cut-piece traceability records.

If multiple heats are supplied under one certificate, make sure the test results are clearly associated with the correct inspection units.

4. Chemistry does not support the claimed grade

Review both the required chemistry limits and any derived values such as carbon equivalent where applicable.

Watch for:

• values outside limits;
• missing required alloying elements;
• calculated CEV/Pcm inconsistent with the reported chemistry;
• a dual-certified grade where the chemistry satisfies only one designation.

5. Mechanical results are inconsistent with thickness or condition

Yield-strength and Charpy requirements can vary with thickness and product standard. A result cannot be judged correctly without knowing the applicable thickness range and delivery condition.

Red flags include:

• yield/tensile values compared against the wrong thickness band;
• Charpy test temperature inconsistent with the ordered toughness class;
• missing test orientation;
• missing specimen size where sub-size specimens may have been used;
• results copied identically across unrelated heats without explanation.

6. Required supplementary tests are missing

Examples include:

• UT;
• Z25/Z35;
• hardness;
• PMI;
• grain size;
• CTOD;
• strain-age testing;
• sour-service testing.

The fact that the base grade is correct does not waive project-specific supplementary requirements.

7. Certificate type or signatures do not match the PO

If the PO requires EN 10204 3.2 but the document is a 3.1, that is a contractual gap even if all chemistry and mechanical properties pass.

See EN 10204 certificate types.

8. Manufacturer identity is unclear

Distinguish:

• original mill/manufacturer;
• stockholder or service centre;
• processor/cutter;
• trading company;
• inspection body.

A stockholder should not be presented as the original manufacturer merely because it reissued a document or supplied the material.

9. Altered, retyped or incomplete certificates

Be cautious when:

• pages are missing;
• logos/signatures look inconsistent;
• test tables appear retyped;
• the original manufacturer cannot be identified;
• the heat number is added manually without controlled traceability;
• an electronic validation method fails.

The response should be verification, not accusation: ask for the original document or confirmation from the issuing mill.

10. Dual certification is asserted without evidence

Dual certification can be legitimate when one heat/product satisfies the requirements of both designations. It is not legitimate merely to print two grade names on the certificate.

See Dual certification in steel: when it is legitimate.

A simple review sequence

1. Match PO → MTC identity.
2. Match MTC → physical marking/traceability.
3. Confirm standard/grade/edition/product-form compatibility.
4. Check chemistry.
5. Check tensile/impact results against the correct thickness and condition.
6. Check supplementary tests.
7. Check certificate type and validation.
8. Investigate anomalies before accepting the material.

Procurement takeaway

An MTC should be internally consistent and externally consistent with the PO and physical material. A single passing chemistry table is not enough. The strongest review is a structured compliance check that links every contractual requirement to explicit evidence on the certificate or associated inspection records.

References and verification sources

• EN 10204 inspection-document overview
• DNV — material manufacturer approval context