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Blog·6 min read·

The 5 MTC Discrepancies Fabricators Find at Delivery — And How to Reject or Resolve Each One

Material arrives. The truck pulls out. The receiving team checks the packing list against the delivery: heat 44821, Grade A572-50, 12 plates. Everything matches. The cert arrives by email the same afternoon. The quality tech opens it: heat 44821, Grade A36.

One of these is wrong. The question is which one — and what you do next.

Incoming cert discrepancies are a routine part of metals receiving. The shops that handle them well have a defined process for each type. The shops that handle them poorly create delays, documentation gaps, and occasionally put non-conforming material into production. This guide covers the five most common discrepancies and the specific resolution path for each.

Discrepancy 1: Heat Number Mismatch (Cert Heat ≠ Tag Heat)

What it looks like: The heat number printed on the material tag (from the mill's rolling/marking process) doesn't match the heat number on the cert.

Common causes: Mill reprint errors (the mill issues a replacement cert with a corrected heat number but ships the original tag), transposition errors in manual entry at the mill, or the wrong cert pulled from the mill's document system.

Resolution path:

  1. Place the material on hold immediately. Do not receive it into stock.
  2. Contact the supplier with both the tag heat number and the cert heat number.
  3. Request written confirmation of which number is correct and documentation supporting that confirmation (mill's internal record, corrected cert, or re-test documentation).
  4. Do not accept the material until the discrepancy is resolved in writing.

What not to do: Do not accept the material "pending cert correction" and move it to stock. Once it's in stock, the hold tag disappears and the unresolved discrepancy gets buried.

Discrepancy 2: Grade Mismatch (Cert Grade ≠ PO Grade)

What it looks like: The cert documents a different grade than what was ordered. Your PO specified A572-50; the cert says A36. Or the cert says A36 Fy = 50 ksi with no grade designation matching the PO.

Common causes: Supplier shipped wrong grade material; supplier pulled wrong cert for the correct heat; or a higher-strength grade is being offered as a substitution without prior approval.

Resolution path:

  1. Hold the material.
  2. Contact the supplier in writing (email creates the documentation trail).
  3. If the supplier claims the material is the correct grade and the cert is the wrong document, request a corrected cert from the original mill — not a re-typed document from the supplier.
  4. If the supplier confirms the wrong grade was shipped, initiate return and replacement.
  5. If the supplier proposes a grade substitution (e.g., A572-50 for A36 because it's "better"), document this and obtain written approval from your engineering team before accepting — a "better" substitution may not be appropriate for the application.

What not to do: Do not accept a supplier-generated Certificate of Conformance as a substitute for the mill test cert when the discrepancy is the grade designation. The CoC doesn't prove what the material actually tested to.

Discrepancy 3: Property Out of Spec (Cert Value Outside ASTM Limit or PO Supplementary Requirement)

What it looks like: A measured value on the cert — yield strength, tensile strength, elongation, chemistry element — falls outside the limits specified by the ASTM standard or by a supplementary requirement in your PO.

Common causes: Marginal heat where properties are at the edge of the acceptable range; wrong ASTM standard applied at the mill; incorrect supplementary requirement communicated at PO time.

Resolution path:

  1. Open a formal NCR with the specific out-of-spec value and the applicable limit.
  2. Place the material on hold.
  3. Contact the supplier with the NCR documentation.
  4. Options for resolution: supplier requests re-test from the mill (if the original test result is questionable); supplier initiates a formal deviation request with the mill; engineering review of whether the out-of-spec value is acceptable for the specific application (with written approval and documentation in the job file).
  5. Do not use the material until one of these paths is completed and documented.

What not to do: Do not proceed to fabrication with out-of-spec material under the assumption that it will "probably be fine." The deviation must be documented before use.

Discrepancy 4: Missing Supplementary Requirements (Cert Doesn't Document Required S-Requirements)

What it looks like: Your PO specified supplementary requirements — S5 (Charpy impact testing), S17 (heat analysis), S1 (normalized condition), or others defined in the applicable ASTM standard. The cert doesn't show results for the required supplementary test.

Common causes: PO didn't clearly communicate the supplementary requirement; supplier's standard cert template doesn't include supplementary test fields; mill didn't perform the test because it wasn't explicitly ordered.

Resolution path:

  1. Confirm whether the supplementary test was explicitly included in your PO language. If it was implicit but not written, this is a procurement process gap as well as a supplier gap.
  2. If it was written in the PO, contact the supplier with the specific PO language and request documentation of the supplementary test.
  3. If the mill didn't test to the supplementary requirement, the options are: new testing from the original heat (if samples are retained), replacement material with the required testing, or engineering assessment of whether the application can proceed without the supplementary data — with written documentation.
  4. If the material has already entered fabrication before this gap was caught, the assessment path is the only option. Document everything.

Discrepancy 5: Document Type Mismatch (Received 3.1 When 3.2 Was Required)

What it looks like: Your PO required an EN 10204 Type 3.2 certificate (witnessed by an accredited third-party inspector). You received a 3.1 certificate (witnessed by the mill's own authorized inspector).

Common causes: PO didn't specify the cert type clearly; supplier defaulted to 3.1 as standard; customer didn't communicate the EN 10204 requirement to the supplier.

Resolution path:

  1. You cannot convert a 3.1 to a 3.2 — the distinction is who witnessed the testing, and that witness cannot be added retroactively.
  2. Contact the supplier and request that they obtain a 3.2 cert from the original mill, which requires a third-party inspection body to witness or review and countersign the test results.
  3. If the material has already shipped and the lead time for 3.2 certification is problematic, contact the customer to discuss — some projects allow documented concession requests for 3.1 in lieu of 3.2 under specific conditions.
  4. Do not present the 3.1 cert as meeting a 3.2 requirement. The auditor will know the difference.

Across all five discrepancy types, the consistent guidance is the same: document every discrepancy in a log, even the ones resolved quickly. Auditors will ask for the trail. A clean record of how discrepancies were identified, what the resolution path was, and who approved the final disposition is the evidence that your incoming inspection process is functional — not just that the certs are filed.

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