EN 10204 3.1 vs 3.2 — What's the Difference?

EN 10204 defines the types of inspection documents. Type 3.1 is issued by the mill's own quality department — the most common form. Type 3.2 is countersigned by an independent third-party inspector (e.g., DNV, TUV, SGS, LLOYDS) in addition to the mill. Critical applications like pressure vessels, boilers, and nuclear equipment typically require 3.2.

Heat Number / Cast Number

Every steel heat (batch) cast at the mill is assigned a unique heat number. This is the primary traceability identifier — it links the physical material to the MTC. Always cross-check that the heat number stamped or stencilled on the material matches the MTC.

Chemical Composition

The MTC lists the actual ladle analysis (chemical composition) of the heat. Compare these values against the applicable standard (e.g., ASTM A312 for SS seamless pipes). All elements — C, Mn, Si, P, S, Cr, Ni, Mo — must be within specification limits.

Mechanical Properties

Tensile strength, yield strength (0.2% proof stress), elongation and hardness (Brinell or Rockwell) are listed. These must meet or exceed the minimum values specified in the relevant ASTM, ASME, IS or EN standard for the grade and product form.

Product Dimensions

The MTC confirms the actual dimensions — outside diameter, wall thickness, length — of the supplied material. For pipes, this includes the schedule or wall thickness designation.

Test Performed

The MTC will list tests performed: hydrostatic, non-destructive examination (UT, RT, PT, MT), impact test (Charpy), intergranular corrosion test, etc. Ensure all tests required by your purchase order or project specification are present and passed.

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