Inspector checking a part against a drawing
Quality

What a 3.1 certificateshould tell you.

JKJohanna Kessler · 18 Aug 2026 · 2 min read
What a 3.1 certificate should tell you before you sign for the parts

An EN 10204 3.1 certificate is the one document that travels with every part we ship. It is also the one most often filed without being read. Here is what to check before you sign the delivery note.

1. The heat number matches the part

Every casting and forging we make is stamped with the heat it was poured from. The same number must appear on the certificate. If it doesn’t, the certificate belongs to a different melt, however good the values look.

2. Chemistry sits inside the grade, not just the tolerance

Check each element against the standard you ordered, not against the last certificate you received. Three things deserve a second look:

  • Carbon equivalent, if the part will be welded later
  • Residual elements such as copper and tin, which can hurt toughness
  • Hydrogen, for thick sections that will see cyclic loads

A certificate is only as good as the test piece behind it. Ask where it was cut, and when.

Aisha Rahman · Quality manager

3. Mechanical values come from the right test piece

A tensile bar cut from a separately cast coupon tells you about the coupon. For heavy sections, ask for integral test pieces or prolongations heat treated with the part, and check that the certificate says which one was used.

Coils of steel in a warehouse, each tagged with a heat number
Every coil, bar and casting in our warehouse carries its heat number on a tag and on the metal.

Five-minute checklist

  • Heat number on the part matches the certificate
  • Grade and standard match your order
  • Test piece type and location are stated
  • Heat treatment matches the delivery condition
  • Signed by someone independent of production

If any of these is missing, call us before the parts go into stock. It is far cheaper to fix paperwork at goods-in than at your customer’s audit.

Johanna Kessler
Johanna Kessler2 articles

Metallurgical engineer and second-generation owner of the works. Writes about quality, paperwork and why both matter on the shop floor.

3 comments

LB
Lars Bergström20 Aug 2026

The point about integral test pieces saved us an argument last year. Worth adding what to do when the drawing doesn’t specify one.

Reply
JK
Johanna Kessler21 Aug 2026

Good idea, Lars. Short answer: ask for it on the order. We’ll cover it in a follow-up.

Reply
MP
Marta Pereira23 Aug 2026

Printing the checklist for our goods-in team.

Reply

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