Material certificate 3.1 for EN 1090: checking on arrival

A material certificate 3.1 is the inspection certificate that the steel manufacturer supplies with a batch of steel. It states the chemical composition and the mechanical properties of that batch. An inspector who is independent of production has checked it. Under EN 1090, it is the proof that the steel you bought meets your order. The FPC procedure for incoming inspection uses it.

Which certificates you need depends on the steel grade and the execution class of your project. The technical requirements themselves are in EN 1090-2. According to Bouwen met Staal (Building with Steel) , a notified body assesses your FPC system. Incoming inspection of materials is part of that.

Short answer: a 3.1 certificate is the inspection proof from the steel manufacturer, checked by an inspector who does not work in production. You check that the certificate matches the order and the batch.

What does a 3.1 certificate contain?

A 3.1 certificate is issued per batch, or per heat. It refers to the order and to the standard that the material meets. It is not a general product specification.

This is a fictional example of the points you check:

Field	Example (fictional)	Check
Certificate type	3.1	Does it state type 3.1, according to EN 10204?
Steel grade	S355J2	Matches the order and the drawing
Heat number or batch number	Heat 4471-A	Appears on the material itself
Chemical composition	Per element, in percentages	Within the limits of the standard
Mechanical properties	Yield strength, tensile strength, impact value	Match the steel grade
Order details	Order number and customer	Matches your purchase order
Validation	Name and function of the inspector	Independent of production

The 3.1 certificate must belong to the material. Steel that you cannot link to a certificate is a weak point in audit practice. You check which requirement the standard sets per class in EN 1090-2.

Why 3.1 and not an ordinary delivery note?

A delivery note or an invoice says that you received steel. A 3.1 certificate says that the steel was checked and that the values were recorded and can be measured. That is the difference. For structural steel, a delivery note is generally not enough as traceable proof of the material properties.

The standard for these certificates is EN 10204. It defines the types of inspection documents. For 3.1, the mark is validation by an independent inspector of the manufacturer. Other types, such as 2.2, lack that independent validation.

A certificate marked 3.1.B uses the designation from the edition of EN 10204 before 2004. Since then, this type is called 3.1. When you place a new order, ask for type 3.1, and if in doubt, have the manufacturer confirm the validation.

Incoming inspection in five steps

Incoming inspection is the procedure in which you check the 3.1 certificate before the material enters the workshop. Below is the order we recommend in the example procedure overview of the FPC system.

Compare the certificate and the order

Steel grade, dimensions and quantity must match. The standard stated on the certificate must also be the standard stated in the order.

Link the batch number to the material

The heat number or batch number must appear on the material itself, for example as a stamp or label. Without that link, the certificate is not usable.

Check that the values fall within the standard

Compare the chemical composition and the mechanical properties with the limits for the steel grade. A value just outside the limit means rejection or extra testing.

Sign off the certificate

Add a signature, date and name to the certificate or to your register. This is the proof that you carried out the check.

File the certificate with the project

Keep the certificate in the project file. At the audit, the auditor wants to see per project which steel was used.

What does the auditor want to see?

The auditor picks a project and asks you to follow the flow of material: from the certificate to the material, and from the material to the welded or assembled part. They want to see that incoming inspection was carried out and that the records are correct.

They pay particular attention to:

Whether the 3.1 certificate is present for the steel grade in the project.
Whether the batch number can be linked to the material.
Whether the incoming inspection is signed and dated.
Whether no material was used without a certificate.

Common mistakes

Certificate without a link to the material. A perfect certificate in a drawer, with no batch number on the plate, is useless in practice.

Delivery note used as a certificate. A delivery note is not a 3.1 certificate. Get the certificate before the material is used.

Copy instead of original. If you use a copy, you must show that it matches the original. Ask the supplier for the original document or a digital version with validation.

Wrong steel grade. A plate of S355 with a certificate for S235 is a deviation, even if the values happen to fit. The steel grade must match.

Frequently asked questions about the 3.1 certificate

Do I need a 3.1 certificate for every piece of steel?

Not per piece, but per batch or heat. Which requirements apply depends on the steel grade and the execution class. Check the requirements in EN 1090-2 and ask your notified body if you are not sure.

May I make a 3.1 certificate myself?

No. The certificate comes from the steel manufacturer and is validated by that manufacturer’s inspector. You may check it, but not issue it.

What if the supplier cannot deliver 3.1?

Then you cannot use that material for projects that require 3.1. Find a supplier who does supply it, or ask the designer whether another material is possible.

How long must I keep the certificate?

Plan for at least ten years. Under Article 11 of the Construction Products Regulation (Bouwproductenverordening) , the manufacturer keeps the technical documentation and the declaration of performance for ten years after placing the product on the market. Agreements with your client may require a longer period.