What is EN 10204? The Mill Certificate Standard Explained

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Your customer’s purchase order says “3.1 certs required.” Your supplier sends a 2.2. Your despatch team doesn’t know the difference. The shipment gets held up, the customer is furious, and someone spends three hours on the phone to the mill.

This happens every day in metals distribution. And it happens because EN 10204 is one of those standards that everyone references and almost no one explains.

Here’s the plain-English version.

What is EN 10204?

EN 10204 is the European standard that defines the types of inspection documents — material test certificates — that metal producers and suppliers can issue to their customers.

It was published by the European Committee for Standardisation (CEN). In the UK, it’s adopted as BS EN 10204. The current edition is EN 10204:2004.

The standard doesn’t tell you what the steel has to be made of. That’s the job of product standards like EN 10025 (structural steel) or EN 10210 (hollow sections). EN 10204 tells you what document the manufacturer must provide to prove the metal meets that product standard.

Think of it as the framework for paperwork. It defines the chain of evidence.

The Four Certificate Types

EN 10204 defines four types of document. They’re numbered 2.1, 2.2, 3.1, and 3.2. The higher the number, the more rigorous the verification.

Type 2.1 — Declaration of Compliance

The simplest type. The manufacturer issues a written statement that the product meets the specified requirements.

No test results are included. No inspector signs off on your specific batch. It’s essentially a declaration on headed paper that says “yes, this meets the spec.”

When is it used? Very rarely in metals manufacturing. Acceptable only for non-critical, low-specification applications where no mechanical or chemical data is needed.

Type 2.2 — Test Report

A step up from 2.1. This document includes actual test results — chemical composition, mechanical properties — but the key point is that those tests were carried out on similar products, not necessarily your specific batch.

The test results come from the same production run, but they’re not tied to your exact heat number. The manufacturer’s representative issues the document based on non-specific inspection.

Where is it used? Some commodity material, lower-specification applications, and situations where the customer isn’t in a regulated supply chain. But be careful: if your customer specifies EN 10204 without naming a type, some will argue that 2.2 isn’t sufficient.

Type 3.1 — Inspection Certificate (Authorised by Manufacturer)

This is the workhorse of steel distribution. Most structural steel, engineering steel, and fabricated components require 3.1 as a minimum.

A 3.1 certificate is validated and signed by the manufacturer’s own authorised inspection representative — a person designated for that role, independent from the production department. The test results are specific to your batch, tied to the heat number on the certificate.

This is the document that travels with the steel through the supply chain. The heat number links the physical material to the certificate. The certificate links the material to its properties. That chain is what makes traceability possible.

Type 3.2 — Inspection Certificate (Authorised by Manufacturer and Independent Inspector)

The most rigorous type. Everything in a 3.1, plus a co-signature from an independent third-party inspector — someone not employed by the manufacturer.

Type 3.2 is required in highly regulated applications:

Nuclear power generation
Pressure vessels and pipework (PED compliance)
Offshore oil and gas
Some defence contracts
Certain aerospace applications

It’s more expensive. It takes longer to produce. Source it only when the application genuinely requires it. Specifying 3.2 unnecessarily drives up cost and lead time without any practical benefit.

Why EN 10204 Matters for Your Business

It’s a contractual requirement

When a customer specifies EN 10204 3.1 on a purchase order, they are making it a condition of the contract. Delivering material with a 2.2 certificate isn’t a minor paperwork issue — it’s a breach.

Worse, if the material ends up in a critical application and something goes wrong, the absence of the correct documentation exposes everyone in the supply chain to liability.

It’s an audit trigger

ISO 9001-accredited businesses are required to maintain documented evidence that materials meet specifications. EN 10204 certificates are a primary source of that evidence. Auditors ask for them. Customers ask for them during supplier assessments. If you can’t produce them, you fail the audit.

It drives operational chaos when certificates are missing

This is the practical day-to-day problem. Certificates arrive as PDFs. Some are scanned at angles. Some are in German. Someone downloads them into a shared folder called “certs” with no consistent naming. Then someone needs to find the cert for a specific heat number from three months ago and spends four hours searching.

Multiply that across hundreds of deliveries per month and you’ve got a significant operational overhead — and a compliance risk whenever something can’t be found.

Common Mistakes Metals Manufacturers Make

Assuming 2.2 is fine when 3.1 was specified. Read the purchase order. Every time.

Filing certificates separately from stock records. If the cert isn’t linked to the specific stock item, finding it later is a nightmare.

Not checking the cert before booking goods in. By the time you discover the cert is the wrong type, the material may already be in production.

Accepting faxed or photocopied certs. For Type 3.2 in regulated industries, the original signatures matter. Know what your customer actually needs.

Failing to archive certs for the retention period. In some industries, you need to retain certs for the life of the product. In construction, that can be 10–15 years.

How GoSmarter Automates EN 10204 Management

GoSmarter MillCert Reader reads mill certificates automatically — regardless of format, layout, or language — and extracts the key data: heat number, grade, EN 10204 type, chemical composition, mechanical properties, and supplier.

That data is stored against the right stock record. When you need to find a 3.1 cert for a specific heat number, it takes seconds, not hours.

The system flags when incoming certificates don’t match what the purchase order requires. If the PO specifies 3.1 and the cert is a 2.2, you know before the material goes into stock — not when your customer calls to complain.

FAQ

What's the difference between EN 10204 2.2 and 3.1?

A 2.2 test report contains test results from the production run, but those tests weren’t carried out on your specific batch. A 3.1 inspection certificate is validated by the manufacturer’s authorised inspector for your exact heat number. If your customer’s purchase order specifies 3.1, a 2.2 is not acceptable. Check the PO every time.

Is EN 10204 a legal requirement?

Not in itself — EN 10204 is a standard, not a law. But contractual requirements and industry regulations often make it mandatory. In construction, the Building Regulations and CE/UKCA marking requirements create an effective obligation to hold appropriate certificates. In regulated industries like nuclear and pressure vessels, the specific legislation may require 3.2 certification. The practical answer: if your customer specifies it, it’s mandatory for that contract.

Does EN 10204 apply to non-ferrous metals?

EN 10204 originated in the steel industry but is routinely applied to other metals — aluminium, copper, stainless steel, and alloys. The types (2.1 through 3.2) carry the same meaning. Some non-ferrous product standards may reference their own inspection document requirements, but EN 10204 is widely used across the metals industry regardless of material.

How long do I need to keep mill certificates?

This depends on your industry and the application of the material. For structural steelwork in construction, retention periods of 10–15 years are common, aligned with the life of the structure. ISO 9001 requires you to retain documented information for the period specified in your quality management system. In regulated industries, specific legislation may impose longer requirements. When in doubt, keep them longer than you think you need to.