When purchased steel plates come with a set of inspection documents. These are commonly known as mill certificates or mill test certificates ) MTC. In order for purchasers to be sure of the quality of the steel that they bought, for engineering and quality assurance purposes as well as commercial ones there are detailed requirements about what the certificates are like and what can be included on them. European standard EN10204 defines what the various types of certificate are and what they mean.
BS EN 10204 is the standard for inspection documents for steel (and other) products. The certificates produced according to EN10204 enable suppliers to demonstrate that legal and regulatory requirements relating to chemical and mechanical properties of the steel have been met
Certification of steel plates rolled in Europe is generally to EN 10204. The actual certificate will depend on the plate offered but will either be 3.1 or 3.2. A 3.1 or 3.2 MTC means that the actual plate or heat sold will have been tested and a Mill Test Certificate (MTC) will accompany the plate.
Summary of EN10204 Inspection Documents
Document Validated By
|EN10204 2.1||Declaration of Compliance with the Order||Statement of compliance with the order||The Mill|
|EN10204 2.2||Test Report||Statement of compliance with the order, with indication of results of non specifics inspection||The Mill|
|EN10204 3.1||Inspection Certificate 3.1||Statement of compliance with the order, with indication of results of specific inspection||The Mill's authorised inspection representative who is independent of the manufacturing department|
|EN10204 3.2||Inspection Certificate 3.2||Statement of compliance with the order, with indication of results of specific inspection||The mill's authorised inspection representative who is independent of the manufacturing department and either the purchasers authorised inspection representative or the inspector designated by official regulations|
EN10204 2.1 Certification
EN10204 2.1 certification is the lowest level of certification to EN10204. In this the manufacturer, or mill, simply declares that he has produced the steel plates to the purchasers specification or order requirements. No evidence in the form of test results is included in the certificate. Likewise it is acceptable for the person in charge of manufacture to issue the certificate.
EN10204 2.2 Certification
EN10204 2.2 Certification is again issued by the steel mill. In this case the mill states that the steel meets the requirements of the customer’s specification or order and test results are included in the certificate to demonstrate that this is the case. There is no separation between the QA department who issue the certificate and the manufacturing department so with a 2.2 certificate it is possible that cases of conflict of interest could arise.
It is also worth noting that the test results may not actually reflect the products that are supplied. What this means is that manufacturer could have a sampling process for their QA system that tested 1% of plates. They then deliver test certificates for this 1% of plates with the order – but the plates actually supplied are never tested. You consequently rely on the strength of the mill’s QA system to be producing a homogenous product with little variability.
EN10204 3.1 Certification
EN10204 3.2 certification requires the mill to do several important things. First it has to produce test results for the plates being bought. So the test results on the certificate are for the actual plates purchased and describe accurately (to the limits of the sampling techniques used to do the test) the actual plates purchased
Secondly it requires the test department to be formally independent of the manufacturing department. This means that the manufacturing department doesn’t do the tests and has no power to alter, amend or influence the test results. As a result, when combined with a quality system such as EN9001:2010, the EN10204 3.1 certificate has significantly more authority than a 2.1 or 2.2 certificate. This is because the steel plates are tested and certified by a person independent of the one who made them
EN10204 3.2 Certification
This is the most rigorous certification level available for steel plates. Like EN 10204 3.1 the test results of the actual plates being purchased are included on the Mill test certificate. The mill’s test department, again independent of the manufacturing department, has to validate the test results. However the purchaser, or the government’s representative have also to validate the test results as well.
What this means is that there is a person who is completely independent of the mill inspecting the test results and ensuring that that reflect the underlying physical and chemical characteristics of the steel plates. Being totally independent he is able to resist and pressure to collude in altering the results and misrepresent the product being sold.
In practice the major classification societies normally acts as the independent third party validation authorities. This may be because they have been appointed by the mill, or because a purchaser requires plates to be approved by a particular classification society; such as Lloyds, TUV or DNV.
EN 10204 3.1 Certification
3.1 is a certificate issued by the mill which declares that the plates are in compliance with the specification and includes the test results.
Test results are validated by the mill’s in–house test department which has to be independent of the manufacturing department.
EN 10204 3.2 Certification
EN 10204 3.2 Certification is more rigorous and the certificate is prepared jointly by the mill’s inspection department and an independent 3rd party inspectors such as TUV or Lloyds Register. The certificate states that the plates are compliant with the relevant specification and the mill test certificate is included.
What does the Independent 3rd Party do Verify a EN 10204 3.2 Certificate
The surveyor, as they are known, will visit the steel mill and then identify the material that he (or she) has to verify. This includes visual inspection of the steel plates, checking the dimensions of some on a sampling basis and confirming that the steel plate can be traced all the way back to the ladle chemical analysis. This is usually done by using the mill’s EN 10204 3.1 certificate that has already been produced.
The key fact here is to establish that the plate has some marking on it that corresponds to the the test certificate which in turn has a documentation trail back to the analysis taking where the steel was being made. The marking on the plate needs to be permanent – ie stamped, etched or stencilled onto the plate. Paint, chalk and grease marks are not acceptable as they could easily be wiped off and replaced.
The 3.1 certificate is also checked to determine that the characteristics recorded on it comply with all the requirements of the standard and a;so for its chemical composition, heat treatment and any NDE testing. The surveyor then identifies the test sample from the plate or heat being tested and then visits the test centre whilst the test is being done.
As part of this they will consider not only the test results but also the test process and the calibration of the test machinery to ensure that the est results are reliable.
Once this is done and everything is in compliance the surveyor then returns to the steel mill and signs and stamps the en 10204 3.2 test certificate and ensures that the product being verified is stamped.
EN 10204 originally started off as DIN 50049 which was a German DIN standard specifying the test certificate requirements for metallic products. When CEN started the process of harmonising European standards in the late eighties it was decided that the German standard fitted the new requirements best (in part because of the heavier influence of manufacturing in Germany and the rapid rise of the concept of Total Quality Management which led to ISO9001). As a result the new European standard in 1991 drew significantly on the German certificate names and definitions.
With broader use and acceptance of test certificates there was pressure to clarify some of the issues and in 2004 the standard was reissued with the list of certificates available reduced and simplified.
Previous Versions of EN10204
In the EN10204:1991 (now withdrawn)
- 2.3 no longer exists
- 3.1B is now replaced by 3.1
- 3.1A is replaced by 3.2
- 3.1C is replaced by 3.2
Cost Implications of EN10204 Certification
As the level of certification the cost of the plates also increases. There are two reasons for this. Firstly there is an economic benefit to certifying better steel plates to a higher level. Secondly there are significant costs associated with establishment of test facilities, operational independence and the fees that third party inspectors charge for validation. Normally this costs are spread over millions of tonnes of steel and thus only have a small impact on a per plate basis. However where plates are upgraded at a later date from a EN10204 3.1 to 3.2 MTC then the costs are applied over a small number of plates.
Pressure Vessel Steel and EN10204
Steel plates used in pressure vessels need to comply with the Pressure Equipment Directive 97/23/EC. Specially according to Annex I section 4.3 they need to have a certificate of specific product control. In annex ZA of EN10204 this is specifically addressed and EN10204 certificates meet that requirement.
Buying Steel from Steel Stockholders and EN10204
In many cases you may not buy steel directly from the mill. In these cases you won’t always receive an original certificate. This is acceptable so long as you receive a copy and it is clear that the copy can be traced back to the original certificate and that the original document can be produced on request.
What this means in practice is that the original purchaser of the steel plates produces a “Certified True Copy” of the certificate and keeps the original in their records department. The person who has bought the steel then does the same thing and this repeats until the steel is kept by the eventual end users. Thus there should always be a clear audit trail to establish the origin and provenance of the steel plate
Remarking of Plates to EN10204
Plates always have a set of mill markings on them to enable them to be tracked and matched with the appropriate certificate. This is normally done through the aid of heat and plate numbers. However the plate markings only appear on one part of the plate. When a plate is cut or profiled this will leave one part of the pate without any mill markings and thus potentially untraceable. If this is the case it is not possible to claim that the plate meets a 3.1 or 3.2 MTC etc. To resolve this issue most stockholders have the authority to remark plates (based on their quality system and specific authorisation of a 3rd party inspector) to EN10204 3.2
Upgrading EN 10204 3.1 Certificates to EN 10204 3.2
A classification society can be appointed to upgrade 3.1 plates at a stockist to EN 10204-3.2. He does this by reviewing the 3.1 certificate and then visually inspecting the plate to ensure that it meets the dimensions of the certificate. He’ll also ensure that the heat or other markings on the plate enable the plate to be traced back to the chemical analysis in the ladle.
Once this is done the surveyor will also check the certificate to confirm compliance of
- chemical analysis
- mechanical properties
- bend tests
- through thickness
- Heat treatment
- Plate Condition
- NDT testing such as UT
The plate also needs to be retested so a test specimen will be cut and sent to a test facility where the testing will be witnesses by the surveyor. If all is acceptable a certificate will be issued by the classification society that st states that the material has been inspected to the intent of EN 10204 3.2 supported by the original 3.1 mill certificate and the lab test report. The phrasing here is important as what the classification society is not a true 3.2 mill certificate but one that fulfills the intent of the standard. In most cases this is sufficient but there will be the rare case where this is not acceptable and mill tested 3.2 plate will have to be purchased instead.
The surveyor will issue a certificate of conformance that details the scope of inspection with EN 10204 3.2 or the intent of EN 10204 3.2 as appropriate.
Application of EN10204 Steel Plates
Generally the level of EN10204 certification for steel plates increases with the consequences of them failing under load. So for example many boiler plates are certified to EN10204 3.2 because consequences of failure of a vessel containing an explosive or toxic substance at high pressure could be catastrophic. The EN10204 certificate however doesn’t assure that the plate won’t fail though. What it does is it provides confidence to everyone in the supply chain that the plate meets the required standards and that this has been independently verified by at least two parties in the case of a 3.2 certificate. the mills test department and the 3rd party validation authority.
For many applications it is the role of the engineering authority to make the decision as to what level of certification is required if not already specified in a purchase order or by national or international regulations or laws.
Purchase of EN10204
You can buy a copy of the latest version of EN10204 from the BSI Shop
EN10204 3.1 and 3.2 Steel Plates Ex-Stock
We stock almost 40,000 tonnes of steel plates certified to EN10204 3.1 and 3.2. We don’t stock anything to 2.1 or 2.2. Our range of stock cover boiler plates, structural steel plates, plates with high tensile strength, steel plates for offshore application and high strength steel plates for shipbuilding. We also have some wear resistant steel plates for mining and construction use.