What are production standards and what are they for?
An overview of the standards of steel pipes should begin with an explanation of the term attestation (or certification as it is sometimes called). Attestation is an inspection ending, as the name suggests, with an approval. However, this is the case only when the product is attested to be in compliance with the requirements specified in the relevant standards. We can therefore say that standards are documents used in the attestation process. They contain the detailed requirements for the quality of steel pipes, and certification is the process of verifying the material being attested with the requirements specified in the standards. The attestation process is divided into three stages:
• the determination of the type of test – on the basis of the EN 102404, EN 10021 standards;
• the determination of the type of inspection document – on the basis of the ISO 10474, EN 10204 standards; and
• the selection of tests to be performed – on the basis of the technical delivery conditions (TDC) for particular types of pipes.
The EN 1024:1991 standard distinguishes between two categories of inspections and various related inspection documents. These are specific and non-specific inspections. The difference between them is that the specific inspections, apart from the mandatory inspections specified in the standard, also include other, selected inspections, and the pipe samples must come from the appropriate delivery consignment. These inspections end with the issuance of a so-called acceptance certificate or special approval, if the manufacturer does not have its own quality control department independent of the production department. On the other hand, non-specific inspections only include the mandatory inspections specified in the corresponding standard, and the samples do not necessarily have to come from the appropriate delivery consignment. The result of non-specific inspections is the issuance of a certificate, i.e. a confirmation from the manufacturer.
Steel pipe standards also define the following groups of inspections to which products may be subjected:
• dimension inspection;
• chemical composition of steel inspection;
• technological tests – for example flaring, flattening, expanding, bending, ring testing;
• mechanical property tests – tensile strength, impact test;
• tightness tests – non-destructive methods, hydrostatic pressure;
• non-destructive tests – transverse and longitudinal defects, duality tests; and
• other tests – for example corrosion resistance, metallography, etc.
See also: Classification of steel grades for the production of steel pipes.
What standards are used in the production of steel pipes?
The European Union has introduced many standards for steel pipes that define the quality requirements of products and the methods of verification of this quality. European standards are marked “EN”, and a large number of them are Polish standards with the status of “euronorms”, designated as “PN-EN”. European standards for steel tubes define quality requirements for specific groups of products. There are three groups:
• pipes intended for construction purposes;
• pipes intended for pressure applications; and
• pipes intended for parts of equipment or for mechanical applications.
European standards for steel pipes set detailed quality requirements. For example, if required by the standard, the product is subjected to an impact test. Sampling and impact testing should be performed in accordance with EN 10045-1, which specifies, that the samples should be made transversely, and if this is not possible, as longitudinal samples, but as wide as possible. On the other hand, the tightness tests are carried out in accordance with the requirements specified in the EN 10246-1 standard. This permits the pipe tightness to be checked using two methods: a hydraulic test and an equivalent eddy current test.
See also: Classification of steel grades for the production of steel pipes
A number of Polish standards for steel pipes have also been developed, which are used in the product certification process. The most popular of them include:
• PN-EN 10204 – Metal products. Types of inspection documents;
• PN-EN 10208-1 – Steel service pipes for flammable media. Pipes with class A requirements;
• PN-EN 10208-2 – Steel service pipes for flammable media. Pipes with class B requirement;
• PN-EN 10216-2 – Pipes for pressure purposes. Unalloyed and alloy steel pipes with specified elevated temperature properties;
• PN-EN 10216-1 – Steel pipes for pressure equipment. Unalloyed steel pipes with required properties at room temperature;
• PN-EN 10216-3 – Pipes for pressure purposes. Alloy fine grain steel pipes; and
• PN-EN 10210-2 – Seamless steel tubes for pressure purposes. Technical delivery conditions.
For products supplied to the Russian market, Russian steel pipe standards such as GOST, STN, and ČSN are used in the certification process.
To conclude, there is no doubt that thanks to the standards developed for steel pipes, it is possible to maintain greater control over the quality of products and objectivity in assessing this quality. Raising the level of quality is constantly achieved by the ongoing modification of current standards and the introduction of new ones.
If you are interested in the standards of the products offered by FERGES, please see our offer or contact the sales department!
