EN 10210/EN 10027 Nomenclature Explained

A lot of time our customers are searching for certain quality grades but do not understand or get confused by the name of the grade and their equivalent. To clarify some of it and to simplify by the same, the below information will be useful:
Steels produced to EN standards – for example pressure vessel steels such as P355 or structural steels S275 have names that tell you a lot about the steel without having to look the details up in the relevant standard. The way that they are named in set out in EN 10027/EN 10210 and by following a few simple rules you should soon be a master of know steel properties from the grade alone.
This page tells you about how to decipher these steel names for some common grade of pressure vessel and structural steels that we have in stock. Once you know how it works it is easy to use. Structural and pressure vessel steels have a standardised naming convention and this is laid out in /EN 10210 Designation System for Steels.
Whilst both are similar they are each subtly different and it is important to know what all the components of a steel name mean
The first letter S standards for Structural. P stands for Pressure and this is the way you initially tell the grades apart.
The next set of 3 digits gives the steel’s minimum yield strength. So S355 has a minimum yield strength of 355 MPa for the smallest thickness range covered by the relevant standard – i.e. EN10025.
These are the basics. You can then have up to 3 groups of characters providing more information.
The first group concerns the impact testing of the steel – what joule value (J, K or L) and at what temperature. (R,0,2,3,4,5,6)

  • J = 27J
  • K = 40J
  • L = 60J


  • R = 20 °C (Room Temperature)
  • 0 = 0 °C
  • 2 = -20 °C
  • 3 = -30 °C
  • 4 = -40 °C
  • 5 = -50 °C
  • 6 = -60 °C

An easy way of remembering the temperatures is that each increase in the digit means another 10 degrees below zero. At Trio Steel, we stock plates and hollow pipes in the below above grades. You can visit the below link for details:

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